[JAH]

Hi,

I plan to digitize some old 45s and LPs when I find a stereo
turntable. Meanwhile as an experiment, I connected an old Pye mono
record player from the early '70s to a laptop and recorded some
tracks. The recorded wave patterns in the editing software appeared to
be slightly off centre with peaks of -5dB on the top but -1dB on the
bottom. Is this asymmetry a result of the mono stylus in a stereo
groove, or is it due to some other mechanical effect? The recordings
still sound surprisingly good from this 'lo-fi' system.

John.

[Eeyore]

JAH wrote:

Hi,

I plan to digitize some old 45s and LPs when I find a stereo
turntable. Meanwhile as an experiment, I connected an old Pye mono
record player from the early '70s to a laptop and recorded some
tracks. The recorded wave patterns in the editing software appeared to
be slightly off centre with peaks of -5dB on the top but -1dB on the
bottom. Is this asymmetry a result of the mono stylus in a stereo
groove, or is it due to some other mechanical effect? The recordings
still sound surprisingly good from this 'lo-fi' system.

Many sounds are naturally asymmetrical. I'd only be concerned if it behaves like
that with every disc you play.

Graham

[Earl Kiosterud]

"JAH" wrote in message
ups.com...
Hi,

I plan to digitize some old 45s and LPs when I find a stereo
turntable. Meanwhile as an experiment, I connected an old Pye mono
record player from the early '70s to a laptop and recorded some
tracks. The recorded wave patterns in the editing software appeared to
be slightly off centre with peaks of -5dB on the top but -1dB on the
bottom. Is this asymmetry a result of the mono stylus in a stereo
groove, or is it due to some other mechanical effect? The recordings
still sound surprisingly good from this 'lo-fi' system.

John.

John,

First, be sure that there isn't a DC offset in the signal. With no record playing, the line
should be at 0, not much above or below. The preamp/audio chain may well not pass signals
down to 0 Hz, but it's worth looking at.

Individual instruments, including voices, are often asymmetrical, but the mix generally
isn't much. What you're seeing may well be a lot of 2nd-harmonic distortion caused by
groove wear or a worn stylus. Try taking something like a thin stick, and applying slight
sideways force to the tone arm, near the pivot, one way, then the other. See if the
asymmetry changes, and if it sounds cleaner. Be very careful -- don't push too hard.

Also, using a mono cartridge is tough on stereo records, as the stylus doesn't want to be
moved up and down, but the groove does move up and down, to the extent that there is
difference between the left and right channel signals.
--
Earl Kiosterud
www.smokeylake.com