OT: line amp?

[Dave Labrecque]

Calling on the studio electronic wizards among us.

My podcast client's home studio needs a little upgrading. The guy who set it up was only quazi-literate as far as studio configuring goes. As a result, because the level of the phones feeding the mixer (it's taken from the headset jack on this two-line VoIP telephone) is way low, he had all the other inputs to the mixer (mics, automation computer) trimmed way low. It works okay, but there's no meter deflection, and the noise floor can't be great, of course. Due to the mixer's channel limitations, the phones are on a stereo line level input, which has no trim control. Anyway -- my thought is to boost the phone's output level so that I can run everything up in the nominal range of the mixer.

Note that budgets are tight, and the caller/receiver lines have very little (if any) crosstalk, since this is all digital, so a POTS type hybrid is unnecessary (and unwanted). It actually sounds pretty good.

I suppose I could investigate the level of the audio feeding the handset to see if I could tap off of that, but I'm assuming it won't be different than what's at the headset jack. Does everyone concur?

So... I think what I need is some kind of simple and inexpensive line amplifier to bring the headset output up 20 or 30 dB (though I haven't checked exactly how much we need).

Any ideas on what to buy would be appreciated.

[Soundguy]

Two thoughts.

If it sounds okay and not noticeably noisy, then it is okay ... so walk away.

What kind of mixer is it? Can you simply put the phones patch into another channel(s) which has gain on the front end?

Do you just want to see meters bouncing to verify that it's working? I have a similar situation at my home studio where I don't want things to be too loud, and sometimes I can hear just fine when the meters are barely showing any indication of signal. When I try to adjust everything as you seem to want to do, it upsets the natural feel of the controls and things become too sensitive and mistakes get made resulting in unpleasant blasts of volume.

Soundguy

[Sound Machine Inc]

RDL STA-1 Stick-On Electronic Transformer/Line Amplifier


right item, not exactly cheap... but it works really well in 2 radio stations I have wired
http://www.performanceaudio.com/buy/...RDL/STA_1/2981

[Craig Allen]

I've used the RDL stuff as well - good stuff for that type of application. But I got to agree with Soundguy - if it's not broke, don't fix it.

[Dave Labrecque]

I've used the RDL stuff as well - good stuff for that type of application. But I got to agree with Soundguy - if it's not broke, don't fix it.

I do appreciate the sentiment, but, as I sort of mentioned, the noise isn't great, so...

[Ian Alexander]

I do appreciate the sentiment, but, as I sort of mentioned, the noise isn't great, so...

To be fair, you said the noise floor can't be great, which I took to mean that you theorized it might be noisy, but hadn't really noticed a problem with it.

If you're looking for ~30dB of gain, maybe a cheap mic pre would do the trick?

[Craig Allen]

I kind of read it the same way... anyway, RDL does make some good products. Also Art has a line of accessories that might have a solution.

[Soundguy]

Yeah, I read it as though you were assuming the noise floor can't be great because you did not see adequate meter readings, but really didn't comment that you were hearing the noise floor.

Soundguy

[Dave Labrecque]

You guys are right. I haven't done any critical testing. But can't be means isn't where I come from. I just feel that running a source so low through a little Behringer mixer that you don't see a meter deflection with the master all the way up is necessarily going to be noisy. It's clearly bad engineering. So I ask for line amp ideas, and I get guys telling me maybe I don't need line amp ideas. What's up with that?

I thank you for the amp ideas that you did provide. The other reason that I do consider it "broke" is that the master output level from the mixer is down 20 dB from where it needs to be deliver an adequate signal to the sound card input.

Thanks again, everyone.

[Soundguy]

So I ask for line amp ideas, and I get guys telling me maybe I don't need line amp ideas. What's up with that?

Because it's quite common to have quality audio output without seeing "high level" meter activity.