Meltrope II servicing

[Ahmed]

Good afternoon folk,

How does one take apart one of these to service it?

I've worked on so many soundboxes, but this is the first I can't figure out how it comes together and really don't want to chance it

Any pointers would be much appreciated

[Orchorsol]

The black face mask is just a spring-fit onto the outer groove on the body, and just takes a little gentle/careful levering or flexing to remove.

I see that's a Wild-tuned one, and still has the tiny cushioning pieces he added - wonderful! Please photograph them when you have it apart, I'd love to see them!

[Ahmed]

The black face mask is just a spring-fit onto the outer groove on the body, and just takes a little gentle/careful levering or flexing to remove.

I see that's a Wild-tuned one, and still has the tiny cushioning pieces he added - wonderful! Please photograph them when you have it apart, I'd love to see them!

Wonderful, thank you. I did think it must be straightforward once you know where you should be looking!

Will take pictures as I disassemble it and post here. Aiming to preserve all the Wild modifications as I clean it up of course

Just given it a spin as is. Although it needs a tidy up, it sounds surprisingly clean

[Orchorsol]

Friend bassethoundtrio is worth talking to about rebuilding Meltropes. I believe he finds that tiny nuances of how the diaphragm lays (where, in a sense, there isn't any real adjustment available) can make a big difference.

[old country chemist]

Yes, Mr Wild was an interesting chap with these Meltropes. He also used sealing wax, or similar, on the black mask at the front, to remove any chance of metallic vibrations. I think that changing the size of the ball bearings, either larger or smaller, can also make a slight difference to the sound quality.
You are quite right Andy,the way the diaphragm when at rest on the internal gasket is important. The big problem with these Meltrope diaphragms is that the stylus bar is pressed into the diaphragm, so the two parts cannot be separated. I expect that is why they only charged 12/6d when new, as this was an easier and quicker way of assembly! I find that when the diaphragm is placed in the soundbox body, and the screws are not taking effect, the diaphragm should lie quite flat on the internal gasket. As the saoundox is sitting face up on the bench, I carefully start to wind in the screw that moves the diaphragm upwards away from this gasket a little. I next tighten up very slowly, the other adjusting screw so that the diaphragm, seen from the side starts to fall again to rest on the gasket in the base of the box. Next, the top gasket which must be a good fit, is gently pressed into place all the way round, and will be held in place by the recess of the top part of thesoundbox. Finally the mask is carefully sprung into place, making sure it does not damage the diaphragm. Also important is a very pliable tone arm connector. The tone of the soundbox can be altered spmewhat by tightening the screwed ring. The No 1 and 1a are probably my favourite soundboxes of the mass produced types.

[HMV130]

[...] As the saoundox is sitting face up on the bench, I carefully start to wind in the screw that moves the diaphragm upwards away from this gasket a little. I next tighten up very slowly, the other adjusting screw so that the diaphragm, seen from the side starts to fall again to rest on the gasket in the base of the box. Next, the top gasket which must be a good fit, is gently pressed into place all the way round, and will be held in place by the recess of the top part of thesoundbox [...]

I managed quite successfully to restore five or more of these soundboxes. The approach suggested by old country chemist is a good way to go. I would suggest you to be sure that, after having levelled the diaphragm to the back gasket by slightly tightening the two spring screws, the exerted pressure is as small as possible.

Regarding the front gasket, I usually pre-cut it (leaving some excess that will be cut properly once inserted) and I start to insert its middle portion in the recess at the top center of the soundbox body. Then I work it all the way round using both my thumbs (keep pressing it clockwise and counterclockwise at the same time). I found that doing so one avoids any force that could make the diaphragm twist on its weakest point. Moreover doing so it would help avoid that the diaphragm, still being held in place by the springs, moves to the left or to the right. If so, once the diaphragm is fully blocked by the now inserted gasket it will make the stylusbar bend on the left or on the right. The springs and the stylus bar are too weak to hold the diaphragm perfectly centred while inserting the front gasket.

Finally I suggest you to be sure to not swap the springs. I noticed that event though these components were probably machined they are not identical (this will cause uneven pressure on the ball bearings that needs to be addressed by tightening one spring screw more than the other).

[Ahmed]

Thank you all for your replies. Annoyingly I've run out of gasket tubing, so it's got to wait a few days while more comes in

Will keep you posted how it turns out!

I love tinkering with reproducers, tweaking here and there until it sounds just right to me. This one looks like it will keep me entertained for a while

[Inigo]

I love that too. The pity is with my Meltrope 3; although I tinkered with it a lot, I couldn't finally get it to sound right, and I got tired of it. The sound is powerful and good on my 194, but I find a certain lack of treble, most noticeable when compared to a good restored sbx HMV 5a or 5b. And although I was told that maybe the cause was that the M3 is not suited for the 194 horn, I finally came to think this was not the cause, but a fault in the Meltrope. Through this horn the bass really pumps out, it is the treble that seems to be muffled. I believe it is something about that diaphragm. The one in the 5a/b seems thinner, and has the spider and the creases and all that, very different thing. But I've noticed that the treble transmission is more related to the weight of the diaphragm, the compliance at the needlebar support, etc. In these aspects the M3 has difficult issues: a heavier diaphragm, a very stiff connection to the needlebar, and the lid springing on the needlebar support plate through these outer balls whose pressure cannot be finely adjusted but with difficulties, leaving the lid screws loose... I experimented adding tiny rubber washers between the lid and the sbx body, but the screws are too short and couldn't held it properly through the washers. In my example, although it seemed to have never been disassembled, the balls seemed to be misplaced: the two larger ones below the plate and the tiny ones over it, jammed by the cover. Result : the needle took a strange angle outside, so it didn't rest perpendicular to the record surface, but pointing slightly outwards. This is the first thing I changed, inverting the position of the balls so the angle was straight. Besides that, it seemed to me a strange arrangement of the diaphragm gaskets, as there were two back gaskets, or on top of the other, and one front gasket. Or somebody had tinkered with it before me, or it was a very strange factory arrangement. Also the front rubber ring was mounted so it pressed against the needlebar plate. Very very strange all it. I corrected all that, but the sound didn't fascinate me. Or that, or my 5a/b is very very exceptionally well tuned, as it sounds much more natural.

[Ahmed]

I love that too. The pity is with my Meltrope 3; although I tinkered with it a lot, I couldn't finally get it to sound right, and I got tired of it. The sound is powerful and good on my 194, but I find a certain lack of treble, most noticeable when compared to a good restored......

Very interesting as my experience has been the exact opposite! I never liked the sound of no.5, finding it too thin/metallic regardless of how it's turned... Controversial, I know


There's a luck of the draw element with the Meltrope III from my experience; you do get ones that just would not happily sing for one reason or another, and ones that songs beautifully with minimal effort. The diaphragm is easily damaged if the needle bar sustains a knock, and it may/may not sing well after that depending on your luck.

I think the thicker diaphragm on the Meltropes plays a huge part in their lovely sound signature over a no.5; a ton less surface noise and none of that "metallic" tinge to the sound

Would very much suggest giving another Meltrope III a try; it's very possible you're just unlucky and yours is too tired!

[Inigo]

Could be... Some time... and I'll go back to it!
My 5a and 5bs sing beautifully, but one of them needed extensive tinkering until I got 'that'sound... We could talk a long hour on my experiences with these sbx...