Sota Sapphire refurb

neobop · « **on:** 17 Sep 2013, 10:33 am »

Hi all,
I have this Sota Sapphire that I picked up in the early '90s and lately I've been trying to figure out what to do with it. It's basically been sitting since then and I figure I should either fix it up, mod it, or sell it. It's a nice looking table, in pieces at the moment. Here's what it looks like:

neobop · « **Reply #1 on:** 17 Sep 2013, 10:35 am »

neobop · « **Reply #2 on:** 17 Sep 2013, 10:38 am »

Guy 13 · « **Reply #3 on:** 17 Sep 2013, 10:40 am »

Hi neobop and all Audio Circle members.
What?
No motor and no arm ? ? ?

Guy 13

neobop · « **Reply #4 on:** 17 Sep 2013, 11:11 am »

Hi Guy,
Yes, there's a motor, and I have a couple of arms I've tried on the table. The armboard in the bottom picture is cut for a Linn pattern. I got the table with an Alphason 100S that fits that pattern. This is a belt drive table witha separate 24V power supply. The supply burnt out and I had it rebuilt with a new transformer.

I have a problem with the basic design which inspired modding the chassis which I haven't done yet. If you look at the photo of the underside of the plinth you'll see the 3 feet and 4 springs (hard to see) all bolted to the underside of the top piece. That's 1/2" MDF and it doesn't seem substantial enough to support the weight of the table, which is considerable.

This is a beautiful ceramic platter and that's the Sota Supermat and reflex clamp. I really wanted to make a custom table with a Teres rim drive motor, but I can't get that right now, so I'm thinking of modding with the stock motor.

First, I have a problem with the thrust plate in the main bearing. It doesn't have one. Sota changed the design a number of times over the years and I understand some of them didn't have a sapphire plate and others varied somewhat in size. The ball bearing is 5/16" and some people have replaced it with ceramic bearings. My problem is the thrust plate as the metal there looks like it has a couple of gouges. I'll try to get a photo of inside the bearing housing. Meanwhile, any suggestions for a thrust plate? Sota wants $40 + S&H and if it doesn't fit, won't take it back.
neo

Guy 13 · « **Reply #5 on:** 17 Sep 2013, 11:21 am »

Hi neobop and all Audio Circle members.
Sorry, can't help you,
I don't have any ideas on how to help you.
To me it looks like a challanging project,
the kind of project I would not take,
but that's me.
If you succeed, it sure will be a nice table to own.
Good luck.

Guy 13

griffithds · « **Reply #6 on:** 17 Sep 2013, 12:55 pm »

Hi Neo,

I do miss the Sota Sapphire that I had. I bought it as a version 1 and had Sota upgrade it to the version 3. That was the highest level there was at the time. It also had the Alphson HR 100S arm. I wonder if it could possibly be the same table? Do you remember who you got it from?

Regards,
Don

neobop · « **Reply #7 on:** 17 Sep 2013, 01:51 pm »

Hi Don Griff,
Can't recall the name of the gent who traded me this table. He lived in New Jersey I believe and wound up with my Studietto/Zeta. That was a trade I always regretted, but I needed the cash. The Alaphason is a really nice arm. The Zeta has a big dramatic sound and was killer on the Goldmund.

Well, I took a better look at the thrust plate and it doesn't look as bad as I thought, although there's no sapphire disk. It's a little hard to tell from this photo, but it looks as if a washer surrounds a steel pad.

I polished the thrust plate area with some steel wool wrapped around the end of a drill bit, using a Dremmel type tool. Seemed to work pretty good. What looked like gouges before, was actually dirt. Now to buff the shaft that holds the ball bearing, use some lithium grease and see how she spins.
neo

thunderbrick · « **Reply #8 on:** 17 Sep 2013, 02:16 pm »

I did a piece-by-piece rebuild on mine and the serial # on the table should ensure SOTA sends you the correct parts. Relative to the other SOTA parts $40 is chicken feed, so go ahead and do it.

I've had my SOTA since '86 and it's been manhandled through many moves and house renovations. Still solid as a rock.

neobop · « **Reply #9 on:** 18 Sep 2013, 12:54 am »

I buffed up the bearing shaft and bolted the housing back on the sub-chassis. After greasing, the platter spins easily and stays spinning a long time. I don't think I need to bother with a $40 thrust plate. Apparently mine came without it and it seems to work just fine as-is.

There were a couple of threads on Karma lately about older Sapphires and dealing with Sota. I'd rather not. One guy with an old exemplar, like mine received a terse, condescending (about DIY) reply saying parts might not fit and are nonreturnable, plus they want $15 S&H. Sota has always been like that. They want you to ship them your table and pay more than it's worth to get it fixed up.

IMo the best thing about the table is the platter, inverted bearing, mat and clamp. Maybe I'll put it back together and try it with a dental floss belt. The original belt was thicker than their newer replacements and the thinner belts seem to perform worse.
neo

thunderbrick · « **Reply #10 on:** 18 Sep 2013, 03:09 am »

My dealings with SOTA about 4 years ago were superb. It sometimes took a few days for them to return calls but they were extremely friendly and supportive, and talked my through the process in each case. Shipping was fast and well-packed.

neobop · « **Reply #11 on:** 18 Sep 2013, 10:01 am »

Things change. Read post #18 from this thread:
http://www.audiokarma.org/forums/showthread.php?t=349308&page=2

I don't care anyway. I don't need any stock parts. I'm trying to figure out how to improve/redesign the table. If I'm going to keep it close to factory, then I'll want to reinforce the top of the plinth that takes all the weight. I'm not crazy about the suspension either, and I think that should probably be replaced, maybe with a solid bolts and bushings. What I'd like to do is use the platter for a completely custom table and use the wood base and dust cover for another table. That's not going to happen right now unless I use a DD from another table to turn the platter. I've seen that done - using video tape (I think) as a belt. That doesn't seem like a good solution though. I guess I could put it back together and sell it. That would probably be the most sensible solution.
neo

Russtafarian · « **Reply #12 on:** 18 Sep 2013, 06:57 pm »

If you can figure out how to retension the springs, let me know. The Sota I rescued from my friend's garage was a bit saggy up front.

Russ

neobop · « **Reply #13 on:** 18 Sep 2013, 09:56 pm »

Russ,
There might be a way to retension the springs, I don't know. They're damped - have some kind of damping material inside. You'd probably have to remove it first. You could probably buy a new set from Sota. Your guess is as good as mine what the cost would be.

The way I see it, you'd have two choices with the suspension, either get new springs or defeat them altogether by replacing them with bolts. All the weight is on those springs and you can see it's considerable. For those unfamiliar, the table weighs around 50 lbs or so. That subchassis has a lead sheet on top and those blocks at the corners are lead or heavy stone. 2 lead bars and a bucket of shot balance the table at the tonearm end.

I'm trying to figure out a way to defeat the springs with a damped bolt, but I haven't figured it out yet. Maybe some kind of hard rubber bushing could replace the spring part of the bolt. It's hard to see the springs from the photo above. I'll take another so you can see what I'm talking about.
neo

thunderbrick · « **Reply #14 on:** 18 Sep 2013, 09:57 pm »

Quote from: neobop on 18 Sep 2013, 10:01 am

Things change. Read post #18 from this thread:
http://www.audiokarma.org/forums/showthread.php?t=349308&page=2
neo

True, but that doesn't change my experience.

neobop · « **Reply #15 on:** 18 Sep 2013, 10:21 pm »

Quote from: thunderbrick on 18 Sep 2013, 09:57 pm

True, but that doesn't change my experience.

This thread isn't about your experience. Do you have anything to contribute other than what you've already said?
neo

thunderbrick · « **Reply #16 on:** 18 Sep 2013, 10:23 pm »

Apparently not.

*Scotty* · « **Reply #17 on:** 18 Sep 2013, 11:07 pm »

neo, bear in mind that theoretically, those springs in combination with the mass that is suspended by them may constitute a tuned suspension system designed to filter out vibrations above some very low frequency, possibly 3 or 4 Hz. If defeated structure borne vibrations may find their way into the system and degrade the sound. It unlikely that a "damped bolt" will be as effective as properly designed suspension. I don't know for a fact, that the table has a well designed suspension system.
Scotty

neobop · « **Reply #18 on:** 18 Sep 2013, 11:18 pm »

Russ,
Here's what the springs look like:

That bolt on the bottom of the spring goes through the subchassis and a nut holds it in place. The bolts with the rubber feet go clear through the subchassis and that top plate is pulled down by the springs/weight and pushed up by the feet at the same time.

I think I just figured out a way to defeat the springs and (hopefully) improve performance. That would be to use a solid bolt instead of the springs with nuts and rubber washers on either side of the subchassis.

Scotty,
The problem with the suspension is it's prone to lateral movement. I've read about others doing this and claiming a dramatic improvement. If I try this I could always reverse it and put the springs back in. This isn't like the LP12 I had with a 3 spring tunable suspension. I could get that to bounce straight up/down. This is 4 springs and all you can do is adjust the ballast near the arm. I think it's worth a try.
neo

*Scotty* · « **Reply #19 on:** 19 Sep 2013, 01:38 am »

Like you say,it's reversible. I have almost zero experience with suspended tables. My current table is unsuspended and weighs in at 65lbs. It has a simple three point leveling system based on three threaded pointed shafts extending through plinth upon which the turntable rests. It has almost zero mechanical complexity excluding the air-bearing platter and tonearm. I have considered building a DIY Ginko Cloud to attempt to isolate the table from structure borne vibrations.
Scotty