HMV 101J, Green Gramophone Sound Box Swap

[Supxor]

...just received a lovely, green HMV 101J, which has a rebuilt number 4 sound box on it. Does the tone arm on the 101J accept a 5a, aluminum diaphragm sound box? It appears that it will, but wish to check with the membership's experts.

[AZ*]

The tonearm on the 101 is skinnier, so to fit a 5a, you would need to replace the 5a's rubber isolator with one from a #4. The outer diameter of the #4 and 5a isolators are the same, but the inside dimension is larger on the 5a isolator.

If it were my 101, I would leave it as is. But if you have a spare 5a soundbox and a spare #4 isolator, it might be fun to experiment to hear the difference. Keep in mind that what you are proposing is a cobble, since the 5a soundbox was not matched to the skinny tonearm.

[Supxor]

Thanks, so much for your cogent reply. My wish was to try the swap to hear the playback contrast. I might obtain a 5a and a 4 isolator just for that purpose. Gratefully, Bob

[Supxor]

Could you suggest where I might seek a 4 isolator in the US?

[AZ*]

Could you suggest where I might seek a 4 isolator in the US?

Since you are in the US, I would suggest contacting Ron Sitko or Walt Sommers for a Victrola #2 isolator which also fits the #4. Walt's and other #2 isolators are also available on ebay.

Note that the construction of the HMV isolators differ from the Victor. On the HMV isolator, the bayonet pin is usually part of the top set screw. On the Victor variety, the bayonet pin is permanently attached to the inner brass ring of the isolator. The Victrola #2 isolator will work perfectly for your application, but you will need to purchase another set screw which should be available at a "real" hardware store.

Your biggest chore may be to remove the isolator from the 5a. Unless it has been recently overhauled, the old isolator may be rock hard, and will require effort to remove. Refer to the bottom of Chunny's For Sale page for tips. Chunny also sells excellent isolators, but he is not in the US.

http://www.gramophonemuseum.com/for-sale.html

I hope this helps. It can be done.

[shoshani]

By coincidence, I have an HMV 5A soundbox that I had Wyatt Markus (MicaMonster here) refit with a No 4 brass ring and his proprietary isolator. I did this for an HMV 109, but quickly realized that the smaller diameter of this soundbox plus its different chuck-to-pivot distance ratio introduced significant tracking error on that gramophone.

However, last night I decided to try this soundbox on my HMV 101. It's an ongoing experiment but so far I'm pleasantly impressed. (And there is a very slight tracking difference, but not extreme enough to concern me. The 101 apparently has a different arm geometry than the 109 tabletop machine.) The 101 has a lot of bass with either the 4 or the 5A soundbox, but I have some records that have a tendency toward overload distortion on the 101 with a 4, that I'm going to try with the 5A.

Half the fun of this hobby is tinkering with things to find out if they can be improved, which was how it was done back in the day as well, judging from 1920s and 1930s issues of Gramophone I've perused.