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arsclist Azimuth and noise floors (was something about tubes)
Hi, Matt,
At 09:40 PM 11/14/2002 -0600, matt Sohn wrote:
I am doing my best not to make bad copies. I am curious about how to
adjust azimuth for optimum playback. Is this an issue with mono 1/2 track
tapes? how do I know if the azimuth is correct for the tape I'm playing?
I'm very leery of changing the azimuth of the machine, which sounds fine
to me. I mostly am dealing with 1/2 track mono material,
It's an issue with all tapes. It's perhaps THE MOST critical issue in
playback that's overlooked. The wider the track and the slower the speed
the more of an issue it is.
First, get a good test tape. Align the recorder's azimuth to that.
Then for each mono tape you receive, GENTLY adjust the azimuth plus and
minus through that good point from the test tape, listening for the
brightest high end you can get. It's a rock-back-and-forth thing like
focusing a camera lens. Don't be afraid to put your ear up to the tweeter
or wear headphones.
but there is a portion of the collection which is (mostly) mono tapes
re-recorded to stereo. Should I adjust each tape's azimuth or shold I just
take the best-recorded channel and mult it to both recording channels..
You can use the two stereo channels and an X-Y oscilloscope (make sure you
get one that doesn't have a fan. A lot of Tektronix 465M gov't contract
scopes show up on eBay and unlike the 465A/B they do NOT have fans. Or you
can buy new from some of the Japanese or Chinese firms. The 465M is a lot
of scope for the money--don't pay more than $200 delivered on eBay. I
bought one for $150 it broke, I fixed it, and I just bought another for $96
delivered. It works. It's more scope than you need, but they're pretty
rugged and cheaper than the new lower-quality scopes.) (sorry for the rant)
Anyway, you should have the mono program ALMOST a 45 degree line. You'll
see it open up somewhat, but try and center that.
Do NOT sum the two channels for your copy. Pick the better one.
Also I would welcome some discussion of power conditioners. I am unhappy
with the noise floor of my system, and would welcome any recommendations on
providing clean power on a limited budget. I work with what I've got and try
to do the best I can. I would love to have better converters, but it just
ain't in the budget.
Noise floor? Will a power conditioner fix that? Maybe BALANCED power will
solve a problem by masking it. Will rewiring fix that? Maybe. Are your
analog interconnects balanced? They should be for the most part. Can you
simplify the system?
I'm concerned that you might invest in a balanced power conditioner and
still have noise.
Cheers,
Richard
-Matt Sohn
Audio Preservationist
Louis Armstrong House and Archives
www.satchmo.net
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For subscription instructions, see the ARSC home page
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Copyright of individual posting is owned by the author of the posting and
permission to re-transmit or publish a post must be secured
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