[Phono-L] Orthophonic Reproducer Gaskets question...

[Greg Bogantz]

    The Victor orthophonic reproducer (or #5 as it is sometimes known) was 
designed to have all the diaphragm flexure accommodated by the pleats 
stamped into the metal diaphragm.  Unlike earlier designs, the gaskets were 
not intended to provide flexure - they were strictly there to seal the air 
leaks where the diaphragm joins the body of the reproducer.  This design was 
purposely done to make the flexure and, therefore, the mechanical resonance 
more consistent from one unit to another and to ensure that it remains 
constant over time.  This provided a much more consistent and predictable 
performance from one production unit to another.  It was known to the 
designers of this reproducer that the earlier designs employing rubber 
gaskets deteriorated over time which resulted in decreased performance.  The 
correct replacement gaskets for the #5 would be those that seal well without 
providing any flexure.  If you do use rubber gaskets, the flexure that they 
provide will lower the diaphragm resonance frequency.  This will emphasize 
the bass frequencies, but at the expense of the treble.  The resulting sound 
will be more bass-heavy and with less treble and brilliance.  The amount of 
this change in frequency response will be dependent on the softness of the 
gasket rubber and on the amount of clamping force you have when they are in 
place.  In other words, the difference will be somewhat unpredictable and 
will vary from one implementation to another and with how the clamping force 
has been adjusted.  This is exactly what one has to deal with when 
rebuilding the earlier designs such as Edisons and the early Victors that 
require flexure in their gaskets, and good restorers are aware of this. 
Some owners may prefer this more bass-heavy sound in the #5, but it will not 
be representing the intended frequency response of the original design of 
the reproducer.

Greg Bogantz



----- Original Message ----- 
From: "john robles" <john9ten at pacbell.net>
To: "Antique Phonograph List" <phono-l at oldcrank.org>
Sent: Monday, March 22, 2010 1:26 PM
Subject: Re: [Phono-L] Orthophonic Reproducer Gaskets question...


My gaskets don't appear to have anything to do with flexibility since they 
are so thin. I can't imagine how they do any more then keep the metal 
backing from touching the diaphragm directly.
John Robles

--- On Mon, 3/22/10, Ron L'Herault <lherault at bu.edu> wrote:

From: Ron L'Herault <lherault at bu.edu>
Subject: Re: [Phono-L] Orthophonic Reproducer Gaskets question...
To: "'Antique Phonograph List'" <phono-l at oldcrank.org>
Date: Monday, March 22, 2010, 9:15 AM

In theory, they only make an air seal, rather than playing a part in
compliance/flexibility, right?

Ron L

-----Original Message-----
From: phono-l-bounces at oldcrank.org [mailto:phono-l-bounces at oldcrank.org] On
Behalf Of Steven Medved
Sent: Monday, March 22, 2010 11:34 AM
To: Phono-l
Subject: Re: [Phono-L] Orthophonic Reproducer Gaskets question...


Hello Al,

The original looks like paper coated with shellac to me. I have spoken to
people who rebuild them and they tell me you get better sound from neoprene.
I would assume Ron Sitko is selling them.

Steve

> From: ClockworkHome at aol.com
> Date: Mon, 22 Mar 2010 05:26:27 -0400
> To: phono-l at oldcrank.org
> Subject: Re: [Phono-L] Orthophonic Reproducer Gaskets question...
>
> Does anyone on this learned list know what material was used as gaskets on

> the Victor Orthophonic reproducer? I have been asked to make a punch and
> die to cut them out but if someone is already making them I don't intend
on
> reinventing the wheel.
>
> Thanks and best wishes to all on the list,
>
> Al
>
>
>
> _______________________________________________
> Phono-L mailing list
> http://phono-l.oldcrank.org

_______________________________________________
Phono-L mailing list
http://phono-l.oldcrank.org

_______________________________________________
Phono-L mailing list
http://phono-l.oldcrank.org
_______________________________________________
Phono-L mailing list
http://phono-l.oldcrank.org