conquistadore
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Joined: 03 Aug 2004
Posts: 514
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| dBu and dBv |
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dBu and dBv is the same? (0dBu/0dBv = 0.775volts??) |
Mon Aug 08, 2005 7:19 am |
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wailingalleycat
Forum Manager
Joined: 07 Oct 2003
Posts: 694
Location: Jersey C.I (UK) |
| Maximum signal level |
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The signal level in a mixer peaks at 1V correct? aka +24dBu
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If In Doubt...Hit It With a Hammer, If Still In Doubt... Find a Bigger Hammer. |
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Mon Aug 08, 2005 1:55 pm |
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AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| nope |
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Nope..
As I said above 0dBu = 0.775 volts
0dBV = 1 volt...
That's the zero level on the meters you need to check the manual for the reference levels yours uses.
edited for typo
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Last edited by AUdIoCoUrSeS on Wed Aug 10, 2005 7:00 pm; edited 1 time in total |
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Mon Aug 08, 2005 8:10 pm |
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wailingalleycat
Forum Manager
Joined: 07 Oct 2003
Posts: 694
Location: Jersey C.I (UK) |
| 1 Volt peak to peak |
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No i mean 1V is the peak power output of a mixer isnt it, so that would be +24dbu, anything more and it clips and distorts, hence the term "1 volt peak to peak"
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If In Doubt...Hit It With a Hammer, If Still In Doubt... Find a Bigger Hammer. |
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Tue Aug 09, 2005 1:05 pm |
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conquistadore
Forum Moderator
Joined: 03 Aug 2004
Posts: 514
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| dbv |
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Yes 0dBV = 1 volt. But I have also come across dBv (in lower case). Is it some kind of print error then? |
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Wed Aug 10, 2005 8:36 am |
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AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| Re: 1 Volt peak to peak |
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quote:
Originally posted by wailingalleycat
No i mean 1V is the peak power output of a mixer isnt it, so that would be +24dbu, anything more and it clips and distorts, hence the term "1 volt peak to peak"
No wailing you are right off the mark here my friend and need some grounding in maths and electronics.
Basically what we are discussing here is "reference levels".
Reference levels are needed when we talk about decibels because decibels as a unit in themselves have no meaning, there is no such thing as "a decibel". A decibel is a means to compare two quantities, it is a means to say level x is so many more times greater or smaller than level y. Therefore we we need some kind of reference point to give level x some meaning, this is where reference levels come in handy.
The list below is the currently exhaustive list you will need:
dBV = 1 volt (notice the upper case V)
dBu = 0.775 volt (European standard)
dBv = 0.775 volt (USA standard)
dBm = 1 milliwatt
dBA = dB SPL, A-weighted response
Now we have some actual reference points we can play with the maths.
For voltages the formula for decibels is:
dB = 20 log (V1/V2)
Lets say we have two voltages V1 = 2 volt and V2 = 1 volt
Working this out with our formula we arrive at:
dB = +6
If we take your example, Wailing, and use the +24dB against a 0dBu referenced desk (as yours is) we can ascertain the unknown voltage.
e.g.
+24dBu = 20 log (?/0.775)
So lets rearrange the equation:
First we will remove the multiply by 20 which gives
24/20 = log (?/0.775)
1.2 = log (?/0.775)
Then the log function:
15.9 = ?/0.775
? = 15.9 x 0.775
? = 12.4 volts out of your mixer if you have +24dB above 0dBu set.
Suprised? - well if you think it through most quality desks are designed to provide enough headroom for normal operating conditions through a decent power supply and internal circuitry. Coupled with that, a standard VU meter (nothing to do the the u abbreviation in reference levels) when set to 0dBu will read -4VU, which is PPM4. So it is really difficult to "clip" the output of your mixer,.
I have used a cigarette box over the needles before when by standers have commented "you're in the red mate", .... mere mortals huh?
p.s. you are also confusing power as volts are not power, watts are.
p.p.s. a doubling of voltage is +6 which is a handy way of quick calculations.
_________________
It's all in the ears. - Learn the concepts not the software.
Audio Courses is a way into the music business for you
Last edited by AUdIoCoUrSeS on Fri Aug 12, 2005 8:49 pm; edited 1 time in total |
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Wed Aug 10, 2005 6:59 pm |
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conquistadore
Forum Moderator
Joined: 03 Aug 2004
Posts: 514
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| dBv,dBV,dBu |
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Yeah, so dBv=dBu, except that dBu is used more commomly to avoid confusion with dBV. |
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Fri Aug 12, 2005 5:59 am |
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