No5 soundbox sounds "shallow"

[12jslater]

My hmv no5 soundbox has been adjusted just as my other no5s however it sound quite shallow and weak compared to my others but the felt gaskets are nearly disintegrating could this effect the sound even though they are still in one piece?

Thanks, Jake

[gramophone-georg]

YES!!!

[OrthoFan]

Is this a 5 or 5a or 5b? I know that felt gaskets were used in the 5a/5b, but I believe that rubber backed paper gaskets were used for the short-lived HMV 5, which is identical to the Orthophonic sound box.

In either case, I agree with gramophone-georg that disintegrating gaskets are the culprit. In addition to providing an air-tight seal, the gaskets are supposed to rigidly and evenly clamp the edge of the aluminum diaphragm, enabling the corrugated section to flex, so the diaphragm pivots (like a piston) with the movement of the needle bar.

OF

[CarlosV]

Is this a 5 or 5a or 5b? I know that felt gaskets were used in the 5a/5b, but I believe that rubber backed paper gaskets were used for the short-lived HMV 5, which is identical to the Orthophonic sound box.

In either case, I agree with gramophone-georg that disintegrating gaskets are the culprit. In addition to providing an air-tight seal, the gaskets are supposed to rigidly and evenly clamp the edge of the aluminum diaphragm, enabling the corrugated section to flex, so the diaphragm pivots (like a piston) with the movement of the needle bar.

OF

I have one HMV-5, but since it works fine AND is made of pot metal, I never tried to open it up to check which kind of gaskets it has. Externally it is identical to the orthophonic, so I presume it has also cardboard gaskets. But I suspect we are talking about a 5A or B here. I never had to replace the felt gaskets of the ones I have (about a dozen), and the few that I opened (these are also made of pot metal) had no gasket issues. I never saw replacement felt gaskets for sale, neither, but these soundboxes are so common (in England) that it is probably cheaper to buy another one.

[epigramophone]

I think the reason why no-one has re-manufactured these felt gaskets is that there has never been a demand for them. Jake's is the first report of a felt gasket failure that I have read.

[gramophone-georg]

I think the reason why no-one has re-manufactured these felt gaskets is that there has never been a demand for them. Jake's is the first report of a felt gasket failure that I have read.

I got one from the UK off eBay that has bad gaskets as well. Sounds terrible.