Agreed 100% - I'm just surprised at the tonal change.
I've a lot of experience with record players, mostly with LP12's and selling and setting them up, so I get the idea of fettling and % increases in performance from small alterations.
I need to strip them both down and build them both up at the same time to see whether there is something I'm missing in the arm mounting or something. Currently you'd think I was running a vastly different VTA on them or something (checked this isn't the case).
I've a lot of experience with record players, mostly with LP12's and selling and setting them up, so I get the idea of fettling and % increases in performance from small alterations.
I need to strip them both down and build them both up at the same time to see whether there is something I'm missing in the arm mounting or something. Currently you'd think I was running a vastly different VTA on them or something (checked this isn't the case).
The presentation between an LP12 and a SL-1200 is extremely different. My experience with LP12s over the years is that they are very colored, but the colors are really, really pretty, so people don't mind.
The SL is a completely different animal, and as soon as the 3 biggest issues with the stock configuration are addressed, (mat, feet, transformer) they lose the bit of darkness that's stock, and become very neutral and precise.
The SL is a completely different animal, and as soon as the 3 biggest issues with the stock configuration are addressed, (mat, feet, transformer) they lose the bit of darkness that's stock, and become very neutral and precise.
I think the coloured LP12 thing is a bit old hat now - since the Cirkus they've been getting more and more like the digital players in terms of tonal balance and presentation. The top deck now sounds absolutely amazing, and nothing at all like the older big-warm-and-bouncy LP12s. The name's the same, but they're different beasts.
With the SL, from my playing with feet and platforms, I think the stock feet are better than they're given credit for. Fixed spikes have not been good thus far, and harder rubber solid feet aren't that different to the stock ones really. Adding a good isolation platform can do good things on the stock deck, with light and ridged seeming to work better than high mass. Note though that obviously the platform to shelf interaction may be the reason for this, so it may not hold true in other situations.
I've tried a few things mat wise, but nothing has blown my socks off - I have to admit though that I've not seen the original rubber mats that came on the decks in probably about a decade! Currently using the felt mat from my '12, and it seems to be doing ok.
At one stage I wanted to try the Grado DJ cartridges, but was put off by the reported hum issues. I did look into making a DJ slipmat that included shielding, but couldn't be bothered in the end. Now that I've got the SMPS in the deck I suppose the Grado's could be something to consider re-visiting.
The bearing seems a likely target for improving the deck? I'd like a longer spindle for manual pitch control whilst mixing anyway, and I was thinking of adding some more mass to the platter underneath the actual record mat so that it could work with slipmats too (ideally the deck doesn't change speed when you use the slipmat as a clutch to stop the record on top). Clearly balancing the bearing in terms of hifi performance vs DJ durability may bring it back to basically the stock design anyway...
Sorry - gone well off topic! 
6L6 - your sketched schematic shows the power switch as I would expect it to be implemented.
The stock PS inside the SL has a three wire switch using a cap and resistor and then appearing to link the live and neutral through these when 'off'.
Am I misreading how it is set up, and if not, why have they gone with this?
6L6 - your sketched schematic shows the power switch as I would expect it to be implemented.
The stock PS inside the SL has a three wire switch using a cap and resistor and then appearing to link the live and neutral through these when 'off'.
Am I misreading how it is set up, and if not, why have they gone with this?
Last edited:
theres enough leakage for the leds to just glow when turned off, the japanese 100v versions dont have this problem so omit the shorting wire from the switch.
Had a japanese 100v sony that I retransformered to 240 and it would slowly start spinning the platter getting faster and faster with the power switch off, I think the leakage is mainly through the switch snubber?
regards
james
I'll disagree.
But I will say that the stock feet do make it easy to level and that's worth a lot.
I've had good luck resting the stock feet on something simple like vibrapods, will take 90% of the objectionable away.
I've had similar experiences.
Sorbothane hemispheres sounded the best, but they are a severe pain to level.
I can unashamedly recommend Isonoes, they are amazing.
A good platform or wall shelf is always wonderful!
I tried felt, and didn't care for it at all. Worse than the stock rubber, and that's saying something.
lol Cork is great, and after trying the Acromat I couldn't be happier.Absolutely worth trying again! It should be quiet now.
The stock bearing is made to be convenient for mass production. Even to the point that the stock oil needs to be low creep so it doesn't drip out.
Making an oil well sees to be a big improvement, I had my stock bearing modded and it was quite beneficial.
Great info here -
Can you improve the stock techie bearing???
Piggy backing on here if that's OK - the table is different but I think the power supply is similar enough.
I bought a motor/platter for the Kenwood KD-500/550 off the swap meet. I see 6L6 posted in the thread
It takes 18V DC to run, so the power supply in this thread looks fine, Antec makes a cute little shielded 50VA 18V transformer for ~25V input to the 317.
Sound right? I don't want to cut it too close to 18VDC, but I don't think you'd want to shed more excess voltage than necessary. Never used the LM317, but I've got the "off piste" page bookmarked.
I had planned to mount it all up in the plinth before I found this thread, searching for LM317. Now I'll move it to a separate enclosure.
As far as I can tell - and I don't know a lot about this motor - it'll hold speed with a decent amount of voltage drift. It has quite a bit of circuitry under the motor, as well as a slotted optical wheel on top.
I've got it running at 18V (the voltage spec in the manual) with the bench supply, dial in the speed with a variable resistor, and it's steady. Lower the voltage to 17V and the strobe dots stay stationary (just running under a fluorescent bench light) without touching the pitch resistor. It'll hold steady down to 12V. Draws about .5A at start up, .05A running without a stylus dragging.
If anything sound glaringly wrong, let me know. I won't clog the thread up - if I get it running I'll do a separate thread on it.
I bought a motor/platter for the Kenwood KD-500/550 off the swap meet. I see 6L6 posted in the thread
It takes 18V DC to run, so the power supply in this thread looks fine, Antec makes a cute little shielded 50VA 18V transformer for ~25V input to the 317.
Sound right? I don't want to cut it too close to 18VDC, but I don't think you'd want to shed more excess voltage than necessary. Never used the LM317, but I've got the "off piste" page bookmarked.
I had planned to mount it all up in the plinth before I found this thread, searching for LM317. Now I'll move it to a separate enclosure.
As far as I can tell - and I don't know a lot about this motor - it'll hold speed with a decent amount of voltage drift. It has quite a bit of circuitry under the motor, as well as a slotted optical wheel on top.
I've got it running at 18V (the voltage spec in the manual) with the bench supply, dial in the speed with a variable resistor, and it's steady. Lower the voltage to 17V and the strobe dots stay stationary (just running under a fluorescent bench light) without touching the pitch resistor. It'll hold steady down to 12V. Draws about .5A at start up, .05A running without a stylus dragging.
If anything sound glaringly wrong, let me know. I won't clog the thread up - if I get it running I'll do a separate thread on it.
That makes sense in terms of energy efficiency and heatsink size, but those series regulators are funny little critters. Both 317 and the lm78xx series seem to like higher input-output voltage differentials. This is not directly specified in the datasheets, but you can see it in the graphs.
317 datasheet specifies best ripple rejection at 15V in-out Voltage differential, and 78xx shows a direct increase in max output current when the differential is above ~7V.
You can also see similar effects with minimum loads, so preloading them is a good idea too.
317 datasheet specifies best ripple rejection at 15V in-out Voltage differential, and 78xx shows a direct increase in max output current when the differential is above ~7V.
You can also see similar effects with minimum loads, so preloading them is a good idea too.
Just ordered a used SP-25 and as I understand it is similar to the Sl 1200 at least in regard to the electronics. I understand remoting the transformer as the advantage is obvious, but why add the LM317 regulator, what is the problem with the technics discrete regulator? And if you do add the LM317 regulator should you not also remove Q2, Q3?
Audio Technica AT-LP1240 PS mod
I tried the external power supply mod on an AT-LP240. I like the table semi-stock with the preamp and switch board removed and tonearm wires run directly to the RCAs, so I had high hopes for the external PS. It was quite a bit different than the one described for the Techincs. The transformer has two windings, one center tapped that is rectified to +/- 30VDC, and another winding that is rectified to 20VDC. I moved the transformer to an external enclosure and added large banks of capacitors, but I'm not sure I like the results. I'm not done fiddling with it, though. I also have a Technics SL-1500 that I plan to mod for comparison.
I tried the external power supply mod on an AT-LP240. I like the table semi-stock with the preamp and switch board removed and tonearm wires run directly to the RCAs, so I had high hopes for the external PS. It was quite a bit different than the one described for the Techincs. The transformer has two windings, one center tapped that is rectified to +/- 30VDC, and another winding that is rectified to 20VDC. I moved the transformer to an external enclosure and added large banks of capacitors, but I'm not sure I like the results. I'm not done fiddling with it, though. I also have a Technics SL-1500 that I plan to mod for comparison.
The original filter capacitor on schematic for sp-25 shows to be 470 uf at 50v so 50v caps should be ok.
Maybe I have read the post wrong but I did not find where Q2 had been removed, it looks to me with the LM317 regulator that Q1 is still biased feeding the base of Q2 which now has its emitter floating. If Q2 is left in the circuit I would not remove R1. But I questioned in my post what is the advantage of using the LM317 over the discrete regulator. The only advantage of IC regulator that I am aware of is possible lower ripple which the improved remote P.S. and filter should take care of as the original P.S. filter only had the mentioned above 470 Uf for the filter.
Maybe I have read the post wrong but I did not find where Q2 had been removed, it looks to me with the LM317 regulator that Q1 is still biased feeding the base of Q2 which now has its emitter floating. If Q2 is left in the circuit I would not remove R1. But I questioned in my post what is the advantage of using the LM317 over the discrete regulator. The only advantage of IC regulator that I am aware of is possible lower ripple which the improved remote P.S. and filter should take care of as the original P.S. filter only had the mentioned above 470 Uf for the filter.
Sorry, I meant transformer for SL-1200.
I am also a bit skeptical about adding LM317 regulator. I am going to build external DC supply, but probably skip the regulator mod...