Power supply for my Thorens

[Dingdong]

I had this idea of trying out a Naim Armegeddon type power supply for my TD160. I've been having a look around various websites about different clones that involve building something with a drop-down transformer a resistor and a cap.
I had this idea that it could be simple and cheap to get myself a 240-110v step-down transformer off of ebay and fit the components in the case and wire the Thorens motor up to that.
Does anyone see a problem with this plan?

[Moko]

You should have a look here at this project which is being tested at the moment for Lenco's, I'm fairly sure somewhere in the long thread it mentions it will work for Thoren's as well.

http://www.lencoheaven.net/forum/index.php?topic=2042.0

I hope this helps

[Dingdong]

Thanks for that. I don't really want to start generating signals to supply the motor.
I was just going thinking of using a step-down transformer to 110v and a 33uF capacitor. I had a look at the Thorens circuit and the cap is all there is for a 110v motor. The 240v circuit has a 56k resistor to drop the voltage as well.
So, if I was to modify a little box with a 110v drop-down transformer in it by adding a 33uF cap and using 4 core mains cable it should work, I think, and possibly make an improvement in a sort of Armegeddony way. Or am I talking bollocks?

[Hypnotoad]

Doesn't the Thorens use a 16vac synchronous motor?

If so you can use the ProJect Speed Box II or Speed Box SE, it gives quartz locked speed control.

Just a thought.

[Dingdong]

The Td160 uses a 16 pole 110v motor. Similar to the older Rega/Linn motors, but they have more poles (24 I think).
My plan so far is to take the 110v step-down transformer I got off of ebay for 99p +p&p, add a .33uF phasing cap and then experiment with resistors to reduce the motor vibration as much as possible while still being able to start.
The transformer is a laminated core one, but I don't think that should give me too many problems. I'll keep it as far as possible from the rest of my hifi.
I reckon I can probably make a sort of Armegeddony clone for less than £20.

[blake]

Lots of info out there on the Armageddon clone and, based on my recent experience, I would say that chances are very high that you'll end up with a serious performance upgrade.

I have an older Gyrodec (Papst AC motor) with the original wall wart power supply and have toyed with buying a used QC Supply or changing to the newer DC motor and upgraded supply for years but we're talking serious money.

Harry Weisfeld from VPI recently suggested running tables with these older AC motors (Empires-one of which he owns-Lencos etc.) off a variac at the Vinyl Asylum so I ended up buying one of these:

http://www.kelinginc.net/VariableACOutputTransformer.html

for $50. Much less than the $500 or so for a used QC Supply or $1000 plus for a new DC motor and supply.

The results are pretty impressive. Different power situation over here in North America, but I start up at full power (120V) and then ramp down to 72V. The key, I think, to getting great results is being able to ramp down as much as possible to reduce motor vibration while at the same time maintaining proper RPM so that is something to consider. In other words, 72V is not even close to being enough voltage to get my turntable started. For maximum results, you are going to have to get the voltage much lower than that which is capable of getting the platter spinning from a dead stop.

In essence, I believe, power supplies like the Armageddon and VPI SDS primarily operate in the same way: starting up with full power and then ramping down considerably (considerably being the key word). I'm sure they do other things as well, but for $50, the variac has been a serious bang for the buck for me. I'm not saying a used QC supply would not be better, but I doubt it would be ten times better and the law of diminishing returns would really be at work.

Drawbacks are the variac is a bit ugly and you have an extra step involved in operation: namely adjusting the variac to reduce the voltage each time a record is played. At the same point in time, the variac is a fairly serious beast compared to many of the lesser name brand supplies, weighing in around 10 lbs. Also, no speed control ability like some of the more sophisticated commercial supplies-I still have to move the belt to the 45 RPM pulley on my table. Fortunately the design of the table makes that pretty easy.

[Dingdong]

Thanks for that. I think I will try running it at around 85-90v first just to see how it works. Then I might experiment with either putting a switch in to lower it or sticking a pot in to reduce it slowly.

[blake]

Thanks for that. I think I will try running it at around 85-90v first just to see how it works. Then I might experiment with either putting a switch in to lower it or sticking a pot in to reduce it slowly.

90V is probably a good starting (and possibly finishing) point. I know of someone who built an Armageddon clone and runs both an Ariston RD11 and Rega P3 with it at 90V and gets excellent results.

[Dingdong]

Got my caps in the post yesterday and started to hook it up. It was at this point I noticed that the cap in Thorens is actually .10Uf and not .33 as I've been reading on t'internet:doh:
Will be ordering a new cap then.

[DSJR]

Remember that the Thorens uses a very flexible belt (one of the dynamic wow "issues" so motor vibration may not be quite the issue that it is with, say, the "stiffer" belt of the Linn.

By the way, I think the Lingo runs the motor at 80V once the full-torque start-up is over and I think NAS run their motors at 50V from memory (the platters need a push to get them going :)). I remember the Armageddon giving the motor a silky-smooth feel if the pulley was held and manually rotated - no "cogging" - but the sound of the deck (90's ones anyway) seemed to return to the un-refined pre 80's sound, which maybe naimies preferred. The Cirkus redressed the balance from memory.

Just to say, don't tar the TD160 with the LP12 brush, as although related in concept, the dynamics of the whole thing are very different I reckon. You'd be better off with a Russ Collinson plinth, which not only makes the thing look tons better, it should improve the sound in a fundamental way as well, as the stock 160 plinth is little more than a frame to enclose everything..

Hope you don't mind my thoughts above - take it slow and obviously, have some fun with it.

[Dingdong]

Your comments are always welcome. I agree that the plinth is not the best in the world.
So far I've slapped a load of dynamat type stuff on the inside, changed the belt and oil and put a new base on it. Oh, and a Blue Horizon mat and Michell record clamp. The power supply was just an idea I had to see if I could make a really cheap upgrade. I reckon, going by comments I've read on Armegeddon clones, it should work.

[bobbasrah]

I would be quite interested in your experiment also Mark, as my old Thorens is due a makeover having been mothballed and travelling in storage for too long.
This poor old thing has been variously modified over the years ranging from platter chassis rubberised bitumen coating and bracing, frame glued to alloy plate, and once having the indignity of being embedded in concrete.
The casing is now shot so a hardwood DIY job is on the cards while a new belt gets delivered (pony express job here).
As you mentioned, the transformation/rectification/regeneration a la Lenco idea is theoretically a perfect solution, but in terms of practicality a bit of a sledgehammer/nut approach.
If the motor is 110v ac, it should be fairly simple to bypass the dropper resistor etc. and feed a more even voltage. I would need to source a new tranny here, so a toroidal looks likely in my own case, and possibly DC control/indication over power from the deck itself. Hmm, time to fire up Autocad 0.5 (pencil/paper)
Look forward to your update on this....

[Dingdong]

I've ordered the caps and a few resistors. I'll let you know how it goes.
If you fancy doing a bit of upgrading I'd recommend a decent mat (Blue Horizon) and a clamp. And maybe a decent arm or a rewire.

[bobbasrah]

Already been there Mark, having tried cutting and bevelling a 6mm annular glass ring and bedding it on Blutac to a very expensive canadian rubber mat all with some stunning and different effects. I still have the latter mat but it looks pretty shabby now, so I may revisit the situation.
The Decca/Hadock combo I used made the audible changes all the more peculiar I might add, particularly off the glass ring with all but the infamous sibilance improved dramatically.

The deck's bearing still feels remarkably smooth and free, but it had always been stored right way up, so I guess the lube is still intact.
Holding the deck upside down for a minute, the spindle stayed in place under suction even when pulling it away gently - I've a vague recollection of the mix containing Wynns or some such Teflon gearbox additive from 20 odd years ago. Quite effective, although I never checked the drag effect as the pitch sounded fine and the belt showed no strain effects.

I will be interested to see how accurately the LP speed turns out (my only need) at 110v then look at a a lesser running voltage, as motor vibration is reportedly reduced to good sonic effect elsewhere. I never noticed any vibes but worth a look during the refurb.
If I can figure out the difference in start and running voltage and notice any sonic improvement, I would have the PSU switch from high torque 110v start to the reduced voltage on a delayed relay.
The DC control switching can be done from the deck along with a natty blue LED run indicator to match the rest of the equipment indicators, but that is a cosmetic mod for the future.

Having spent so many years on the 24 and 16 bit digital side of the hobby, revisiting the analogue side will be interesting.

[bobbasrah]

What progress Mark?

[Dingdong]

Sorry, missed this. I'm still experimenting with resistors for each motor connection. Just replacing the cap has improved things a bit. Getting a cheap stethoscope from ebay to check on the motor noise.
Will report back soon with what I finally end up with. Or I could just bin the idea and get a TD125.