Technics SP10 mkII

[fordy]

I’ve just joined the SP10 club. I came across an SL1000 mkII, an SP10 mkII in the SH-B3 plinth for a decent price at Hifido.



Long term I will probably mess about with a new plinth but I thought I’d best get the measure of the SH-B3 plinth first. It seems to me it’s had a lot of BS spoken about it over the years, especially much regurgitated internet “consensus”. Anyway I’ll let my ears decide.

[pure sound]

It's a handsome thing. Which arm is that?

[fordy]

I’ve done a bit of digging on the Technics Obsidian plinths and they are quite interesting, especially given the latest plinth damping measurements Cat Squirrel has done and the plinth making vanguard headlong into mineral loaded polyester resins.

So let’s revisit the “Obsidian” plinths from Technics. The Technics SL-1000 was the SP10 in a special massy plinth with three variants over time; SH-B3, SH-B5 and SH-B7.

Firstly let’s look at the SH-B3. This was marketed by Technics as Obsidian in their sales literature of the time.




It seems to me the word Obsidian conjures up “glass” and glass is bad for plinths right? Hence the plinth being dismissed early on. But what is this plinth really? There is no way Technics machined Obsidian plinths from big chunks of volcanic glass!

The top part of the plinth appears to be some kind of hard resin that is heavily loaded with a mineral material. Probably powdered Obsidian or some kind of synthetic equivalent. I’ve seen it described by many people as resin/stone and looking at mine it certainly appears to be. It’s clearly been cast in a mold and the shiny black finish that gives it the illusion of being Obsidian is actually a very thin outer veneer, mine has thin veneer-like slithers missing here and there. Behind the veneer, which is relatively soft and scratches quite easily, it is obviously a dull grey composite stone type material. This heavy composite stone top piece sits on a thin sheet of rubber which in turn sits on a nice piece of plywood. All very CLD.

The armboard is a very thick piece of veneered ply which sits in a cast aluminium cradle, itself sitting on a thin rubber gasket between it and the stone. The motor unit is solidly bolted to the composite stone top.

Precisely what the “Obsidian” is actually made from is difficult to determine but it is clear that Technics went onto to drop the Obsidian name in the marketing of their next two plinths for the SP10 series, the SH-B5 and SH-B7. Now both of these are almost always referred to as Obsidian on the internet. Not so according to Technics. They are made from TNRC and were only ever referred to as such in the sales literature.





In the 70's Sony developed a polyester loaded with some powdered minerals and fiberglass called ‘Sony Bulk Molding Compound (SBMC)’. Technics followed with ‘Technics non-resonance compound (TNRC)’. It was loaded in many CD players and record decks of the time. There is also something known as Pocan, again a polyester resin with fiberglass loading. Kenwood were also at it with their ‘Anti-Resonance Compression Base’ (ARCB) which was “molded from limestone particles, glass powders and unsaturated resin” in the classic LO-7D. Quite who was first to market with any of these acronym riddled anti-resonance materials I have no idea but it was state of the art in the 70’s and 80’s. Also it appears Kenwood were using Corian in plinths earlier than this and even went so far as to use ARCB ‘bricks’ in the plinths of some of their models to mass load them.




Sounds like these 1970’s concepts are very similar to the Bentonite loaded polyester resin ideas. Did the Japanese giants already have the right idea for plinth designs 30 years ago?

So anyway, back to the SH-B3, it could be that the “Obsidian” tag was just a marketing term which was subsequently dropped and all three plinths are really the same material or, more likely, that the material used in the Obsidian SH-B3 was further developed to become TNRC. Clearly Technics engineers were playing around with resins loaded with inorganic materials at the time. The B5/B7 plinths also dropped the CLD construction of the B3 variant, they are just TNRC. They are both also massier than the B3 which suggests that the Technics engineers where refining their ideas and their understanding of what the SP10 responded too. I’ve never seen an SH-B5 or SH-B7 in the flesh to compare to the SH-B3, however my feeling is that the “Obsidian” SH-B3 and “TNRC” SH-B5/B7 are probably different types of mineral loaded resins.

The SP10 mk3 also has TNRC loaded in its chassis, as does the SL1200/10 series from mk3 on I believe. The SH-B5 base, which I think was only available in the SL1000 mk3 package, has the circular cutout so that it can only receive the SP10 mk3. This appears in a German Technics catalogue from 1987. A similar catalogue from 2 years later only mentions the SP10 mk 2 as a stand alone unit (mk3 appears to have been dropped) and only the SH-B7 base, again only referred to as TNRC but this time cut to accept both SP10 mk2 and mk3’s.

As an aside, I read somewhere that some of the Denon plinths (like DK200) for their direct drives (like DP6000) where made from a kind of resin loaded ply - sounds like an early type of Panzerholz to me...

Have we come full circle on plinth materials?

What have I done here is to try to put a few facts back into the collective SP10 memory. To be specific the only facts here are the ones shown in the Technics literature, everything else is my opinion, a bit of conjecture and day dreaming and regurgitated internet snippets and ‘consensus’ cleverly pieced together to suit my own argument. Stuff I read on the internet in the last few hours basically…and remember, never believe anything you read on the internet.

So anyway, as to whether the SH-B3 plinth is any good or not, I’ll let my ears decide.

[fordy]

What I like most about the SP10 so far (coming from a Pink Triangle Anniversary/SME IV) is the usability. It starts and stops on a penny and doesn't bounce around forever, which I hate about the Pink. The SP10 is simply a joy to use. I’ve played with various Lenco’s over the last few years as well as numerous other Pinks, LP12s, Gyros, Thorens and I always prefer to use non-suspended designs. I don’t know why bouncy annoys me…which is a problem because the best deck I have ever heard in my system is the Anni. Despite being a pain to use, the Anni has stayed put while all else just passes through.

My SL-1000 came with a basic arm, Technics EPA-101s, which has no antiskate at all, is really short and not a bit like the nice EPA-100/500 arms. It was the budget option I think. It’s in decent condition but it sounded only mediocre. So I duly bought the sprung downforce Ortofon RS-212D which is an OEM Jelco and more substantially built than the Jelco SA-750D (which I also own along with a couple of SA-375H). Anyway the bearings were really loose and rattling around so it had to go back. They couldn't replace it so I had to have the cheaper AS-212S which omits the sprung downforce and is slightly less substantially built. There is a tiny hint of play in the bearing on this one too, something I’ve seen commented on many times. I’m not impressed at all with the build quality of these Jelco Ortofon’s. It sounds ok so far though so I will persevere with it.

Having butchered the original ply armboard to fit the RS-212D mount I was gutted to discover that the AS-212D mount is smaller and now it won’t fit. So I had to hand fashion a completely new armboard. I decided to omit the ali cradle and chose what I think is a piece of ebony instead (hard to tell in a hardware store were all the labels are in Japanese!) which turns out to be as hard as f##k and difficult to work. I can’t bring myself to buy 100V power tools so only buying nice hand tools. I managed it though. Chuffed. Looks ace.







I also scored a few new cartridges and headshells to play with and the Oyaide MJ-12 mat and STB-HW weight. Very bling.

Early days yet but this Techy is a real nice deck to play my recs on and is showing a lot of potential. I need to spend a lot of time on arms, headshells, carts, mats, weights and isolation yet though. Much fookery to come.

[pure sound]

Have you got your eyes on anything (plinthwise) to compare it with?

Great summation so far, repped.

Any cut price FR arms available locally? I have a 64S but haven't tried it on the SP10 yet.

[russ abbott - royds brother]

Lovely looking deck.

[gthang]

Nice! I must admit I'd like an SP10, i'll get 'round to it one day.

Is that a 501mk2 in the last couple of pictures?

[fordy]

I did a monster birch ply lenco 88 a few years ago which worked quite well. Also got loads of 2 inch thick slate slabs in the garage at home which has long been pending a PTP lenco project. So it will probably get a massive slate plinth at some stage to compare it too. Thats a few years away until we live in the UK again and all my projects get reunited together! A mate is looking into panzerholz so could start with something simple with that for a quick compare. Also tempted to get Russ to make something beautiful along the lines of the Porter plinths. Given how little time I have for projects, and lack of workshop and tools here, seems like the easy option.

FR arms are available but with the strength of the Yen at the mo, nothing is a bargain. I had a 64s a year or so back for a Koetsu but it sucked the life out of it so I gave it up. The Koetsu was better in the SME on the Pink. I'd be tempted with an FR64fx though when I get my Koetsu back.

[fordy]

good spot yes it is a 501.2. Excellent it is too.

got these to play with too :-)



left to right...
Audio Technica AT50 ANV in an Ortfon LH-8000 headshell
Audio Technica AT33 mono in a Jelco headshell
Phase Tech P3 Alexandrite in a Phasemation CS-1000 headshell
and a lonely Yamamoto HS4S which is probably going to have the Shelter in it next.

[bigdur]

Cor! Well done

[Birdbrain]

I've often seen the plinth criticized.

This might be of interest.

I recently set up my SL1000 after finally fitting an arm to it.
There was an annoying hum.
The hum happened when the stylus contacted the record surface.
I searched all over to try to cure it.
I swapped cartridges, checked wiring, went on and on..........
I noticed there was a very slight hum from the power supply transformer. I tried a spare PS (which also hummed slightly).

Finally I had the idea to pick up the PS. EUREKA!
SL1000 was sitting on a rack with the Power Supply 3 shelves down.
The very slight vibration from the PS was carrying up the rack, through the isolating feet, into the plinth, through the rubber isolation in the plinth and being picked up by the stylus.
That just demonstrates how susceptible any stylus is to any outside vibrations.
I temporarily put the PS on some bubblewrap.

So when people are criticizing this plinth, perhaps it just needs better isolating feet on it.

It's not that easy to find arms of the correct length to fit either.

[Tarzan]

oh dear l need to go to the toilet...................................

[f1eng]

I've often seen the plinth criticized.

This might be of interest.

I recently set up my SL1000 after finally fitting an arm to it.
There was an annoying hum.
The hum happened when the stylus contacted the record surface.
I searched all over to try to cure it.
I swapped cartridges, checked wiring, went on and on..........
I noticed there was a very slight hum from the power supply transformer. I tried a spare PS (which also hummed slightly).

Finally I had the idea to pick up the PS. EUREKA!
SL1000 was sitting on a rack with the Power Supply 3 shelves down.
The very slight vibration from the PS was carrying up the rack, through the isolating feet, into the plinth, through the rubber isolation in the plinth and being picked up by the stylus.
That just demonstrates how susceptible any stylus is to any outside vibrations.
I temporarily put the PS on some bubblewrap.

So when people are criticizing this plinth, perhaps it just needs better isolating feet on it.

It's not that easy to find arms of the correct length to fit either.

It was shown to me in 1975 that if one attempts to measure rumble on a solid plinth type turntable it is all but impossible. Footfall, cars going by (and the lab was on the 4th floor with a 100yd wide car park between it and the road) and so forth were all picked up by the stylus. -20dB was measured if a bus was going by on a deck that was -65dB if mounted on the suspended seismic table.
All solid plinth designs have this problem, the only thing that varies is the quantity and frequency range of the pickup...
One of the reasons why suspended decks are more faithful but have "less" bass IMO.

On the seismic measuring table the Technics SP10 was the lowest rumble and wow and flutter turntable we had measured (though I believe there was a contemporary Sony unit about the same).

BTW I believe the experiments with various bulk moulding compounds for plinths back then was at least as much to do with styling freedom of curved surfaces as anything to do with sound...

[f1eng]

FWIW to use 5Hz suspension which will isolate well from 10Hz up and not interfere with arm dynamics, the static deflection of the unit on the suspension is just over 15mm.
If you have "isolating feet" which deflect less than this they are not isolating the whole audio band, and may/will be accentuating some frequencies being fed back through the structure to the stylus.

[pure sound]

Mine sits in around 60 Kg of slate (2 layers) but that all stands on springs and it bounces at 1-2 Hz or thereabouts. It seems very well isolated from footfall, passing lorries, earthquakes etc!
Not sure about whether slate is quite the right material though.

[f1eng]

Mine sits in around 60 Kg of slate (2 layers) but that all stands on springs and it bounces at 1-2 Hz or thereabouts. It seems very well isolated from footfall, passing lorries, earthquakes etc!
Not sure about whether slate is quite the right material though.

The material of the plinth, its shape and where the arm and turntable are monted all have an influence. I was surprised how much a strategic hole or slot could alter the dynamics of the system.
Anyway with a 2Hz natural frequency of support the mechanical isolation will be about as good as it gets. with a 60kg lump of slate the bits most likely to pick up airborne vibration will be the disc itself and the arm.
Sounds like a great deck.

[pure sound]

I think the SP10 perhaps has different requirements of a plinth than a 301/401 would. Those two do seem to produce quite alot of vibration which needs to be dealt with (suppressed) somehow. Arm mounting arrangements also have to be chosen to isolate the arm from said vibration. Motor units like the SP10 are much quieter in operation but do want a substantial, stable, well isolated platform to sit in.

[russ abbott - royds brother]

Does your deck sit straight on the slate guy, or is there any material inbetween?

[Birdbrain]

I also have an EMT.
Apart from being able to play a record when it is tilted at 45 degrees, I have not seen anything with such shock isolation. I can hit the chassis hard when a record is playing, and it has no effect !

[pure sound]

Straight into the slate. There'd be scope to experiment there I suppose.