[Phono-L] An interesting observation

[Greg Bogantz]

    Robert, I'm not quite sure what's going on in your reproducer 
experiment.  The needle mounting cavity in the Victor ortho reproducer's 
needlebar is nothing special, it's merely a triangular bore with a setscrew 
located approximately halfway along the length of one of the flat sides to 
clamp the needle into the opposing "V" trough of the bore.  But I can guess 
at several things:

    (1) You could have some dirt inside and at the very end of the bore that 
is causing the needle to not seat firmly into the V groove when you insert 
it fully.  This will cause some decoupling of the needle with the needlebar. 
When you don't insert the needle fully, you don't engage the dirt which then 
allows the needle to seat into the V more tightly.

    (2)  You don't mention which direction the loudness changes.  Inserting 
the needle less fully into the bore will result in it's sticking out farther 
which changes the mechanical "gain" of the needlebar system.  The longer the 
distance from the needle point to the pivot of the needlebar, the less 
loudness you will get.  Just a small change here can be audible.

    (3)  If you are inserting the needle just enough so that the thumbscrew 
just engages the blunt end of the needle, you are not securely clamping the 
needle against the V groove.  As it wiggles, the needle itself will lever 
against the thumbscrew as a fulcrum and flex against the V groove, causing 
some error in transmitting the vibrations to the needlebar.  This will cause 
a loss of volume.

    Any of the above scenarios will change the volume as well as change the 
frequency response and may cause distortion which can be interpreted as 
"improved" high frequency response.

Greg Bogantz



----- Original Message ----- 
From: "Robert Wright" <esroberto at hotmail.com>
To: <phono-l at oldcrank.org>
Sent: Friday, August 28, 2009 5:00 AM
Subject: [Phono-L] An interesting observation


>
> Been meaning to post this for a few days now...
>
> I was recently
> spinning some discs on my Victor Orthophonic suitcase model, and it
> dawned on me to try something out.  I slipped a new needle into the
> shank, and I pulled it back out maybe a millimeter or so, just enough
> to keep the blunt end from resting against whatever it rests against
> before tightening the thumbscrew.  I immediately heard a noticeable
> difference in volume (maybe 1 to 2 dB), slightly wider frequency
> response, and most significantly, an openness (for lack of a better
> word) I'd never heard before on any windup phono.  It seemed like all
> this time, something was slightly constricting the diaphragm, just like
> pretty much every windup phono I've ever heard in person, and suddenly
> there was a whole new freedom to the sound pouring out of it.
>
> Has anyone else ever tried/noticed this?  Mr. Bogantz, is this my 
> imagination?
>
> Best to all,
> Robert
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