HMV Arm Guidance Needed

[Inigo]

It was me. Since I discovered these red rubber isolators made for the Meltrope, fit perfectly on the back necks of the no4 and no5a hmv soundboxes (removing the original black rubber connector and its screws) they have been installed on my gramophones.
There are made in several different sizes, both external and internal, for use with different tonearms and different Meltrope versions.
The ones made for the Meltrope III have an outer diameter that fits snugly on the back necks of no4 and 5a/b, as they are equal.
You can buy different internal diameters, and there is one for the thin tonearm (as for no4 sbx) and another one for the thick tonearm (as for no5a sbx).
Added advantage: not having the inner brass insert not the pin screw, you can adjust infinitely the needle angle on the record, and get the best tracking alignment. I'm especially glad with the thin hmv tonearm, which in the tabletops and portables, has a bad tracking angle at the outer edge of a 12" record. By changing slightly the needle length and the soundbox angle, you can improve the tracking noticeably.

[SteveM]

It was me. Since I discovered these red rubber isolators made for the Meltrope, fit perfectly on the back necks of the no4 and no5a hmv soundboxes (removing the original black rubber connector and its screws) they have been installed on my gramophones.
There are made in several different sizes, both external and internal, for use with different tonearms and different Meltrope versions.
The ones made for the Meltrope III have an outer diameter that fits snugly on the back necks of no4 and 5a/b, as they are equal.
You can buy different internal diameters, and there is one for the thin tonearm (as for no4 sbx) and another one for the thick tonearm (as for no5a sbx).
Added advantage: not having the inner brass insert not the pin screw, you can adjust infinitely the needle angle on the record, and get the best tracking alignment. I'm especially glad with the thin hmv tonearm, which in the tabletops and portables, has a bad tracking angle at the outer edge of a 12" record. By changing slightly the needle length and the soundbox angle, you can improve the tracking noticeably.

Ahhh yes Inigo ... I was QUITE sure it was you, but not 100% There is a seller on UK ebay that I've bought from ... I'll see what he may have, currently. Edit: THANK you, by the way.

[gramophone-georg]

Wow, I popped onto the forum today for a couple reasons ... 1) to see if Georg was still working on his 32, and 2) to see if anybody was using Meltropes on their 32s or 31A's. This thread is like a 2-fer.

(I'll probably start a new thread anyway, but ...) while you guys are here ... I've been using a Meltrope isolator gasket on my 5b for use on my 32 and I'm pretty pleased with it (in lieu of an entire Meltrope, which I can't find). Question is, can I get a larger-bore Meltrope isolator gasket to fit onto my 31A's 5b? I think I read here awhile ago that someone was doing it, and was pretty thrilled with the result.

Yeah, I finally came up with a plan for this woodworm farm of a machine by going all "Cal Custom" on it. Purists will hate it, but the only other real alternative was scrap, so...

Anyways... I have an Orchosol soundbox that I am going to couple with a 5 foot long hyperbolic flare sound chamber stuffed into the cabinet and a Victor 24 flower horn. I am looking forward to it failing miserably!

[Inigo]

How are you going to put a 5' horn into that cabinet, with the motor inside an hyperbolic flare?
You can install inside only a conduit to link the tonearm with the horn throat.. certain that you can make a long conduit surrounding the motor but this will be not more than 3' long... yet you have to match the start and end bore to the tonearm and to the horn throat. The flower Victor horn will make the end, and then it will be 5' long in total.... It can find pretty well! And similar to the original...

[gramophone-georg]

How are you going to put a 5' horn into that cabinet, with the motor inside an hyperbolic flare?
You can install inside only a conduit to link the tonearm with the horn throat.. certain that you can make a long conduit surrounding the motor but this will be not more than 3' long... yet you have to match the start and end bore to the tonearm and to the horn throat. The flower Victor horn will make the end, and then it will be 5' long in total.... It can find pretty well! And similar to the original...

I did it- stuffed 5 feet in there. It wasn't easy! I am lousy at taking photos so neglected to do it. I actually just tested it and it doesn't sound half bad- almost Orthophonic. I need to do some tweaking still. I think there is still too much drag on the arm, but it may be the Victor auto brake I added. We'll see. I also want to compare the Orchosol to a NOS No. 16. From soundbox to outside of horn there's just under 8 feet.

[gramophone-georg]

Sneak peek- flame suit on and zipped. Still need to install decal to the horn and stripe it. I think my basic design on the sound chamber is correct, but it needs to be a different material and with less or no sound deadener around it. Ambivalent on the auto brake- it works 75% of the time. I also need to play with different soundboxes. There is something a little off with this Orchosol box but I cannot quite put my finger on it.

I also need to refinish the crank (winding key) knob. In all the veneering, painting, finishing, and re- plating I somehow overlooked that little detail.

[Inigo]

It looks marvelous as it is... Congratulations! Pity we couldn't see that internal horn part, would have been very instructive... Enjoy it!

[SteveM]

Sneak peek- flame suit on and zipped. Still need to install decal to the horn and stripe it. I think my basic design on the sound chamber is correct, but it needs to be a different material and with less or no sound deadener around it. Ambivalent on the auto brake- it works 75% of the time. I also need to play with different soundboxes. There is something a little off with this Orchosol box but I cannot quite put my finger on it.

I also need to refinish the crank (winding key) knob. In all the veneering, painting, finishing, and re- plating I somehow overlooked that little detail.

wa wa WEE wa!

[gramophone-georg]

Well. one of my balls jumped loose again, so I de- balled it and I just have the arm riding on the inner collar (where the "spout" goes in) with three copper washers as shims and grease sealing everything. Not right, but works like a charm and you can't tell by looking.

Now... Horn details.
It seems these were gold striped on the bell edge, along the outside panel seams, and the circular seam where it goes into the elbow, but NOT inside the horn like a Victor. Is this correct?

I wasn't happy with my internal sound chamber performance. I think this needs to be metal like the original. So, I have the original connector in there for now. It doesn't sound bad at all!

I am going to talk to a sheet metal fabricator about building a round graduated tube like the original, but 5 feet long, elbowed to fit in the cabinet. Who knows- if it works out maybe I'll have more made and peddle them as conversion kits!

Also- I swapped the Orchosol box for my HMV No. 16 and that really gave it life!

[Inigo]

You could try to copy an original tinplate hmv internal horn, I mean, the snake narrow part until you reach your horn base. Maybe the shape of a101, or the longer one of a 127 would fit into your case. Anyway, these are made with plane thin sheets, simply curved to gain the increasing cross section. It seems not difficult to make from tinplate sheets, or balsa wood... You'd better calculate the cross section progress in exponential form, giving an expansion factor that matches: 1) the available length, 2) the cross sections at the tonearm base and at the horn spigot. It will be a thin conduit, placed around the motor, running by three of the case sides. You could form it using straight balsa wood boards, glued to the inner case boards using the corners of the inner case as bottom and outer sides of the horn conduit, adding only the upper and inner sides, and make Plano-reflex style corner boards at 45 degrees, instead of curved elbows, etc. It would be easy to make. And balsa wood is easy to cut, light and sound inert...?
I do my trials with another material, which is that board used by architects to make building mockups. It is a sandwich made of white cardboard and polyurethane foam in between. The total thickness is somewhat 3-4 mm or similar, and it is cheap and easy to cut.
Do you imagine what I'm proposing?