Syntrillium Backup Forums :: View topic - What are the disadvantages of unbalanced inputs?

Liquid Brain Child · Posted - Fri Apr 04, 2003 9:59 am

Will they just make the signal lower? Are they good for a certain thing like guitar, bass, hi z mics ect...? If I do use mics on them would it be totally unusable or just a lower signal? If the latter was the case you could just match the volumes up at the mixdown stage but in that case you would have an overall lower volume level, right? Someone please enlighten me on this. Could I get by with some unbalanced inputs until I get preamps? Could I use them the way they are or should I get preamps for them or should I just steer clear of them all together?

SteveG · Location: United Kingdom

This has nothing directly to do with signal levels at all. The purpose of a balanced input is simply to provide a circuit configuration that is capable of rejecting electrical noise that gets picked up by cables. The basic idea is that you have the signals flowing around in a circle, so that at any given point, an external signal induced into one lead is induced into the other one as well. But the clever part is that because of the circular path, this interference signal gets cancelled out of the eventual output. It's used with microphone signals, because these are always low level, and therefore more susceptible to interfence attacks anyway.

It is relatively easy to convert from balanced to unbalanced, but you require a little more kit to go the other way.

Guitars are normally unbalanced signals, as are high impedance mics, which tend to be cheapies anyway. A dynamic mic is inherently balanced, if you have it in a metal case - the two leads from the capsule are isolated from the case, and the metal case is the screen. And that's all you need to do as far as these mics are concerned.

High impedance mics tend to use single-ended capsules, where one side of the capsule is joined to the case, and therefore the screen, and since this is actually one of the output connections, the other one, being on its own now, is essentially unbalanced, and therefore susceptible.

Liquid Brain Child · Posted - Fri Apr 04, 2003 4:11 pm

Will it really matter then to use a balanced mic or device on an unbalanced input? Would the quality degrade or will there be noise or interference? Wouldn't I get good results with xlr to 1/4" converters for low z mics? Would a hi z mic do fine on unbalanced?

SteveG · Location: United Kingdom

Most of the time, you will get away with no problems at all. Usually, the interference problems arise on location, and in hostile environments. If you are just recording at home, then there is probably no need for you to worry about this at all.

So yes, you can unbalance a mic and use it on an unbalanced input. It won't alter the quality at all, and you can only pick up interference if it's there...

The higher the impedance, the greater the chance of interference intruding, but if you are only running a few feet of mic cable, this won't be an issue. The biggest problem with XLR to 1/4" converters is that they are heavy, and tend to wrench sockets around a lot, often leading to broken connections. The sensible answer is to make up adaptor leads with an in-line socket, a bit of coax, and a plug - this saves a lot of trouble trying to get the soundcard, or whatever, repaired.

So if it sounds okay, then it probably is!

Liquid Brain Child · Posted - Fri Apr 04, 2003 7:55 pm

Thanks alot steve, I am clearer on the subject now. It shouldn't hurt to use xlr to 1/4" adapters on break out boxes or portable multitracks should it? Or should I use the other method you described on devices other than soundcards?

Craig Jackman · Location: Canada

The same advice would apply. An XLR-1/4" adapter is a long heavy thing. Adding the XLR connector and cable to the and would place all the weight far away from the jack socket. It's really easy to bump the connector and break internal connections ... just the wieght itself will lean against the internal connections loosening them over time.

In almost every possible situation it is best to not use single piece adapters, but to solder up adapter cables to lessen the strain on the connections.

SteveG · Location: United Kingdom

When it comes down to it, I can only think of two solid adaptors in regular use that are generally okay - the 1/4" to 1/8" stereo adaptors that come with headphones, and the similar 1/4" to RCA (phono) mono ones that are quite useful with some musical instruments, like drum machines, synths, etc when you want to connect them with an RCA-RCA lead. I'm not even very happy about the 1/4" to XLR ones that you'd think wold be okay - I've seen a few wrecked XLR sockets caused by these too.

Havoc · Posted - Mon Apr 07, 2003 1:17 pm

Some XLR-RCA adaptor are quit useful also. Never go out without them.

SteveG · Location: United Kingdom

jonrose · Location: USA

heheh!

...grinning, knowingly...