Meltrope soundboxes.

[chunnybh]

I haven't seen the "IIa" before. That's very interesting. What size of tonearm does it fit?

[HMV130]

I haven't seen the "IIa" before. That's very interesting. What size of tonearm does it fit?

Neither do I with the exception of this one of course. I bought it in 2014 on eBay (I do not recall if from Uk) and it came with an attachment that allows the use of soundboxes on Edison Diamond discs machines.

It can fit both the normal and the large tonearm (the backplate has the larger compression ring). This soundbox is incredibly light in relation to others Meltrope - if it is of interest I have a document with the weight of each model.

[chunnybh]

Yes please put up the weights. Can we have another picture of the front too?
It's a huge leap from the Meltrope II to the III. This looks like an early attempt to reduce the diameter and therefore weight.

[HMV130]

Yes please put up the weights. Can we have another picture of the front too?
It's a huge leap from the Meltrope II to the III. This looks like an early attempt to reduce the diameter and therefore weight.

Yes I think so, they tried to improve the original design but the great reduction in weight (the rim of the body is almost absent) caused the performance with fibre needles to be unsatisfactory so a new design was required which came to be the mod. III.

Following the weights for each model:

• Mod. I ------------------------------------------ ?
  Mod. II, Continental tonearm --------------- 139,8g
  Mod. II, HMV tonearm ---------------------- 138,4g / 138,7g
  Mod. IIa --------------------------------------- 98,6g
  Mod. III early --------------------------------- ?
  Mod. III late ---------------------------------- 135,4g
  Mod. IIIa -------------------------------------- 132,1g

The fact that the mod. IIIa is slightly lighter than the late mod. III probably is due to having more cut off of in the front plate.

If you have in your collection a mod. I and an early mod. III (with triangular needle socket) would you be so kind to share their weights?

[chunnybh]

Thanks for the pictures. What an unusual item that Meltrope IIa is.
Unfortunately I do not have my soundboxes handy. Hopefully someone else can add weights for the missing two.
What I do have handy is a Meltrope III with a rectangular needle holder marked as Selecta. The body cast is unusually heavy and has swollen so much that the compression nut has seized. It's 148g. I'd like to see some more Meltrope III's with rectangular needle holders.

[Oedipus]

Here (if I can upload it this time) is a photo of the nastiest Meltrope I have ever seen, a Number 4 in tired condition with a broken stylus bar. The mask has a couple of little dimples to press on the stylus bar plate, instead of 2 balls, and there is no Wright back (some of the later Decca versions also manage without Mr Wright's contribution).

While about it, I show also, in rather better condition, a Meltrope 1, one of the few I have seen with the number actually displayed.

Incidentally, the reason why Selecta is among the many names found on Meltropes is that Selecta (the Decca sales department in its later years) took over the Meltrope soundbox.

[Lucius1958]

I believe the III I have is an earlier model, as it has the triangular needle chuck. Unfortunately, I do not presently have access to a scale on which to weigh it.

- Bill

[epigramophone]

To add to this interesting thread, here are some fitting instructions :

[emgcr]

Here are the weights (grams) of the various Meltrope soundboxes I have in my collection---all with identically-sized knurled clamp rings and rubber washers to the tonearm :

Meltrope 2 with triangular needle holder :

1. 136.6
2. 138.7
3. 142.1
4. 144.4

Meltrope 3 with triangular needle holder :

1. 137.4
2. 142.6

Meltrope 3 with circular needle holder :

1. 131.3
2. 136.5
3. 137.5
4. 140.9 (Decca)

The picture is thus rather confusing as two (or more) seemingly identical soundboxes can have differing weights. The analysis is not particularly helpful.

In addition, there is a further important detail which I have never seen in the literature regarding some Meltrope 3s and the 3a. I recently bought a 3a on eBay which was in a very badly oxidised condition and which unfortunately turned out to be scrap. The Mazak was cracked and the diaphragm eaten away by damp to the extent that no airtight seal was realistically possible. However, one very important discovery was made. Instead of the normal three part diaphragm, this one had four parts---there was an additional centre-part on the back of the diaphragm reaching to the outer diameter of the annular rings---see first photograph. Whilst rebuilding other Meltrope 3s I observed that some indeed did have the four-part diaphragm too---it was not exclusive to the 3a. I have found no reference to this development anywhere but clearly Meltrope went to a lot of trouble and must have thought it worthwhile. Further investigation is called for, particularly in relation to exactly how the second annular ring section is fixed to the first. Both are clearly clamped at the centre by riveting, together with the two smaller inner and outer "washers" (or "Spiders" in Meltrope's terminology), but were the outer parts glued or mechanically joined in some way so as to avoid possible rattling ? There are no obvious clues without destroying.

The problem for us enthusiasts so many decades later is that these Meltrope diaphragms were "mass-produced" and assembled by machinery so that, once damaged, they are not really repairable. The riveted joints can indeed come loose even when handled with extreme care, at which point gluing would seem to be the only practicable option---not very satisfactory. EMG, Expert and Astra, by contrast, employed a bolt or machine screw to hold the stylus bar to the (single) diaphragm which is easily demountable and reassembled---infinitely more satisfactory, stronger and sealed with beeswax.

Forever fascinating !

[HMV130]

Here (if I can upload it this time) is a photo of the nastiest Meltrope I have ever seen, a Number 4 in tired condition with a broken stylus bar. The mask has a couple of little dimples to press on the stylus bar plate, instead of 2 balls, and there is no Wright back (some of the later Decca versions also manage without Mr Wright's contribution). [....]

Thanks for showing us such interesting pictures. You have a splendid mod. I and regarding the mod. IV it is the first time I see one and I never heard about it before - considering the absence of steel ball bearings and the rough manufacture could it be a cheap war time model?

To add to this interesting thread, here are some fitting instructions :

Thank you "epigramophone" for sharing the instruction leaflets for mod. I and possibly for the late mod. III.

It is interesting to notice that the statement "for fitting to gramophones with bayonet or continental type of tonearm" has been changed in "for fitting to gramophones with hmv or continental type of tonearm" after the introduction of the mod. II - the word "hmv" or "continental" were covered according to the size of the compression ring of the soundbox with which the leaflet would be attached to (please consider the attachment "Meltrope_5").

[...] In addition, there is a further important detail which I have never seen in the literature regarding some Meltrope 3s and the 3a. [....] Both are clearly clamped at the centre by riveting, together with the two smaller inner and outer "washers" (or "Spiders" in Meltrope's terminology), but were the outer parts glued or mechanically joined in some way so as to avoid possible rattling ? There are no obvious clues without destroying. [...]

First of all thank you for sharing so many wights. It is startling to read about such different in weights among soundboxes of the same model!

Good point about the four-part diaphragm. I always thought that this type of diaphragm was a peculiar feature of the mod. IIIa only.
I clearly remember to having noticed it while restoring one of the two mod. IIIa soundboxes I bought some years ago - unfortunately now I can not confirm to you that both featured a four-part diaphragm because stupidly I sold one.
In any case if you also have found this type of diaphragm in mod. III then probably it is the last improved one and it has been reviewed by the expert committee of The Gramophone in February 1931 (please consider the attachment "Meltrope_3" in my previous post) together with the at the time newly introduced mod. IIIa. Possibly the use of a fourth element in the diaphragm construction reduced the high pitched resonances produced by the first mod. III soundboxes.

Nevertheless what puzzles me is the supposedly paint coating of some mod. III diaphragm - when it has been introduced? Was this coating for cosmetic purpose only?