Overdub recording problems - distorted sound

[Gale Andrews]

Split from http://forum.audacityteam.org/viewtopic ... 84#p162651

Using Audacity 1.3.13 beta. Windows 7. Not Linux

I am overdubbing with a mic. First (overdubbed) track is fine, sometimes the second and third, sometimes not. Anyway, sooner or later a recorded track plays back with lots of crackling/ buzzing. I've tried changing various levels settings as in previous posts, to no avail. The workaround I am having to use is as follows:

1. Have a duplicate copy of my project
2. On the master copy, make two tracks - first track and overdubbed.
3. Copy & paste these to duplicate copy.
4. In duplicate, mix and render the two tracks.
5. In duplicate version, record next overdubbed track.
6. Copy and paste this track to master copy - it will work fine
7. Go back to duplicate and repeat mix and render (so you end up with a single track again)
8. Repeat step 5 etc. etc.

OK but I have now split this to a new topic on the Windows Beta board.

Did you look at the link I posted
http://wiki.audacityteam.org/wiki/Playb ... h_Playback ?

And as you are on Windows 7, mismatched sample rates between Windows, your sound device and/or Audacity are quite likely. Please try these solutions:
http://wiki.audacityteam.org/wiki/Troub ... ings#drift

What sound device are you recording with?


Gale

[alka]

I have read your previous posts, and tried most of the tips there. I will try again any I'm not certain about. The only one I know I haven't tried yet is the increased audio to buffer setting. I'll try changing it to 150 (or would you suggest a diferent setting?)

My sound device is shown as VIA High Definition Audio. Drivers all up to date.

As I struggle with this, I can be clearer about the symptoms. If I record with Line In, the first track is fine, the second (third etc) track is now always (uniformly) distorted by a continuous crackle. If I use any input device setting other than Line In - though I am still recording through the line-in lead - I re-record the first track along with the new track, just as if I was recording through a Mic with the speakers on. It seems to me that the sound device is somehow making the first track interfere with any subsequent track. I've tried all settings at 44100 and at 48000.

Would it help if I sent you a two-track sample?

Thanks
alka

[alka]

Update - I have found the source of the problem. The overdubbed track(s) are distorted when the mic (which is contantly plugged in) is switched on! It seems to generate an electrical crackle through the sound device, even if I am recording via Line-in. Sorry for all the red herrings, but I've learned a lot about tweaking Audacity settings. Thanks for the interest and advice.

If anyone out there can advise me on what kind of mic to useto avoid this happening (so I can record some tracks through the mic) I'd be grateful.

alka

[Gale Andrews]

What mic have you got now? Is it a physical mic that plugs in to the computer (if so, what port is it plugged into?), or do you mean an internal mic?

What has line-in got to do with this? Have you got a physical mic connected to a physical pre-amplifier, and that pre-amp is connected to line-in?




Gale

[alka]

All the mics I have tried are external, physical, plugged in (jacks, not USB).

All are cheap mics, which in the past have produced satisfactory results (in Windows XP, and with a different computer and therefore a different sound card)
2 of them are dynamic mics, 1 is of unknown type (just a stick with on-off switch). All 3 of these produce the problem I described. All of them work OK when used with an XP netbook. A fourth mic, which is part of a cheap headset (small knob on a flexible stalk) works fine with the W7 desktop!!! (What kind of mic is that likely to be, please? This is obviously the type I need)

I don't use a pre-amp, and none of the mics has a power supply of any kind.

When you ask what port the mic is plugged into, do you want the port number, or just the socket where the jack goes? If the latter, I've tried using both Front Mic and Rear Panel Mic (both red coloured). I wouldn't know where to find the "port number" if that is what you are asking.

Regarding the Line-in mention. What I'm doing is recording some tracks through a mic (e.g. vocals, saxophone) and some through line-in from a keyboard (e.g. rhythm tracks). Even when doing the latter, second and subsequent tracks are crackled if the mic was switched on while recording.

[steve]

A fourth mic, which is part of a cheap headset (small knob on a flexible stalk) works fine with the W7 desktop!!! (What kind of mic is that likely to be, please?

Difficult to say for certain, but it is quite likely that is an electret microphone. These types of microphone require a low voltage supply current to make them work. Typically computer sound cards provide a low voltage supply for this type of microphone (most "computer mics" are electret).

Dynamic microphones do not require powering. It is possible that the microphone power supply is noisy when not being used and so causing a problem when you use a dynamic microphone, but that does not really explain all of the symptoms that you describe. In particular it does not explain why the problem should occur only on the second and subsequent tracks. On the other hand, I can think of no logical explanation as to why one type of microphone should be OK on multiple tracks while other microphones are OK on the first track and not OK on subsequent tracks.

[alka]

Thanks. I'd come to the conclusion that it' s probably an electret mic, so my options seem to be:
a) use the headset mikewith the W7 desktop PC
b) use any mic with the Wxp netbook
c) buy a better electret mic
d) maybe buy a better soundcard (recommended for Audacity-type multi-tracking)

Thanks for your help.

[Gale Andrews]

It's quite common on Windows 7 (more so in laptops and smaller computers) for the internal mic to be always on and for there to be a setting for the internal mic and external "red" mic port to be "tied" as one input.

Even though it's less common on Desktops, it may still be worth going to the sound device's own control panel in Windows and see if there is a "Tie up same type of input jacks" / "separate all input jacks as separate input devices" control (choose "separate") and see if there is a mute button for the mic.

Even if this helps, it doesn't really explain everything either.



Gale