[ARSCLIST] Record flattening test proposed

[Eric Jacobs <ericj@xxxxxxxxxxxxxxxxxxx>]

Generally, I'll slow-speed transfer before I flatten.

However, some warps are severe/sharp enough that the bottom of the
cartridge contacts (or rests on) the disc, and the stylus is raised
out of the groove - I'm talking about the stylus not touching the
disc even when the disc is not spinning.  The disc is impossible to
play at any speed, with any cartridge, with any VTF.  In this case,
you have no option other than to flatten the disc.

As was pointed out by Steven Barr, it is unclear if the hiss is a
result of the warping or the flattening.  And how were the hissy
discs flattened (what temp, how slowly, what pressure)?

If anyone wants to do an independent before-and-after test, I'd be
happy to flatten discs and compare transfers.  For those willing
to participate in such a test, I'll contribute flattening at no
charge, and everyone pays their part for shipping.  I'd be happy
to compile before-after transfers onto a CD-R for participants to
compare.  A nice diversity of discs (acoustic and electric 78s,
some microgroove mono and stereo LPs, and some 45s) would make the
test more interesting.  We could further define the test - such as
speeds and EQ for both the before and the after transfer.

Anyone interested?  I'd be happy to write a final report and share
conclusions with the group.

Eric Jacobs
General Manager

The Audio Archive
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx




-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of Steven C. Barr(x)
Sent: Monday, October 23, 2006 7:22 PM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] Fw: [ARSCLIST] Record flattening


----- Original Message -----
From: "Dick Spottswood" <dick@xxxxxxxx>
> I've never been convinced that you can apply heat to flatten a disc
> without partially collapsing groove walls in the process.  I don't know
> about 33s, but heat-flattened 78s sound hissy to my ears.
>
> Before and after photos under that microscope would be interesting to see.
>
That might be because in a lot of cases the heat that caused the
warping also damaged the grooves...?

Steven C. Barr