why is -10 "hotter" than +4?

[maskedman72]

i thought -10 was 10db below zero db(quiter),and +4 is 4db above zero(louder).
if this is true why is it when i switch to -10 it is hotter? i thought it was better to run your gear at +4. if the signal is weaker at +4 than you would want to run at -10 right? you wouldnt have to crank the pres as much resulting in less noise. could someone shed some light for me?

 

[spankenstein]

Becuase it's what the signal is.

At -10db it's expecting to have to bring a -10db signal to 0db where at +4 it's expecting to pad a +4db down to 0db

 

[Blue Bear Sound]

I'm afraid you both have got it all a bit mixed-up.....

First of all, the units for each are different, because their respective voltage references are different...

0 dB VU on gear running at +4 dBu translates to an actual voltage level of 1.228 VRMS.

0 dB VU on gear at -10 dBV translates tor 0.316 VRMS.

Notice the difference in units (and neither of them are dB!)

Also note that there is an 11.79 dB difference in level between the lower -10dBV signal and the higher +4dBu signal....

When it comes to combining gear that operate at different gain structures, you really have to pay attention to the level a particalur connection is expecting....

 

[DonF]

Blue Bear, you are absolutely correct. But it's still very confusing. There's a really good explanation of decibels (with all the various references explained) at www.tonmeister.ca.

 

[maskedman72]

Also note that there is an 11.79 dB difference in level between the lower -10dBV signal and the higher +4dBu signal....

but the -10 signal is the higher one.

im still a bit confused.

 

[Blue Bear Sound]

Then you've got a mismatch in gain structure somewhere in the chain and you're misunderstanding the relationship between the gear you're interconnecting. A signal level of 0.316 vrms (-10dBV) can never be stronger than a signal of 1.228vrms (+4dBu).......

The +4dBu gain structure has the higher signal level (ie, further away from the noise floor than a -10dBV signal by 11.79 dB)

You have to understand the ratios are relative -- if you feed a +4dBu signal into a unit that expects to run at -10dBV, that signal will be appear to be EXTREMELY hot at the inputs. Contrast this to a unit that expects a +4dBu signal will see a -10dBV signal as requiring excessive gain on input (ie, it's too low).....

 

[noisedude]

can anyone offer any links to any good articles on gain structure? i've read loads but still have a gap in my understanding and i guess there are some others with the same problems. i understand the decibel system, that it's logarithmic etc and is not an absolute measurement, but when it comes to whether i set my sound card inputs to expect +4, line or -10 i'm never quite sure. am i right to guess that my mixer outputs at line? (is that not the point of it in fact?)

 

[DonF]

can anyone offer any links to any good articles on gain structure?

http://www.mmproductions.co.uk/gain1.html

 

[Blue Bear Sound]

You have to know what kinds of signals your gear expects.... but it's not much of an issue unless you mix 'n match consumer/semi-pro/pro gear....

Line-level of 99% of consumer gear is at the -10dBV level, while 99.9% of pro gear operates at the +4dBu gain structure. Semi-pro is more varied - operating at one or the other, and sometimes has switches to operate at either.

Normally, the idea is to make sure all your gear is inter-connected at the same gain structure level. It's when you mix it up that you run into difficulty.

 

[maskedman72]

so +4 yeilds the highest quality?
the back of my mp2nv has 1/4 inch outputs that say "-10 unbalanced"
does that mean that the xlr ouputs are +4 balanced?(i would assume so)
so when connecting the 1/4 inch -10 outs of the 2nv into the inputs on my digi 002 rack that has a -10/+4 selector switch,put that switch to -10 right? and if i use the xlr's put the switch to +4?
so what this means is that if you have a -10/+4 switch on a input,that switch's position determines what that input jack expects to see signal wise?

 

[Blue Bear Sound]

By george, I think you've got it!!!

 

[Aloha]

I'd just like to add one thing that I think is relevant. You can have both a balanced and unbalanced signal at either level. Which means that contrary to popular belief -10 levels can be balanced sometimes and not all +4 levels are balanced all the time.

 

[Blue Bear Sound]

TRUE - but I didn't bring the point up here because the topic didn't specifically come up, and there's already enough confusion about gain structure and balanced/unbalanced wiring I didn't think there was a need to introduce it!

 

[Aloha]

No doubt!

 

[krimson]

Just to confuse some more....

I have a Mackie 1642 and its meters at 0 are .775V. My question is what do i hookup the di from the preamps to my RME Multiface which can be selectable of -10, +4, and one other one that is much higher than +4 but I can remember right now?

 

[Rev E]

There's a really Thorough with a capital "T" article on www.prorec.com. Here it is: http://www.prorec.com/prorec/articles.nsf/files/EA68A9018C905AFB8625675400514576

It explains in great detail what Blue Bear and a few other said in brief. It will answer all of your questions and more.

Here's part II of that article http://www.prorec.com/prorec/articles.nsf/articles/3F50D03B51D16EF386256904007DFFC0

 

[Blue Bear Sound]

Great article link Rev!

 

[maskedman72]

thanks for all the info everyone.