Post by Owen Y on Oct 31, 2019 17:05:18 GMT 12
Buoyed by the success (so far, work continues) of the Technics SP-10MKII here & while my Decca cartridge is back in England (maybe it hates being away from home), I've been meaning to try out one of Jeremy's SL-1210MKIIs. The choice of cartridge falls to a venerable Ortofon VMS20E MkII (which I've owned since the 70s) - Ortofon say it's " probably one of Ortofon’s most highly acclaimed magnetic cartridges". The first problem - not wishing to de-mount the Shure M44-7 DJ cartridge from the Technics headshell, I found that the only headshell to hand that was light enough to balance on the SL-1200 arm, was a Audioquest/Orsonic AV-101b - even then, I had to fit auxiliary rear counterweighting using a brass M4 screw, nuts & a lump of Blu-tak). The 2nd problem, was that the VMS20E is a very long cartridge & it was a tight job to fit headshell leads. 1gm VTF set, the 3rd problem was that the new headshell with Ortofon cartridge is considerably less in height than the Shure cartridge on Technics headshell. The SL-1200/1210 has a very nicely engineered, double-helicoid, brass arm-lifter arm-base ring - except that this one, like a lot of these TTs, had seized solid (lubricating grease hardened over time). There are various remedies (heat gun, complete disassembly), but I was eager to see if the TT ran & if the cartridge was still alive, so the TT was hooked up with VTA way out (by at least 8mm armbase height).   (Arm-base lifter ring)
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Post by Citroen on Oct 31, 2019 17:09:56 GMT 12
And?  Was the cartridge alive? How did it sound?
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Post by Owen Y on Oct 31, 2019 17:11:20 GMT 12
 (Additional counterweight, ugly but it works.)  (Ortofon VMS20E MkII, AV-101b headshell.)
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Post by Owen Y on Oct 31, 2019 17:16:29 GMT 12
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Post by michaelw on Oct 31, 2019 18:03:55 GMT 12
all those nuts on the counterweight extension remind me of naim tapons. 
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Post by Owen Y on Oct 31, 2019 21:40:58 GMT 12
The humble SL-1210 is a weighty little beast - 12.5 kgs, surprisingly, most of it is in the solid base plinth. First impressions of the sound - powerful bass, plenty lively & decent sized sonic presentation (with this cartridge) - ie musical & engaging, good first impressions. Time will tell if we can dig some finesse, nuance & magic out of this thing. Now, we've got to free-up the arm base height adjuster. PS. I've ditched that Serato slip-mat of course & using a rubbery drawer-liner mat from the Aura. (I wonder if J has got the original Technics mat?)
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Post by michaelw on Oct 31, 2019 21:57:41 GMT 12
my old sl1210 m5g came with one of those thin faux felt mats with TECHNICS printed in big letters. it was awful and did nothing to inhibit the ringing platter. it was also covered in a zillion microbits of polystyrene foam as the idiot seller did not bag the tt, just surrounded it in foam for shipping. 
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Post by Owen Y on Nov 3, 2019 9:33:43 GMT 12
I think the stock mat with these was a ribbed rubber job (now lost from our SL-1210s), similar to the SP-10 mat - which I have & will try on this SL-1210. Time to disassemble & fix that arm height adjuster arm-base....  The TT needs to be turned upside down (platter removed). Around 21(!) screws need to be removed to renove the 4 'audio insulator' feet & a very heavy mass-loaded rubber base. 
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Post by Owen Y on Nov 3, 2019 9:54:38 GMT 12
A profiled sheet of 'deadening rubber', fixed to the underside of the cast aluminium top frame, is also removed.  Tonearm removed (3 screws + ground wire):   (Arm-base cover plate has been removed.)
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Pundit
Post by SL1210 on Nov 3, 2019 11:06:31 GMT 12
my old sl1210 m5g came with one of those thin faux felt mats with TECHNICS printed in big letters. it was awful and did nothing to inhibit the ringing platter. it was also covered in a zillion microbits of polystyrene foam as the idiot seller did not bag the tt, just surrounded it in foam for shipping. Good point about the mat. Most times a mat is nothing to get too fussed about but with a metal platter it does become important. Technics have damped the platter with a rubber underlay but it is only about 50% successful. The reason is partly that rubber is not such a good damping material. Worse is that the glue used to adhere the mat to the platter is unevenly applied. Good mats will provide some isolation and / or damping. The Oyaide BR12 mat, and the Funk Firm Achromat are good options. Another option, that I may have mentioned elsewhere, is to strip out the rubber underlay, and pour in an epoxy. It is a prick of a job and easy to screw up. However it is one of the best upgrades one can do.
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Pundit
Post by SL1210 on Nov 3, 2019 11:10:34 GMT 12
A profiled sheet of 'deadening rubber', fixed to the underside of the cast aluminium top frame, is also removed. While you have the beastie open that is a good time to place dynamat on the metal surfaces. It is a bit of a pain cutting them to shape but is well worth it. I have done this to all 3 of my 1200s.
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Post by Owen Y on Nov 3, 2019 11:36:15 GMT 12
The arm-base rings separated (the grease was a bit dried but not solid). You can see the cast alloy outer 'bracket' (fine-threaded) & arm base & the brass adjuster middle ring (which has different inner & outer threads). The arm-base is 'multi-start' threaded. All in all, nice engineering I'm told, typically Japanese. 
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Post by Owen Y on Nov 3, 2019 12:38:12 GMT 12
Hi SL1210 - resin fill is a good technique, something I was planning on parts of the SP-10. Did your SL-1200s have a heavy rubbery profiled damping sheet/block, between the bott base & the top alloy plate? (The piece that J is holding in one of the pics above.)
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Post by Owen Y on Nov 3, 2019 20:31:08 GMT 12
SL-1210 top plate with platter removed. Unlike the SP-10, the motor electronics are all accessible from the top, under the slotted plastic cover.  Underside of platter, with heavy rubber damping attached. The motor rotor ring magnet is attached to the platter - there is no sub-platter. 
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Post by Owen Y on Nov 3, 2019 20:35:16 GMT 12
Close-up of the motor stator (12-pole, 15-pole on the SP-10), spindle & main bearing. 
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Pundit
Post by SL1210 on Nov 4, 2019 4:31:50 GMT 12
Hi SL1210 - resin fill is a good technique, something I was planning on parts of the SP-10. Did your SL-1200s have a heavy rubbery profiled damping sheet/block, between the bott base & the top alloy plate? (The piece that J is holding in one of the pics above.) Yes. Technics built them in three layers. Metal on top, rubber underneath. I have never understood what the middle layer is made from. It is sort of chalky but very hard. When I have used custom armboards and they were not a perfect fit, it is easy enough to file away some of that chalky layer. Incidentally, I have put on a Jelco arm and an Origin Live Arm. My conclusion is that overall the standard arm is ok. The Jelco arm is a keeper. However the Origin Live arm I installed was crap. I put in a latest iteration Origin Live Conqueror. Mk3C IIRC. I simply could not put up with it and the standard technics arm was better.  
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Post by Owen Y on Nov 4, 2019 11:23:00 GMT 12
One slightly tricky aspect of re-assembling these SL-1200 helicoid arm-bases, is to align the mult-threaded tonearm base properly, before screwing back on, so that it is calibrated correctly in relation to the dial numbers of the adjuster ring. Be sure to line up the adjuster mark '2' (approx) with the line on the arm-base (as below), before carefully engaging the threads. (The bottom/outer ring is also opposite threaded )  (Threads cleaned with iso alcohol & re-greased before re-assembly.)
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Post by Owen Y on Nov 4, 2019 14:05:21 GMT 12
The SL1200/1210 arm-base arm-height adjustment scale is calibrated from 1 - 6 in mm. This is a v cool feature that other tonearm makers should consider. The SL-1200/1210 operating manual has a table correlating cartridge heights to this arm-height scale (below).  
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Post by Owen Y on Nov 5, 2019 11:57:44 GMT 12
With the Orsonic headshell & the VMS20E cartridge, arm-height adjustment is problematic, as you can see by the pic below comparing the a Stanton (Technics clone) headhsell, the Technics & the Orsonic headshells. The Orsonic design places the cartridge platform a few mm higher than on the standard Technics / Stanton h'shell, which, together with the low height VMS20E, makes it too low for the SL-1210's arm height adjustment. So, whilst the Orsonic headshell (legendary for its stiffness & low resonance) might be contributing to the generally good initial sound that I heard, sadly I have to ditch it for the spare Stanton h'shell on hand - the Technics h'shell looks actually quite good, lightweight, but with siffening webs cast in underneath. The Stanton doesn't look quite as nice as the Technics which has gold contact pins.  
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Post by michaelw on Nov 5, 2019 13:18:59 GMT 12
did your sl1200 come with the simple plastic overhang jig ? 
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Post by Owen Y on Nov 5, 2019 13:32:43 GMT 12
I have not seen this amongst J's kit (but I will ask). Although J looks after his stuff, these SL1210s have seen a fair bit of dance club DJ action & were obtained s/h originally I believe. The original rubber platter mats, for example, have long gone. Replaced by slip-mats  With the Stanton-Technics shell in place, well guess what? The Technics arm-height table seems to work fairly accurately 
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Post by michaelw on Nov 5, 2019 14:36:23 GMT 12
 quality engineering in action
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Post by Owen Y on Nov 5, 2019 17:07:59 GMT 12
And with the correct headshell, no need for auxiliary counterweight While we're at it, we'll give the bearing a couple of drops of oil. Technics specify:  ie. Similar to the SP-10, the SL-1200 bearing requires very little lubrication. This is an oil which I've found to have the similar low temp. viscosity to the Technics SFWO 010 oil (a SAE 30 synthetic). 
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Post by michaelw on Nov 5, 2019 21:31:54 GMT 12
if mobil 1 is good enough for porsche, lexus et al it should be good enough for technics,
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Pundit
Post by SL1210 on Nov 6, 2019 2:05:42 GMT 12
And with the correct headshell, no need for auxiliary counterweight While we're at it, we'll give the bearing a couple of drops of oil. Technics specify: ie. Similar to the SP-10, the SL-1200 bearing requires very little lubrication. This is an oil which I've found to have the similar low temp. viscosity to the Technics SFWO 010 oil (a SAE 30 synthetic). Excellent move with the oil there Owen. KABUSA (wonderful resource by the way) offer an 'original' oil. I say oils must have advanced since the 1970s. A viscous motor oil will be plenty good enough. It is important that the oil be not too thin or it will run down the shaft and need replacing. Incidentally if you are going to open the beastie from the top you may as well give the bearing a good service. That means taking it apart, checking for wear on the base of shaft that sits on the thrustpad, cleaning the spindle and the housing - think piston and cylinder, polishing the base of the spindle - use autosol for example. And you may as well put in an aftermarket thrustpad. Again KAB do a Delrin Thrustpad that is pretty much the equal of Peek (a hard species of Teflon). It is $47 and my measurements showed a significantly longer spin-down time! that could only be attributed to lower friction.
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Post by Owen Y on Nov 6, 2019 11:04:37 GMT 12
Thanks chaps - I've learnt a bit about the Technics DD main bearings, from examining the SP-10 & SL-1200. 1) The Technics bearing shaft is small diameter, same as the record spindle (~7.2mm diam.). With a DD motor, there are no side loads on the bearing with a balanced platter, the shaft does not need to be any stronger & rotation speed is slow. I see some after-market replacement bearings offer large diam. heroic-sized bearing shafts - unnecessary IMHO. Technics' engineers knew what they were doing methinks. 2) Technics install a ball at the bottom of the spindle, with a 'thrust pad' under. This thrust pad looks to be a low friction, high-wear grade plastic which does not appear to require lubrication - the SP-10 thrust pad is downward-facing on the bott of the spindle, whereas the SL-1200 thrust pad is upward-facing, exposed in fresh air. 3) The Technics oil, they say, was a synthetic SAE 30 grade. Mobil 1 5W-30 has similar viscosity at low temps. (Of course engine oils have all sorts of additives, but they'll be inconsequential I expect at the low temp/speed/loads in a TT.) At this stage, I want to get back to listening to this SL-1210. In future, we may contemplate closer examination of the bearing & thrust pad - which necessitates removal of the motor & main PCB. There is no obvious bearing side-play on our 1210s.
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Post by Owen Y on Nov 6, 2019 11:41:50 GMT 12
For the record, the SL-1200/1210 model timeline: 
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Post by Owen Y on Nov 8, 2019 19:50:54 GMT 12
Ok... starting to get a feel for the sound of this thing. (For the record, I am not using the original headshell leads - some Hitachi LC-OFC (SSL-101) happen to be flexible enough & not too long. Also, the TT is not sitting on its isolation feet, it's sitting bottom-base straight onto a 3-legged steel stand - just because it fits my space & because the stand is triangular, without a rectangular platform on top. However, I will report on how it sounds on its 'isolation feet' when i figure out somewhere to sit it.) The first thing one needs to do is to get rid of the Technics rubber mat - punchy sound with warmth, strong lower-mid presence & ample 'sustain', but treble is 'steely'. Overall a bit 'noisy', 'hashy', gritty - ultimately fatiguing. Focus is also 'indistinct'. 
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Post by Owen Y on Nov 9, 2019 17:08:57 GMT 12
Next up, the rubbery 'dashboard-liner' mat I used on the Aura: The grittiness & treble grain/steeliness is gone. Some upper mid dynamic glare still remains. Overall very much sweeter voice & guitar tone. Maybe a bit 'dull', lacking 'bite', on this TT. 
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Post by Owen Y on Nov 9, 2019 17:16:51 GMT 12
A thin rubbery Aura mat (also supplied by D Whittaker at one time): Good, quiet backgrounds, nice treble, dynamically open. Focus still diffuse. (Note - I did not bother to adjust VTA for this slightly thinner mat.) 
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quality engineering in action