Tracking Alignment Adaptor for the Exhibition Soundbox

[emgcr]

Jamie, to produce the Pathé part I used a local 3D printing firm who were excellent and very helpful. I can give you full details if you would care to send me a pm. The equipment they use is fascinating and very expensive ! The camera to take photographs from every angle to produce the 3D computer file (CAD) costs in excess of one hundred thousand pounds and the resin printer about half a million. The actual printing lays down material at a rate of about 4 microns per pass. My "onions" took all night to build each one but the technology is improving every day and is rapidly becoming mainstream---at the expense of pattern-making/casting etc. The costs too are reducing constantly and are already reasonable but metal printing remains expensive.

I take your point about the lack of material around the fixing screw and it may indeed be desirable to factor in additional depth (boss) to give strength. The great thing about 3D printing is that all such modifications are simplicity itself with a few strokes on the computer keyboard. You may have noticed that the Pathé part has internal strengthening webs which were not present in the pot metal original (in my case totally missing) but took one second to introduce on the computer. Threading the swinging section of the tonearm and copper plating your adaptor (plus boss) would, I should have thought, give adequate structure for all practical purposes. The copper is very strong in both shear and compression.

[jamiegramo]

That's a really great piece of work Jamie, thanks for posting. As well as alleviating record wear it's interesting to hear that later records actually sound better too.

It's exciting to think you could possibly make some of these along the lines that Graham has suggested - perhaps if the resin/copper won't quite support the screw with enough strength, you could bond a threaded insert in? If you do end up producing a number of these in future, I may well be in line for one for my baby monarch!

Thanks for the comments and it would be exciting to copy with 3D printing if the price isn't too prohibitive. Unfortunately the baby monarch (or Victor 1) has a smaller tonearm. I think this is fairly unique to the Victor 1 but maybe is also found on the Victor O, a US member will know. This would require its own custom made adaptor. I may get round to it as I like these small machines. The effective tonearm length is around 8 ½ inches so although not as good as the larger tonearm it can certainly be improved.

[Orchorsol]

Thanks for the comments and it would be exciting to copy with 3D printing if the price isn't too prohibitive. Unfortunately the baby monarch (or Victor 1) has a smaller tonearm. I think this is fairly unique to the Victor 1 but maybe is also found on the Victor O, a US member will know. This would require its own custom made adaptor. I may get round to it as I like these small machines. The effective tonearm length is around 8 ½ inches so although not as good as the larger tonearm it can certainly be improved.

Thanks for clarifying - I hadn't thought of that, though I suppose the difference is fairly obvious! These machines aren't really my main gramophone interest, but I was lucky enough to be offered a very nice baby monarch a couple of years ago, couldn't resist it and really enjoy having it.

[Inigo]

EDITED AND ERROR CORRECTED. SORRY
I've rescued an old adaptor I made from a standard 45° 18mm copper elbow, which I cut at the desired length to adjust the tracking. I made it for another gramophone, but it fits the exhibition and gooseneck in my new HMV Model 3 hornless Gramophone.
You can see it in action in this video:
https://youtu.be/4tVigBi43P4
The tracking has improved a lot, and at the naked eye is almost perfect even for 12" records, from the rim up to the label!
I'll post later photos of the copper adaptor... It's so simple! I only had to cut the desired length, add a locking pin at one side, and cut a slot at the other end to fit the exhibition pin. A little intermediate cushion has been added for perfect airtight connections (paper strip and teflon band). Enjoy! And it plays electric records marvelously, with the logical limitations of an exhibition and non exponential horn!

[jamiegramo]

I've rescued an old adaptor I made from a standard 45° 18mm copper elbow, which I cut at the desired length to adjust the tracking. I made it for another gramophone, but it fits the exhibition and gooseneck in my new HMV Model 3 hornless Gramophone.
You can see it in action in this video:
https://youtu.be/FdZ2gsJu1dw
The tracking has improved a lot, and at the naked eye is almost perfect even for 12" records, from the rim up to the label!
I'll post later photos of the copper adaptor... It's so simple! I only had to cut the desired length, add a locking pin at one side, and cut a slot at the other end to fit the exhibition pin. A little intermediate cushion has been added for perfect airtight connections (paper strip and teflon band). Enjoy! And it plays electric records marvelously, with the logical limitations of an exhibition and non exponential horn!

Inigo, the link says the video has been removed by user. I look forward to seeing your photos. It makes a lot more sense if you can find existing parts to adapt rather than starting from scratch. Glad you noticed the improved sound on electrical records.

[Inigo]

I'm sorry. Error corrected, post edited.
Of course, the elbow can be better made, this is a fast approach and a test. I'll try to make it better...

[jamiegramo]

I was interested in this device that just appeared on eBay described as a rubber Lifebelt back. The Lifebelt would add compliance but it's length would not improve offset and therefore tracking alignment by much. I wonder if the bolts can be adjusted to alter the angle of the soundbox and therefore improve tracking alignment. Has anyone seen a device like this and have experience of whether it can be adjusted to significantly alter tracking alignment?

https://www.ebay.co.uk/itm/Antique-HMV- ... Sw6zheAefR

[Marco Gilardetti]

I don't get what they meant with "lifebelt", however it looks as if this gizmo was made in order to enhance soundbox-to-tenarm isolation. As it is mounted on springs, which seem to be adjustable to some degree, perhaps it may help to improve the tracking error a bit, but I would say that this wasn't the primary task for which the device was made. It also looks pretty heavy and will most probably greatly raise the tracking force over the record.

[Orchorsol]

It's evidently had the back of an Orchorsol soundbox grafted onto it. This page of the late Graham Barber's website has good photos and an explanation of the lifebelt: http://www.graham-ophones.co.uk/orchors ... 4594029474

It's a fascinating combination and I'd very much like to hear how it sounds, but it's extremely expensive for a "Frankenbox"!

[audioengr]

This is a cool adapter, but I think I have another equally effective method. If one changes the location of the pivot-point of the tonearm, it will accomplish the same thing. See the analysis below:

Original alignment

Needle-tracking-analysis-orig..pdf

(7.23 KiB) Downloaded 89 times

Offset alignment

Needle-tracking-analysis.pdf

(8.7 KiB) Downloaded 92 times

I have a suspicion that this is why they put the "bustle" on the back of the VictorII. To move the tonearm pivot point back. I will try to add a spacer to the mount of the tonearm assembly. I should be able to get at least .25", maybe more.