AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| Week 10 - MIDI |
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1. Explain why it is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously.
2. Explain why some multitrack hard disk recording systems can play back much slower than normal speed, but only a little faster.
3. State TWO major advantages of hard disk recording systems over digital tape recorders.
4. Describe THREE major operational advantages of having two modular digital multitrack recorders such as the ADAT or DTRS formats over a format which records sixteen tracks on the same tape on a single machine.
5. Explain why the punch in process on a hard disk recorder is more flexible than that on an analogue or digital tape recorder.
6. With reference to an analogue multi-track recorder briefly explain
a) the term `sync' output
b) why the `sync' output is required when overdubbing.
7. It is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously. Why is this?
8. Some hard disk recording systems have mixing facilities so that several tracks can be mixed into a stereo output. If no other outputs are available why must the system incorporate reverb internally?
9. What are the two major advantages of hard disk recording systems over digital tape recorders?
10. What piece of equipment is necessary to use a sequencer with a multitrack tape recorder?
b) Why is it preferable to use MTC rather than MIDI clocks and Song Position Pointers when synchronising a sequencer to a tape recorder?
c) If MIDI Machine Control (MMC) is not used, describe briefly the two distinct stages of operation when recording a piece of sequenced music to multitrack tape.
d) What is the advantage of MMC?
e) In a system using MMC, while playback or recording progresses the multitrack and sequencer will be running in sync. At this moment which is master and which is slave?
11. You have been given an unlabelled tape to play which starts with a warbling tone. What noise reduction system might have been used?
b) You have been given an unlabelled tape to play which starts with noise. What noise reduction system might have been used?
c) Name three domestic noise reduction systems invented by the Dolby company.
d) Give the name of another fairly common analogue noise reduction system.
e) Where would you find the ATRAC digital noise reduction system?
12. When recording onto analogue or digital multitrack tape, in a situation where synchronisation is going to be used, what procedure must be carried out before any recording can begin?
b) Your studio manager has given you a multitrack tape containing music and timecode to copy. What must you do to ensure that the timecode is copied correctly?
c) A multitrack tape of a band with no sequenced instruments was striped with timecode at the start of the session and has subsequently been edited? Would it be good practice to use the existing timecode as a synchronisation reference for the console automation system during the mix?
d) Referring to c) above, why would it not be a problem to re-stripe the tape with timecode and erase the original timecode, even if the generator does not have a jam sync function?
e) You have striped timecode on track 24 of an analogue tape and recorded a bass guitar on track 23. When you try and synchronise a MIDI sequencer using a cheap timecode to MTC convertor, the sequencer often stops or loses sync. Why?
13. When working with MIDI and multitrack tape, does the multitrack recorder synchronise to the sequencer or does the sequencer synchronise to the multitrack tape?
b) When working with an ADAT recorder, why wouldn’t you necessarily have to stripe the tape with timecode to synchronise a sequencer?
c) Imagine that several tracks of a MIDI sequence have been transferred to multitrack tape. The producer decides that he wants to varispeed the tape a little faster. Should this be done before or after the remaining sequencer tracks have been transferred to tape? Explain your answer.
14. Noise reduction systems such as dbx and Dolby cause the noise level in a recording to vary. Explain why this is so.
15. You have been asked to remix a song (in the sense of creating a completely new version) originally made on multitrack tape in the early 1970s.
a) What would be the main problem in synchronising a sequencer to the original tape?
b) If you decided only to use the vocal track from the original recording, how would you make the lines fit in time with your new MIDI sequencer arrangement?
c) Suppose you want the song to be around 15% faster in tempo. What should you do to speed up the vocals?
d) The record company decides that it wants to keep a lot of the original instrumentation, but also likes your strict tempo MIDI sequence. What type of equipment should you use to put everything together?
16. You are working with a multitrack recorder that will slave to SMPTE/EBU timecode from (for instance) a video machine, but has no other means by which it may be externally controlled. Imagine you stop the master machine, rewind the tape to the beginning and start playing. What will the multitrack do?
17. What is the frame rate of NTSC?
18. What is the frame rate of PAL (and SECAM)?
19. What is 'drop frame timecode'?
20. Comment on the requirements for recording timecode onto analog tape
21. Comment on the problems that occur when using timecode on analog tape
22. Why must timecode be regenerated when it is copied?
23. What is an 'offset'?
_________________
It's all in the ears. - Learn the concepts not the software.
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Mon May 09, 2005 7:45 am |
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JohnA
Joined: 20 Jan 2005
Posts: 28
Location: Mid Glamorgan, UK |
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Audio Course
AURT03
Week 10
MIDI
JohnA (mixindown)
1. Explain why it is common for a multitrack hard disk recording system to be able to store more tracks in synchronization than it can play simultaneously.
It is common for multi-track hard disk recording systems to be able to store more tracks than it can play simultaneously because of the “virtual track” recording system.
Extra tracks can be recorded beyond the normal “track count” on this type of system. Many multi-track hard disk systems allow you to record possible “8” virtual tracks on each of the tracks of the recorder. So if your recorder has 24 tracks, it will have 24 tracks x 8 virtual tracks = 192 tracks available, from which you can play a maximum of 24 at any one time. These virtual tracks are usually displayed by selecting a drop down menu at the side of the track number onscreen. Having all these tracks available to you means that you have a far greater choice of which “take” to use than you would on a tape system. Also, you can edit virtual tracks just like any other tracks so you can take 8 virtual tracks of a vocal and “comp” the vocal to one track.
2. Explain why some multitrack hard disk recording systems can play back much slower than normal speed, but only a little faster.
When a multitrack hard disk recording system plays back audio, it has to retrieve the audio from the hard drive. Playing back audio files at a slower rate is asking the hard disk to transfer data at a slower rate (which it will be able to do). However, for the hard disk to access data at a faster than normal rate than it is built to do is far more difficult. The hard disk can only transfer data to its maximum data transfer rate. Other factors also come into question here such as the data transfer rate of the CPU etc.
3. State TWO major advantages of hard disk recording systems over digital tape recorders.
Two major advantages of hard disk recording systems over digital tape are:
1. You can access the data on hard disks much faster than you can on digital tape.
2. It is far easier to edit from hard disk than from digital tape.
4. Describe THREE major operational advantages of having two modular digital multitrack recorders such as the ADAT or DTRS formats over a format, which records sixteen tracks on the same tape on a single machine.
When you have two modular digital multitracks that can each record 8 tracks, instead of one machine that records 16 track, three major advantages are:
1. You can duplicate cassettes from one machine to the other for backing up files.
2. You could record “alternative-takes” as an example, by first recording the basic rhythm section to a song on the first machines cassette, then record the rest of the tracks (9-16) on the second machines cassette. You could then take a third cassette and record different versions of tracks 9-16. You could continue to do this on a number of cassettes. Once you have tracks 9-16 to your liking, you could then compile the second cassette from all these different takes to go with the original rhythm section you recorded.
3. You could use the second machine to record edits from tracks the first machine.
5. Explain why the punch in process on a hard disk recorder is more flexible than that on an analogue or digital tape recorder.
Punch in on hard disk recorders is more flexible than that on an analogue or digital tape recorder because:
a. You can see the waveform in the software of the hard disk. Being able to see the punch-in points makes the whole process easier.
b. On most hard disk recorders, the recording of the punch in is non-destructive. This means that if a punch-in did not work the first time, the way you wanted it to, you can simply “step back” to before the punch-in took place and do it again.
c. Once the punch-in has been done, any necessary editing can easily be achieved on screen with a hard disk system. This can make some “less than acceptable” punch-ins on a tape system becomes “acceptable” on a hard disk system because they can be edited.
d. You could punch in a little earlier which would make it easier to crossfade once you come to the editing point.
6. With reference to an analogue multi-track recorder briefly explain
a) the term `sync' output
Sync output refers to using the record head as the play head whilst overdubbing with an analogue multi-track recorder.
b) Why the `sync' output is required when overdubbing.
Sync output is required when overdubbing to analogue multi-tracks recorders as a means of getting around the problem of a delay in tracking when recording overdubs. If you were recording a singer, for example, and they were singing in time with the output from the play head, the new vocal being laid down will be recorded late (a few cm) onto tape. The reason for this is because there is a gap between the record and play head. This causes a delay between the monitored and recorded signal. To get around this problem when overdubbing, the “record” head is used as a “play” head. In this situation, “sync output” refers to the playback from the record head (the record head being used in this way).
7. It is common for a multitrack hard disk recording system to be able to store more tracks in synchronization than it can play simultaneously. Why is this?
Same answer as question 1: It is common for a multi-track hard disk recording system to be able to store more tracks in sync than it can play simultaneously.
The extra tracks that can be recorded beyond the normal “track count” of many multi-track hard disks recording systems are called virtual tracks. Many multi-track hard disk systems allow you to record possible “8” virtual tracks on each of the tracks of the recorder. So if your recorder has 24 tracks, it will have 24 tracks x 8 virtual tracks = 192 tracks available, from which you can a maximum of 24 at any one time. These virtual tracks are usually displayed by using a drop down menu beside each track on the software. Having all these tracks available to you means that you have a far greater choice of which take to use than you would on a tape system. Also, you can edit virtual tracks just like any other tracks so you can take 8 virtual tracks of a vocal and “comp” the vocal to one track but you are not using 8 tracks of your recorder because they are all on track one.
8. Some hard disk recording systems have mixing facilities so that several tracks can be mixed into a stereo output. If no other outputs are available why must the system incorporate reverb internally?
In the above system, there are no outputs available to send the signal to an external reverb unit to add the reverb. So if there are no outputs such as “auxiliary sends” the system must incorporate reverb internally to be able to add reverb.
9. What are the two major advantages of hard disk recording systems over digital tape recorders?
This is the same answer as question three above. Two major advantages of hard disk recording systems over digital tape are:
a. You can access the data on hard disks much faster than you can on digital tape, not having to rewind a tape and wait for it to arrive at the correct destination.
b. It is far easier to edit from hard disk than from digital tape and does not involve any splicing of tape or any of the necessary extra equipment to edit tape.
10. What piece of equipment is necessary to use a sequencer with a multitrack tape recorder?
a. A SMPTE Generator / MTC converter is necessary to use a sequencer with a multi-track tape recorder. One such piece of equipment is the Philip Rees TS1 MIDI Tape Sync. Firstly this will generate the SMPTE tone to be recorded onto the multi-track tape. Then it will convert that tone into MIDI Time Code so that the sequencer can read it.
b) Why is it preferable to use MTC rather than MIDI clocks and Song Position Pointers when synchronizing a sequencer to a tape recorder?
It is preferable to use MTC rather than MIDI clocks and SPP when synchronizing a sequencer to a tape recorder because MTC is really a MIDI form of SMPTE.
MTC is really a MIDI form of SMPTE so it is absolute time in hours minutes seconds and frames. This makes it more accurate than MIDI clock or SPP
Multi-track tape recorders use SMPTE Time Code to synchronize to other pieces of equipment. Because SMPTE is a continuous stream of positional data, it knows exactly where it is supposed to be even if it comes across a short section of corrupted code on the tape.MIDI Clock and Song Position Pointers are based upon the musical beats/bars and ticks from the beginning of the song.MIDI Clock does not contain any positional information. It works like the sprocket-holes in a reel of cine film. But with SMPTE, if the MIDI Clock loses the sync pulse, the clock will continue to follow along with the SMPTE Time Code, even if it is one SMPTE pulse late.
c. If MIDI Machine Control (MMC) is not used, describe briefly the two distinct stages of operation when recording a piece of sequenced music to multitrack tape.
If MMC is not used when recording a piece of sequenced music to multi-track tape, the following tow stages of operation are used.
To record a piece of sequenced music to multitrack tape you first have to stripe the tape with SMPTE Time code. This will enable the multitrack to be the master.
Then set the sequencer to sync with the multitrack over a MIDI cable. This could be done with a SMPTE Generator that converts SMPTE to MTC. The recording process can now start.
c) What is the advantage of MMC?
The advantage of MMC is that it allows the user to control the transport features of other machines that are connected to it that use the MMC protocol. Therefore, the user could press record on one machine and it would control the record function of another.
d) In a system using MMC, while playback or recording progresses, the multitrack and sequencer will be running in sync. At this moment which is master and which is slave?
In a system using a multi-track recorder and a sequencer that are using MMC, the sequencer would be the master. Pressing play on the sequencer sends an MMC play message to the multi-track recorder. This then begins to play. As the multi-track plays, it generates MTC which the sequencer chases (synchs to). When stop is pressed on the sequencer, the multi-track also stops, and ceases sending out MTC. When MTC stops, the sequencer stops chasing.
11. You have been given an unlabelled tape to play which starts with a warbling tone. What noise reduction system might have been used?
a. The noise reduction system that might have been used could have been Dolby A. This divides the audio spectrum up into 10 separate bands to reduce noise. The warbling tone is an alignment signal from the encoding processor (the Dolby unit). This is recorded at the start of the tape and is used to calibrate the decoding process on re-play.
b) You have been given an unlabelled tape to play which starts with noise. What noise reduction system might have been used?
Dolby SR noise reduction system might have been used. This gives a pink noise signal as an alignment from the encoding processor (as above).
c) Name three domestic noise reduction systems invented by the Dolby Company.
Three domestic noise reduction systems invented by the Dolby Company are:
a. Dolby B (Dolby’s 1st generation system for the consumer market)
b. Dolby C
c. Dolby S.
d. Give the name of another fairly common analogue noise reduction system.
Another fairly common analogue noise reduction system is DBX. This used a fixed-ratio compressor, which reduced the dynamic range of the signal being recorded.
e. Where would you find the ATRAC digital noise reduction system?
Adaptive TRansform Acoustic Encoding is found on Mini-disc recording systems. It is an audio coding system that takes the input signal and divides it into three sub-bands. These are then transformed into the frequency domain using variable block length. ATRAC compresses CD audio to approx. 1/5th of the original data rate with virtually no loss in sound quality.
12. a. When recording onto analogue or digital multitrack tape, in a situation where synchronization is going to be used what procedure must be carried out before any recording can begin?
When recording onto analogue or digital tape where synchronization is going to be used, SMPTE Time Code must be striped onto a track. On a multi-track tape recorder, it is prudent to stripe the outer or highest-number track with Time Code to reduce the chances of crosstalk.
b. Your studio manager has given you a multitrack tape containing music and timecode to copy. What must you do to ensure that the timecode is copied correctly?
You must ensure that the jam sync function is used when copying the timecode. The reason for this is that timecode degenerates quickly with each copy made. With each new copy, it gets harder for any slave device to read the timecode. The best way to copy timecode is to “regenerate” it. Regenerated Time Code is often called “Jam Sync”. When Jam synching, a time code reader/generator looks at the external incoming time code and “jams” with it, creating a brand new timecode, based on the original sygnal it is “jamming” with. This new time code will be in identical time with the original. Additionally, if there was a piece of the original timecode missing, jam sync will keep supplying new timecode so it will “add” any missing pieces. Jam synching is also good for replacing degraded or defected time code.
c) A multitrack tape of a band with no sequenced instruments was striped with timecode at the start of the session and has subsequently been edited? Would it be good practice to use the existing timecode as a synchronization reference for the console automation system during the mix?
No. If the timecode on this tape has been edited, it would not be reliable. It would be better to regenerate the timecode with jam sync.
d) Referring to c) above, why would it not be a problem to re-stripe the tape with timecode and erase the original timecode, even if the generator does not have a jam sync function?
It would not be a problem to re-stripe timecode on this tape because all the instruments have already been recorded onto the tape. We are adding timecode to a track here as a means of synching this machine to another machine.
Jam sync would only be important if we were keeping the original time code to use to regenerate the new time code with jam sync. As this is not being done, it is no problem to erase the original time code.
e) You have striped timecode on track 24 of an analogue tape and recorded a bass guitar on track 23. When you try and synchronize a MIDI sequencer using a cheap timecode to MTC converter, the sequencer often stops or loses sync. Why?
The most likely reason that the sequencer is stopping or losing sync with the analogue tape is because there could be audio crosstalk. This is the breaking through of the sync tone signal onto audio signal(s). It is usually caused by timecode that has been recorded too hot (above –3dB on pro analogue machines and –7dB on digital recorders).
13. When working with MIDI and multitrack tape, does the multitrack recorder synchronize to the sequencer or does the sequencer synchronise to the multitrack tape?
When working with this system, the sequencer is synchronized to the multi-track tape.
b). When working with an ADAT recorder, why wouldn’t you necessarily have to stripe the tape with timecode to synchronize a sequencer?
The ADAT signal carries its own internal word clock, which is embedded into the signal. As both these systems use clocks, there would be no need to stripe the tape with timecode. To sync the sequencer and the ADAT recorder, you would have to connect a unit such as a JL Cooper DataSYNC2. This will convert the ADAT internal word clock to MTC for the sequencer.
c). Imagine that several tracks of a MIDI sequence have been transferred to multitrack tape. The producer decides that he wants to varispeed the tape a little faster. Should this be done before or after the remaining sequencer tracks have been transferred to tape? Explain your answer.
The varispeed should be done after the remaining sequencer tracks have been transferred to tape. The varispeed needs to be applied to all of the tracks at once. If the varispeed takes place before the additional tracks are added to the tape, this pitch of the additional tracks, when added, will be out of tune with the original tracks (put out of tune by the varispeed operation). I seem to remember a varispeed problem with the Beatles “Strawberry Fields Forever”. Lennon had recorded it at different sessions and the last verse was recorded at a slightly higher pitch. Goerge Martin had to slow it down to keep the correct pitch, hence the slow dragging vocal on the last verse.
14. Noise reduction systems such as dbx and Dolby cause the noise level in a recording to vary. Explain why this is so.
a. What Dolby Noise Reduction does is it prevents noise from being added to the music in the first place. This is done as the music is being recorded to tape.
It is a two-stage process
c. The first stage of the Dolby circuit encodes the music as it is being recorded –making the the quiet parts of the music louder. It works by increasing certain frequencies during recording (encoding)
d. The second part decodes the music as it is being played back. When playing back, the circuit switches around and plays the previously boosted (louder) recorded parts quieter, taking the noise down with it. This is why the noise reduction system should be switched on when both recording and playing back to and from tape.
So the noise varies first, by being increased on record, then decreased on playback.
When recording to tape, the Dolby circuit makes the quiet parts of the music louder. When playing back, the circuit switches around and plays the previously boosted (louder) recorded parts quieter.
15. You have been asked to remix a song (in the sense of creating a completely new version) originally made on multitrack tape in the early 1970s.
a) What would be the main problem in synchronizing a sequencer to the original tape?
If there is no accurate time / tempo based click track or timecode striped on the original tape, the timing will have come from the musicians “natural timing”. So the main problem would be of finding a way of getting an accurate time / tempo based code that would allow you to sync the sequencer to the tape.
b) If you decided only to use the vocal track from the original recording, how would you make the lines fit in time with your new MIDI sequencer arrangement?
The vocal could be copied to the sequencer then cut up into sections and edited (which would probably include editing with timestretch to make the lines fit in time with the new MIDI arrangement). Once the editing is completed, these individual edits could be rendered into a complete track and stored in the sequencer.
c). Suppose you want the song to be around 15% faster in tempo. What should you do to speed up the vocals?
You could use time compression/expansion (timestretch) on the vocal. With timestretching, it leaves the pitch of the signal intact while changing its speed.
d). The record company decides that it wants to keep a lot of the original instrumentation, but also likes your strict tempo MIDI sequence. What type of equipment should you use to put everything together?
I would use a multitrack tape recorder, a DAW with sequencing package, a SMPTE to MTC converter.
I would first copy all the original tracks from the original master tape onto another multi-track tape recorder. Then delete from this copy, one of the tracks that the record company does not want to use. On this track I would stripe time code. I would then run this into a SMPTE to MTC converter and on into a MIDI / audio sequencing package in a DAW or HDR system.
I would record all the tracks from the copied multitrack tape into the sequencer and align them as closely as possible with the tempo the record company liked. Anything not aligned would be timestretched to fit.
16. You are working with a multitrack recorder that will slave to SMPTE/EBU timecode from (for instance) a video machine, but has no other means by which it may be externally controlled. Imagine you stop the master machine, rewind the tape to the beginning and start playing. What will the multitrack do?
The multi-track will go to the SMPTE time position and follow the master? I’m not sure here. I’m not clear about this answer because SMPTE not working whilst in rewind mode. Maybe the tape does not start to rewind until play is pressed on the video?
17. What is the frame rate of NTSC?
The framerate of NTSC is 29.97FPS
18. What is the frame rate of PAL (and SECAM)?
The framerate for PAL and SECAM is 25fps "EBU Time Code" for PAL /SECAM video
19. What is 'drop frame timecode'?
Original black and white TV programs ran at exactly 30fps. Colour TV changed this and runs at exactly 29.97fps. So there is a discrepancy of .03.
To get around this problem there is a SMPTE timecode called Drop Frame Timecode?
To realign the frames, drop frame timecode “drops” two “addresses” of two frames at the beginning of every minute (except minutes 0, 10.20.30.40 and 50 of every hour).
20. Comment on the requirements for recording timecode onto analog tape
To record timecode onto analogue tape you would need to generate a timecode signal and record in onto tape. You could use a SMPTE Generator to generate the timecode. Use the highest track available to record the SMPTE to avoid crosstalk with other audio signals. The timecode signal must be recorded at the correct level, around –3dB for tape. Make sure that the start of the timecode signal comes in before the start of the song.
21. Comment on the problems that occur when using timecode on analog tape
Problems can occur when using timecode on analogue tape if the timecode signal is recorded incorrectly (the signal being recorded too loud or too quiet). This can make it difficult for the slave recorded to read the timecode when synched.
One of the main problems that can occur is audio crosstalk. This is where the timecode signal has been recorded too loud. Timecode that has been recorded at too high a level has a tendency to bleed into other adjacent tracks. As a precautionary measure, always record timecode onto a tapes highest track (and ideally with a blank track between the timecode and the closest audio track.
22. Why must timecode be regenerated when it is copied?
It must be regenerated when it is compied because it may become unreliable it is a second or third generation copy. The slave device would have difficulty synching to it.
23. What is an 'offset'?
An offset is a calculation of the difference in “time addresses” between reels.
If one reel starts at 01:00:00:00 but reel two starts at 01:00:50:00 then there is a 50-second offset for reel two. You can enter an offset value on a synchronizer controller to compensate for this. In the above example, a +00:00:50:00 offset would be entered for machine two. The synchronizer will keep reel two (the slave) 50-seconds ahead of the master (reel one). Offset values will work both ways, so the slave could be either in front or behind the master.
John A
http://www.soundonsound.com/sos/1996_articles/jun96/miditimecode.html
http://www.sweetwater.com/insync/word.php?find=DolbyB
http://www.minidisc.org/aes_atrac.html
http://www.sweetwater.com/insync/word.php?letter=J
Studio Recording Engineer Rane Reference
http://artistpro.com/index.php?module=PnCourses&func=getPage&course_id=21&page_id=125
http://www.soundonsound.com/sos/1997_articles/may97/analysinganalogue.html
http://www.dspdimension.com/html/timepitch.html
http://www.channel101.com/forum/viewtopic.php?t=726
Last edited by JohnA on Thu May 19, 2005 10:54 am; edited 2 times in total |
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Fri May 13, 2005 9:22 am |
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chemira
Joined: 03 Jan 2005
Posts: 50
Location: Nova Scotia Canada Eh! |
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Week 10 Recording Techniques
1. Explain why it is common for a multi-track hard disk recording system to be able to store more tracks in synchronization than it can play simultaneously.
Most multi-track hard disk recorders can store what are called virtual tracks within a specified track number. This creates the capability to select tracks for playback among the takes by selection the track and the take within the track. This also enables mix-down of tracks to another virtual track thereby creating a sub-mix of several tracks bounced down to one or two tracks. This increases the track count potential in the mix but not track simultaneous playback
potential
2. Explain why some multi-track hard disk recording systems can play back much slower than normal speed, but only a little faster.
Multi track hard disk recorders have a limited amount of buffer that can be used for speeding up the playback. Eventually the buffer will deplete to the point that there is not enough data available to play audio. Manufacturers place a limit how much faster the audio can play with stability and quality audio.
3. State TWO major advantages of hard disk recording systems over digital tape recorders.
Hard Disk Recording systems are very capable of performing cut copy and paste edits with ease and ALL of the edits can be non destructive in nature, not affecting the original audio track.
4. Describe THREE major operational advantages of having two modular digital multi-track recorders such as the ADAT or DTRS formats over a format which records sixteen tracks on the same tape on a single machine.
(1) The studio will have more flexibility for archive, playback and out of studio tape formats, (2) small projects could use only one tape or one tape machine saving on tape medium and machine wear and (3) mix/editing by taping eight tracks onto one machine and sub mixing into stereo bussing tracks on the other will increase the track count potential where the 16 track will still only be 16 tracks.
5. Explain why the punch in process on a hard disk recorder is more flexible than that on an analogue or digital tape recorder.
The punch in process on a hard disk recorder will be non destructive and can be manipulated after the punch in occurs. Analogue and/or Digital tape on the other hand is going to overwrite the section therefore making a destructive or permanent edit.
6. With reference to an analogue multi-track recorder briefly explain
a) the term `sync' output
Synch output is the utilization of the recording head as a playback head so that the timing that would normally occur between the playback and recording head is reduced to the point that it is negligible or non existent. The audio quality is not as good as the playback ead but is sufficient enough for monitoring purposes.
b) why the `sync' output is required when overdubbing.
There is no or little delay between the playback and recording timing from the synch output so the recorded track will not de out of time with the rest of the tracks.
7. It is common for a multi-track hard disk recording system to be able to store more tracks in synchronization than it can play simultaneously. Why is this?
Referring to Question (1) there are a limited amount of playback outputs and the recorder will also have a limit to the amount of data that it can access and playback at the designed specification. An eight track recorder may store eight virtual tracks for every real track giving a potential stored and synchronized track count of sixty four. The machines maximum playback potential data wise may only be slightly more that the eight tracks with room for editing processing potential.
8. Some hard disk recording systems have mixing facilities so that several tracks can be mixed into a stereo output. If no other outputs are available why must the system incorporate reverb internally?
If there was no internal reverb then all of the tracks would be receiving the same amount of reverb from the outboard reverb unit. In the example of a drum mix, The snare may need more reverb than the room or overheads and the kick may need no reverb. An internal reverb would address this by only sending the tracks that need the effect to the internal reverb, snare and room, overheads are sent to reverb to the desired effect and the kick is not. This keeps the kick, clean dry and punchy in the drum mix, not boomy or with unwanted echoes.
9. What are the two major advantages of hard disk recording systems over digital tape recorders?
Hard Disk Recording systems are very capable of performing cut copy and paste edits with ease and ALL of the edits can be non destructive in nature, not affecting the original audio track.
10. What piece of equipment is necessary to use a sequencer with a multi-track tape recorder?
A SMPTE Time code generator must be used to stripe the multi track tape first so that the sequencer can lock on to the tapes actual position on the tape. Once the tape has been stripped all devise will use this as a point of reference. [1]
b) Why is it preferable to use MTC rather than MIDI clocks and Song Position Pointers when synchronizing a sequencer to a tape recorder?
MTC is a more accurate synchronization method that will give an absolute reference point to the accuracy of the tapes position.
c) If MIDI Machine Control (MMC) is not used, describe briefly the two distinct stages of operation when recording a piece of sequenced music to multi-track tape.
xx no joy xx
d) What is the advantage of MMC?
MMC allows remote control of any device that can be connected via MIDI cable and can be controlled by System exclusive messages. Each device that can be controlled by MMC can also be assigned an identification number that would allow control of collective or individual devices.
e) In a system using MMC, while playback or recording progresses the multi-track and sequencer will be running in sync. At this moment which is master and which is slave?
As soon as the MMC starts the multi track the multi-track becomes the master and the sequencer will lock up to it.
11. You have been given an unlabelled tape to play which starts with a warbling tone. What noise reduction system might have been used?
b) You have been given an unlabelled tape to play which starts with noise. What noise reduction system might have been used?
c) Name three domestic noise reduction systems invented by the Dolby company.
Dolby B is the first noise reduction system designed for tape recorders invented by Dolby. It gave a ten decibel reduction in noise in the high frequencies that normally contain hiss.
Dolby C is a refinement on Dolby B giving 20 dB reduction in hiss used in mid to premium tape decks and pro VCR’s. Dolby S again reduces hiss by 24Db and also lowers low end noise allowing higher recording levels at the higher and lower frequencies.
d) Give the name of another fairly common analogue noise reduction system.
DBX
e) Where would you find the ATRAC digital noise reduction system?
Adaptive Transform Acoustic Coding is used as an audio compression format for Mini Disc recorders that enables good quality file reduction reducing the size by one fifth. This encoding process also incorporates a noise reduction to reduces quantizing noise that are artifacts of the compression process.
12. When recording onto analogue or digital multi-track tape, in a situation where synchronization is going to be used, what procedure must be carried out before any recording can begin?
The multi-track tape must be encoded or striped with a time code such as SMTE. Without time code reference no other device can lock up to the multi track.
b) Your studio manager has given you a multi-track tape containing music and time code to copy. What must you do to ensure that the time code is copied correctly?
By using Regeneration this will follow the existing time code and re-record a new time code. The reasoning behind the regeneration feature is that for every subsequent recording of the original the signal is degraded.
c) A multi-track tape of a band with no sequenced instruments was striped with time-code at the start of the session and has subsequently been edited? Would it be good practice to use the existing time-code as a synchronization reference for the console automation system during the mix?
Depending on the editing the SMPTE time code may be suspect altered or subject to dropouts. If the tape editing has been completed and there is a track available to record, or rerecord the SMPTE time code, rerecording the time-code is the best solution. The mix has no sequenced instruments so there will be no negative effect rerecording the time-code. The new time-code will be then suitable for automation synchronization.
d) Referring to c) above, why would it not be a problem to re-stripe the tape with time-code and erase the original time code, even if the generator does not have a jam sync function?
There is nothing requiring synch from the original mix, the automation will be performed to the new edited tape.
e) You have striped time-code on track 24 of an analogue tape and recorded a bass guitar on track 23. When you try and synchronize a MIDI sequencer using a cheap time-code to MTC converter, the sequencer often stops or loses sync. Why?
The bass guitar has probably caused enough crosstalk from it’s track to obscure the MTC signal and the cheap time code to MTC converter is not able to lock on.
13. When working with MIDI and multi-track tape, does the multi-track recorder synchronize to the sequencer or does the sequencer synchronize to the multi-track tape?
The sequencer must synchronize to the multi-track tape because it is the most susceptible to stretch and the slowest to respond to timing changes.
b) When working with an ADAT recorder, why wouldn’t you necessarily have to stripe the tape with time-code to synchronize a sequencer?
ADAT recorders transmit MTC so if the sequencer can synch to MTC there is no need to stripe a track with a time-code that the ADAT already transmits.
c) Imagine that several tracks of a MIDI sequence have been transferred to multi-track tape. The producer decides that he wants to vari-speed the tape a little faster. Should this be done before or after the remaining sequencer tracks have been transferred to tape? Explain your answer.
All tracks must be transferred to the multi track tape to ensure that they all stay the same relative altered pitch and all track to the same timing reference.
14. Noise reduction systems such as dbx and Dolby cause the noise level in a recording to vary. Explain why this is so.
15. You have been asked to remix a song (in the sense of creating a completely new version) originally made on multi-track tape in the early 1970s.
a) What would be the main problem in synchronizing a sequencer to the original tape?
Bell Bottoms create a very “flared” low end. This makes the tape warble unless the engineer counter acts this with a brightly colored shirt. Scarves are now illegal and big hair is a moot point. Ahem, I’m still looking for something about a format change or industry standard revision.
b) If you decided only to use the vocal track from the original recording, how would you make the lines fit in time with your new MIDI sequencer arrangement?
Dump the vocal lines into a sequencer edit the tracks for timing and pitch, then trigger them at the appropriate time.
c) Suppose you want the song to be around 15% faster in tempo. What should you do to speed up the vocals?
By using a time compress algorithm set to 87%. This will reduce the vocal lines to fit into the 15% faster tempo.
d) The record company decides that it wants to keep a lot of the original instrumentation, but also likes your strict tempo MIDI sequence. What type of equipment should you use to put everything together?
OK the record company is talking to me in $$ I’m in for pro tools.
Lock it up to a sequencer with all the tracks dumped in to a sequencer editor, keep the timing master/sequencer as the Master and align the tracks to the Midi sequence using a time alignment edit. Some items may need to be sliced into clips to facilitate this. Once all the tracks are in the Daw or hard disk multi track, nudge to keep the alignment tight.
16. You are working with a multi-track recorder that will slave to SMPTE/EBU time-code from (for instance) a video machine, but has no other means by which it may be externally controlled. Imagine you stop the master machine, rewind the tape to the beginning and start playing. What will the multi-track do?
XX no joy XX
17. What is the frame rate of NTSC?
NTSC is set to 29.97 frames of video per second.
18. What is the frame rate of PAL (and SECAM)?
Pal standing for Phase alternating Line 25 frames per second for it’s refresh rate.
19. What is 'drop frame time-code'?
Drop frame time-code is the video standard that followed the 30 frames per second black and white standard which reduced the speed to 29.97 frames per second which allowed the extra time required to transmit the extra information within color video.
20. Comment on the requirements for recording time-code onto analog tape
Time code must be recorded on the tape itself to ensure that if the tape was to stretch the synchronized devices would follow along with the tapes timing increase or decrease.
21. Comment on the problems that occur when using time-code on analog tape
Time code on analogue tape can suffer from dropouts or the adjacent track may impart distortion or inaccuracy onto the time-code track which may affect the accuracy of the following synchronized devices.
22. Why must time-code be regenerated when it is copied?
As a tape is copied the new tape will have a degradation of the time code unless regeneration is selected. Jam Synch is a feature that enables the copying tape machine to interpret damaged time code and create an accurate approximation of the original timing.
23. What is an 'offset'?
Illusive term!!!
[1] http://www.alesis.com/support/cc/sync.html
http://www.beoworld.co.uk/dolby2.htm
http://www.t-station.net/md_tech.html
http://www.jeepjazz.com/handbk.html
http://music.northwestern.edu/links/projects/midi/pages/miditmcn2.html
http://www.borg.com/~jglatt/tech/mmc.htm |
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Fri May 13, 2005 7:52 pm |
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hoaxwagon
Joined: 28 Feb 2005
Posts: 27
Location: Boulder Creek, CA USA |
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hoaxwagon week 10 RT
Yikes this week was a doozy 
1. Explain why it is common for a multitrack hard disk recording system to be able to store
more tracks in synchronization than it can play simultaneously.
One way that Virtual Tracks are used is to store multiple versions of each track (all the takes for
example) in synchronization for sifting through later on (in post production perhaps). A 24 track
recorder can have more than 24 tracks to choose from if the Virtual Tracks are used. This method
of recording sure beats bouncing tracks or parts of tracks around on tape recorders in real time, I
think.
2. Explain why some multitrack hard disk recording systems can play back much slower
than normal speed, but only a little faster.
3. State TWO major advantages of hard disk recording systems over digital tape recorders.
Virtual Tracks and plug ins and quicker access to recorded material (no rewinding and fast
forwarding)
4. Describe THREE major operational advantages of having two modular digital
multitrack recorders such as the ADAT or DTRS formats over a format which records
sixteen tracks on the same tape on a single machine.
The decks can be opperated independantly of one another for effects such as offset to be used.
5. Explain why the punch in process on a hard disk recorder is more flexible than that on
an analogue or digital tape recorder.
The recoreded material on a hard disk recorder can be further edited (non destructivly) after recording therefor making it less critical that the punch in time be perfect.
6. With reference to an analogue multi-track recorder briefly explain
a) the term `sync' output
The term Sync output is the low latency result of the record head pulling double duty. The record
head replays pre-recorded tracks while simultaneously recording another track.
b) why the `sync' output is required when overdubbing.
The sync output is obtainable through the use of sync replay. Sync replay allows the record head
to be used as the replay head for the monitoring of pre-recorded tracks during overdubbing.
Without sync replay a delay would most certainly exist between the material being monitored
from the replay head and tracks being overdubbed using the record head because of the heads
physical distance from one another. The record head doesn’t offer the replay quality that the
replay head does but equalization is used to make up for this. The slightly diminished sound
quality while using sync replay wouldn’t even be an issue if the record head and the play back
head were closer together to begin with.
7. It is common for a multitrack hard disk recording system to be able to store more tracks
in synchronization than it can play simultaneously. Why is this?
The stored tracks are Virtual Tracks that enable a kind of editing unobtainable on tape recorders.
Assembling a track from parts of virtual tracks is a little less cumbersome form of editing than
bouncing tracks back and forth on a tape recording system.
8. Some hard disk recording systems have mixing facilities so that several tracks can be
mixed into a stereo output. If no other outputs are available why must the system
incorporate reverb internally?
An available output on a recorder would be necessary for using an external reverb unit. If no
other outputs are available than a signal can’t be sent to an outboard reverb unit and back to a
recorder input for access to that reverbs effects through an effects loop of sorts. If reverb is what
you want and there are no available outputs on the recorder than the reverb would have be
generated internally.
9. What are the two major advantages of hard disk recording systems over digital tape
recorders?
Non linear editing capabilities, internal digital processing (plug ins) and less maintenance
requirements because of the fewer moving parts are three advantages of hard disk recording
systems over digital tape recorders.
10. What piece of equipment is necessary to use a sequencer with a multitrack tape
recorder?
A format converter (R-BUS, TDIF and ADAT Optical) , or multitrack soundcards (LAYLA) are
necessary for a sequencer to be used with a multitrack tape recorder. When using MTC to sync
the sequencer to the tape recorder, a MIDI cable is connected to the MIDI out of a keyboards
sequencer or MIDI interface to the MIDI input on the tape recorder. The sequencer is the slave
and the recorder is the master.
b) Why is it preferable to use MTC rather than MIDI clocks and Song Position Pointers
when synchronizing a sequencer to a tape recorder?
With MTC mute and fader automation is possible and other MIDI controllable devices can be
slaved and controlled by the master ( the recorder).
A receiving device may take a little while to respond to SSP messages.
c) If MIDI Machine Control (MMC) is not used, describe briefly the two distinct stages of
operation when recording a piece of sequenced music to multitrack tape.
Striping the multitrack tape with timecode and synchronizing the sequencer to the multitrack
would be the first step. The actual recording would be another. Cue up the sequencer so it is
where you want it to be and start playing the sequenced material at the same time you start record
on the multitrack. This one has me stumped.
d) What is the advantage of MMC?
MMC can be used with remote automation to control Modular Digital Multitracks.
e) In a system using MMC, while playback or recording progresses the multitrack and
sequencer will be running in sync. At this moment which is master and which is slave?
The sequencer sending MMC would be the slave while it reads MTC from the recorder.
11. You have been given an unlabelled tape to play which starts with a warbling tone. What
noise reduction system might have been used?
Dolby A
b) You have been given an unlabelled tape to play which starts with noise. What noise
reduction system might have been used?
Dolby SR
c) Name three domestic noise reduction systems invented by the Dolby company.
Dolby B , Dolby C , Dolby S-Type
d) Give the name of another fairly common analogue noise reduction system.
DBX
e) Where would you find the ATRAC digital noise reduction system?
ATRAC (Adaptive Transform Acoustic Coding) digital noise reduction is used by SONY’s
MiniDisk.
12. When recording onto analogue or digital multitrack tape, in a situation where
synchronization is going to be used, what procedure must be carried out before any
recording can begin?
Time code would be recorded onto the tape and the various machines should be synchronized
before starting any recording..
b) Your studio manager has given you a multitrack tape containing music and timecode to
copy. What must you do to ensure that the timecode is copied correctly?
The time code will need to be regenrated, using a generater, when copying.
c) A multitrack tape of a band with no sequenced instruments was striped with timecode at
the start of the session and has subsequently been edited? Would it be good practice to use
the existing timecode as a synchronization reference for the console automation system
during the mix?
If the tape has been edited (spliced) then the integrity of the timecode on the tape has been
compromised. Perhaps not the best way to enable console automation. MMC can be used to send
messages for use in automation.
d) Referring to c) above, why would it not be a problem to re-stripe the tape with timecode
and erase the original timecode, even if the generator does not have a jam sync function?
the jam sync function allows the generator to lock to an external timecode and is not necessary in
this case when a all you want to do is re-stripe a tape with timecode.
e) You have striped timecode on track 24 of an analogue tape and recorded a bass guitar on
track 23. When you try and synchronize a MIDI sequencer using a cheap timecode to MTC
converter, the sequencer often stops or loses sync. Why?
Crosstalk between the two tracks can cause the sequencer to lose sync.
13. When working with MIDI and multitrack tape, does the multitrack recorder
synchronize to the sequencer or does the sequencer synchronize to the multitrack tape?
The sequencer synchronizes to the multitrack tape reading its MTC. MMC return messages are
also sent back to the sequencer to finish the ‘hand shake’ between the 2 devices.
b) When working with an ADAT recorder, why wouldn’t you necessarily have to stripe the
tape with timecode to synchronize a sequencer?
Because the deck itself has internal timecode and a sequencer can slave to it.
c) Imagine that several tracks of a MIDI sequence have been transferred to multitrack
tape. The producer decides that he wants to varispeed the tape a little faster. Should this be
done before or after the remaining sequencer tracks have been transferred to tape?
Explain your answer.
To Varispeed the tape a little faster can be done before the rest of the tracks and then after
recording the rest of the tracks you can set the VariSpeed control back to neutral and the recorded
track's pitch will be equal to the song's pitch.
14. Noise reduction systems such as dbx and Dolby cause the noise level in a recording to
vary. Explain why this is so.
Because some Dolby systems work on 4 separate bands of frequencies independently the noise
reduction in one bands relationship with the noise reduction in another band is a constantly
changing ratio that hopefully is not so audible but the varying noise level is taking place.
DBX with its 30 db of noise reduction has a fixed degree of compression/expansion and does not
depend on the level of the music therefor a modulation of background hiss is sometimes audible,
and in music with a wide dynamic range this modulation is most evident.
15. You have been asked to remix a song (in the sense of creating a completely new version)
originally made on multitrack tape in the early 1970s.
a) What would be the main problem in synchronizing a sequencer to the original tape?
A problem would arise if there was not a blank track on the tape onto which timecode can be
stripped.
The main problem would be the tape age. If the tape is old enough or has been stored improperly
than the tape could be shedding. This leads to rescue attempts like baking the tape. It would be
hard to record onto a tape in such condition.
b) If you decided only to use the vocal track from the original recording, how would you
make the lines fit in time with your new MIDI sequencer arrangement?
Using MIDI Machine Code and MTC to create the sequencer (master) to multitrack (slave)
senereo. The sequenced part can now be rolling along and when it gets to the point where the
vocals are to come in the cued up multitrack starts playing the vocals. You could just record the
vocal part into the sequencer (Pro Tools) and combine the parts together there.
c) Suppose you want the song to be around 15% faster in tempo. What should you do to
speed up the vocals?
There is a software plug in for Protools called speed that can change the pitch of the song
(including the vocals) without changing the tempo or can change the speed of the song without
altering the pitch. I would use this type of processing for the above situation.
d) The record company decides that it wants to keep a lot of the original instrumentation,
but also likes your strict tempo MIDI sequence. What type of equipment should you use to
put everything together?
A time code generator, MIDI cables, synchronizer, MIDI sequencer and a multitrack recorder
would be used to put all this material together.
16. You are working with a multitrack recorder that will slave to SMPTE/EBU timecode
from (for instance) a video machine, but has no other means by which it may be externally
controlled. Imagine you stop the master machine, rewind the tape to the beginning and
start playing. What will the multitrack do?
The multi-track (slave) would follow the video machine (master) and go to its beginning since
they are in sync with one another.
17. What is the frame rate of NTSC?
the frame rate of NTSC is 29.97 frames per second. SMPTE drop frame time code is the same
rate
18. What is the frame rate of PAL (and SECAM)?
Also called EBU, PAL and SECAM has a frame rate of 25 frames per second
19. What is 'drop frame timecode'?
Drop frame time code has 29.97 frames per second and by means of dropping 2 frames every
minute except for every 10th minute the true video (30fps timecode) can stay synchronize with
NTSC video (29.97 Drop Frame). Its accuracy results in only a 75 milli-second drift in 24 hours.
20. Comment on the requirements for recording timecode onto analog tape
There should be a track on the edge of the tape that is open (track 1 or track 24 if working with a
24 track machine. The multitrack should have a sync input so the timecode generator can be
locked to the speed of the tape.
21. Comment on the problems that occur when using timecode on analog tape
I think that the time code can only be read while the tape is running.
22. Why must timecode be regenerated when it is copied?
since timecode is on the tape it can suffer from drop out and need to be regenerated to ensure a true time code is being copied.
23. What is an 'offset'?
An offset is the mathematical difference between two different time codes. An offset is created
when a synchronizer keeps a slave multitrack deck a determined amount of time ahead or behind
a multitrack master deck |
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Sat May 14, 2005 12:56 pm |
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rachelh
Joined: 16 Jan 2005
Posts: 35
Location: Trinidad WI |
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RT -WEEK 10 - MIDI
1. Explain why it is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously.
It is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously, because with synchronisation between devices, the number of available tracks are combined but for simultaneous playback of all utilised/ combined tracks, more memory than is associated with any one machine is needed; synchronisation does not necessarily increase the memory resources for a device when it is put to join forces with another similar device it merely allows the devices to work together simultaneously in a real time environment. For multitrack hard disk recorders the limit on the number of tracks that can playback simultaneously is reliant on the amount of memory available and the capabilities of the processor. Thus, virtual tracks are often incorporated to store ‘unplayable tracks’ that cannot be allocated to an output, but can be exchanged with a real track when or if the need arises.
2. Explain why some multitrack hard disk recording systems can play back much slower than normal speed, but only a little faster.
Some multitrack hard disk recording systems can play back much slower than normal speed, but only a little faster because slower playback calls for less of the systems resources while a faster playback time will call for more resources to be utilised, which might not be comparable with the capabilities of the processor, thus the system may stop playing, freeze, or crash, or simply drop out may occur.
3. State TWO major advantages of hard disk recording systems over digital tape recorders.
Two major advantages of hard disk recording systems over digital tape recorders are
I. To optimise the performance of a hard disk recording system the most the engineer/ user has to do to periodically defragment the disk, erase it or add more memory, for a digital tape recorder one has to go through the task of hiring a technician to clean the parts and align the playing heads, attempting to do this on ones own can prove disastrous to the system, often costing thousands of dollars. Thus in terms of maintenance, hard disk recording systems are easier to maintain than digital tape recorders.
II. Price – hard disk recording systems not only are cheaper than digital tape recorders but, are also cheaper to maintain, especially when it comes to maintenance and replacing/ acquiring new tape cartridges, whilst the disk has infinitely more memory than a tape and this info can be easily transferred to a CD ROM which in essence is way cheaper than a tape cartridge.
4. Describe THREE major operational advantages of having two modular digital multitrack recorders such as the ADAT or DTRS formats over a format, which records sixteen tracks on the same tape on a single machine.
In the situation that we are presented, both ADAT and DTRS have 8 tracks each thus the total output of tracks would be 16 if the machines are synchronised together, the same as the single machine. Thus, the advantages of this synchronisation would have to do with
I. Firstly editing. Editing would be made easier as one segment of audio can be easily moved to another track on the other machine, also tracks can be easily bounced in the digital domain- thus no signal degradation.
II. One machine can be used to edit and the other can be used to store edited audio
III. Bouncing can be made easier.
5. Explain why the punch in process on a hard disk recorder is more flexible than that on an analogue or digital tape recorder.
The punch in process on a hard disk recorder is more flexible than one on an analogue or digital tape recorder because punching-in in the analogue domain would mean that the pitch would have to be the same to blend in with the parts before and immediately following the punch-in, this is a difficult task to achieve on tape whilst in the digital domain automated punch –ins are blended smoothly with existing data via update mode which can be used to go back at a later time to alter mix settings originally written to memory, once a control is altered or if automation is re-recorded or reversed in the input strips the updated settings can be changed by adding or subtracting from the track data rather than completely re-writing it. In this way complex moves can be obtained and remain intact while other changes are implemented. The data is blended smoothly due to the process of level matching which ensures that the punched in data levels correspond to the pre-existing ones, allowing for seamless transition. When using a moving fader this is automatic, for VCA this is done manually by observing the nulling indicator.
6. With reference to an analogue multi-track recorder briefly explain
a) the term `sync' output
The sync output refers to the process by which the record head is used as a playback head.
b) Why the `sync' output is required when overdubbing.
Sync output is required when overdubbing because of the necessity to be able to listen to or monitor previously recorded tracks whilst performing an overdub. The gap between the record and playback heads makes this difficult as it causes a delay in the recorded signal; thus, the record head is used as a playback head – in a process known as sync output. This sync output is not of the best sound quality as the recording head is not meant for playback but, the sound produced is good enough for monitoring and thus serves this purpose.
7. It is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously. Why is this?
It is common for a multitrack hard disk recording system to be able to store more tracks in synchronisation than it can play simultaneously, because with synchronisation between devices, the number of available tracks are combined but for simultaneous playback of all utilised/ combined tracks, more memory than is associated with any one machine is needed; synchronisation does not necessarily increase the memory resources for a device when it is put to join forces with another similar device it merely allows the devices to work together simultaneously in a real time environment. For multitrack hard disk recorders the limit on the number of tracks that can playback simultaneously is reliant on the amount of memory available and the capabilities of the processor. Thus, virtual tracks are often incorporated to store ‘unplayable tracks’ that cannot be allocated to an output, but can be exchanged with a real track when or if the need arises.
8. Some hard disk recording systems have mixing facilities so that several tracks can be mixed into a stereo output. If no other outputs are available why must the system incorporate reverb internally?
In the above situation, reverb would have to be incorporated internally because there are no available outputs to connect an external reverb device.
9. What are the two major advantages of hard disk recording systems over digital tape recorders?
Two major advantages of hard disk recording systems over digital tape recorders are
I. To optimise the performance of a hard disk recording system the most the engineer/ user has to do to periodically defragment the disc, erase it or add more memory, for a digital tape recorder one has to go through the task of hiring a technician to clean the parts and align the playing heads, attempting to do this on ones own can prove disastrous to the system, often costing thousands of dollars. Thus in terms of maintenance, hard disk recording systems are easier to maintain than digital tape recorders.
II. Price – hard disk recording systems not only are cheaper than digital tape recorders but, are also cheaper to maintain, especially when it comes to maintenance and replacing/ acquiring new tape cartridges, whilst the disk has infinitely more memory than a tape and this info can be easily transferred to a CD ROM which in essence is way cheaper than a tape cartridge.
10. What piece of equipment is necessary to use a sequencer with a multitrack tape recorder?
The equipment necessary to use a sequencer with a multitrack tape recorder is a SMPTE time code converter, which would be used to apply time code to the data on the multitrack tape, to make it compatible with the sequencer. If a MIDI device was being used, a MTC to SMPTE converter would have to be utilised.
b) Why is it preferable to use MTC rather than MIDI clocks and Song Position Pointers when synchronising a sequencer to a tape recorder?
It is preferable to use MTC rather than MIDI clocks and SPP when synchronising a sequencer to a tape recorder because MTC provides a cost effective and easily implemented way of transmitting SMPTE time code which allows a break down of hours: minutes: seconds: frames whilst SPP and MIDI clocks synchronise to tempo speeds.
c) If MIDI Machine Control (MMC) is not used, describe briefly the two distinct stages of operation when recording a piece of sequenced music to multitrack tape.
If MMC is not used the two distinct stages of operation when recording a piece of sequenced music to multitrack tape are:
I. Formatting the tape, placing time code on it – or to stripe the tape
II. Recording the sequenced music onto the formatted tape
d) What is the advantage of MMC?
MMC/ MIDI Machine Control allows for MIDI sequencers, hard disk recorders, tape and video transports and other recording systems to be remotely controlled via MIDI.
e) In a system using MMC, while playback or recording progresses the multitrack and sequencer will be running in sync. At this moment which is master and which is slave?
In the above system the master would most likely be the multitrack.
11. You have been given an unlabelled tape to play which starts with a warbling tone. What noise reduction system might have been used?
b) You have been given an unlabelled tape to play which starts with noise. What noise reduction system might have been used?
c) Name three domestic noise reduction systems invented by the Dolby company.
Dolby, D, S, and C are three domestic noise reduction systems invented by the Dolby noise company.
d) Give the name of another fairly common analogue noise reduction system.
The name of another fairly common analogue noise reduction system is
e) Where would you find the ATRAC digital noise reduction system?
12. When recording onto analogue or digital multitrack tape, in a situation where synchronisation is going to be used, what procedure must be carried out before any recording can begin?
In the abovementioned situation the procedure that should be carried out before all else is to format the tape, that is, striping time code onto it.
b) Your studio manager has given you a multitrack tape containing music and timecode to copy. What must you do to ensure that the timecode is copied correctly?
If the studio manager gives a multitrack tape containing music and timecode to copy to ensure that the timecode is copied correctly one has to make sure that the tape onto which the audio is being recorded to is striped with timecode whether SMPTE or MTC. A Jam Sync device can be utilised to make sure that there is linearity during the recording.
c) A multitrack tape of a band with no sequenced instruments was striped with timecode at the start of the session and has subsequently been edited? Would it be good practice to use the existing timecode as a synchronisation reference for the console automation system during the mix?
It would be in good practice to utilise the existing timecode reference for the console automation during the mix as it contains references to edit points and so on, if the tape was not edited it would be okay to re-stripe the entire tape [since there were no sequenced instruments in the first place]. A Jam Sync generator can be utilised in this process, as it would ensure that the data being transferred and recorded onto the medium is distortion free, the Jam Sync option that I deem useable for this situation is Continuous Jam Sync whereby the original address numbers are kept intact.
d) Referring to c) above, why would it not be a problem to re-stripe the tape with timecode and erase the original timecode, even if the generator does not have a jam sync function?
In this situation it would not be a problem to re-stripe the tape with timecode and erase the original timecode because no sequenced instruments were utilised in the original stance.
e) You have striped timecode on track 24 of an analogue tape and recorded a bass guitar on track 23. When you try and synchronise a MIDI sequencer using a cheap timecode to MTC converter, the sequencer often stops or loses sync. Why?
In this case, the sequencer would often stop or loose sync because the converter was unable to convert the timecode accurately.
13. When working with MIDI and multitrack tape, does the multitrack recorder synchronise to the sequencer or does the sequencer synchronise to the multitrack tape?
When working with MIDI and multitrack tape the sequencer synchronises to the multitrack tape.
b) When working with an ADAT recorder, why wouldn’t you necessarily have to stripe the tape with timecode to synchronise a sequencer?
When working with an ADAT recorder it wouldn’t be necessary to stripe the tape with timecode to synchronise a sequencer because the ADAT recorder comes with its own sync clock which in essence is independent of SMPTE.
c) Imagine that several tracks of a MIDI sequence have been transferred to multitrack tape. The producer decides that he wants to varispeed the tape a little faster. Should this be done before or after the remaining sequencer tracks have been transferred to tape? Explain your answer.
The varispeed of the tape should be done after all tracks have been transferred onto the tape to ensure that the time relationship between all tracks stay constant – they maintain their real-time relationship. After the varispeed if you add additional audio which came from the original source of the ‘varispeed audio’ it would playback at a rate which is slower than the existing audio on the tape which has been made to play faster. The only way to ensure that audio added after the varispeed is in time with it is to speed it up to that level on its original source before transferring it onto the tape.
14. Noise reduction systems such as dbx and Dolby cause the noise level in a recording to vary. Explain why this is so.
15. You have been asked to remix a song (in the sense of creating a completely new version) originally made on multitrack tape in the early 1970s.
a) What would be the main problem in synchronising a sequencer to the original tape?
The main problem in synchronising a sequencer to the original tape would be
b) If you decided only to use the vocal track from the original recording, how would you make the lines fit in time with your new MIDI sequencer arrangement?
c) Suppose you want the song to be around 15% faster in tempo. What should you do to speed up the vocals?
d) The record company decides that it wants to keep a lot of the original instrumentation, but also likes your strict tempo MIDI sequence. What type of equipment should you use to put everything together?
16. You are working with a multitrack recorder that will slave to SMPTE/EBU timecode from (for instance) a video machine, but has no other means by which it may be externally controlled. Imagine you stop the master machine, rewind the tape to the beginning and start playing. What will the multitrack do?
17. What is the frame rate of NTSC?
The frame rate for the National Television Standards Committee is 29.97 fr/sec.
18. What is the frame rate of PAL (and SECAM)?
The frame rate for PAL and SECAM is 25 fr/sec.
19. What is 'drop frame timecode'?
Drop frame time code refers to the code applied to a synchronised setting utilising a colour program as the medium. Because of the fact that Black and White/ monochromatic [non-drop frame time code] has a code rate of 30 frames per second and the rate for colour [set by the NTSC [National Television Standards Committee] for the USA and Japan] is 29.97 frames per second there is a .03 second difference in rate between the two. Thus if a time code reader set up to optimally read the monochromatic program was being utilised to read a coloured program there would be an excess of time 108 frames in an hour, thus the extra 3.6 seconds are dropped from each frame during the playback at an average of 2 frame counts per minute, with the exceptions of minutes: 00,10,20,30,40,50.
20. Comment on the requirements for recording timecode onto analog tape
To record timecode onto analogue tape the requirements are that
21. Comment on the problems that occur when using timecode on analogue tape
The problems associated with using timecode on analogue tape arise from
22. Why must timecode be regenerated when it is copied?
Time code should be regenerated when it is copied because during synchronisation the linearity of the waveform may be compromised. The jam sync function found on many synchronisation machines is designed to combat this problem thus turning a distorted wave into a restored linear square wave. The two options available for jam sync are one-time jam sync where the entire time code is re written and continuous jam sync where the actual time code of the original waveform is utilised
23. What is an 'offset'?
An offset is the process by which synchronised material can be edited that is, the time can be edited if it is off cue, meaning that one can take off and even add in time as improve the synchronisation process. An offset is needed when there is a time discrepancy between two or more transports. |
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Mon May 16, 2005 3:32 am |
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