gain-staging: balanced/unbalanced

[FALKEN]

If I have a preamp with balanced output, and I am sending it to a recorder with an unbalanced input, is there some sort of conversion required? I have just been plugging an unbalanced cable into the balanced output of the pre. is this ok? Or am I screwing up my gain-staging?

Thanks.

[Farview]

You need to check you manual to see if it is OK to plug an unbalanced cable into the output of your preamp. (it is normally OK with any preamp under $1000)

The only thing that will be happening to your gain staging is you will be loosing 6db. That might not be a bad thing if you are coming out of a +4 output and going into a -10 input. As long as you aren't running out of headroom in the preamp when you are driving the recorder at good levels, you will be OK.

[FALKEN]

dude...

thanks. its all starting to make sense. I noticed my dbx gave more reasonable levels If I ran it at +4 even though it was going into a -10 input. otherwise it requires ridiculous makeup gain.

another oddity is that I usually have to put the threshold ridiculously high, like say at +5 to get a normal gain reduction of say 8 db. but my preamp was showing levels coming out at 0.....

I really need to get my gain-staging under control.

what methods do you all use to accomplish this?

any links would be appreciated.

[FALKEN]

you know, the signal coming into the compressor too hot, and coming out too weak, you would think my settings were off. but i experienced this problem with the ratio at 1:1.

[Cave Dweller]

ifthe output of your pre is +4, you will need to set the compressor to
+4 as well.

[RawDepth]

Why don't you just use an impedance matching transformer between your two pieces of gear?

http://www.musiciansfriend.com/srs7/...se_pid/422414/

I don't know if the gender is correct, but you get the idea. Radio Shack may have them even cheaper.

Good Luck

[FALKEN]

Originally Posted by RawDepth

Why don't you just use an impedance matching transformer between your two pieces of gear?

for one that is for impedance matching microphones. that would not work between a preamp and a compressor, or a preamp and my tape machine.

for my purposes, are you just supposed to play with the gain faders until you find the optimal settings? is this what is typically meant by "gain staging"??? or am i supposed to find connectors?

does the fact that a signal is balanced have anything to do with impedance? if not, I don't think this connector is what I want.

[RawDepth]

Originally Posted by FALKEN

for one that is for impedance matching microphones. that would not work between a preamp and a compressor, or a preamp and my tape machine.

Yes, I think it will work. I have been using them in all sorts of situations like that for years. But, suit yourself. It just says it is for microphones because that is how they chose to market it.

Originally Posted by FALKEN

does the fact that a signal is balanced have anything to do with impedance? if not, I don't think this connector is what I want.

Perhaps this will help...it talks about impedance.
http://homerecording.com/bbs/showthread.php?t=155974

Cheers

[FALKEN]

Originally Posted by RawDepth

However, what WILL make a difference is impedance. A balanced XLR connection usually carries lower impedance which yields a much stronger signal level at or near +4dB. Unbalanced connections are naturally higher impedance and carry a weaker signal level such as -10dB, (often called line level.)

ok. so If I plug a "stronger signal" balanced signal (from my preamp) into an unbalanced input (on my tape machine), first that signal will be halved. so now I don't know if that makes it stronger or weaker than line level.

secondly, the level coming out of the mic should be the lowest of all three, since it comes Before the preAmp. I am not sure what the impedances are After the PreAmp, or if that connector would work on levels that hot.

really, I have no idea. I wish I knew a good reference for all of this stuff.

[RawDepth]

Impedance matching is a very complex world that I am not sure we want to enter into too deeply for argument's sake. I was trying to keep it simple by mentioning only general level ranges as it applies to most audio gear.

I believe the matching transformer works the same (in general) whether it is between mic and preamp, or between preamp and recorder. It should serve to correct the apparent level of the signal by a sufficient amount, or at least bring it toward a more usable range for the recorder. ...and isn't that all you wanted?

I know it is not a perfect world solution. I just seems to work in a pinch.

Sorry I couldn’t be of more help.

Can anyone else shed more light on this?

[mattamatta]

I dont see why you would need such a thing between two line level pieces of gear.

[RawDepth]

Originally Posted by mattamatta

I dont see why you would need such a thing between two line level pieces of gear.

Both are not line level. That is the problem.

[FALKEN]

oookay.

say I have a preamp that gives a balanced output.

and I run that into a compressor that has only unbalanced inputs and outputs. and that runs into my deck, which is unbalanced.

all three units are running at "line" level.

I am pretty sure that when I run the balanced signal through my patchbay into the unbalanced inputs of the comp, there will be something going on with the signal. my guess is that it will be hotter because all of the signal is on one line and not two?

[FALKEN]

ok i found this link off of another link on another post on another website:

http://www.jensen-transformers.com/an/an003.pdf

I think this has all the answers but I can't understand it.

I think what makes it more confusing is that some of my gear can do +4 or -10 but the connection is still balanced.....wha?

[Farview]

Balanced, impedance, line level are 3 different things that are not necessarily related.
All of your stuff is line level, you need to figure out if it is +4 or -10. Find out what the operating level of the equipment you can't change is and set everything else to that level.

Just because something uses and xlr connector doesn't mean it is low impedance. Don't confuse the conector with the signal it is carrying, the two things aren't related.

If you plug a balanced signal into an unbalanced thing, you will loose 6db. This is because 1 of the legs is not connected.

set the preamp so that the meter dances around 0db. Plug it into the compressor, what does the input meter read? If they are both the same operating level, the meter will read -6. If the preamp is +4 and the compressor is -10, the meter should read +5. If it is the other way around, it should read -17.
Once you get that sorted out, what does the meter on the recorder read? If it is a digital recorder, a line level signal should read -12dbfs. If it is an analog recorder, it should read the same thing that the compressoer is. (without compression)

[FALKEN]

Jason,

your replies are always useful.

these ratios are a good place for me to start understanding why I am seeing what I am seeing.

Originally Posted by Farview

If you plug a balanced signal into an unbalanced thing, you will loose 6db. This is because 1 of the legs is not connected.

kewl. what happens with the opposite? say I run a pre-recorded unbalanced track through a balanced compressor?

Knowing what to expect should help these things. I guess what I am wondering is how to you overcome these differences? Just by knowing where to apply the gain and cut the most effectively? at what point to use what cable? or when to use converters?

also, I have a balanced patchbay. is it a problem to use it with unbalanced gear??

I really didn't give any of this stuff much thought until I came to the conclusions that

1) my shit does not sound as good as it could.

2) my levels are all over the place; and I have just been adjusting them the best I can until I get a good signal onto tape.


thanks for all of the help.


I have been posting a lot of questions that I Think should be important to a lot of people!! I have been home recording for almost 10 years and I think some of these issues are talked about sort of on the surface but never really detailed. A search on the subject comes up with 15 different threads on what guitar cable to use. If I were to post "what mic should I buy for polka under 300 bucks?" I would get 15 responses in an hour but a question about gain staging few people have much insight. so you have to be grateful for anyone sharing this sort of knowledge, because its really good shit and hard to come by. I mean, shit. somebody masquerading as a blabbering idiot got probably a hundred replies today. so thanks jason for sharing this knowledge with somebody who is actually trying to accomplish something and not just jacking off in public cuz they're bored. even if I am an idiot for not already knowing.

[Farview]

Originally Posted by FALKEN

kewl. what happens with the opposite? say I run a pre-recorded unbalanced track through a balanced compressor?

I'm not sure, it will either be the same or loose 6db. I've been up too long and can't think.

Originally Posted by FALKEN

I guess what I am wondering is how to you overcome these differences? Just by knowing where to apply the gain and cut the most effectively? at what point to use what cable? or when to use converters?

The differences are just differences in the voltage that the equipment expects to see. If you are running a +4 device into a -10 device, you will need to turn down the output of the +4 device so you don't overload the -10 unit. The idea is to match the output signal level of the first device with the input signal level that the second one is expecting. That is really all there is to it. If everything has its own meter, they should all be hovering around 0db. (for digital, -15dbfs)

Originally Posted by FALKEN

also, I have a balanced patchbay. is it a problem to use it with unbalanced gear??

No. the unbalanced gear just won't use the third connection. (it will short it to ground)

[FALKEN]

good to finally be able to upgrade my system without paying anything for it!!!

I thought I was going to have to run out and buy 900 connectors.

[FALKEN]

arrgh!

ok. so I can plug all of my balanced and unbalanced gear into my patchbay and pretty much use all of it without worrying about it, as long as the meters look ok, right?

I mean, If I patch a balanced equalizer through the insert on a channel coming off of tape (unbalanced), I am probably going to want to boost the trip to get it to the right level, right? and it would probably be a bad idea to go tape(unbalanced)-->eq(balanced)-->mixer(unbalanced)? or does it just not even matter?

thanks thanks.

[Farview]

You are overthinking this. The signal level you put into the EQ (in this instance) is the signal level you will get out of the EQ. (plus what ever you EQ'd)

The inserts are already unbalanced by design, so you won't loose anything there. An EQ is not dependant on gain to do it's job, (like a compressor) so it doesn't matter. Even with a compressor, you just have to turn the threshold down to make it work like it is supposed to.

[mr.rich]

yeah id say that your think into it too hard also. if your goin balanced into un balanced just start low and watch your meters so you dont clip the -10 with to hot an input. if your goin unbalanced to balanced youll be losing a bit and will have to compansate with output which sucks sometimes because with noisy gear youll be raising noise floor. i just had to deal with this alot because the board i bought is mostly unbalanced and all my pres are balanced. what i did is set up a seperate snake for pres only, hit that then go straight into the balanced inputs on my tape machine. then i know ive got a good strong signal to tape. then i go to a bay which is unbalanced for monitoring and mixing which is where i patch in most of my comps. seems to work well and havnt had any noise problems yet.

[FALKEN]

i can see that. imagine this situation!!

pre is balanced. that goes right into my unbalanced tape recorder. which upon playback goes into a balanced compressor, then an unbalanced mixer. aarrrgh!! on top of it, I have some eq's that have balanced TRS jacks, and unbalanced rca jacks, which I could patch to my patchbay if I made some cables. then I could patch it in as balanced OR unbalanced. faaahq! so far i haven't done this.

[Farview]

going from the balanced pre to the unbalanced tape input, you won't loose anything. You only loose 6db going from unbalanced to balanced. Still it isn't a big deal as long as you have the headroom and gain in the unbalanced piece.

[FALKEN]

EXCEPT on one of my balanced (tube) pre manuals it says you have to have the volume at least past 5 or you are not getting the full sound. AAAAAAAAHHHHHHHHHHH!!!!!!

[Farview]

Is your tape deck -10? You might want to put a compressor in line (set at 1/1) and use the output gain to turn down the level.

It is a common problem. Trying to keep a dynamic source into a mic pre enough to get that 'sound' is a pain.