mono LPs - recording

Discussion in 'Music Corner' started by ascot, Oct 1, 2002.

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  1. ascot

    ascot Senior Member Thread Starter

    Location:
    Wisconsin
    I started a new thread rather than continue in the Doors mono LP one:

    Ok, I have a question now about recording mono LPs. I would like to transfer my mother's mono Beatle LPs to CD-R. These are just the Capitol versions and I'll be putting the stereo version along with it. (Sadly, she stopped buying their albums after Revolver.)

    In the Doors thread, Steve H. said to get a double Y adapter for listening to mono LPs properly. I presume this would combine the two channels into one then split them back to two channels for the two speakers.

    I thought I read that when recording mono for transfer to CD-R, you should not combine the channels and record the .WAV file as a single mono .WAV.

    Instead, record the two stereo channels as if it were a stereo recording. After de-clicking, select the cleaner channel and copy it to the other side.

    This is what I did with some tests and it came out pretty well.

    So, if I throw in a double Y adapter before the signal goes to my soundcard, will I improve the quality of the transfer or just create sonic sludge? :confused:
     
  2. sgraham

    sgraham New Member

    Location:
    Michigan
    Generally speaking you will get the best result if you do this:

    Record to hard drive in stereo
    Do any de-clicking that you want to do
    Then have your software sum the left and right channels. It's very easy to do this with Cool Edit, and I think also with most other software. Make sure it adds them both at 50% (unless you recorded it quietly) so that the summed result doesn't go above the maximum permitted level.
    The file will still be a "stereo" file, which is what some CD-burning software needs, but the contents will now be mono.

    When you combine the channels any noise that is vertical in the groove vanishes completely, and distortion is reduced noticeably.

    Of course there might be some records that are noisy on one channel and clean on the other, and in that case you may be better off with just the one channel.

    There is another oddball exception. IF the master tape was mono but the cutting was done by playing the tape on a stereo machine and cutting with a stereo cutter head, and if the engineer was sloppy about adjusting the tape head to match the azimuth on the tape, then when you combine to mono you'll get phasey stuff. You can usually correct this by shifting one channel in time slightly so that the waveforms line up and then doing the stereo to mono conversion. And in any event this is quite an unusual situation.
     
  3. Grant

    Grant Life is a rock, but the radio rolled me!

    I used to be of the camp that recommended copying to stereo first, then choosing the best channel before processing.

    But, if you copy as stereo, then combine them with the software, you can cancel out some of the noise that is common and of equal strength to both channels to get a cleaner mono file. once you combine the two sides, you can process in mono because it's fsater. If you work at a higher bit depth, you can just turn your mono files into stereo before you dither back. If you work at 16-bit, use the software to convert to stereo. I personally wouldn't trust the CD burning software to do it. I do everything in Cool Edit and Sound Forge.

    One more thing, if you process at the recommended 32-bit float, you need not worry if you go over digital FS "0", because you CAN'T clip at 32-bit float! Even if those meters say you've clipped at 32-bit float, you didn't! Just remember to bring everything back down to "0", or just below before you convert back to 16-bit! Important! If you don't, you WILL clip!
     
  4. sgraham

    sgraham New Member

    Location:
    Michigan
    Hah! That's a useful thing to know. Thanks, Grant, I didn't realize it.
     
  5. Todd Fredericks

    Todd Fredericks Senior Member

    Location:
    A New Yorker
    I find what usually works best for me is to use a y-connector from the preamp to the DAC. A lot of noise will be cancelled out and the music/recording will have more focus. If click removal is neccesary then it'll be easier (why remove clicks, etc. if they may be cancelled out anyway?). I beleive getting the playback & recording levels as optimum as possible before hitting the record button....

    Todd
     
  6. Grant

    Grant Life is a rock, but the radio rolled me!

    It's useful because you can process to your heart's content without worry of degrading your sound or going over. But once you finish your work and before going to 16-bit, or even if you go to 24-bit, you MUST pull your peaks to or under FS 0 or you WILL clip. I just had to repeat that because it is so important.

    But, try it. Convert a file to 32-bit FLOAT, amplify your file, hmmmm, make it 700%, save it, then go back to or under 100%. You will hear NO change in your file! Depending on your soundcard, you may even be able to play a file with boosted amplitude.
     
  7. Grant

    Grant Life is a rock, but the radio rolled me!

    Correct. It just depends on whether you want to use a Y connector or do it with software. Of course, if you use a standalone recorder, you have to use a Y connector.
     
  8. ascot

    ascot Senior Member Thread Starter

    Location:
    Wisconsin
    Thanks, Grant. I do use Cool Edit, and I do use the 32-bit float for all recording / processing. I did not know about the lack of clipping at 32-bit float. I always try to keep the peaks just below 0db to be safe.
     
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