Odd distortion

[JulianHJ]

I've just started the process of digitising my 12" vinyl collection, and have run in to some difficulties with getting consistent high-quality results.

I am using a Technics 1210 with Stanton 500 cart. This is currently being run through an Intimidation Blue DJ mixer in to an M-Audio 2496 PCI sound card.


I am recording a variety of dance music, from ambient to techno. The issue is that on some tracks the bass sounds very distorted on playback. The live input sounds fine on these tracks during playback, and I've experimented with the mixer's gain controls to try and eliminate the problem. Even with the gain right down on the mixer, I still get really poor quality on some records, despite sounding great when heard directly.

Where am I going wrong?

[kozikowski]

Are you listening to the mixer or the computer?

I can't find any technical information on the mixer. Does it have a Tape-Out? Sometimes the Tape-Out is isolated from the final mixer controls and the volume doesn't go up and down like you think. Tape-Out also sometimes bypasses the equalizers and special effects.

Did the sound card come with software to control volume? Do the controls show up in the Windows Control Panels, or is it a separate application?

Koz

[JulianHJ]

I'm listening to the computer. The mixer was a fairly decent one when new (15 years back). I'm running the master output to the sound card. I've tried altering the software levels to no avail. The sound card has no gain control as such.

[JulianHJ]

OK, I've installed and tried a different software recorder and found that I have a similar issue. I guess this points a finger at my hardware/recording technique. As I mentioned before, the audio sounds fine when listening to it through the computer as I'm recording, it's only in playback that the distortion becomes apparent.

[whomper]

could you be clipping the bass booms when the drum gets hit?
my first thought was your cartridge was tracking too lightly but if it sounds good going in and bad on playback i am thinking you are clipping. record low for plenty of headroom. you can make it louder after you have it recorded right.
are you using an riaa curve to fix the levels that are recorded?
does the mixer have that option? does the sound card ??
are you doing any f/x processing?

[kozikowski]

<<<are you using an riaa curve to fix the levels that are recorded? >>>

That's built into the mixer. The sound delivered to the system is flat and undistorted.

<<<record low for plenty of headroom.>>>

I think that's what he's trying to do.

This is a perfectly recorded piano solo...

http://kozco.com/tech/audacity/Audacity1_playback.jpg

Your bouncing light meters may look different. Note the blue waves never reach "1", either wave, either direction. You'll need to take my word for it that the bouncing light meter never goes to maximum.

If your waves look like that, then you have a perfect recording and the problem is listening to it. If your blue waves constantly smack "1" or worse yet, turn red, then yes, the recording process is messing up.

Did you try reducing the Audacity recording level with the little microphone slider?

Koz

[JulianHJ]

The light meters look similar to the .jpg

I've tried adjusting the various levels within Audacity to no avail, even recording with minimal levels, the distortion is still there. I'm gettign more convinced that this could be a hardware issue, but I can't think what. I'm going to try a different source tomorrow, both direct to the sound card and via the mixer. The issue was present without the mixer, when I used a Behringer PP400 Phono Pre-amp - this gave me no hardware gain control, so I figured at the time that was the issue - too much gain. I'm beginning to think the issue is with either the PC itself or the soundcard. I'm going to try moving the card to a different PCI slot as well.

[steve]

Have you tried burning the recording to audio CD and playing on a CD player? This would serve to eliminate the possibility that the distortion is produced by computer playback.

[JulianHJ]

Yes, I've tried burning to CD - the distortion is still present.

[kozikowski]

<<<Yes, I've tried burning to CD - the distortion is still present.>>>

You need to work with us. Shortcuts don't work well when we're troubleshooting.

And you played the CD on Something Else? Not the same computer?

Do the blue waves have a lot of even tops and bottoms like somebody took a ruler here and there and evened them all out? I don't have an illustration for that. Sorry.

My piano solo has a lot of uneven spikes and valleys and no obvious flat spots except at the beginning and end which is normal.

Koz