AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| Week 9 - MIDI and Recording |
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Lots again for this week guys.
Best of luck and any probs get in touch.
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
3. Why is it convenient to DI a synthesizer?
4. Comment on the stereo output of many synthesizers?
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
6. Comment on the use of loops in recording.
7. Comment on tape loops.
8. Comment on looping using a sampler and sequencer.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
11. Comment on the suitability of audio sequencers for sample looping.
12. What is timecode?
13. Comment on LTC, VITC and MTC.
14. Comment on MIDI Clock.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
17. Why is it desirable to synchronize a sequencer to multitrack tape?
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
19. What is an audio sequencer?
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
21. Comment on the suitability of an audio sequencer for sample and loop editing?
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
23. What parameters of effects can often be controlled via MIDI?
24. Why would you want to control effects parameters by MIDI?
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
26. Does MTC contain an address?
27. Does MTC contain a clock?
28. Is MTC useful for synchronizing a MIDI sequencer?
29. Is MTC useful for synchronizing digital audio?
30. Is MTC useful for synchronizing analogue audio?
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
32. Why is it a problem to use hard disks for long term storage?
33. Onto what media does backup/archival storage take place?
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders?
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
37. List the common digital multitrack tape formats and describe their characteristics.
38. What is 'formatting'?
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack?
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
41. Who carries out routine maintenance?
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
44. What are the effects of neglecting cleaning?
45. Why must an analogue machine be periodically demagnetised?
46. What happens if a machine is never demagnetised?
47. What might happen if the demagnetised is operated incorrectly?
48. Why do analogue tape recorders need to be lined up?
49. Do digital recorders ever need to be lined up?
50. Comment on the three elements of line up.
51. Explain the need for monitoring in sync.
52. Why is the sync signal inferior to the playback signal?
53. Why does this matter in track bouncing?
54. Is it possible to edit 2" analogue tape?
55. Is it possible to synchronise two 24-track recorders?
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface?
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a 24-track tape recorder?
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations?
61. What information is stored in the session file?
62. Are session files usually transportable between different systems?
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
64. What is 'fragmentation'?
65. Comment on archiving to CD-ROM.
66. What are 'virtual tracks'?
67. What is meant by 'edit density'? What are the implications of high edit density?
68. Does the editing and trimming of regions delete audio data from the disk?
69. In editing, what is the difference between 'slip' and 'grid' modes?
70. When might it not be possible to create a crossfade?
71. What is 'bouncing', in the context of mixing?
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing?
_________________
It's all in the ears. - Learn the concepts not the software.
Audio Courses is a way into the music business for you
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Mon Oct 27, 2003 2:08 pm |
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mommi
Joined: 21 Apr 2003
Posts: 47
Location: Tallinn, Estonia |
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And who has got ideas about audio sequencers?
Waitin' for that also 
I must confess -- I misused the repetition found here. My answers to some questions I remember to have been covered in the past are just exact copies of what I wrote in the past 
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
A record is put on a turntable, which drives the record into motion. A stylus – needle - is held by a cartridge. It’s tip is inserted into the groove of a record and mechanical movements of a stylus (corresponding to the recorded material) get transformed into AC electrical signal in the cartridge by means of electromagnetic phenomena. The cartridge itself is being held by a pickup arm. The pickup arm allows to put the cartridge/stylus at the appropriate place on a record and follows the groove as the record is turning. Mixing consoles are called Mixers by DJs, and are typically designed to conveniently crossfade between any pair of inputs on opposite sides of a mixer – the mixer is split into two sets of inputs with a cross fader in between.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
http://www.hut.fi/Misc/Electronics/circuits/phono.html
http://www.sweetwater.com/insync/word.php
First, the cartridges have low output level, 2 to 5 millivolts for moving magnet or 1.5 to 2.0 millivolts for moving coil as opposed to hundreds of millivolts required for line level input. Also the output of moving magnet (the most common type) cartridges is designed to be fed into 47 kohms or higher impedance. This means microphone inputs cannot be used either, as these provide an input impedance of around 2 kohms.
Second, signals are applied pre-emphasis EQ before cutting them to the disk. This EQ diminishes low and enhances high frequencies relative to a 1kHz reference point, so as to avoid too large movements of the cutting stylus. During playback, de-emphasis process (called RIAA equalization) is required to get an overall flat frequency responce.
So a phono preamplifier should be used to match the impedances, amplify and EQ the output from a cartridge.
3. Why is it convenient to DI a synthesizer?
You don’t need to send the output from a synth into an amplifier and loudspeaker just to use a microphone to get the synth sound in. This way the sound is not being coloured by the amp/speaker/room/mike system.
4. Comment on the stereo output of many synthesizers?
Modern synthesizers not only have stereo outs but also have assignable outs as well. An audio signal can be sent to any one of up to 8 individual outputs.
On the other hand, I happen to remember having read that the stereo outs often provide just two identical signals, ie no stereo at all. Could it be so 
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
Either you are after the colour an amp/cabinet system provides or you want to capture the room / ambience sound.
6. Comment on the use of loops in recording.
By using loops you can get along with less resources, both human and machine. E.g. record a drum sample and create a loop from it – no need to have a musician playing the same material all the time. Takes less time and media space. If the material gets too boring, use several different samples or have a musician playing on top of the loop.
7. Comment on tape loops.
Tape loops are made by cutting the tape to an appropriate length and glueing (taping) it’s ends together so it forms a continuous „circle“. The tape machine must be modified for playing back the loop, because you cannot utilise the supply and takeup reels.
8. Comment on looping using a sampler and sequencer.
It is easier to use a sampler and sequencer for looping. A sample (loopable music fragment) is recorded in the sampler and assigned to a note on a specific MIDI channel. A sequencer is used to trigger the sample periodically.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
Looping in the sampler can be a subject to timing drift. There is always a difference between samplers and sequencers in how exactly they deal with time. Given there can be say a 0.5 % difference between the nominal and real tempi, you arrive at 1 beat misplace error after 200 beats. When retriggering the sample each time from the sequencer, you rely on a single clock, and the 0.5 % difference is not an issue during a single bar or two.
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
A sequencer is a recording device just like a multitrack. It just records the performance information, not sounds. Another device (a synth, a sound module or sampler) is used for actual sound production together with the sequencer. This means there is no need to devote tape tracks to these sounds, as they are already „recorded“ elsewhere. The only necessity is to be able to play the devices in sync, so their outputs can be mixed together in a console.
11. Comment on the suitability of audio sequencers for sample looping.
If audio sequencers are what I think them to be, then you can store audio data (samples) on them along with MIDI. If so, it could be quite convenient to retrigger these samples as you would do with a combination MIDI sequencer / sampler.
12. What is timecode?
Timecode is organisational data (signal) used to run different devices in sync with each other.
13. Comment on LTC, VITC and MTC.
LTC – SMPTE Longitudinal Time Code – uses modulated audio signal to represent binary data, and LTC is recorded into an audio track. Longitudinal means it is usually recorded along the length of a tape. LTC can only be read while the tape is moving relative to the tape head.
VITC – Vertical Interval Time Code – is an alternative type of timecode, inserted into the vertical sync period of the video frame signal. So VITC is part of a video signal. VITC can be read even while the video tape is paused.
MTC – Midi Time Code – is a standard that incorporates SMPTE timing information (hours, minutes, seconds, frames) into MIDI, so a sequencer can be synchronised to an absolute timing reference.
14. Comment on MIDI Clock.
MIDI Clock provides a means for relative timing reference. Timing Clock message is sent 24 times per quarter note.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
The units can be run in sync this way, one of them acting as a master and another as a slave. The slave gets information from the master such as where and when to start playback (Song Pointer and Continue messages) and what the tempo is (Timing Clock message).
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
They are fundamentally different approaches. MTC is an absolute reference (hours, minutes, seconds, frames), while MIDI Clock is related to the tempo (quarter note). Song Position Pointer is literally a counter indicating the number of MIDI Timing Clock messages that would have elapsed since the beginning of a song.
17. Why is it desirable to synchronize a sequencer to multitrack tape?
The benefits are the same as for other forms of synchronising. The sequencer will follow the multitrack, start playback together with it at exactly the same position of a song. It can be imagined as if you had just more tracks on your multitrack.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
For synchronizing purposes, a track (by convention a track with the highest number available) on the multitrack machine should be striped with SMPTE LTC timecode. The signal from the timecode track should then be routed to the sequencer’s external sync input. It is advisable to set a Start Time around 30 seconds (00:00:30:00) or so on the sequencer, meaning the sequencer will begin playback 30 seconds from the start of the tape. Now whenever the tape is played, the sequencer will stay in sync with it.
19. What is an audio sequencer?
It is a device for recording, editing, storing and replying MIDI sequences and audio data. Is it
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
Really don’t know. What duration the samples can be there? If their duration is limited to a bar or so, then it cannot replace a multitrack recorder. If there is no limitation, then seems it can be a replacement.
21. Comment on the suitability of an audio sequencer for sample and loop editing?
For some reasons an audio sequencer looks for me somewhat as a combination of a MIDI sequencer and a sampler. If it is, then editing the audio samples should be normal on them
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
Is there any difference from a MIDI sequencer?
23. What parameters of effects can often be controlled via MIDI?
I suppose most readily bypass on/off and effect type, though other parameters shouldn‘t technically present a problem either.
24. Why would you want to control effects parameters by MIDI?
When used with a sequencer, the effects can be programmed to follow the program material this way.
Otherwise, MIDI can be used for remotely controlling the effects equipment, so you can select different effects just by means of whatever MIDI control you’ve got.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
Yes. From
http://www.borg.com/~jglatt/tech/mtc.htm
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The first (of eight) Quarter Frame message contains the low nibble (ie, bits 0 to 3) of the Frame Time. The second Quarter Frame message contains the high nibble (ie, bits 4 to 7) of the Frame Time. The third and fourth messages contain the low and high nibbles of the Seconds Time. The fifth and sixth messages contain the low and high nibbles of the Minutes Time. The seventh and eighth messages contain the low and high nibbles of the Hours Time. The eighth message also contains the SMPTE frames-per-second Type (ie, 24, 25, 30 drop, or 30 fps).
26. Does MTC contain an address?
If to interprete absolute time as an address, then yes. Otherwise, no. Maybe I just don’t understand the question.
27. Does MTC contain a clock?
Yes.
28. Is MTC useful for synchronizing a MIDI sequencer?
Yes.
29. Is MTC useful for synchronizing digital audio?
Yes.
30. Is MTC useful for synchronizing analogue audio?
Probably yes.
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
Standalone recorders are self-contained recording equipment that need no other devices for recording and editing (except for microphones etc of course).
Computer based systems use standard computer industry hardware and OS-s, to where additional hardware and software is installed.
32. Why is it a problem to use hard disks for long term storage?
Hard disks are not very robust, as they contain precision mechanics. They also are sensitive to magnetic fields. And yet another reason – hard disk formats change quite rapidly, there is no reason to assume you are going to find a place where to read your precious data after, say, ten years.
33. Onto what media does backup/archival storage take place?
Preferably some kind of optical: CD, DVD. Also Zip, Jazz, Exabyte.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
Copy / paste / delete and other operations are non-destructive, just a matter of menu choices on hard disk recorders. Better yet, hard disk recorders can offer at least some kind of visual representation. Plus you can benefit from Undo function on them.
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders?
Standalone hard disk recorders are purpose made for recording and as such, they are generally more robust and less prone to crashing than computers. Computers are built to perform many different tasks, and usually their parts come from several different manufactures. So quality and reliability are usually not as readily guaranteed as with standalone recorders.
On a standalone recorder, you need special units to use effects, while on a computer based recorder a wide variety of software can be used for effects.
Standalone recorders can be simpler to use, computers offer greater visual feedback.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
If you are after analogue sound, using a multitrack tape for recording is your choice. Transferring the material from multitrack to Pro Tools adds the benefits of powerful digital editing to the warm sound of analogue.
37. List the common digital multitrack tape formats and describe their characteristics.
http://www.audiomasterclass.com/units/body/12ltdigitalrecording.html
DASH (Digital Audio Stationery Head). 1/4” (6.3 mm) and 1/2” (12.55 mm) tape, either Normal Density or Double Density. Depending on the sampling frequency required, the tapes can be run under different speeds. Sony 3324 allows 24 tracks of digital audio on a 1/2” normal density tape plus two analog cue tracks, a timecode track and a control track. The same tape can be used for 48 digital tracks on Sony 3348.
MDM (Modular Digital Multitrack) formats, allowing to stack several machines together to get more tracks:
ADAT (Alesis Digital Audio Tape). 8 tracks on S-VHS tape, 60 minutes maximum record time. Resolution can be enhanced to 20 bits, reducing the number of available tracks.
Tascam DTRS (Digital Tape Recording System). 8 tracks on Hi-8 tape, up to 108 minutes of recording time. Resolution can be enhanced to 24 bits, reducing the number of available tracks.
38. What is 'formatting'?
Formatting means storing a kind of administrative data on the tape. Digital data is recorded to the tape following a predefined pattern, called footprint. DAT, for example, stores ATF (Automatic Track Finding) signals plus Sub Code (including timecodes) in addition to audio data. The footprint is created during formatting.
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack?
Advantages:
Better sound quality, at least with respect to SNR.
Cheaper equipment (with exception of DASH) and media
Possibility to increase available track count by stacking several machines together (modularity) – ADAT and DTRS
Disadvantages:
Compatibility problems
High maintenance costs (especially ADAT and DTRS)
Tape cannot be edited by splicing, except on DASH (it is found to be unreliable, though)
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
There are much more issues that can (and must) be done with regard to maintenance of an analogue recorder in contrast to having only an option to run a cleaner tape on digital recorders. The necessary actions are cleaning the heads, guides and rollers, demagnetizing, lining up.
41. Who carries out routine maintenance?
Sound engineer, or nowadays often a specialist technician. Especially the line-up is often performed by a specialist technician.
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used.
The heads and metallic guides are cleaned by a cotton bud dipped into an isoprophyl alcohol.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
The pinch wheel is often cleaned the same way as above, i.e. with isopropyl alcohol, though it shouldn't – it is made of rubbery plastic and should be cleaned with special cleaner available from pro audio shops. A mild abrasive household cleaning liquid can also be used.
44. What are the effects of neglecting cleaning?
The recording and playback heads' gaps get filled with dust particles, which has a negative effect on recording/playback of HF components. The guides get dirty, which can cause unwanted friction and increased modulation noise. The pinch wheel gets dirty and looses necessary friction, once again causing irregularities in tape moving speed.
45. Why must an analogue machine be periodically demagnetised?
As tape passes by metal guides, these will gradually build up residual magnetism. This will increase noise on the tape and erase the tape a little bit, degrading sound quality.
46. What happens if a machine is never demagnetised?
The metallic parts the tapes go by will collect more and more residual magnetism, resulting in partial erase of any tape put on that machine.
47. What might happen if the demagnetised is operated incorrectly?
It can make things worse by even increasing the residual magnetic charge. Or, least harmful, it could have no effect at all.
48. Why do analogue tape recorders need to be lined up?
To get the maximum sound quality from the machine and to ensure consistent recording/playback levels and quality between different machines.
49. Do digital recorders ever need to be lined up?
Yes, digital tape recorders have to be lined up once in a six month or so. However, this has to be done by a trained specialist with aid of special equipment (PC and software).
50. Comment on the three elements of line up.
Azimuth. The heads' gap have to be absolutely perpendicular to the direction the tape moves, othewise the HF components will suffer.
Bias. The tape is not very eager to get magnetized if the magnetizing field is below a certain level. To get over this, an AC bias is applied to the recorded signal, bringing the magnetic field strength up to where it will get recorded on the tape. On the upper end of magnetizing, the tape reaches saturation. Bias adjusting is all about to find a proper balance between noise, maximum output level and distortion.
EQ. HF playback EQ should be adjusted by means of a calibration tape with a 10 kHz signal on it, as well as both HF and LF recording EQ-s to achieve flat frequency response.
51. Explain the need for monitoring in sync.
Tape recorders have separate heads for recording and playback. When overdubbing not in sync, the pre-recorded tracks in foldback lag behind the recorded signals by the time it takes the tape to travel from recording to playback head. When monitoring in sync, the foldback is taken from the recording head so both the existing and new material sound together at the right time.
52. Why is the sync signal inferior to the playback signal?
The sync signal is taken from a recording head, which is not specifically tailored for playback and has a reduced HF output in playback.
53. Why does this matter in track bouncing?
Track bouncing is a critical operation since the bounce destination tracks will be included in the final mix. Given that, it is not wise to use inferior quality playback (from a recording head) for bouncing.
54. Is it possible to edit 2" analogue tape?
Yes. The tape is placed in a special precision-machined aluminum editing block, and cut with a single-sided razor blade, guided by an angled slot. Splicing tape is available with exactly the right degree of stickiness to join the tape back together.
55. Is it possible to synchronise two 24-track recorders?
Yes.
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface?
A standalone recording system is designed by a single manufacturer. This means a kind of quality guarantee. Also, these systems are often easier to operate.
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders.
If the characteristic analogue sound is not looked for, then disk recorders can sure be considered as replacment to analogue multitracks. And even were you after an analogue sound, you could mix to an analogue tape later.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
24
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a 24-track tape recorder?
24 would be good, though you can have more tracks than there is inputs/outputs.
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations?
The number of different signals that could be recorded simultaneously would be limited to two. This means that were you after recording a drum set, you should mix it to stereo before feeding into the multitrack.
As the number of outputs was also limited, this recorder could not be used for feeding a mixing console. Probably it had mixing functions built in.
61. What information is stored in the session file?
Audio files used, sample rates / bit resolution
Edits
Track assignments
Mix and Plug In data
62. Are session files usually transportable between different systems?
No
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
SCSI is a high speed (up to 80 MB/sec) parallel interface, suits well for audio recording. The drawback is price, which is relatively high for SCSI.
ATA drives are slower (and cheaper) and can represent bottleneck in the data exchange. Newer ATA standards like ATA 100 or ATA 133 would do well, though.
Firewire or IEEE 1394 is a fast external bus standard allowing for data transfer rates from 400 Mbits per second (IEEE 1394a) to 800 megabits per second (IEEE 1394b). Firewire also supports isochronous data transfer. This means data delivery within certan time constraints, which makes it ideal for transferring big amounts of data real-time.
64. What is 'fragmentation'?
Fragmentation describes how data is stored on the disk physically. Physical space on magnetic disks is organised into blocks, and the files are usually written to first available blocks. If a file has been deleted, the blocks it occupied will be used for new files. When a file does not fit into a continuous series of free blocks, parts of it will be written in different locations. Over time, more and more files will have their data scattered. This increases the time it takes to read a file (latency), since additional positioning of disk and its heads is necessary.
65. Comment on archiving to CD-ROM.
It is quite reliable and affordable media. Holds up to 70 minutes of 44.1 kHz stereo signal of 16-bit per channel.
66. What are 'virtual tracks'?
Virtual tracks is a concept that allows to record different takes or whatever you want under a single track number. The takes are in sync with each other and the rest of the tracks. They are virtual because you only have one virtual track active per track number, others are „hidden“ from the sight. You choose what virtual track you are going to record / play back for any given track.
67. What is meant by 'edit density'? What are the implications of high edit density?
The more the audio is edited and scattered, the more the hard disk drive has to search for each segment. The harder it has to work, the slower it will retrieve the audio.
Edit density refers to number of edited regions, their length and proximity to each other and how far they are physically separated on disk. The greater the edit density, the less tracks can be played simultaneously.
68. Does the editing and trimming of regions delete audio data from the disk?
Usually not. Just descriptive data is added which the recorder combines together with the audio data to get the desired result (like hiding the trimmed region from sight). For actual deletion, special menu functions could be provided, named as „optimize“ or something like that.
69. In editing, what is the difference between 'slip' and 'grid' modes?
Slip mode allows you to move the audio data freely while the grid mode insists limitations as to where the data can be put. It does so by restricting movements to a grid, the size of which is configureable.
70. When might it not be possible to create a crossfade?
When there is not enough material to make a crossfade of desired length.
71. What is 'bouncing', in the context of mixing?
Bouncing is the process of creating intermediary mixes. Several tracks are mixed down (usually in stereo) and the mix recorded to two free tracks. The original tracks can then be used for additional recording / editing or whatever the needs are.
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing?
Latency is the time (delay) it takes for a signal to propagate through a device. DSP processing has advantages with respect to this as here the data is processed in parallel, using dedicated processors, each having its own job. Host-based processing puts all the overhead on the single host processor, with an inevitable consequence of increased latency.
Last edited by mommi on Sat Nov 01, 2003 5:11 pm; edited 2 times in total |
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Sat Nov 01, 2003 2:16 am |
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Albow
Joined: 02 Sep 2003
Posts: 27
Location: Spain |
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1. Describe the following equipment used by a DJ: Cartridge and stylus,
Pickup arm, Turntables, Mixer.
Cartridge - postioned at the end of the arm and holds the stylus, which is
the needle that connects to the grooves on the vinyl disc.
Pickup arm - contains the cartridge and stylus and is used to move them to
the disc
Turnatables - are the circular platform that the discs are laid on.
Mixer - gives the equipment the possiblility of playing 2 or more records at
once. Each record can be faded in or out while the other plays.
2. Why cannot the output of the cartridge be connected directly to a mixing
console?
The output from the cartridge is not powerful enough. Its output level is
between 0.5 to 5 volts and the standard line level for the mixer to recieve
the signal would need to be approx 100v. Furthermore the signal is
RIAA-standardised to play vinyl records. This would have to be reversed.
3. Why is it convenient to DI a synthesizer?
Because there is no need to amplify the sound and mic the amped sound which
involves more equipomment, cost and effort.
4. Comment on the stereo output of many synthesizers?
The stereo output in many synthesisers is augmented by further individual
outputs which can turn stereo into srround sound.
5. Why might it be desirable to amplify and mic up a synthesizer, as you
would an electric guitar?
Amplifying and miking up a synth can give an extra distortion and warmth to
the sound, which might be preferred for certain sounds. I have heard of
Chick Corea doing that to get the extra bite on the electric piano sounds for
Miles Davis' bitches brew. For live performance he would use a pre-amp to
achieve it even more aggressively.
6. Comment on the use of loops in recording.
Loops are used in particular for a constant drum sound in a song, and
instrumentation that requires repetition. Using loops guarantees uniformity
and perfect time-keeping throughout a performance. They are also
additionally for saving storage space in computerised mixing, as they are
stored as a small unit that same unit is used repeatedly throughout the song.
7. Comment on tape loops.
These are made by tracking the length of tape that contains the loop, and
splicing the tape and attaching its end to its beginning.
8. Comment on looping using a sampler and sequencer.
Looping with a sampler requires that the start and end time of the sample be
specified. This must be done with unerring accuracy as if it is not perfect
it will not keep time with a sequencer.
9. Why is the sample looped using the sequencer in preference to looping it
in the sampler?
If it is looped in the sequencer, then a request is made for the sample to be
triggered at the beginning of sepcified bars. This guarantees that the
sample is played in sync if the tempos of the track's bars and the loop are
matched.
10. Comment on the significance of synchronizing the sequencer to multitrack
tape.
The significance is that the sequencer does not have to take up space on the
tape. The sequencer can be syncronised with the multitack tape so that on
starting together they can be played in sync. This is made possible by a
midi track which is played onto one track of the multitape and played back to
the device. This enables to keep live parts on one media, and digital parts
on the other, while perfectly syncronising the two.
11. Comment on the suitability of audio sequencers for sample looping.
Audio sequencers are very useful for sample looping. With mixing software,
the user can judge perfectly by the sound graphs where a sample should end
and begin, and copy and paste the sample in the track where required.
12. What is timecode?
Timecode is the means by which MIDI keeps track of time, so that midi devices
and recording devices can be syncronised.
13. Comment on LTC, VITC and MTC.
Longitudinal Time Code (also audio SMPTE) measures out time on an audio or
the audio part of a video tape
Vertical-interval time code (also video SMPTE) measures out time over a video
tape through units of time and frames
Midi Time Code takes midi-measured time, which is seen in terms of notes and
music tempo, and reconciles it with the above time codes which are measured
universally in seconds, minutes and hours.
14. Comment on MIDI Clock.
Midi has a clock which acts as the template for all tempo patterns that are
required. This enables 2 midi instrument to be played in sync; one is the
master and provides the clock for the other, which as the slave is set to
follow the master's midi clock.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
This way you are guaranteed exact digital synchronisation as explained above.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
Midi Time Clock reads the data contained in the MIDI clock in terms of real
time. Song position pointers can then be used as markers for insterting
samples at the required bar in the song. Along with this the real time can
be seen alongside the bars and the information about the song's content.
17. Why is it desirable to synchronize a sequencer to multitrack tape?
This way the track can take up one track of the tape and additions can be
made from either the midi instruments or other live instruments onto the tape
and manipulated according to the wishes of the producer.
18. Comment on the two stages of building up a recording on multitrack tape
with the aid of a sequencer.
The first stage would be to format the multitrack tape with midi time code.
You could build the tracks to your satisfaction on the sequencer, adding in
all the required tracks until happy with the outcome, making sure that there
are no more tracks to feed onto the tape than there are tracks available.
19. What is an audio sequencer?
A program that can be run as software on a computer or dedicated hardware
device for the purpose of recording, editing and playing sound.
20. Is an audio sequencer suitable as a replacement for a multitrack tape
recorder (analog or digital)?
Not at present it isn't, as there are far too many setbacks. The media is
not as easily trasportable for one. CD does not have the necessary storage
and hardware sequencers are cumbersome. There are problems of compatibility
between file types of sequencer programs. Until the world's computers are
comprehensively connected through one super computer it is difficult to see
how it could be a universal standard. For a home-made recording of a
particular type of recording it might be enough, but for a band sound, even
if you were to record all of their output into the sequencer, you would still
look to put it onto tape to create the master.
21. Comment on the suitability of an audio sequencer for sample and loop
editing?
For this purpose the audio sequencer is perfect as the editor can zoon into
the graphical representation of the sounds and ensure that they have perfect
zero crossing for the loops. The samples can be inserted exactly where they
need to go by charting prospective entry points with markers.
22. Why is it not straightforward to synchronize an audio sequencer to
multitrack tape?
The main issue is which format takes preference as a master. Once the
multitrack tape is striped with time code, it can be dificult for the
sequencer to send it tempo changes as the time tracks are set in stone. If
you use the tape as the master then we can't syncronize with the sequencer.
23. What parameters of effects can often be controlled via MIDI?
From what I have seen you can change parameters just as you would on the
effects were they in a pedal, ie decreasing/increasing delay times, decay,
sustain etc.
24. Why would you want to control effects parameters by MIDI?
You could play through tracks and try them with different effect settings to
see what they sound like with various effects added. This is easy to do and
non-destructive.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
I believe it does, that there is a built in toggle converter to adhere to the
particular SMPTE timecode when using MTC. I don't know if this is a standard
thing.
26. Does MTC contain an address?
Yes, it will contain a binary address so that it is recognised by a system's
OS.
27. Does MTC contain a clock?
Yes, it keeps track of hours, minutes and seconds and tracks frames against
them
28. Is MTC useful for synchronizing a MIDI sequencer?
Yes
29. Is MTC useful for synchronizing digital audio?
Yes
30. Is MTC useful for synchronizing analogue audio?
Yes
31. Comment on the difference between standalone hard disk recorders and
computer based hard disk recorders.
Standalone hard disk recoerders are made specifically for that job and have
built in features to carry it out. A computer is not built for that purpose
but can be turned into a recorder by adding software and hardware if
necessary.
32. Why is it a problem to use hard disks for long term storage?
All hard disks are mechanical devices and will ultimately fail. Once a hard
disk has failed it is an arduous and expensive process to attempt to retrieve
data from it, which may not be possible if the mechanical failure leads to or
is accompanied by OS corruption.
33. Onto what media does backup/archival storage take place?
Favorite is still tape, as it is the most efficient method of archiving
abundant storage and does not easily corrupt. Other options are optical
storage disks.
34. What are the advantages of standalone hard disk recorders (compared to
tape) for editing?
The advantage is that they can store a lot of data and a lot of different
tracks as datasets which can be mixed and matched as required. Then parts
can be cut and paste with the minimum of fuss and the changes undone if not
up to scratch.
35. What are the advantages and disadvantages of computer based hard disk
recorders compared to standalone hard disk recorders?
The advantages are that the computer can be changed into a powerful recording
console with the addition of hardware soundcards and a myriad of
possibilities of software applications and that any data can be saved and
transferred between systems of broadly similar specifications. The
disadvantages are that computers are more prone to crashing and that they are
not purposefully made for the job as are standalone devices. Adding
recording-based software may affect the running of other everyday
applications on the system.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
Pro-tools can be used to master and edit on multitrack tape. The tape can be
taken and a track loaded into Pro-tools, changes superimposed, and if they
are not preferred then they do not have to be incorporated.
37. List the common digital multitrack tape formats and describe their
characteristics.
DAT - Digital Audio Tape Very small tape 16bit 48k
DASH - Digital Audio Stationary Head - 24 track - reel to reel tapes
ADAT - Alesis Digital Audio Tape - 8 track video - systems can be synced to
enable more tracks to be added
38. What is 'formatting'?
Formatting is preparing a blank tape for use with its intended OS
39. What are the advantages and disadvantages of digital multitrack compared
to analogue multitrack?
The quality concerning the quality of sound is the basis of the advantages of
digital over analogue. With each copy of analogue made, the signal to noise
ratio would deteriorate. The disadvantage is that with digital, the fact
that there is no distortion at all can lead to observations that it lacks in
warmth and is over-sterile.
40. Compare the maintenance and cleaning of an analogue recorder to that of
a digital recorder?
For a digital recorder, to clean the apparatus, you would insert cleaning
media and select cleaning options. To thoroughly clean the analogue
recorder, much more manual tasks are required, from cleaning heads and
rollers, to also cleaning with demagnetising tapes.
41. Who carries out routine maintenance?
The studio engineer
42. Describe how the heads and guides of an analogue machine are cleaned.
Mention the materials used.
With a cotton swab and isopropyl alcohol.
43. Describe how the pinch roller of an analogue machine is cleaned.
Mention the materials used.
The pinch wheel is often also cleaned with isopropyl alcohol, but as it is
made from a rubber-based plastic it shouldn't really be used on account of
its fragility. Instead a specific rubber cleaning agent or a mild abrasive
such as fairy liquid are preferable.
44. What are the effects of neglecting cleaning?
The basic primary effect is that the recording will suffer. This will happen
firstly as a result of a magnetic iron oxide deposits on the heads. If the
mechanicalcomponents become dirty they may not function smoothly. This could
affect the effect the quality of the recording by introducing faults from
mechanical glitches. Eventually if the mechanical parts become clogged up by
dirt or dust they will fail and require replacing.
45. Why must an analogue machine be periodically demagnetised?
A magnetic film will build up on the heads and it only requires a layer the
thickness of a fingerprint to begin to cause signal degradation.
46. What happens if a machine is never demagnetised?
It can erase the tape
47. What might happen if the demagnetised is operated incorrectly?
It could have the reverse the effect and magnetise the tape further.
48. Why do analogue tape recorders need to be lined up?
Firstly, you would line the tape up so that it would play dependably when
transferred to another tape machine. Secondly, to set the bias so that the
signal to noise ratio does not suffer.
49. Do digital recorders ever need to be lined up?
The correct sample bit rate must be selected, and care must be taken to
ensure if changing tapes between systems that the same tape block compression
rate is chosem
50. Comment on the three elements of line up.
Azimuth - the heads must be perfectly vertical in relation to the tape.
Bias - to optimize distortion, line level and noise
EQ - High and Low Frequency levels are lined up to standard levels.
51. Explain the need for monitoring in sync.
The need to monitor in sync is so that when playing to the track, the
recording that will be merged with the basic track is in time. As the
recording head and the playback head are separated by a matter of inches, and
as such if the monitoring is not done in sync there will be a delay between
the recording and the playback
52. Why is the sync signal inferior to the playback signal?
The playback head is optimised for playback and the record head is optimised
for recording, so the playback signal on the recording head will be inferior
to the playback.
53. Why does this matter in track bouncing?
As bouncing is irreversible, it is essential that the signal being bounced is
the superior signal - we must check therefore that the signal is coming from
the playback head and not the recording head.
54. Is it possible to edit 2" analogue tape?
Yes, by cutting the tape and splicing it back together. This is far trickier
however than digitising the output and editing it on a sequencer.
55. Is it possible to synchronise two 24-track recorders?
Yes, by allocating SMPTE to both tapes on each recorder and assigning one to
master and the other slave.
56. Why is it often considered better to use an integrated disk recording
system rather than one that uses a personal computer as the user interface?
All the disk recorder's processing power is dedicated to the recording and
editing of the disk whereas with a computer, its resources are not
exclusively given over to the recording process.
57. Comment on the presentation of some disk recorders as replacements for
tape multitrack recorders.
The presentation is to mimic the presentation of the analogue recorders, but
replace the analogue features for digital.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it
have?
24
59. How many inputs and outputs would a disk recorder need if it was to be a
replacement for a 24-track tape recorder?
I am not sure. I imagine that if it was an exact replacement it would need
24, but if it was not an issue to add tracks in at other points, then it
would be any multiple of 24 (?)
60. If a disk recording system had two inputs, two outputs, and was capable
of twenty-four tracks, what would be its main limitations?
You could only record 2 instruments at a time, which would delay the
recording process.
61. What information is stored in the session file?
Track information, plug-ins used, sample bit rate, edits and fades.
62. Are session files usually transportable between different systems?
Not usually. If there was the slightest difference between 2 systems, then
there may be incompatibility issues. If there is any difference in
input/output numbers or plugins, OS, applications, then it will not work.
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for
audio recording.
SCSI would be preferable to ATA, as it is quicker and able to support several
devices on its bus. It is also less prone to bottlenecking. Firewire is
faster still, and is preferable where possible, although there are no
firewire disks as such. The disks would be SCSI/IDE/FCAL, although the data
transfer between the devices would be quicker with Firewire.
64. What is 'fragmentation'?
Fragmentation is when data pertaining to related files are scattered over the
disk surface. This happens when files are updated, the data that imposes the
change is added to the disk sectors sequentially. This causes greater head
movement and slows down disk performance. The performance can be improved by
defragmenting.
65. Comment on archiving to CD-ROM.
Archiving to CD is preferable to doing so by hard disk in that it is a more
reliable form of storage, but DVD rom is preferable as it offers more storage
space. For long term storage DAT or DLT storage would also be preferable.
66. What are 'virtual tracks'?
Before digital tape and hard disk-based recorders, virtual tracks provided a
means of recording a finsihed products through virtual MIDI tracks. Through
midi tones, a signal processor, a sequencer and a mixer, the tracks can be
played back and mixed down on the fly.
67. What is meant by 'edit density'? What are the implications of high edit
density?
Edit density refers to the amount of processing power is used by the system to
perform editing functions. High density editing is demanding on the system
resources.
68. Does the editing and trimming of regions delete audio data from the
disk?
Not unless the changes are saved. Otherwise it just plays back the section
with the modifications made. There is the option to undo any changes.
69. In editing, what is the difference between 'slip' and 'grid' modes?
In grid mode you can move audio sections from one grid location to another.
With slip mode, sections can be selected and repositioned freely.
70. When might it not be possible to create a crossfade?
In a loop. This is apparently because to create a crossfade, the cross-fader
takes a bit from the beginning and the end of a section. At the very beginning
or end of the sample there is no data to draw from.
71. What is 'bouncing', in the context of mixing?
Bouncing is playing a number of tracks to be recorded to one vacant track. This
then frees up the other tracks to add further music tracks to the bounced
track. The producer must be happy with the mix of the bounced track as it
cannot be changed back later.
72. What is meant by 'latency'? What is the difference between DSP
processing and host-based processing?
Latency is the time lag between playing and hearing a note.
DSP processing involves the software application doing its own processing.
Host-based processing involves full use of the system CPU to carry out
processing. |
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Sat Nov 01, 2003 2:52 am |
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AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| Clarify |
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Some good stuff starting to appear here.
Let's run with it, as much of the missing information is beginning to answer itself.
Jump in at any point if you need to clarify with each other.
Cheers
_________________
It's all in the ears. - Learn the concepts not the software.
Audio Courses is a way into the music business for you
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Sat Nov 01, 2003 5:40 am |
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mommi
Joined: 21 Apr 2003
Posts: 47
Location: Tallinn, Estonia |
Still waiting for the audio sequencer concept to clear out. If it really is a
quote:
Originally posted by Albow
program ... on a computer or dedicated hardware device for the purpose of recording, editing and playing sound
then I don't see why it cannot replace a multitrack recorder. Or how it differs from a harddisk recorder, for example (except that you probably can fire audio samples from that).
All my queries about
audio sequencer
on the web resulted in
MIDI-plus-audio
. So far I'm still confused.
Comments anyone? |
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Sat Nov 01, 2003 5:28 pm |
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Fenderocks
Joined: 09 Aug 2003
Posts: 26
Location: Music City, USA |
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1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer. The cartridge and stylus is used to position at the end of the arm that holds the stylus, the needle that connects to the grooves in the vinyl. The pick up arm is what will hold the cartridge and stylus, the turntables are what DJ’s use to spin records and the mixer is what holds enable the DJ to spin two record and have the ability to fade them in or out.
2. Why cannot the output of the cartridge be connected directly to a mixing console? To what I’ve read about the cartridge the volts are too low for the line level for the mixer.
3. Why is it convenient to DI a synthesizer? It’s convenient to because you don’t need to use the output of the synths into an amp and speaker just to be able to get the synths in.
4. Comment on the stereo output of many synthesizers? The synthesizers have you normal outputs but they also have assignable outs too, they also have the ability to make stereo into surround sound as well.
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar? It really depends on what sound you trying to achieve, when hooking up a synthesizer to a amplifier the sound you will receive is more distortion and warmth compared to going striate in which you will indeed have a more bright of a sound.
6. Comment on the use of loops in recording. While using loops in recording you are doing a few things first you are saving space on your computer, second you won’t have to worry it being on time and virtual will have a perfect track to always play too.
7. Comment on tape loops. Tape loops is when you cut a segment of a tape and piece together end to beginning for as long as you need it, you also want to modify to tape so you don’t take up the tapes reels
8. Comment on looping using a sampler and sequencer. Well looping on a sampler is set up for it, samples are small musical pieces, so only thing you do is just paste them together linking repetitions and you good to go, what the sequencer does triggers the sample.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler? The sample looped by the sequencer is always in preference vs. just using the sampler. Because the sequencer is more prone to staying in perfect time using loops sometimes you run into timing drifts which is why the sequencer is preferred.
10. Comment on the significance of synchronizing the sequencer to multitrack tape. The sequencer does not have to take up space on the tape. The sequencer can be synchronized with the multitrack tape so that on starting together they can be played in sync. Using a midi track which is played onto one track of the multitape and played back to the device, by doing this it enables to keep live parts on one media, and digital parts on the other, while perfectly synchronizing the two.
11. Comment on the suitability of audio sequencers for sample looping. Audio sequencers are great to use for sample looping because the user can predict by the sound graphs where the sample should start and end, by just copy and paste where needed.
12. What is timecode? Timecode is where MIDI keeps track of time, so that the MIDI devices and what other devices you are using can be synchronized.
13. Comment on LTC, VITC and MTC. They all are timecodes used differently starting at:
LTC (longitudinal time code) - measures out time for audio or the audio part of video.
VITC (Vertical-interval time code) - this measures time for a video tape in frames of time.
MTC (MIDI time code) - Measures out time for MIDI all of these in sec, mins, and hours.
14. Comment on MIDI Clock. The MIDI clock is used for keeping time for MIDI devices and allows two MIDI tracks to be played in sync with each other. The MIDI clock also takes care of all the tempo patterns required.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock? By Using the MIDI clock in this situation you ensuring that the devices are in perfect time, how you ask? By the master which provides the clock for the other and the slave always shadows the master in any situation.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers? The MIDI time clock reads the information in the MIDI clock. The SPP is used pretty much as markers so that inserting samples is made easier.
17. Why is it desirable to synchronize a sequencer to multitrack tape? Well first of all more tracks and second of all the sequencer is going to follow the multitrack tape in forms of master and slave, to get perfect sync information and audio together.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer. FIRST STAGE is getting the multitrack tape to the MIDI time code. Then build up your tracks until satisfied taking all the tracks up.
19. What is an audio sequencer? Designed to record and edit as well as playing sound, it is software or dedicated hardware devices.
20. is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)? No, way too many set backs as far as CD’s not enough storage, problems with transporting the information and the quality of it all would not be that good.
21. Comment on the suitability of an audio sequencer for sample and loop editing? It’s perfect because of the functions zoom in and out, and with the copy and paste you can have the samples anywhere you want them.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape? Too many problems can occur as far as it will be hard to send new tempo changes and as well as if you use a tape for the master you can’t synchronize it.
23. What parameters of effects can often be controlled via MIDI? Delay, chorus, reverb, you also can use groove quantizing and other options as forth.
24. Why would you want to control effects parameters by MIDI? You can use whatever effects you got by the MIDI control
25. Does MTC come in all the frame rates of SMPTE/EBU timecode????
26. Does MTC contain an address? Yes, recognized by the systems os
27. Does MTC contain a clock? Yes, it keeps track of hour’s mins and seconds, and what ever else is in the tracks.
28. Is MTC useful for synchronizing a MIDI sequencer? Yes
29. Is MTC useful for synchronizing digital audio? Yes
30. Is MTC useful for synchronizing analogue audio? Yes
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders. Standalone hard disk recorders are built for the job and have features to help the process vs. computer based hard disk recorders can do the job if you have the right software and hardware.
32. Why is it a problem to use hard disks for long term storage? Hard disks suck and usually fail from time to time.
33. Onto what media does backup/archival storage take place? Tape is the most effective way to do it as far as storage goes with out failure.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing? They can hold lots of data and lots of different tracks.
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders? The advantages of computer based hard disk recorders you can build the ultimate set up with the right hard ware and software available. The disadvantages are that the computer may crash and you lose everything.
36. Comment on the use of Pro Tools as an accessory to multitrack tape. Pro tool would be best used to master and edit the tracks of the tape, by bringing them in trough a track loaded into pro-tools
37. List the common digital multitrack tape formats and describe their characteristics. All right you have DAT- Digital audio tape that only carry’s 16 bits 48k the next is DASH Digital audio stationary head that has 24 tracks reel to reel tapes, an the final tape is alesis digital audio tape(ADAT) where if in sync can add more tracks.
38. What is 'formatting'? Formatting is preparing a blank tape for use of the os.
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack? Advantages of digital multitrack you have as many tracks as you want it’s easy to edit and record the music but the disadvantages are it’s going to lack the warmth of the analogue. The advantages for analogue is that the quality sound of the analogue is better with the disadvantages you are spending a lot more time editing, mixing down on the fly, and more copies you make the more it deteriorates.
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder? With Analogue the maintenance is much more intense, to cleaning heads, cleaning the pitch roller, and demagnetized tapes, as far as the digital audio you need to buy a disc and pop it in.
41. Who carries out routine maintenance? The engineer
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used. Cotton swabs and isopropyl alcohol.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used. The pinch wheel is often also cleaned with isopropyl alcohol, but as it is made from a rubber based plastic there are better products to use, cotton swabs is the material that the cleaning liquid is put on.
44. What are the effects of neglecting cleaning? Well unwanted fiction and modulation noise and could cause problems in tape speed. Basically you need to take care of the equipment so all you recording will be at the quality the you intend.
45. Why must an analogue machine be periodically demagnetised? The metallic parts of the tape will collect residual magnetism, causing the tape to erase some of the material on it and make the overall sound quality sound bad.
46. What happens if a machine is never demagnetised? The above answer, but worse.
47. What might happen if the demagnetised is operated incorrectly? It will cause more residual magnetism or nothing.
48. Why do analogue tape recorders need to be lined up? To get the best possible sound you can from the machine.
49. Do digital recorders ever need to be lined up? Yes, but it has to be done by a trained specialist with the aid of special equipment.
50. Comment on the three elements of line up.
First is the azimuth, this is where you set up the heads’ gap perpendicular to the direction of the tape. The second is Bias and is not just used for analogue recording, All guitar head that have tubes as far as the mesa dual and triple rectifier and the Marshall jmc 2000 dual and triple super lead for example need this as well, but the bias is where adjust the proper balance between the noise, maximum output level and distortion. In the heads for my example you have to do that with the tubes of the amps. And the last the EQ should be adjusted to 10 kHz signals on it.
51. Explain the need for monitoring in sync. The reason we monitoring in sync is because, the foldback taken from the recording the, material being played back and the material being recorded is in time together, if not the foldback lags behind a little causing the final result to sound a little off when they played the material back.
52. Why is the sync signal inferior to the playback signal? The sync signal is inferior because it is taken from the recording head. The playback is from the HF and the signal reduced during playback.
53. Why does this matter in track bouncing? Track bouncing is where after you mix all you tracks the way you like them, you highlight them and form them into one track. Since the bounced tracks are going into the final mix it’s not wise to use the playback for bouncing.
54. Is it possible to edit 2" analogue tape? Yes the tape is placed in a special precision- machine aluminum editing block. After this it is cut very carefully using a single sided razor blade, to rejoin the tape the stickiness has to be exactly the right degree to bring them back together.
55. Is it possible to synchronise two 24-track recorders? Yes.
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface? A standalone recording system is designed just to do that and has guarantee of a quality and is much easier to operate.
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders. If not wanting the analogue sound then the disk recorders as a replacement is a good thing, and still being able to mix down to an analogue tape later.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have? It has 24 tracks
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a 24-track tape recorder? 24 are what’s coming to my mind
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations? The number of tracks that could be recorded at the same time would only be two.
61. What information is stored in the session file? Track assignments, edits, audio files, sample rates, bit resolution, and mix plug-ins data.
62. Are session files usually transportable between different systems? No
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.SCSI is great for recording because of it’s parrell interface but is $$$$, ATA drivers are slower but cheaper, but problems may arise. And finally firewall disks are fast, but data delivery would have certain time constraints, which makes transferring big amount ideal for real-time through.
64. What is 'fragmentation'? It describes how data is stored on a disk. So when information is stored on a disk it is often in blocks, and when those are erased it will store different audio in those blocks. In time the data is spread out in different locations which causes a problem, slow movement in between files you wish to bring up and more dropouts will occur. A way to fix this is defragmitize you system once a month and you shouldn’t have any problems with latency.
65. Comment on archiving to CD-ROM. Great to use and holds up to 70 min. which is 44.1 kHz stereo signal to sixteen bits per channel.
66. What are 'virtual tracks'? A virtual track is where you record under a signal track number different takes or samples or whatever; the tracks are always in sync together. Per track only one virtual the rest are hidden.
67. What is meant by 'edit density'? What are the implications of high edit density? It occurs when you edit and edit and edit lots of different material, which in return scatters it and makes the hard drive look for it. The implication of high edit density is when fewer tracks can be played at the same time.
68. Does the editing and trimming of regions delete audio data from the disk? Not usually, just descried data is added to tell to edited part what it needs to sound like.
69. In editing, what is the difference between 'slip' and 'grid' modes? Slip modes is where it allows you to move the data freely as for the grid modes it adds limitations where you can put the data. Making sure that the size of the data is configurable to where you are going to store it.
70. When might it not be possible to create a crossfade? When the length or not enough data to make the crossfade a success.
71. What is 'bouncing', in the context of mixing? Say you have a 4 track recorder and you have 4 tracks of audio data on it, but you need a few more, you can bounce the 4 tracks two one to free up 3 more tracks, making sure that it’s already mixed correctly cause once you change you can’t go back and just edit one.
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing? Latency is the time it takes for a signal to go through a device. DSP processing has advantages to this as the data is processed in parallel, using dedicated processors, each having its own function. Host-based processing puts all the overhead on the single host processor, increased latency. |
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Sun Nov 02, 2003 7:07 am |
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ruiabreu
Joined: 15 Sep 2003
Posts: 12
Location: Portugal |
| recoreding techniques week9 |
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Hello Chris
I finish my answers yestarday, but couldn't connected to the net till now.
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
The cartridge holds the stylus. The stylus is a diamond head that is in contact with the vinyl and picks up the vibration from the grooves. This vibration is transmitted to the cartridge were it is transformed into an electric signal. The pickup arm holds the cartridge and allows the free movement of the cartridge. The turntables support the vinyl record and spins it a certain constant speed. The DJ mixer is a special mixer that receives input from two turntables allowing the control by the DJ of the passage from one music to another.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
Because the output of the cartridge is to low (5 mV) and you need to amplify the signal to line level (0,775 V).
3. Why is it convenient to DI a synthesizer?
A Synthesizer usually has line level output so you don’t need to pre-amplify the level. A DI may be convenient to turn the signal from unbalanced to balanced signal. A balanced signal can travel through a long cable without being degraded.
4. Comment on the stereo output of many synthesizers?
A synthesizer might have sound effects that play around with panning. There can be a filter per example that sweeps the signal from one side to another at regular intervals. If you don’t have stereo output then you can’t output these effects.
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
It’s desirable to get a different original sound. Every synthesizer that is equal to yours will sound similar for the same patch and when outputted to the line input. You might want the typical sound of a specific amplifier. Also you might want a more live sound. This is done by miking the room ambiance.
6. Comment on the use of loops in recording.
The use of loops is a way of quickly arranging a music piece. Although there are a few disadvantages in using loops, the speed of music making is increased and you may lay down an idea before it disappears. For me at least it is like this. A wide range of professional sound loops are commercially available specially drum loops. You can use this loops instead of a drummer saving time and money. The big disadvantage is the robotic fell of the loop when compared to a real drummer. When performing, a drummer will make slight shifts in tempo and level. These shifts are what make the sound more organic and real.
Also using loops saves up disk space as the loop is repeated time after time and usually is not a very big file. Still the use of audio loops may increase the editing density.
7. Comment on tape loops.
8. Comment on looping using a sampler and sequencer.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
Left these for last, still have to go back to sampling questions. Haven’t done then yet.
Synchronization
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
With a sequencer you usually start working in a music piece using his MIDI capabilities. After laying a number of MIDI tracks you may find that you’re arrangement will be quite complex and you may want to backup the music. Of course you can simple save the song as a file specific of you’re sequencer. But many times you may want to record the tracks you have already recorded into a multitrack tape recorder as audio tracks. This will free up MIDI channels for use with other MIDI instruments you might want to use. After more tracks are made you can bounce this tracks to tape too and you end up with a tape with all tracks. From this point you just have to mix from tape using a mixing console. This style of work mimics the typical tape recorder environment and some people may like it better. Other advantage is that even if you record the song as a sequencer song file (you should do it any way) this arrangement is right in that moment but the sequencer setup changes quickly and when taking the arrangement to another sequencer you might find it hard to setup as the original sequencer. With tape, after you record the tracks they are audio signal and won’t change no matter what system you use.
11. Comment on the suitability of audio sequencers for sample looping.
Audio sequencer can have audio and MIDI tracks mixed on the same song. Because of this they are ideal for sample looping. You can record an audio signal and use it to make an audio loop sample. Then you can just place the sample wherever you want on the music piece timeline and copy it as much times as you want. You can also use the midi capabilities of the audio sequencer and use the sample loop just as a MIDI instrument triggering the sample with MIDI events.
12. What is timecode?
Timecode is a digital signal that ranges an entire music piece and has information about the music piece timeline. Timecode enables music equipments to read the tape or digital file and know were they are in the music piece.
13. Comment on LTC, VITC and MTC.
LTC (Longitudinal Timecode),VITC (Vertical Interval Timecode) and MTC (MIDI timecode) are all timecodes. LTC and VITC use SMTPE timecode. MTC has his own code but you can perform a SMTPE to MTC conversion. LTC is used for audio and low cost video synchronization while VITC is used mainly on video synchronization for high-end systems. MTC is a timecode used just for audio systems and because it is cost-effective and easy to use it has as been gaining a wide acceptance.
14. Comment on MIDI Clock.
MIDI devices usually have a built-in MIDI clock protocol that can be used to synchronize all devices on a MIDI net of connected devices. This clock uses 1 byte MIDI real-time messages, the timing clock messages. A timing clock message is sent 24 times on each frame.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
Like with others synchronization systems you want to assign a master device and slave the rest of the devices to the master. This means that you just need to use time related changes in the master and not on all MIDI devices on your system. For example when you pressed play in the master device he will send the appropriate MIDI real-time message to all the slave devices and they will all start playing.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
MTC is a timecode implementation to synchronize MIDI devices with audio related devices. When a MTC timecode is in use the MIDI devices are set up to external clock and the MIDI clocks are not used (this is a guess as I did not see it anywhere). MIDI clock is just for a MIDI only system. Song position pointers are MIDI messages that state the beat current position in a song. My guess is that they are used in both MTC and MIDI clock synchronization. Another option is that MTC slaves the MIDI clock and both time code coexist.
17. Why is it desirable to synchronize a sequencer to multitrack tape? See question 10.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a
sequencer.
With this system you first arrange the music in the sequencer using MIDI devices and they start recording these tracks to a tape analogue or digital multitrack recorder. When you have your first MIDI tracks you set the sequencer to external sync so that it can respond to MTC timecode coming from the tape recorder. You have to make shore that the music tempo is right because you won’t be able to change it later when MTC becomes in charge.
19. What is an audio sequencer?
It’s a recent type of sequencer that can handle MIDI and audio tracks at the same time. This means that it’s all done on a computer.
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analogue or digital)?
This question as an ever changing answer. My answer nowadays is yes. The principal problem to address here is “latency”. “Latency” happens when a computer isn’t capable of delivering a track in real-time. “Latency” is the time between the moment you press play until the sound comes from the loudspeaker or the headphones. This is particularly serious in overdubbing, because a musician has to hear the tracks already record and the system has to record the track in sync at the same time. The more recent systems can reduce “latency” to less than 3 ms witch is the limit for a workable situation.
21. Comment on the suitability of an audio sequencer for sample and loop editing?
Audio sequencers are ideal for sample and loop editing. You can record or import a audio sample or loop and then place it on the song time line and them arrange the audio sample or loop my moving it or copying it to another place on the song. You can easily integrate these audio events in a MIDI time frame (bars and beats) and audio samples conform to the tempo of a MIDI song. With a longer audio event that has a tempo associated with it then you may have to adjust the tempo of the MIDI tracks to the tempo of the loop sample.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
A MIDI sequencer and a multitrack tape synchronize using MTC timecode. In this case the SMTPE timecode of the tape is on charge and the sequencer obeys through the MTC after a SMTPE to MTC conversion is performed. In an audio sequencer you can have audio tracks, and the problem with these tracks is that they can’t synchronize to MTC because there is no clock pulse. In this case the audio tracks of the audio sequencer might drift when the external sync is on.
23. What parameters of effects can often be controlled via MIDI?
Using controller change messages you may have the ability to control any parameters of an effect. The effect has to be able to respond to the MIDI control messages of course. An example of parameters controlled by MIDI would be the decay times when using a reverb effect.
24. Why would you want to control effects parameters by MIDI?
MIDI parameter changes can be recorded and this way we can automate effect parameters over time. You can for instance increase the effect gain during the chorus of a song.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
Yes. It’s SMTPE/EBU that is in control, MTC is derived from SMTPE/EBU and comes in his frame rate may it be 25, 29,97 or 30 f/s.
26. Does MTC contain an address?
Yes. It’s an address derived from the SMTPE/EBU time code.
27. Does MTC contain a clock?
No. MTC is derived from a SMTPE/EBU signal and relies on his signal clock pulse. There is no need for more MIDI messages as signal clock pulse.
28. Is MTC useful for synchronizing a MIDI sequencer?
Yes. When you want to synchronize the MIDI sequencer to an external tape (analogue or digital) or video machine.
29. Is MTC useful for synchronizing digital audio?
Yes. But only if you are using a digital multitrack tape machine with a MIDI system or device and this machine has a striped SMTPE timecode on one of his audio track.
30. Is MTC useful for synchronizing analogue audio?
Yes. Again only if you are synchronizing a analogue audio tape machine to a MIDI system or device and this machine has a stripped SMTPE timecode on one of his audio track.
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
35. What are the advantages and disadvantages of computer based hard disk recorders compared
to standalone hard disk recorders?
Standalone hard disk recorders have: dedicated computer processing power, inputs and outputs, the system is self contained and because of this the performance is usually more reliable, they are also normally more expensive and it can be more difficult to upgrade. A hard disk recorder relies on consumer computers and inputs and outputs are usually supplied in a sound card or in an external box connected to the computer. Performance can be a problem as there is a big variety off computer components and incompatibility and reliability problems may arise. Still these types of systems are usually cheaper and easier to upgrade.
32. Why is it a problem to use hard disks for long term storage?
Hard disk long term store maybe a problem because a hard disk has mechanical parts that may fail in time. This is not the problem for tape or optical storage. Digital tape as well as CD-Rom or DVD-Rom are likely to be stored for years before any type of problem may arise. Also hard disks are still expensive compared to tape or CDs.
33. Onto what media does backup/archival storage take place?
Usually digital tape or optical storage like CDs and more recently DVDs.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
The biggest advantage is that in a standalone hard disk recorder the tracks are not fixed in a timeline to each other like in a tape recorder. You can easily cut a part of a music like a first chorus for example and place it on a second chorus. You can to this in a tape recorder but the process would be more complex. Also you can access the track in an almost instantaneously as data is recorder in a three dimensional manner while in tape if you want to go to the beginning you have to rewing the tape.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
Pro Tools is often used for his editing facilities and not as a self-contained system. This means recording with another system and editing with Pro Tools.
37. List the common digital multitrack tape formats and describe their characteristics.
DAT, DASH, ADAT and DTRS.
DAT is a format that was developed to replace cassettes and so it has small width of tape (10,5 mm). Can record 16bits / 48 kHz. It has rotary heads that record tracks diagonally to the tape edges. With this technique there is more information that can be recorded because the tape speed isn’t actually the writing speed (3.933 mm/sec for tape speed and 13,591 meter/sec for writing speed!!!
DASH uses reel to reel tape with ¼’’ and ½’’ t | | | |
