Ron L is correct. But both of these springs were bad ideas to begin
with. They were a lame attempt to account for the escessive bias placed on
the diaphragm by the extra weight which causes the diaphragm to be stressed
(and strained) downward even more by the tension in the stylus bar link.
The extra weight used in the Dance and Edisonic models was required to
reduce mistracking and distortion when playing highly modulated records,
particularly the later electrics. It DOES NOT make the reproducer play
"louder", contrary to the bilge in the Edison blurbs to that effect. The
loudness can only be controlled by changing the mechanical "gain" of the
stylus bar which is the ratio of the stylus tip distance to the bar pivot
relative to the distance from the bar pivot to the link. This ratio is the
same for ALL Edison DD stylus bars, hence they all play at the same
loudness. You can confirm this to yourself by using the different models of
reproducer to play very soft recordings which do not tax the reproducers -
they will all sound the same loudness. The fact that they may sound
different when playing loud recordings is due to the differences in
mistracking and distortion that they exhibit on those records.
This biasing of the diaphragm is indigenous to the tracking of vertical
modulation and is one of the several problems with that technology. (This
problem does not exist with lateral reproduction.) Having a permanent bias
or bend in one direction while playing a record causes the diaphragm to
exhibit assymmetric nonlinear behavior (due to it nonlinear elasticity)
which is yet another contributor to the generation of even orders (2nd, 4th,
6th, etc.) of harmonic distortion. Edison tried to reduce this bias (or
permanent bending offset under playing tension) of the diaphragm with the
addition of these springs into his later models of DD reproducers. There is
a lot of bloviation about the purpose of the springs in his patent
disclosure for the Dance reproducer, but compensation for the bias was their
intended purpose. It didn't work. Mostly because he didn't account for the
added spring constants these springs introduced into the diaphragm resonance
which changes and/or adds to the mechanical resonances of the system. In
particular, he didn't damp the springs sufficiently or at all. The
diaphragm spring was designed with some damping in it, but it was
ineffective. The stylus bar spring has no damping that I can find.
Consequently, you can hear this spring "ring" when you play records. If you
pay attention, you can hear a ringing noise behind the music which is this
spring boinging or oscillating. Bad idea. My advice is to just remove both
of these springs. The reproducer will sound cleaner and clearer with fewer
resonances and extraneous noises.
Greg Bogantz
----- Original Message -----
From: "Ron L" <[email protected]>
To: "'Antique Phonograph List'" <phono-l at oldcrank.org>
Sent: Thursday, May 08, 2008 2:07 PM
Subject: Re: [Phono-L] edisonic vs. dance?
>I believe one has two springs and the other has only one. I think the
> Edisonic has the spring only on the needle bar and the Dance has one on
> the
> diaphragm as well, hence the bolt-on neck.
>
> Ron L
>
> -----Original Message-----
> From: phono-l-bounces at oldcrank.org [mailto:phono-l-bounces at
> oldcrank.org]
> On
> Behalf Of Peter Fraser
> Sent: Thursday, May 08, 2008 1:46 PM
> To: Antique List Phonograph
> Subject: [Phono-L] edisonic vs. dance?
>
> can anyone expound on the differences between the Edison Dance
> reproducer and its successor, the Edisonic? As near as i can tell,
> it's just the bolt-on neck...but does the little spring have different
> characteristics? is there anything else? do they sound appreciably
> different when equally restored?
>
> thanks for anything you can offer...
>
> -- peter
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