Because the Victor Exhibition wasn't good enough........

[MicaMonster]

The Victor Exhibition is an institution within itself. It has *nearly* everything going for it. A well sealed and balanced mica diaphragm, a soft gum rubber vibration insulating mounting flange, and a solidly constructed needle bar and fulcrum that could take a beating and still sound FABULOUS.

It is also the victim of many good-intentioned bad repairs. I've seen it all, even sneaker string being used as a gasket replacement. Elements of a proper Exhibition rebuilt should always include proper balance spring fulcrum pressure and diaphragm pre-load.....often overlooked, as well as rubber flange quality. I've been fighting that fight for years. Going as far as heating the current rubber parts in an oven to soften them to be more like the original soft rubber parts from the early 20th century.

Back to the line of the story: Exhibitions were constructed for general use.....and in that, this meant that they had to be servicable in rural environments being transported on a buckboard wagon, and survive a share of needle drops, and general rough handling.....and still sound good. I thought I knew ALL the tricks to make a phonograph reproducer sound good, until I started to play with my E.M.G. soundbox. And even then, I took things a little farther by installing a glass diaphragm in the E.M.G., and I haven't looked back.

Here are the main modifications that I am currently undertaking with the Exhibtiion soundbox:

A. Install Glass diaphragm
B. Reduce the clamping pressure of the face bezel and back plate to allow the diaphragm to work at optimal efficiency
C. Eliminate sound energy loss at the balance springs
D. Increase balance spring compliance
E. Re-invent the rubber mounting flange to allow even BETTER vibration control, and allow the adjustment of needle angle

-In Order:

A. New white rubber gaskets installed with a new glass diaphragm. The glass diaphragm does NOT have a center hole drilled in it, so a small....and I mean, SMALL drop of industrial strength glass adhesive has to be applied to the needlebar foot to keep it attached to the diaphragm.

B. Taking multiple measurements, I inserted small medium hardness rubber washers between the face bezel and the back plate. This allowed the three screws to hold the unit together, but not clamp the glass diaphragm with such force as to reduce the bass response. To make all the gaps the same.....dial caliper. On the EMG, all back plate screws are insulated along the threaded length of the screw, as well as the screw heads. This COULD be done with this Exhibition, but to do that I would have to lathe the threads down below the screw head and install a silicone insulator, or drill the holes in the backing larger, which I refuse to do. I don't want to modify any original parts, rather, modify through re-arranging parts.

C. The balance springs on an Exhibition are solidly connected to the balance spring screws, which thread into the reproducer face bezel. I mounted the springs upside down to accomodate the addition of rubber washers under the screw heads to reduce the direct transmission of vibrations to the face bezel through the springs.

D. The balance springs on an Exhibition are TOO STRONG. I will be making them narrower (not pictured yet), to allow more compliance. They are also adjusted to have "just enough" down pressure on the fulcrum knife edges to keep from buzzing. Victor balance springs are overbuilt....... It wasn't until the Victrola #4 and Orthophonic that the idea of non-restrictive balance springs would come into play as a means of allowing more sound transmission to the diaphragm.

E. I have drafted a new Exhibition rubber flange design that will not only offer softer material than what is currently available (even softer than the flanges I have been providing), but also allow the phonograph operator to adjust the needle angle to approximately 60-65* degrees. Varying turntable heights, amongst other factors, have made steel needle tracking angles much too low, or too high. This is a limitation of the "L" channel on the Victor tone arm, and the geometry of the machines as they aged and received repairs. I am very excited about this development, and am hoping to see the prototype in my hot little hand in the next 3 weeks.

My opinion is that everyone should have ONE or TWO machines that sound PHENOMINAL to demonstrate just how good acoustic discs can sound. This was the reasoning behind the use of a glass diaphragm.....it reproduces sound so much more detailed than mica.....because it is more uniform in shape.....no waviness.....no delaminating. The details that you never hear before become so clear with glass. My thanks to Norman Bruderhofer in Germany for providing the glass for this project, and my EMG!

Not having a flange ready, I mounted the reproducer to my EMG with a piece of rubber I had sitting on the workbench. Did I play an acoustic disc for its first play? NO. I grabbed one of the strongest electric discs I had.......and WOW. Bass response....clarity, and I was floored by it. I'll be lightening up the balance springs, and re-adjusting everything to have it ready for the rubber flange. It will be some weeks, though. Set-up fees for these kinds of projects are a beast. For anybody that owns one of my current offset Exhibition flanges, I will send out the newest flanges to you free of charge on exchange. Hopefully there are no snags. Expect more photos in the future when this comes to full fruition!

Here is the mule reproducer, exhibiting all modifications except the mounting flange and thinned balance springs.

[briankeith]

Wyatt = in your professional opinion, would it be easier to order (or drill) the glass diaphragm for the tiny screw just in case (?) the glass adhesive doesn't hold up in say 20 ++ or so years? I know some adhesives do break down over time. (I used to work for 3M)

[HisMastersVoice]

Wyatt = in your professional opinion, would it be easier to order (or drill) the glass diaphragm for the tiny screw just in case (?) the glass adhesive doesn't hold up in say 20 ++ or so years? I know some adhesives do break down over time. (I used to work for 3M)

I would guess that it would alter the structural integrity of the glass. By the time the adhesive breaks down, I'd imagine it would be time for new gaskets anyway.

[donniej]

I'd be happy to help with the gaskets. I can probably mold anything you'd want out of silicone rubber, in whatever hardness you like.

The adhesive they sell at automotive stores to attach rear view mirrors to the windshield would probably work well.

Ps. A while back I wrote about making new, correct one piece gaskets for the #2.

[JerryVan]

Wyatt,

At what point does the softness, or compliance, of the back flange cause it to absorb too much of the sound energy that's input to the reproducer, rather than transmit it to the diaphragm? Simply stated, when do you run the risk of vibrating the whole reproducer body, versus just the diaphragm? How are you gauging when the back flange becomes more compliant than the rest of the system?

My point is analogous in some ways to bicycles that have compliant shock absorbers on the frame & front forks. The downward force of the rider's foot goes to compress the shocks/springs and is not fully transmitted to the rear wheel. It cuts the overall efficiency.

[MicaMonster]

Wyatt,

At what point does the softness, or compliance, of the back flange cause it to absorb too much of the sound energy that's input to the reproducer, rather than transmit it to the diaphragm? Simply stated, when do you run the risk of vibrating the whole reproducer body, versus just the diaphragm? How are you gauging when the back flange becomes more compliant than the rest of the system?

My point is analogous in some ways to bicycles that have compliant shock absorbers on the frame & front forks. The downward force of the rider's foot goes to compress the shocks/springs and is not fully transmitted to the rear wheel. It cuts the overall efficiency.

This is an excellent question. Being an empirical experimenter you try to find a material that allows vibration insulation while being supportive. .... not too soft. 40-45 durometer is the material I am working with. I guess my answer isn't as scientific as I would like it to be. Like Edison and light bulb filaments.... try different materials....

Here are the balance springs after making them narrower.....

[hearsedriver]

Very interesting and well thought out. What do you charge to do this modification?

[MicaMonster]

After much more play and experimentation.....I was NOT happy with the modified springs I had made. There was still mechanical restriction of the needle bar. The EMG bar is so free.....but firmly held to the knife edge fulcrum points. So, here is my next revision. I used rifle spring wire and created a spring bar that goes slightly diagonally across the needle bar center point. I bent the wire in an "S" to achieve this, and added a small dip into the center of the wire, and made a similar yet longer cross-tension-wire that goes through the dip, affixed with the original balance spring screws, insulated slightly with rubber washers.

This modification achieved several things:

1. It creates a central point of down pressure directly under the needle.
2. A SINGLE pressure point
3. Firmly holds the needle bar down on the pressure points
4. Allows ABSOLUTE FREE movement of the needle bar with nearly no restriction.
5. NO MODIFICATION to original needle bar or body castings
6. Downpressure can be adjusted via screws
7. Reversible.

And does it sound good? Oh myyy......it made a Victor Red Seal of Edward Johnson not just tolerable, but enjoyable! EVERY studio sound and nuisance of his voice came through. THIS is "almost" EMG territory. Obviously there is no 10+ft long horn available to most Victor owners to take advantage of the wave propagation and stretching along a long horn of great size, BUT I believe that this will be ear opening for collectors that listen to their records on original equipment.

So, at this juncture, I will state that the reproducer is DONE, and now awaiting the newly designed rubber mounting flanges from the manufacturer. Stay Tuned!

[MicaMonster]

Here is a teaser! Dimensions aren't quite right yet, as I am trying out different shapes

[JerryVan]

Here is a teaser! Dimensions aren't quite right yet, as I am trying out different shapes

Wyatt,

Since you're going for a much softer durometer, would it be advisable to make the mating face of the flange somewhat convex? The idea being, It would make better seal with the reproducer body as the flange will contact first near the I.D., then flex a bit to apply even more pressure to that contact area. A softer flange may try to arch up a bit, (i.e. gap), in the area between the two screws otherwise. At least it does in my mind's eye...

I like your spring replacement scheme.