record clamps and cracked records!

Archived from groups: rec.audio.high-end (More info?)

Raja Abdul Razak wrote:
> I think the clamp on my Oracle Alexandria Mk. II cracks records! I can
> tell by the creasing of the label around the spindle hole, and a
> cracking sound when I clamp the disc. Although the cracks may be
> superficial, they are worrying nonetheless, not to mention disfiguring.
>
> Could it be that I am clamping the records too tightly? I usually twist
> the knob until it 'locks' tight.
>
> If I remove the plastic 'raiser' (the little disc that sits under the
> mat which raises the label area), this may ease the tension somewhat.
>
> Help anyone?

I had an Oracle Delphi Mk III table for years and yes, it is possible to
crack an LP, especially the thicker ones. But it's easily avoidable. The
purpose of the clamp is to get a tight fit between the LP and the
turntable mat. I found even a little clamp pressure was enough that - if
the mat was really clean - the LP would fit so tightly that I had to
literally peel it off the mat. So there's nothing to be gained by
affixing it any tighter than that.

Archived from groups: rec.audio.high-end (More info?)

On 3 Jun 2005 00:13:31 GMT, "Ron Stewart" <ron8074@sbcglobal.net>
wrote:

>The beveled disk is there so that when you tighten down with the screw
>clamp, pressure is applied to the outer areas of the record. This is a very
>clever and simple design and one of the things that sold me on the Oracle. I
>have had mine for almost 20 years and have never cracked a record. You
>should never tighten the clamp all the way down as you will get the cracks
>you have noticed.

Indeed so. I have a similar Michell GyroDec, and I've modified the
central washer so that discs are squeezed with enough deflection to
ensure that they are flat, but not so much that the vinyl is
overstressed. One of the nice things about the Oracle is that the
'sticky' mat allows you the same excellent full-surface contact with
even less pressure.

--

Stewart Pinkerton | Music is Art - Audio is Engineering