+4dBU or -10dBV

I have never use ff800 but to my knowledge, it would mean to adjust the gain of the singal to or fr. the interface if it is too low, it can be step up by +4 bdu if its high, then go with -10dbv to take it down, like wise the outs, these application applies to some interface, such as delta1010 its eighter you boast or you cut, in the level of decibels which monitor the singnal.

Fr. Blayzay.

Yes, it does have to do with what kind of gear you use. Impedance, I am pretty sure not.

Consumer gear, and sometimes "prosumer" gear run on -10 dBV. It's a different voltage reference than what pro gear runs on, which is + 4 dBu. Do note, these are different references so it's not actually +14 dBU/dBV difference. Although the + 4 dBU carries a stronger signal, which from what we are learning about in our Intro To Studio Maintainence class, helps keep down noise from outside sources. Also note that most pro gear is strictly balanced cabling and consumer and some "prosumer" gear runs on unbalanced.

So yes, it does depend on what gear is going into where. It's mostly to keep levels in check and in accordance with one another.

This section below should explain it better... found it on an Sound on Sound forum, http://sound-on-sound2.infopop.net/2/OpenTopic?a=tpc&s=215094572&f=884099644&m=2 433075903


Not sure if this will answer your question but I'll throw it out anyway. I've heard that there is no real difference between -10dBv and +4dBu. They're just different ways of describing the same thing.
taken from a great article on db at http://www.prorec.com/prorec/articles.nsf/files/EA68A9018C905AFB8625675400514576
There has always been a lot of confusion about the whole issue of the nominal operating level of "professional" gear versus the nominal operating level of so-called "consumer" gear.
You may have heard that professional gear is "+ 4 dBu" and consumer gear is "- 10 dBV." Because only professionals used this stuff back when it was new (and expensive!) technology, and the older dBu designation was all they had to work with, the original designation of operating level (expressed in dBu) has stuck. By the time consumer audio products were introduced in a big way, the dBV has been invented, and so dBV was used for consumer gear. (Remember, they are both simply ways of comparing voltage levels -- nothing more. That + 4dBu is somehow inherently "better" than -10 dBV is a big, fat myth, kept alive by the somewhat arbitrary labels of "professional" and "consumer" attached to them.)
I'll just bet that a lot of you have glanced at this "+4 / -10" thing, and just assumed that the difference between the levels is 14 dB. But now we know better, don't we?
The reason the difference isn't 14 dB is because the reference levels between dBu and dBV are different! Remember, dBu is referenced to a voltage level of .775 V, and dBV is referenced to 1V. Armed with the knowledge you now possess, can you figure out what the true difference in operating level is, between + 4 dBu and -10 dBV?
+ 4 dBu = 20 * log (voltage / .775 V)
voltage = 1.228 Volts
- 10 dBV = 20 * log (voltage / 1V)
voltage = 0.3162 Volts
20 * log (1.228V / 0.3162V) = 11.79 dB
You can confirm this by doing a little experiment. Plug a piece of consumer gear with -10 dBV outputs into a piece of gear with + 4 dBu inputs. If they both have VU meters, calibrated such that 0dBVU on each piece of gear corresponds to it's nominal operating level, you'll find that 0dBVU on the consumer gear causes a reading of -11.79 dBVU on the pro gear's meters.


Hope that helps!

~trevor

PowerMac G5 Dual 2.0 Ghz, Rev. C, 2.5GB Ram. Logic 7.1.1, Presonus FireBox. Mac OS X (10.4.9)

You are so right it will run eighter way, it just depends on what gear you're using.

Hi,

You can look at all the gear you own and use.Then determine how much of it is +4 "pro" level,and how much is -10 "consumer" level.

Also,electrically,if you are using long cable runs which are balanced,it's best to have them use +4,which means they will cause less RF interference.Otherwise,if you have shorter runs (15ft or less) you can use the -10 with no fear of singal degradation,unless you are under a radio transmission antenna 😉

According to Bob Katz,there are good and bad things about each operating level.You can go to his website,and read up on his opinion.I agree with some of what he says.

In the end,what you use should be determined by what works with each patricular piece of gear.Follow the gear manufacturer's specs.And even more importantly,follow your ears.If some piece of gear does not sound right,then correct the issue.

Cheers

Allow me to add to this.

+4dBu is "louder" signal. Its does not reduce interference. Interference remains the same but it will be lower in level relative to +4dBu compared to a -10dBV line level and so the signal to noise ration will be better for +4dBu (ie the interference will sound less). Please excuse my pedantic point.

Consumer gear uses -10dBV as the reduced voltage level means you can use cheaper componants (less demands on power supply and less heat for eg).

+4dBu outputs usually signifies a balanced line - something that is desirable (assuming you have +4dBu inputs!).

feed a +4dBu output into a -10dBV input and you could get overload distortion. You'll have less "headroom". You could get problems due to feeding a balanced source to a non-balanced input too. It is quite common though that where there is a switch to change your inputs from +4 to -10 that the -10dBV will also accept a balanced line. Yes, -10dBV ~can~ be balanced but its worth taking a rule of thumb that -10dBV is un-balanced. Check the manual -it's the only way to know for sure.

Feed a -10dBV line to a +4dBu input and the signal will be a bit quiet. It will be more quiet again if you are feeding a non-balanced line (which is typical of -10) to a balanced input.

In the studio you will probably find the end result is just a change of level when miss-matching -10 and +4. Usually. -10dBV and +4dBu are two different standards and it is always best to work to one standard. Otherwise its easy to make mistakes, overlook problems etc. If there is a choice always use +4dBu. Where possible always match the outputs of one device to inputs of another. If there is no labeling on some device then it is probably -10dBV. If its on phono connectors (RCA) it'll (ok, almost) definately be -10dBV.

Hmmm..

There are more differences than just the "loudness" i.e. the voltage.

"Pro" or +4bDV is balanced because it used three wires,the two hots being electrically opposed in phase to each other,plus one ground wire.The device using this type of wiring only looks at the DIFFERENCE in voltage between the tow wires,REJECTING anything else.Therefore it does reject RF better than an unbalanced wire.This is why it was invented,in order to reject nearby noise sources such as radio receivers,etc.

"Consumer" or -10 dBV uses two wires,one hot,plus one ground wire.This often can turn into an antenna,picking up RF and other noises.This is why these kind of cableing are almost never used for long cable runs.

When you hook up an unbalanced signal into a balanced input,you are feeding not only the "hot" signal,but also the ground signal,which gets connected to pin 1 AND pin 3,or pin 2 depending on the particular equipment.

So in this case you are in fact reducing the signal strength by connectin part of the input to GROUND.That is why this sounds "softer". Also the frequency range is reduced,making for a more "muffled" sound.

In the case of hooking up a balanced signal to an unbalanced input,you are overloading the "hot" AND the gound,because you are feeding the positive part of the signal "hot+" to an input that is not designed for that much voltage input,and also feeding the negative signal "hot-" to the ground.This results in an automatic overload situation,and extremely undesirable.

So,although you are close in your description,you are not being very accurate as to what is really happening,electrically.

And,in actuality both signals,when properly connected are equal in level.It is the mismatch of the two that causes the level drop or rise.

Also,the interefernce is completely ignored on a properly balanced system,and is not completely goten rid of in an unbalanced system.That is they way it IS.

Here is a quote from you,which I recommend ALL posters ignore,because it is inaccurate:

In the studio you will probably find the end result is just a change of level
when miss-matching -10 and +4

Not only are you not getting the level correct,you are ALSO getting a frequency loss of the signal itself.Making for a very bad recording.

Cheers

I believe we are both singing from the same hymn sheet here, noeqplease. It is clear you understand this subject too but as you have pointedly aimed at my comment with an air of correction, then allow me to do the same to you...

Do not confuse balanced lines as being directly related to the line level standard that is +4dBu. Yes its a professional standard but only one of many in a long list of standards that "professionals" are advised to work to. A balanced line to carry audio is also a sort of standard for audio professional use. Two distinct, separate standards if you like. A balanced line does not mean by definition, that it will be operating at +4dBu and vice versa.

Balanced lines are used in many transmission lines that work to different voltage levels. Your analogue phone line is balanced for example but the nominal voltage level wont be at +4dBu.

That line level standard points to the fact that inputs/outputs are designed to work at a nominal level of +4dB above the reference of 0.775 Volts. Whether an audio line is balanced or not is irrelevant. In practice, it is unusual to see a +4dBu i/o that is not balanced and it is indeed highly likely to be balanced if its not marked as such. But not all +4dBu signal carrying lines are balanced and not all balanced lines carry signals at +4dBu.

+4dBu and -10dBV are simply standards that allow voltages to be related to signal level. If we are both using level meters, callibrated to +4dBu my sound meters will show the same reading as yours. It is just a nominal signal level.



All the gear I have that is switchable between +4dBu and -10dBV provides a balanced line regardless of that switch position. It is very unusual to find unbalanced i/o that works at +4dBu, granted, but the OP was wondering about what to do with those switches and that is why I made the points I did.

Regarding the comments on s/n ratio... Well designed balanced lines reject interference in effect and I am well aware of what they do. My point ignored whether things were balanced or not and I was simply pointing out that a line that takes a higher level of signal will have a better s/n ratio. For a given cable, balanced or not you will have better s/n ratio for +4dBu than -10dBV simply because the former is louder than then the latter.

Now this point you make I do not understand...

When you hook up an unbalanced signal into a balanced
input,

<<<snip>>>>

So in this case you are in fact reducing the signal
strength by connectin part of the input to
GROUND.That is why this sounds "softer". Also the
frequency range is reduced,making for a more
"muffled" sound.

and you go on to say (and dare I say, rather pompously)...

Here is a quote from you,which I recommend ALL
posters ignore,because it is inaccurate:

In the studio you will probably find the end result

is just a change of level

when miss-matching -10 and +4

Not only are you not getting the level correct,you
are ALSO getting a frequency loss of the signal
itself.Making for a very bad recording.

What is all this "muffling" stuff and "frequency loss" you are on about?

Are you saying I will get "frequency loss" when I connect a -10dBV line to a +4dBu input?

If you are saying that, that is simply not true. perhaps you'd like to clarify that for me.

Hi Thomas,

You wrote:

What is all this "muffling" stuff and "frequency
loss" you are on about?

The frequency loss when you partially feed your signal to ground,as I desribed in my older post.

Are you saying I will get "frequency loss" when I
connect a -10dBV line to a +4dBu input?

Yes.Exactly that.

If you are saying that, that is simply not true.
perhaps you'd like to clarify that for me.

I'd love to.Please hook up a frequency analyser to you equipment,and run some tests for yourself.
Please use a GOOD frequency analyser,one that can go past the human hearing range,in both directions.The reason for this,is that it WILL be more accurate in the human hearing range.That's all.

Record complex material,say from a CD,or a good microphone,or better yet,direct from your D.A.W. Please try to use material that has a full frequency range.Make the changes between the +4dbV connections,and the -10dbV connections.

Don't cheat,as this is for your edification,not my "embarrasment".I could not care less about your belief that I am wrong.I know I am correct,because I studied this stuff in college.I'm on my second degree,this time for Physics.
Also, I can hear the difference,it is glaringly obvious,at least with someone paying close attention to the signal path,and what's coming out of the speakers.

Cheers,and please let us know what you found on your testing.

Hey FP, I dont think it is a bad idea. I did the same thing
for a different reason. I did it to help eliminate any hum
from the stray unbalanced cable I might have and found
that the unbalanced to balanced signal was a nice feature
I had not thought of until I look at the units . I got the
Ultra DI Pro. I have learned much from this thread since
I am not an electrical engineer but I do want the quietest
(in terms of noise) and strongest (in terms of signal strengh)
chain I can get. I think this addition has helped.

hi, fp, the analog stages of most i/o's really don't have a lot of headroom.
the designs are based on the dollars, not the music.

a safe headroom above any given reference would be 14db.
most prosumer gear will be fed less than pro levels so the -10 setting is favoured.
designing good circuits takes time and money, so only the very best units will live up to being pro.