Computer recording volume

[Eric***]

I'll start with the question and end with some explanations:

How can one increase the input volume when recording on a computer? Right now I use a Digitech RP100 headphone out -> soundblaster line in (1/8" stereo on both ends). The DAW is Ardour, which seems very similar to my experience with Sonar.

When I'm running without any amp models on the pedal, I can't seem to get enough juice. I have to max out all of the volume sliders in Ardour and it ends up being just barely enough volume. I don't need it to be too loud, but I'd like it normalized to what I play on the computer the rest of the time.

I don't want to make this a Linux-only question. Am I supposed to be putting a preamp in there somewhere? This is the part of recording that I don't get -- impedence, balanced/unbalanced, voltage, etc.

Just looking for a little help.

[t_ross33]

Try the mic input rather than the line in. Not sure if it will be better or worse, but I've always found it to be different than line-in.

The weak link in any computer based home-recording setup is usually with the soundcard. I've found USB interfaces to be a bit better than the line/mic input on the soundcard. Lots of good options in a wide range of prices available out there.

[Eric***]

Try the mic input rather than the line in. Not sure if it will be better or worse, but I've always found it to be different than line-in.

The weak link in any computer based home-recording setup is usually with the soundcard. I've found USB interfaces to be a bit better than the line/mic input on the soundcard. Lots of good options in a wide range of prices available out there.

I'll give it a whirl -- thanks. I'm at least very encouraged that I was able to get jack/ardour/some ladspa plugins working. It's been a long time coming.

Regarding the USB interface, I have a Line 6 guitarport (the simplest one from them) that doesn't work too well in Linux, and have been looking at a cheap Behringer UCA202 interface that supposedly does. I might spring for that soon, but I need to take a break from guitar capital for a little while.

[guitartango]

To be honest Eric i would drop Linux for sound recording and stick to Windows applications such as cubase. I tend to use Linux for web surfing/developing and email.

Sometimes the darkside does has it benefits.

[Eric***]

To be honest Eric i would drop Linux for sound recording and stick to Windows applications such as cubase. I tend to use Linux for web surfing/developing and email.

Sometimes the darkside does has it benefits.

I hear you, but honestly, I've had my share of problems in Windows too. The only real advantage Windows poses at this point is the use of VST plugins and hardware from closed-source ninnies (e.g. Line 6).

I'm getting very close to making this work in Linux. I'm thinking I'll check out the input preamp volume in the ALSA mixer as well.

[Ch0jin]

Sounds like you've missed a setting on the RP100 or a software setting on your PC.

If your using a "real" sound card (i.e. a sound blaster or similar rather than on-board audio) then you've got it connected right. You should not have to connect the RP100 to the mic input, and if you do, it should sound awful. The mic input on a PC sound card is designed for cheap electret microphones, the kind you find in gamer headsets, webcams, video cameras and so on. The signal from one of these mics is tiny compared to what your RP should be pumping out.

To quickly check, plug your headphones into the RP. If it's clear and loud in the cans you have a PC issue, if not, check your output volume on the RP. You could also double check by using an ipod or similar into the PC and see what that sounds like. If it's still almost inaudible, you have a PC issue for sure.

Regarding voltage, impedance etc, the simple answer is that your RP, like my POD, or any MP3 player etc will meet and usually exceed Line Level voltage specs and impedance in this case is a non-issue as the RP will definitely have a low Z output and line level is definitely High Z. Simply, this is the right way to connect your stuff.

My gut feel is either your sound card is not correctly configured under linux, or you've overlooked an input level somewhere.

The long answer is as follows...

Impedance (Z) is the resistance of a circuit to alternating current, such as an audio signal. Technically, impedance is the total opposition (including resistance and reactance) that a circuit has to passing alternating current.
A high impedance circuit tends to have high voltage and low current. A low impedance circuit tends to have relatively low voltage and high current.

When you connect two devices, one is the source and one is the load. The source is the device that puts out a signal. The load is the device you are feeding the signal into. The source has an "output impedance", and the load has an "input impedance".

Nowadays, nearly all devices are connected in "bridging" mode, i.e. low Z out to high Z in because this results in the most voltage transferred between components. As opposed to "matched" mode, which sees maximum current transfer, which is a consideration if you start talking internals of a tube amp, or connecting your amp to speakers (where you want current rather than voltage)

Example: If you connect a low-Z source to a high-Z load, there is no distortion or frequency-response change caused by this connection. But if you connect a high-Z source to a low-Z load, you might get distortion or altered response. For example, suppose you connect an electric bass guitar (a high-Z device) into an XLR-type mic input (a low-Z load). The low frequencies in the signal will roll off, so the bass will sound thin. We want the bass guitar to be loaded by a high impedance, and we want the mic input to be fed by a low-impedance signal. Thats where things like direct (DI) box or impedance-matching adapter is used. Any bass player who has been forced to go direct into the desk will know about this scenario. This is also why you get little or no sound if you plug headphones directly into your guitar.

Lastly a little more on Mic's.

Without out going full on into it, just know that a mic with a phono connector and a mic with an XLR connector are very different beasts. Thats why mixers might have phono and XLR mic inputs. XLR style mic's (all the ones you'd ever see on stage or in a studio) are Low Z devices because this enables long cable runs where as cheapo mics with phono connectors are high Z devices designed for short cables and PA use. As such they both expect a different input Z. Thats why some mixers will have both XLR and Phono inputs for mics.

In the previous example I said that a guitar has a high output impedance, and I also mentioned ipods, your RP, My POD etc all will have a low output Z.

That's why
A. You shouldn't plug your ipod into the guitar input of your amp, and why some of the new amps have a dedicated ipod (or whatever) input.
and
B. You see spruikers in shopping malls with mics plugged directly into the "guitar" input of small transistor amps. Those mics obviously have a phono connector, meaning they are High Z devices rather than stage/studio quality Low Z mic's.

Anyway, I now find myself with an empty beer so I think that means times up

I know that probably doesn't help solve your specific issue, but maybe it's helped you get your head around Impedance as it relates to audio.

Note: Some of this content was taken from here and then cleaned up and somewhat paraphrased and enhanced to make it clearer. Feel free to go there and read it all if you want further information.

Peace

[Eric***]

Sounds like you've missed a setting on the RP100 or a software setting on your PC.

If your using a "real" sound card (i.e. a sound blaster or similar rather than on-board audio) then you've got it connected right. You should not have to connect the RP100 to the mic input, and if you do, it should sound awful. The mic input on a PC sound card is designed for cheap electret microphones, the kind you find in gamer headsets, webcams, video cameras and so on. The signal from one of these mics is tiny compared to what your RP should be pumping out.

Cool. Thanks!

I do get sound from the RP with just headphones, and I am using what I thought was a SB that I bought for $10, but is identified by Linux as an Ensoniq (based on the module, anyway). Apparently it's on the computer end.

Now I can't get Jack to start with regularity and have no recorded volume after upgrading to Ubuntu Studio, so there's more work to be done. Someday I'll figure this all out...

Thanks again for the info.

[deeaa*]

Eric, sad to say but really, if you want to use Linux for audio the very least you will need is a properly Linux cartified soundcard. Even then, its definitely not suitable for anybody but real linux savants is my experience. nothing wrong with linux but youll just save yourself so much headache just going windows and Asio such as with cubase. they just work plus do anything youd ever need in music.

[Eric***]

Eric, sad to say but really, if you want to use Linux for audio the very least you will need is a properly Linux cartified soundcard. Even then, its definitely not suitable for anybody but real linux savants is my experience. nothing wrong with linux but youll just save yourself so much headache just going windows and Asio such as with cubase. they just work plus do anything youd ever need in music.

That had been my experience previously, but I've been chipping away at it, and I have to say that it works fine now. Actually a little bit better than what I was doing in Windows, because I finally have a good grip on how Jack works, which is more than I can say about ASIO in Windows (Jack is the Linux low-latency architecture).

I'll grant you that it's not easy, but Ubuntu Studio helped a good bit as far as getting things in the right place. Now that I know what depends on what (i.e. Jack, ALSA, etc.), I feel much more stable.