Unusually large diaphragm

[WDC]

Here's another Goldring Juwel Electro with a lateral attachment on my Edison B-19. It harmonizes quite well with the exponential horn too:

[youtubehd]http://www.youtube.com/watch?v=rEAuFSIFibE[/youtubehd]

[epigramophone]

The largest diaphragm reproducers I have are shown below: it is an unbranded German on the left, followed by a Swiss Pianina on the center. A HMV 4 is shown on the right for comparison. I have also the Pathé Concert reproducers, which are of the same diameter as the Pianina (both shorter than the German one). As to how they sound, haven't found yet, I could not get a machine that would match the height of the turntable with the reproducer, so for now they remain curiosity pieces inside my drawer ...

Even larger than the Pianina was the Astra, so large that the tonearm connector had to be offset to fit a gooseneck. The diaphragm was made of compressed silk, and there is no way of knowing how it's acoustic properties might have changed over 90 years. Here are my two examples together for comparison :

[Stan]

I really appreciate the video links and pictures. I'm all thumbs when it come to adjusting needle bar tension, the "sweet spot" seems to elude me, but I suspect that may be the source of the problem. I experimented with an aluminum diaphragm - no significant improvement, but interesting sound.
BTW, the original flange rubber (?) insert was really thin and dried out. I replaced it with a few layers of electrical tape - that's all that would fit. The opening is small - it's a tight fit on the Victrola tone arm but is made somewhat easier with lubricant.

[WDC]

It's really not as difficult as you would expect. You keep turning each screw evenly for something like ¼ turn until there is some resistance. Then you check if the needle bar can move sideways from the diaphragm. If so, than you just need a tad more tighter screws. Then you check the free movement towards the diaphragm. Again, while still detached, it should be able to balance out just by its own weight.
Once that is ensured, you then carefully tighten the nuts, may put a tiny drop of crazy glue on the nuts (not the bearings, of course) and you should be good with putting it back together.

When you mentioned the gaskets, this is has to be at least 50% of the whole problem. I would recommend to stick to the original mica diaphragm and get some good gasket material from Ron Sitko. It's really inexpensive and makes a world of difference. Any kind of tape will be way too stiff.

[Menophanes]

I do not know how the following Pathé Concert sound-box compares in size with the Astra, but with a diaphragm diameter of 62mm (2.44") id does pretty well on its own account. The diaphragm is peculiar on other ways than mere size, since it is made of a material which is pale brown and transparent but is certainly not mica. It is not flat but has a shallow curvature, it seems to have been roughly cut to shape with shears or scissors (imagine cutting mica with scissors!), it is slightly flexible, and it has shallow parallel ridges or striations on its inner (concave) surface. I believe it is some kind of animal horn.

This box comes from a crude English-made table gramophone of the 1920s. The machine was perfectly useless, since despite the provision of a telescopic section in the tone-arm it would never track properly; the stylus would not stay in the groove for more than a few seconds. The only way I could play vertical-cut records was by using two gramophones to play one record; an H.M.V. 101, placed on a higher table beside the Pathé and with its speed-control run up to the limit, provided the motive power, and the Pathé tone-arm and sound-box, swung right over the side of its own machine so as to meet the 101 turntable, did the rest. I have still got the 101, but I no longer have the energy or the sheer strength (the crypto-Pathé machine is right on the limit of my ability to lift) to replicate the arrangement today.

From what I remember from over thirty years ago, the Pathé box had a very thick and murky tone. I can no longer test it, since the gaskets have ossified and the stylus-arm has come unglued from the diaphragm. However, I have found that I can actually play vertical-cut records after a fashion by fitting the Pathé stylus directly to the No. 4 sound-box of the 101. The sound is faint and pinched, rather like that of a horn gramophone with the horn taken off, but it is reasonably clear and there are no tracking errors. Of course the vertical grooves are trying to make the needle-arm vibrate in the wrong plane, so that one cannot expect a good result; I am pleasantly surprised that it works at all.

Oliver Mundy.

[CarlosV]

I do not know how the following Pathé Concert sound-box compares in size with the Astra, but with a diaphragm diameter of 62mm (2.44") id does pretty well on its own account. The diaphragm is peculiar on other ways than mere size, since it is made of a material which is pale brown and transparent but is certainly not mica. It is not flat but has a shallow curvature, it seems to have been roughly cut to shape with shears or scissors (imagine cutting mica with scissors!), it is slightly flexible, and it has shallow parallel ridges or striations on its inner (concave) surface. I believe it is some kind of animal horn.

Oliver, from what I see the diaphragm and the needle bar in your sound box are not original. The Concert has a nice and round mica diaphragm and its needle bar connects to the diaphragm through a single screw. Yours looks like a home-made adaptation. The Concert sound box is actually very good in terms of sound reproduction: with new gaskets and new rubber back tube (and a good sapphire) it is the best to play hill-and-dale records.

As to size, its diaphragm size is the same as the Pianina's, so the Astra and the unbranded German I showed are larger.

[Stan]

When you mentioned the gaskets, this is has to be at least 50% of the whole problem. I would recommend to stick to the original mica diaphragm and get some good gasket material from Ron Sitko. It's really inexpensive and makes a world of difference. Any kind of tape will be way too stiff.

Re: the gaskets, I replaced the white tubing that came with it, since it was dry and crumbling. I tried the light, foam like rubber ones as well, but they weren't an improvement; it may actually be too wide for them. I used the black electrical tape to replace the flange which was really thin. I was able to salvage the metal ring itself, and wrapped a few layers of tape around it.

[Stan]

I attached samples of 2 records played on the Triumphonic and, for comparison, the HMV No.4.
The Triumphonic produces a fuller sound, but the HMV offers more clarity. The castanets in the opening of Rio Rita are much clearer with the HMV.
The opening of Easy to Love tends to overwhelm soundboxes, even an Orthophonic, but the HMV allows you to hear some of the detail.
The voices also come through better on the HMV; the Triumphonic is louder, but the overall effect is dullness - at least to my ears. Is it possible to improve the clarity? Maybe I haven't found the right adjustment for the Triumphonic needle bar tension.

Thanks,
Stan

[Stan]

I just wanted to add that I finally achieved a more desirable sound - Wyatt M suggested that the white tubing was probably too thick, so I replaced one with a spare rubber foam gasket - I had to stretch a bit to make it accommodate the wider diaphragm, but it was still thick enough. Now the Triumphonic produces a sonorous sound, somewhat comparable to my Credenza.

Thanks everyone for all your help!

Stan