Good Tests but Distorted Results

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Good Tests but Distorted Results

Postby Stefano » Mon Apr 11, 2005 3:37 am

I've just set up my turntable, and done a few tests. I tried a stereo album which came out quite well, but I am having an issue with some other tracks that just happen to be mono. When I run a record test, the volume levels are fine and the sound is good. However, once I record the track, the playback sounds somewhat distorted, in both the high and low frequencies. Like a fuzzy (worn out grooves) sound. I have no idea why this would sound good in the test mode, even in hearing the recording as it goes, but not in the playback. Any ideas?

Thanks.
Stefano
 
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Postby citguy » Mon Apr 11, 2005 7:13 am

Hi Stefano. Are you using a sound card and if so which one. Check all the cable connections to make sure you are on the correct inputs and outputs. Is there a control panel that will allow you to choose input and output settings for your computer. I assume you are using a preamp in and a preamp out from the computer or are you just using computer speakers? Finally, what processing are you doing with Wave Corrector? Over processing can cause undesireable results.
Stan
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distorted recordings

Postby Stefano » Tue Apr 12, 2005 2:06 am

Stan,

I am using a Bozak premap (RIAA. etc.) to the line-in in the back of my computer to connect the turntable. I have the ground wire from my turntable attached to the chassis of my computer to decrease hum. For hearing what I am recording/playback, I am using the computer speakers. I adjust the volume through Windows. Like I said, it sounds fine during the tests and during recording, only during playback does it sound distorted (but apprently the recording has the distortion). Before I even scan it through WaveCorrector, the track played back sounds distorted. I just use the program to record and remove clicks. I am using the soundcard my computer came with, which I believe is Soundblaster Live with 5.

Thanks for your help.
Stefano
 
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Postby citguy » Tue Apr 12, 2005 3:01 am

Stefano. Do you have a "line out" on your card that you can connect to an aux input on your Bozak and listen to the recorded material with headphones to eliminate the "computer speakers"? Also do you have a "properties" screen where you can mute unused inputs during recording? I apologize because I'm stabbing in the dark. I assume you are using Wave corrector to create the wave file as well as process it. I'm confident someone in the group will help zero in on the problem. Have you tried recording at a much lower level and correcting later?
Stan
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Postby Stefano » Tue Apr 12, 2005 4:55 am

Yes, I am recording the tracks with Wave Corrector. I have not tried listening to the recorded tracks through another means. I assume since it sounds fine when testing, that the final recording should sound fine too. I did record something that had lower levels, and normalized it afterward, but that didn't help with distortion any. Would there be a separate device for playback then for recording? I don't understand why it sounds fine during recording, but not when playing back the recording. There must be some difference in the way the sound is recorded.
Stefano
 
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Postby Derek » Tue Apr 12, 2005 8:33 am

Stefano

Your problem is rather puzzling. There shouldn't be any discernible difference between the original and recorded sounds. So there is definitely something wrong with your set-up.

There are different paths through your soundcard when you play back a recording compared to when you simply pass through the line-in signal. So it is possible that your soundcard is faulty. It might help of you could email me a short sample (to support@wavecor.co.uk) as this might provide a clue to the problem.

Some Soundblaster cards do tend to distort if you record at too high a level (above about -3 dB) but you have already proved that this is not the reason.

Another possibility is that you have a very high level of rumble on the source or a DC offset. This can cause the A/D converter to overload even though the wanted signal is below peak. However, this would also cause the Wave Corrector volume meters to go into overload and I assume this is not happening.

I can't really think of anything else at the moment but if you send the sample it may lead to more suggestions.
Derek Higgins
Wave Corrector Developer
http://www.wavecor.co.uk
Derek
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Postby Ray Bell » Tue Apr 12, 2005 12:43 pm

Stefano

If you have not already done so I suggest you read the useful information available on the links page available from the "links" button on the Wave Corrector homepage. In particular the "LP to CDR tips" has details about setting up the recording source on your soundcard as Stan advised. ONLY 'line in' should be selected and all other inputs disabled or you may get all sorts of junk on your recording. There is also information about other processes running on your computer which may compete for its resources and possibly interrupt the writing of data to disk. In particular follow this link in the LP to CDR tips
http://www.delback.co.uk/pcaudiofaq.htm#record
which covers a host of possible problems.

Ray
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Postby Wayne R. » Sun May 08, 2005 7:56 pm

I had almost exactly the same problem. My PC had a Turtle Montego sound card in it, and output during recording was fine - playback was terrible, though. Low levels and lots of clipping.

I replaced that card with an M-Audio 2496. Poof! Perfect results.
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