J.A. Michell Prisma restoration

[AngrySailor]

I’m looking forward to putting her back together! Hopefully hear from the shop reproducing the lid soon. Belt and stylus are in transit.

 

[laatsch55]

Good luck with that project Andrew..

 

[AngrySailor]

Talked to the plastics fabricator today, clarified some details about the closing stop/grab buttons on the sides of the lid. They might end up a little different that original, I’m not sure yet. His concern was the glue joint between the button and the side of the cover. Concerned that it could get messy and stain the plastic or if not enough glue was used it may not be transparent. I’m tossing the idea around of machining either brass or stainless knobs and polishing them. I could then “bolt” them through from the inside with custom plugs that would act as the closing stops. He’s going to send me a piece of acrylic round stock to mess with in my lathe if I want to attempt the clear buttons. Otherwise he said no problem to duplicate a lid from pictures. I told him “close” and “pretty” was good enough, nobody is going to put a micrometer to it and most people who will see it have no idea what it is. Sounds like he will be o to it next week.

The belt and stylus made it to the local post office at least also!

 

[laatsch55]

Coolness...

 

[AngrySailor]

Does anyone have any details of the prop rod? This will be machined from scratch. I figure I can get pretty close by the pictures but wondered also about the operation. Is there tension or if free to move? I figure a strategic O-ring or possibly a Belleville washer could provide a little drag on it. Just ont want to chew up the cover either. A rough length and hole location wouldn’t hurt either if someone has a prisma to measure! Thanks

 

[J!m]

There is one of these transcriptors at the hi fi museum. I'll be there tomorrow. I'll take some pictures for you.

 

[J!m]

Here’s the pictures I promised.

The dust cover, is all tempered glass, not plexi. Seems odd since it rings but I got closeups if the lid latch and a few general ones. The latch is simply a rod that goes into a catch in the lid hinge.

 

[AngrySailor]

I really appreciate you taking the time to do that! Unfortunately, that’s not the same model as the one I’m working on... I’ve never seen that model before though, so very cool! Thank you again! Hi-fi museum... sounds like a fun day also!

I’m expecting to hear from the fabricator soon and will post pics as soon as I have any. The belt and stylus have been picked up and are waiting at home for me. I forgot to ask the girlfriend to look for the SME manual, I’ll see if she has time to scan it in case anyone wants a copy.

I’m also waiting to hear from the repair guy about the Rotel and PL2000, hoping to have them repaired and shipped home by March.

 

[J!m]

This is the model shown in “A clockwork orange”.

 

[AngrySailor]

I always thought it was a hydraulic reference in CWO, was there more than one TT in the movie? I don't really remember the closed in glass sided TT.
Here's some information I found about Transcriptor's and Michell Engineering though:

http://udiradiostar.blogspot.com/2013/03/transcriptor-turntable.html

 

[J!m]

Yeah, it does look different for sure. I'm going by what Mike said at the museum...

A couple things I don't like about the design: The barely coupled record itself. Yes, it prevents bearing noise from transferring to the record; however, it does nothing to dampen any resonance of the record itself.

And the (in the case of the one at the museum) tempered glass enclosure. I tapped it to verify what it was and the lid rang like a bell. So do the side panels. I don't think that's ideal either.

 

[AngrySailor]

My uncle removed the lid and original feet for some of those reasons... He said it picked up acoustic feedback until he removed them. I'm not sure what listening levels he was at, but he has a PL400 and some substantial speakers so... I'm planning to put it in my living room for occasional use/display and also planning to make use of my RT-707 RTR to tape records that I want to listen to frequently or at higher levels so I'm not so concerned about the feed back. I remember it at my uncles studio as a kid so it will be cool to have it going again. They were a "unique" design for sure!

 

[AngrySailor]

How's this for "barely coupled"... I would think the record itself would resonate like mad.

 

[J!m]

Well, yeah!

The record would be subject to it's own vibrations as well as atmospheric (speaker feedback).

But, these designs do give me ideas for my design.

 

[AngrySailor]

Reproduction lid is being picked up at the fabricators this afternoon. I’ll post pics hopefully this evening.

 

[laatsch55]

Uber coolness..

 

[stuwee]

That tonearm is a trip....

What the hell Lee? It's a Shure SME 3009 series IV, Very,very nice!! That Shure V15 IV is the perfect match with it, sell the Denon and buy some nice Lps

 

[laatsch55]

Too late to start collecting records again..

 

[AngrySailor]

Awww yeah... a little small on the bend radius maybe but that’ll work!

 

[Wheel-right]

That is a nice piece, hope it works for you.