How to adjust very loud audio clipping during capture?
 

I posted a month ago about needing to transfer two separate linear audio tracks from a VHS tape to a computer. The nice folks here led me to the Panasonic AG-DS850, which outputs via XLR connections. I also purchased an M-Audio Mobile Pre, a little mixer that accepts the two XLR cords and outputs to the computer (Mac) via USB. The Mobile Pre has gain dials for the two XLR channels. I was able to capture the two channels separately just fine in Final Cut Pro along with the video.

Here's the problem: the audio is SO LOUD, I can't capture it without distortions and clipping. The Mobile Pre mixer has lights that show when the audio for each channel is clipping. But even with the dials for both channels turned all the way down, the audio clips. (Channel 2's clip light basically never turns off.) And the audio meters on the AG-DS850 indicate that the audio indeed hits above 0 db most of the time.

I am not a real audio pro (getting this far has been a challenge!) so I was hoping someone might have some advice for me. Is there a capture program that can turn the gain down further than what the hardware mixer can do? Or another approach I should try? I don't want my capture of this audio to be so loud and so distorted...unless this is an issue that can be easily fixed in software? Obviously confused here. :-) Thanks in advance for the help.

The M-Audio Mobile Pre may just be cheaply made, and adds automatic gain. You could add a quality mixer before it, like the Behringer Xenyx 802 ($50 @ Amazon), and then adjust the gain down. Of course, adjusting gain up/down isn't ideal or desirable, but it's a functional and feasible workaround.

If the clipping is recorded into the tape, there's not much you can do:
(1) Use a mixer to reduce the loudness, then
(2) Filter away the distortions in Sound Forge, or your other favorite digital audio editing software

If the audio on the tape is fine, and the M-Audio device is fine -- and the VCR is at fault -- then the normal advice would be to try another VCR. Of course, given the unique situation you're in, where the audio required a special VCR to begin with, I don't know what to tell you. Perhaps there's a way to control volume in the VCR hardware? Either in a menu, or by tweaking some of the actual hardware?

There won't really be a way to "fix" this in software. At best, software can try to hide the distortions, but it will augment the rest of the audio in the process. You'll often lose tonal quality when filtering away distortions, because a large swath of frequencies have to be carved out to remove the noise.

Thanks for the ideas.

I'm leaning toward the idea that the VCR is inflating the gain, especially after reading a similar thread on this forum in which someone believed his VCR was making the audio too loud. I tried another tape in this VCR (an old purchased VHS of "The African Queen"--not a very loud movie!) and the M-audio mixer registered clipping coming out of the VCR from that tape too!

Trying two courses of action: First, I ordered two XLR-to-RCA cables so I can bypass the M-audio mixer. I probably should have just tried that from the beginning. At least that would rule out the mixer as a problem.

While I hope that will work, I really only think this will be solved by trying another VCR, which is the second thing I will probably wind up doing. Wish I had another deck that could output the separate linear channels, but that's how I ended up in this situation to begin with. I do have a lead on another unit, so that's not the problem--just not crazy about spending more $$$$ on this!

If none of these things work, I'll try the Behringer mixer you mentioned--thank you for the reference on that.

Just to quickly follow up...

I purchased two XLR-to-RCA cables, which enabled me to hook the VCR directly to the Canopus digitizer. That did the trick. The audio is now perfectly listenable, and registers normally (no clipping) in Final Cut Pro's capture window audio meters.

So it WAS the M-audio mixer that was inflating the gain. Very disappointing.

But, lesson learned: just try the conversion cables first!

A peek of the manual for the M-Audio adapter reveals that it might have been expecting mic level input on the XLR connections, hence the amplification.

There was no way to change that, though. The mixer itself has very few settings or switches on it.

Although the M-Audio equipment is marketed as "professional", I've never considered it to be any more professional than Sima or other low-end type gear. Or as another comparison, to the overhyped and overpriced Canopus DV converters. I don't care if it is owned by Avid. Let's not forget that Avid also owns that buggy operation known as Pinnacle.

Aside: As far as I'm concerned, M-Audio gear is largely for people who want to be audio pros, but lack the skills and knowledge on what they ought to be buying. It's one reason I think you so often find it marketed to Mac users (sold in same stores, sections), as Mac users are a demographic full of people who think being a digital-anything pro is as easy as buying a Mac. I've never seen M-Audio gear in a studio. At most, I think I saw a mega-church using some appliances back in 2008. Unfortunately, sometimes the marketing and hype snares non-audio pros such as yourself, because you're not purely an audio user. You're just a video pro -- or rather, somebody in an adjacent field that also needs the same gear from time to time. I had to learn about some of this the hard way, too. /rant.

Something like this doesn't even remotely surprise me.

For a $200 device touted as "professional" to auto adjust gain is not just pathetic, but inexcusable. Auto adjusting gain is something a newbie needs -- not a professional user. Professional audio equipment should be completely manual. Even a cheap $50 Behringer mixer doesn't boink the gain.

There is some selective M-Audio gear that I'd consider, but most of it is at least $300 or more.

As always, you have to be REALLY careful with the hardware you choose. :(