Re: Dumbest Question of the Week (not much about audio)
- From: "Peter Larsen" <plarsen@xxxxxxxxxxxx>
- Date: Thu, 13 Dec 2007 22:53:01 +0100
Scott Dorsey wrote:
Peter Larsen <plarsen@xxxxxxxxxxxx> wrote:
Luddites of the World Unite! ... all power to the Luddites! ... on a
similar note, Luddism that is, it might be an idea to make a 45 rpm
frequency response calibration disk for those that transfer vinyl
.... takes the guesswork out of calibration, and it would be
surviveable to mail distribute. Just an idea, dunno if the market is
there, but if the vinyl "things" sites would like to you perhaps a
business idea worth looking in to?
It's actually very hard to make a good calibration disc.
You can use the current Shure S16 test record at 33 rpm. The only
calibration that is speed sensitive is the actual speed itself, and
that's something
you can measure directly with a strobe disc. So align at 33 rpm, then
change the motor speed and calibrate the speed with the disc.
OK, then make a 33 rpm disk in single size for frequency response
calibration, one that is "good enough" to get a cartridge from a 5 dB
tolerance zone to a 2 dB tolerance zone.
The AES Committee on Transfer Technologies just recently managed to
reissue the 78 rpm wide-groove test record from EMI this past fall.
They are selling them for $80 a pop, which considering the collapse
of the dollar and the general inflation comes to about what they were
selling for in the fifties when they were new.
Hmmmm .....
You can ask them about 45 rpm disks, but I think since there are
still a couple good 33 rpm test records available than the demand
will not be there.
Scott, I wasn't thinking about lab quality records that are made for exact
measurements, I was thinking of something that could be the radio shack
meter of the test records, "good enough" and of a convenient size to ship
cheaply and retail via mailorder only.
The current Shure test disc was originally cut by Don Grossinger on
the
DMM lathe at Europadisc. He had to do a few of the tracks at
half-speed too... the square waves on that disc are beautiful and a
lot better than
I could get out of my lathe even at half speed.
OK, OK, OK ... I get the drift, specmanship could make me go for it. There
is some merit to using a 12 inch disk. But what will do well for most home
transfers is a single sized disk with a 20-20 stereo sweep on each side,
from a geometry viewpoint the placement of it will be reasonable. You know a
lot more than I do, it may be a wild herring, or it may be a viable business
idea for you in collaboration with the vinyl transfer websites .... use idea
free of charge or disregard as you see fit. It might even be an idea to get
one included with each grammophone sold by some vendor or manufacturer ....
there are many riaa-amps out there, but also many variations between them,
so the only real solution is to verify and possibly compensate after
digitizing.
--scott
Kind regards
Peter Larsen
.
- References:
- Re: Dumbest Question of the Week (not much about audio)
- From: Romeo Rondeau
- Re: Dumbest Question of the Week (not much about audio)
- From: David Morgan \(MAMS\)
- Re: Dumbest Question of the Week (not much about audio)
- From: Scott Dorsey
- Re: Dumbest Question of the Week (not much about audio)
- From: Peter Larsen
- Re: Dumbest Question of the Week (not much about audio)
- From: Scott Dorsey
- Re: Dumbest Question of the Week (not much about audio)
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