Need help restoring a Meltrope III soundbox

Discussions on Talking Machines of British or European Manufacture
User avatar
Inigo
Victor VI
Posts: 3753
Joined: Mon Dec 18, 2017 1:51 am
Personal Text: Keep'em well oiled
Location: Madrid, Spain
Contact:

Re: Need help restoring a Meltrope III soundbox

Post by Inigo »

After later listening sessions comparing the HMV 5B and the Meltrope III, definitely my Meltrope sounds good, but there is only a little treble. WHen compared with the 5B, which sounds much more clear, the Meltrope III is a good soundbox, but there is lack of treble, at least in my unit. The bass seems a bit stronger than with the 5B, more similar to my restored 5A/B (a 5B with a restored 5A diaphragm). But still the Meltrope seems to have less treble even than the 5A/B.
I have to make trials with a smaller machine, as Orchorsol advised. I'll try on the HMV 127 tabletop and on the 102 portable.
Thanks for your attention.
Inigo

User avatar
Inigo
Victor VI
Posts: 3753
Joined: Mon Dec 18, 2017 1:51 am
Personal Text: Keep'em well oiled
Location: Madrid, Spain
Contact:

Re: Need help restoring a Meltrope III soundbox

Post by Inigo »

Also tried on my 102, and the effect its the same muffled sound, no treble as clear as a 5B soundbox.
Next step will be trying to make a new diaphragm from thin tinplate, aluminium, lacquered paper, dense styrofoam or thin wood... the laboratory is opened....!
Inigo

leels1
Victor I
Posts: 137
Joined: Sat Jun 27, 2020 8:40 am

Re: Need help restoring a Meltrope III soundbox

Post by leels1 »

Hi Inigo,

Not sure if you get this as it’s an old thread.

I have several M3 sound boxes and all are different sounding. I get what you mean about the bassy “muffled” sound but it also depends on what record you play and machines.

I don’t think it’s coincidence that they are on portables a lot. They seem to help the sound on a simple type horn. I use them on the HMV 152, 130, 145 and they sound great on earlier acoustic recordings on Winner and suchlike. Also good on later recordings too.

Interesting you removed the bronze from the diaphragm. I think that adds to the sound.

Re gaskets, I’ve always used 3.2mm but on some a 4mm rear gasket is needed. All the needles seem to sit at an odd angle. It’s they way they are I think.

The front ball bearing is 1.5mm. The front doesn’t have to be screwed on 100% tight as the springy nature almost hold it in place. As far as “tuning”goes, I don’t think it really exists, just a different sound to be obtained. Altering the screw near the needle bar will help this!

User avatar
Inigo
Victor VI
Posts: 3753
Joined: Mon Dec 18, 2017 1:51 am
Personal Text: Keep'em well oiled
Location: Madrid, Spain
Contact:

Re: Need help restoring a Meltrope III soundbox

Post by Inigo »

Yes, thanks! I've used that method of tuning, with the screws at mid way. And it's true that of the better m3 sound on smaller horns. I've been using mine on a hmv127 tabletop, and the sound is great. It is only that on the 194 horn, the treble doesn't sound so well (or it becomes hidden under the prominent mid-low and bass).
The 5b has a more powerful treble, and the sound is more balanced.
I believe that the adjustment of my m3 has to be different for the 194. I should do something to soften that mid range, so the treble becomes more apparent. It has something to do with the screws pressure, and with the back gasket, which is defining the position of the diaphragm and the size of the air chamber behind it. A thinner air chamber (a thinner back gasket) might do the trick. The air chamber in the 5/a/b is thinner, and besides that, the backplate follows the shape of the diaphragm, so the air chamber is of uniform depth. In the m3 this is not this way.
Inigo

old country chemist
Victor II
Posts: 283
Joined: Mon Nov 14, 2011 5:06 pm

Re: Need help restoring a Meltrope III soundbox

Post by old country chemist »

Hello Inigo- the 3.2mm outer diameter black rubber gasket tubing is the correct sort for Meltrope 3. I have never found any new supply of, only a 4mm size, which, of course, is too large.
My apologies if this has already been mentioned. I hope by now the soundbox is producing the sounds you want to hear.

User avatar
Inigo
Victor VI
Posts: 3753
Joined: Mon Dec 18, 2017 1:51 am
Personal Text: Keep'em well oiled
Location: Madrid, Spain
Contact:

Re: Need help restoring a Meltrope III soundbox

Post by Inigo »

Thanks, Alastair... It's playing very well, but on the small horns. I got tired of experimenting with it. When I will resume experiments, I'll try again on the big horn! :D
Inigo

User avatar
Curt A
Victor Monarch Special
Posts: 6412
Joined: Fri Jul 09, 2010 8:32 pm
Personal Text: Needle Tins are Addictive
Location: Belmont, North Carolina

Re: Need help restoring a Meltrope III soundbox

Post by Curt A »

Is the diaphragm aluminum? Admittedly, I have no experience with a meltrope, but with Victor reproducers it is important not to have downward or too much upward pressure from the needle bar that distorts the diaphragm. Something definitely looks wrong from your pictures. The cover should not exert pressure on the needle bar or diaphragm, it should go back together without that large gap. The cover's only purpose is to protect the needle bar and diaphragm from damage (and hold the ball bearings), all of which should go back together level. The picture in the ad shows it closed normally.

Apparently this is an old thread and it appears that you have solved the problem, so disregard this... :roll:
Screen Shot 2021-07-22 at 1.05.51 PM.png
Screen Shot 2021-07-22 at 1.05.51 PM.png (169.03 KiB) Viewed 815 times
"The phonograph† is not of any commercial value."
Thomas Alva Edison - Comment to his assistant, Samuel Insull.

"No one needs a Victrola XX, a Perfected Graphophone Type G, or whatever you call those noisy things."
My Wife

Post Reply