Subject:insert compression/limiting whilst recording audio

Posted by: Paulie

Date:7/20/2003 5:43:20 PM

When recording my vocals, I would like to add some gentle compression into the signal chain, just to make sure I get a decent level and smooth out big spikes.

Is there some kind of software out there that would act like a software mixer and let me insert FX. This would then have to appear to acid as if it was the audio channel.

My other option would be to buy a vocal strip, but i have lots of good compressors etc already.

Thanks
Paulie

Subject:RE: insert compression/limiting whilst recording audio

Reply by: pwppch

Date:7/21/2003 8:27:44 AM

ACID does not permit plugin FX to be inserted on its inputs.

The notion of inserting a software compressor on an input will not result in the same effect as using a real hardware compressor as part of the signal chain between your mic and your preamp. You would be adding compression AFTER the A to D conversion. Any clips or overs you would get would be in the digital signal and the software compression would only be working on the already clipped singnal. That is, the spikes and low amplitude passages would not be compressed correctly as they are already part of the digital signal.

Assuming that you have recorded your dry signal correctly - no clips and at a reasonable overall gain - you can easily apply a plugin Compressor to the digital signal after the fact.

It still wont give you what you desire though. For recording vocals, an external compressor/gate is the correct way to do what you want. If you lack the external hardware, then correct use of your preamp and proper vocal techniques will provide you the best overall recorded digital signal where a small amount of software based compression could help "smooth" things out. Doing this after the actual recording is also a better thing as you then have far more control over the overall signal and application of the compression using automated parameters.

Peter

Subject:RE: insert compression/limiting whilst recording audio

Reply by: Paulie

Date:7/21/2003 12:49:50 PM

Peter,

Many thanks for this great explaination.

One thing that puzzles me though is that the output from my M-Audio Duo USB is digital (i think) so i would have thought that it couln't possibly output a signal greater then 0db, though I get the CLIP message from ACID if i'm not careful.

This suggests that the M-Audio and other interfaces I have used are capable of presenting ACID with a signal >0db.

No big deal, just curious

Paulie

Subject:RE: insert compression/limiting whilst recording audio

Reply by: Iacobus

Date:7/21/2003 2:21:39 PM

Correct. The Duo does output digital audio via its USB and S/PDIF outs. (Its 1/4" outs are analog.) You want to be careful when recording digital audio because it can clip, so get the signal hot enough for recording but don't overdo it. Around -6 to -3 dB is ideal.

HTH,
Iacobus

Subject:RE: insert compression/limiting whilst recording audio

Reply by: Paulie

Date:7/21/2003 3:28:54 PM

Thanks to Peter ad Iacobus. Just to continue my education ..... can u help ?

If my Audio Duo converts the mic signal to digital, then I am assuming it clips everything to 0db. This is obviously not the case, otherwise ACID would never receive anything above 0db from the duo. Therefore digital devices do transmit signals >0db. Is this a digital voltage type value rather than db values referred to in sound editors?

I think my misonception comes from the fact it is not possible to have a wav file with a value >0db.

Paulie.

Subject:RE: insert compression/limiting whilst recording audio

Reply by: pwppch

Date:7/21/2003 4:40:35 PM

Correct, there is no such thing as a digital signal > 0 dB.

ACID considers a 0 dB signal as a clip since there is no other mechanism to indicate an overage when dealing with digital audio signals. (Actually it treats a specific number of contigous samples at 0 dB a clip, since for all intent and purpose, the A/D convert has recieved a signal that is 'most likely' pushing beyond a 0dB in the conversion.)

Peter

Subject:RE: insert compression/limiting whilst recording audio

Reply by: Paulie

Date:7/22/2003 12:07:47 PM

Peter,

Got it. The Duo presents a stream of "pre clipped" samples at 0db which Acid interprets and flags as CLIP.

Can I just say many thanks for your patience and careful explaination of what to me at least is a difficult subject. I'm getting there.

Much Appreciated
Paulie

Subject:RE: insert compression/limiting whilst recording audio

Reply by: Jacose

Date:7/22/2003 4:25:40 PM

what i would say for you is to definetly get a hardware compressor, behrginer has a real cheap one perfect for vocals, the ultravoice pro.

It really helps, i was facing the same situation as yourself ;) so I got one.