Tim, I should have added that because of the drastic difference in shapes, a plinth custom-made for a Mk3 would not fit the submergible portion of a Mk2 chassis. It's a square peg into a round hole, where the side of the square is at least the same as the diameter of the hole, and maybe bigger. Vice-versa mismatch would "work", as described.
Technics SP-10 mkII speed adjustment question
Hi,
I'm on my way to complete my Technics SP-10 mkII project. Actually, a friend of mine, a professionnal audio technician, is working to upgrade the PSU, which is done but a small adjustment on the speed must be done and he need some cue on this issue.
We already asked Bill Thalmann, Artisan Fidelity and Oswald Mill audio. Plus, I'll post on DIY Audio today. We'd like to get the answer as quickly as possible to finalized this for the week-end. Hope someone on Audiogon can help.
Here's the message from my technician:
"Hello,
I'm an electronic technician and I do repair for audio equipments, vintage, hifi pro and more. I have a client here that brought me his turntable Technics Sp-10 MKII to fixed. I have a little question about it and he gave me your email because he pretended that you have some experience with this kind of materiel. So, hope that you can response my technical question.
I replaced all capacitors in the power supply and a big solder job. I checked for defect solders or capacitors on the circuit boards inside the turntable and I tied to do the adjustments . Everything seem good right now, the turntable work fine. I tried do do the period adjustment with the VR101 and VR102 potentiometers like in the service manual ( see attachment, Period adjustment method). When I looked the stroboscope at the front of the turntable, It's pretty stable but I can see a tiny rumble at 33 1/2 and 78 speed. 45 is the more stable speed for the stroboscope. So, I fixed the phase reference with T1 at 18us of period and I try to do the period adjustment at the point test T and S on the board with the O point for reference. When I put my scope probe on the T point, I can observe the stroboscope running. It is not stable at all. If I pull off my probe, the stroboscope is stable again. So When I have the 2 probes at point S an T at the same time to do the adjustment, it's impossible to fixed the wave T because it going right to the left on my scope. When I turned the VR101, the T wave going faster or slower but never stable. I tried to ground lift my scope, plug it into the same power bar and try to pull off the reference at the O point. I can't have a setup that I can see a stable T wave in my scope with the one that I can do the right adjustment. Why? Is there a problem with the turntable or maybe it's a incorrect probe or ground setup? Please let me know what you think.
Best regards"
Thanks for help,
Sébastien
I'm on my way to complete my Technics SP-10 mkII project. Actually, a friend of mine, a professionnal audio technician, is working to upgrade the PSU, which is done but a small adjustment on the speed must be done and he need some cue on this issue.
We already asked Bill Thalmann, Artisan Fidelity and Oswald Mill audio. Plus, I'll post on DIY Audio today. We'd like to get the answer as quickly as possible to finalized this for the week-end. Hope someone on Audiogon can help.
Here's the message from my technician:
"Hello,
I'm an electronic technician and I do repair for audio equipments, vintage, hifi pro and more. I have a client here that brought me his turntable Technics Sp-10 MKII to fixed. I have a little question about it and he gave me your email because he pretended that you have some experience with this kind of materiel. So, hope that you can response my technical question.
I replaced all capacitors in the power supply and a big solder job. I checked for defect solders or capacitors on the circuit boards inside the turntable and I tied to do the adjustments . Everything seem good right now, the turntable work fine. I tried do do the period adjustment with the VR101 and VR102 potentiometers like in the service manual ( see attachment, Period adjustment method). When I looked the stroboscope at the front of the turntable, It's pretty stable but I can see a tiny rumble at 33 1/2 and 78 speed. 45 is the more stable speed for the stroboscope. So, I fixed the phase reference with T1 at 18us of period and I try to do the period adjustment at the point test T and S on the board with the O point for reference. When I put my scope probe on the T point, I can observe the stroboscope running. It is not stable at all. If I pull off my probe, the stroboscope is stable again. So When I have the 2 probes at point S an T at the same time to do the adjustment, it's impossible to fixed the wave T because it going right to the left on my scope. When I turned the VR101, the T wave going faster or slower but never stable. I tried to ground lift my scope, plug it into the same power bar and try to pull off the reference at the O point. I can't have a setup that I can see a stable T wave in my scope with the one that I can do the right adjustment. Why? Is there a problem with the turntable or maybe it's a incorrect probe or ground setup? Please let me know what you think.
Best regards"
Thanks for help,
Sébastien
- ...
- 144 posts total
Lew, thanks for your clarifications. I think I should have approached my question a little differently. Since I have a SP-10 Mk2A I'd be interested to hear from anyone who modified their Mk 2 chassis. Since the number of Mk 2 and 2A (same chassis I'm sure) so greatly exceeded the production of Mk 3 motors it seems reasonable there might be more interest in Mk 2 and 2A upgrades. I'm not interested in going to the extent of eliminating the chassis and mounting the platter/motor directly to a plinth but if performance upgrades (reduced resonance) can be achieved by chassis modifications (damping) I would like to hear about specific recommendations. Thanks. |
12-18-12: Lewm A friend who listens with us occasionally is the first person getting Krebs MK2 mods, at least on this side of the world. His MK2 was still at Bill's two weeks ago but hopefully it's near completion. My friend (Ken) also has a Krebs Technics MK3 so he's clearly the person to answer this question. He has an ultimate system, very high resolution and pro tape machines that serve as baseline for sound. Depending on his report I may invite myself back to his home so I can hear for myself. |
To clarify the design evolution on the Porterhouse plinths, I will start from the beginning. In August of 2007 I built the first plinth to Albert's specifications from Baltic birch covered in wenge. It can be seen here: http://farm9.staticflickr.com/8204/8283876129_eda99c9574.jpg As you can see, the corners are chamfered and the chamfer along the top edge resulted in a facet on the corners. Albert asked me how I could eliminate that facet and improve the appearance of the next iteration and I told him that by rounding the corners instead of chamfering them there would be a smoother transition. In December of that year I built the first of the Panzerholz plinths from material I had left over from another job. They were for the Garrard 301 and the Thorens 124. Albert was intrigued by these designs and asked me to incorporate Panzerholz in the next SP-10 plinth along with other improvements in design such as eliminating the facet, enlarging the armboard for more versatility, and my own idea of chamfering the bottom edge as well as the top to eliminate the chunky appearance. At this time I hadn't seen a Technics obsidian plinth since the seventies (which by the way is molded from crushed obsidian in a polymer matrix, and not carved from solid obsidian) so from my point of view the resemblance between the two plinths is coincidental. The improved plinth can be seen here: http://farm9.staticflickr.com/8500/8284935462_ef0d60ecc3.jpg There was a significant improvement in background blackness with the Panzerholz plinth so I began building simple plinths for our friends. One of our group suggest that we produce these plinths for a broader market but I wasn't that keen on the idea. However interest began to build on Audiogon and Albert sold a few of these simpler models there. There wasn't a whole lot of money to be made on these so Albert asked me to develop a two arm version of his ebony plinth so as to move up-market. He shelled out the $7500 for the Panzerholz after my supply had been exhausted and we began building this model on a limited basis: http://farm9.staticflickr.com/8076/8283876371_c1d095f9b2.jpg Shortly thereafter some cheaper clones appeared on the market which mimicked the exterior appearance but of cheap construction and they sold in the $750 price range. Later Artisan Fidelity came out with a higher end version which appears to me a cold copy of the Porterhouse design, although of different construction technique: http://farm9.staticflickr.com/8068/8284935288_9b85c6d9ff.jpg I can't say that the whole business hasn't been without problems due the difficulty in working with Panzerholz and its tendency to expand and contract a great deal with changes in humidity, not to mention similar problems in consistency with ebony and its own problems with movement and subsequent cracking. To this day I feel badly about the problems that arose with Kent's plinths and in the end I have to put it down to improperly dried ebony slabs, since none of the other ebony plinths experienced splitting to that degree. I hope I have answered most of the questions anyone may have had about the Porterhouse plinth and its evolution. John |
- 144 posts total