Thanks to Craig Brougher for more historic information on the
Dynavoice.  From all reports (Rollie in Michigan) the original
Dynavoice plant was in Plymouth, near Detroit.  Maybe the Kansas site
was of the other unnamed, similar key-top unit, or Dynavoice may have
relocated there.

Mr. Brougher is correct about the design flaw that resulted in broken
nipples on the plastic pneumatics.  Of the four units that I'm familiar
with, only mine, which is the earlier Model P-51, serial #2202, did not
suffer from this problem.  Two units which I acquired for parts (P-52s
both in the 4000 series range) had extensive breakage of the vacuum
outlet nipples, over 50%.  As Mr. Brougher surmised, there is a simple
fix for this, of inserting a brass tube at that point.  I repaired
several control nipples on my unit by this same method.  Mike Stehney's
unit (P-52, 3000 series) appears to have been retrofitted before it
even got out of the factory, or by a prior owner, as all, or a major
portion of the vacuum port nipples had been replaced by metal tubing.

I'm not sure about Mr. Brougher's observation about rough tracker bars.
Maybe my transposing bar started out rough, but by the time I got it,
after about fifty thousand miles of paper going over it, it is quite
smooth. I have found that to apply a little Pledge wax to it with my
finger and polish it up, makes it very smooth indeed.  The tracker bars
on the later models are non-transposing and appear to be of an inferior
alloy.  They may not track as smoothly as the originals, and it may be
this latter version that Mr. Brougher saw.

Regarding the tracking system.  The units had two variants of the
tracking system that I'm familiar with.  The earlier units, up into the
3000 series, utilized an opposing set of the same accordion bellows,
controlled by an adaptation of the same valves used for the striker
pneumatics.  A later adaptation of this system was introduced that
eliminated the valve control chambers.  This system put the bellows
under constant suction and regulated them directly by the centering
control holes on the tracker bar, acting as bleeds to each bellows.

The earlier system works fine for me, but at some point I want to
retube my centering system to the later version for comparison.  I know
the earlier system can tend to overreact and be a bit jerky sometimes.
I suspect the latter version was introduced to eliminate this condition,
and smooth out the action.

I have found that the Dynavoice centering system can successfully
auto-track rolls that are in relatively good condition and not too
badly distorted.  In my case that only applies to about 10% of my
rolls.  Fortunately the opposing bellows of the centering system are
mounted on the player frame in such a way that it is a simple matter
to attach a manual assist, push-pull knob, to the centering system.
The knob comes through the case just to the right of the player frame
and a bit above the control panel.  Very convenient and easy to use.
Even the most badly distorted and wandering rolls can be handled with
a combination of the manual centering assist and a little help from the
transposing option.  The fact that the unit is right in front of you on
the key-board make this operation very easy to perform.

Another very important use of the centering manual assist is that it
allows more control upon rewinding, in order to avoid paper shredding
disasters common to old rolls.  In addition to pulling out the left
flange 1/4", the rewind motor should be on a variable foot switch for
total control of the rewind system.  A sewing machine foot switch,
though a little touchy, will work fine.

I would recommend that anyone considering rebuilding a Dynavoice should
try to acquire the earlier model (P-51) with the transposing tracker
bar as it also has the better quality turbine.  The transposing bar and
the 2-speed turbine were probably done away with, in a cost cutting
move, when the company was floundering.

Tom Lear
San Francisco CA