The Talking Machine Forum — For All Antique Phonographs & Recordings

Hello All,
The Exhibition reproducer is probably the most common soundbox found on pre-1920’s gramophones. It was copied extensively and appears under a whole array of brand names.

The biggest problem I find with the Exhibition is the rubber flange that connects it to the tonearm. In most cases, I find time has petrified it into a hard, brittle and miss-shaped mess. This causes air leaks at the most crucial point and also inhibits the soundboxes flexibility. The result is, terrible reproduction.

I know there are several sources for replacement flanges and I have used several of these only to find then unsatisfactory. They might look good but in my mind the rubber used is still too hard.

I recently had to replace this flange on a Victor Exhibition. I had run out of replacements so I decided to have a go at making my own. I found a local source for custom made washers. I ordered some in natural rubber, neoprene and nitrile. After a few experiments I decided to use neoprene on the outside and the softer nitrile on the inside which touches the back of the soundbox housing and creates an air-tight seal.

There is a significant improvement in reproduction and I can imagine it is how an Exhibition would have sounded when new. I used contact adhesive and next time would perhaps punch out the mounting holes after gluing the two parts together. You also get to reuse the original brass ring.

Here is the process in pictures.

Thanks for the explanation and for the company...! I've started to feel I was the only one who thought that the modern exhibition back replacements currently for sale these days were too hard! I was sure the original natural rubber was much supple... You've given me the punch to seek for other modern replacements that may result... I'm not glad with the sound of my three exhibitions, and the rubber hardness was one of the things I blamed, let apart the tricky adjustment...

Great idea... thinking outside of the box.

Ever since Rocky Mountain Rubber went the way of the dodo (how long has it been??), there really hasn't been a commercially produced Exhibition rubber flange that compared. I think I still have one or two that I'm holding onto, before I have to resort to similar creativity.

Thanks! I might try that!

- Bill

So the solution is nitrile rubber? I think I can try a hardware store and look for rubber washers (well, rubber-like) in the plumbing/gardening sections, to see what is currently available. I'll try the softness to see what suits better.
I'm always thinking of the two big screws that hold the rubber to the exhibition backplate. These are pretty big screws, and the joint they proovide must be very stiff, despite the rubber. So I'm tempted to remove them and glue directly thhe rubber to the sb plate. I'll try one of these days to see what happens.
The exhibition amplifys sound very well, but there's that harshness in certain tones... Once I tried an altered exhibition, adding soft rubber tiny washers here and there to get more compliance in the needlebar, and also loosened the sb screws so the rubber gaskets exerted the lightest pressure on the diaphragme edge. This way also the air chamber behind the mica is deeper. I then sealed all the joints around the sb body,, and sealed the loose scrrews too, etc. With this transformation, I have to say that I got an exhibition that played electrical records very very well! But acoustics sound dull. So I finally removed all the alterations and came back to the original status. These hard needlebar leaf springs also worry me. I'm tempted to try to thin them by grinding, or try thinner leaf springs to see what happens.
I'm still not able to master the tuning of an exhibittion soundbox, and this is frustrating. More trials and time would finally show me the way, I hope.