Suitable parts for Technics SL1200 TT ext psu

[eldarvanyar]

Hi Guys,

I would like to build an external psu for a Technics SL1200 TT.

My question is if I buy a toroidal Transformer 230v 30v to use

Details of one I have seen

The primary winding is 230V, secondaries are as follows:
2 of 30V 5A
1 of 12V 2A

This gives 300VA at 30V and 24VA at 12V. Perhaps good for a power supply where you need an auxiliary 12V supply?

Other spec:
Weight, 3.11kg
Diameter, 120mm (not including cables)
Height, 60mm


Would this regulator be suitable. I have copied the details here


July-19th, 2013 Revised:
Upgrade electrolytic capacitors to Rubycon brand.

This item has been assembled, and electrical test passed.
5 Amps voltage regulator module, based on National Semiconductor LM338T regulator IC design, AC or DC input, DC output, output voltage LED indicator.

Used high-quality electronic components:
Thickness 1.6mm FR-4 fiber glass PCB (double layer).
HQ terminal blocks easy connection wire.
RUBYCON 4700uF/50V input and output filter capacitors, 100nF/100V metal film capacitors, conducive to filtering high-frequency noise.
Precision multiturn(28+-3 turns) trimming potentiometer adjust output voltage.

LM338T IC Datasheet: Not Found
Module Specification: http://www.audiowind.com/pdf/A-210.pdf, No paper specifications, please download this document.

Input voltageC 4 - 35V, or AC 4 - 26V.
Output adjustable range: 1.5 - 32V DC.
Maximum continuous output current: 5 Amps.
Module size: 80 x 76.2 x 55 mm (L x W x H)
3.15 x 3 x 2.2 inch (L x W x H)

It’s just over £60 for both of these plus a suitable bid to put it in which is a lot cheaper than many of the commercial box’s. Any advice or help much appreciated.

😀

 

[6L6]

I'd suggest using the stock Technics transformer.

The improvement in sound from an external PSU is much, much more about removing the transformer from the TT chassis than anything else. Then having clean DC on an umbilical instead of Mains AC.

In the case of a PSU, a toroidal is actually a worse choice than an EI, as the toroid is much more efficient at coupling all the noise, hash, noise, and general yuckyness on the mains to the audio circuit.

Technics SL-1200 DC Power Supply

 

[eldarvanyar]

Thanks for your reply, which is very helpful. Could you please educate me why most modern hifi amps etc go down the toroidal route and not the EI or R Core route. Is it down to cost?

Also does the regulator screen out a lot of the mush or noise? Or, does it just bring the voltage down and keep it that way? Would this regulator be an inprovment on the stock one?

Really appreciate your input.

 

[6L6]

From what I understand, torodial transformers are cheaper to produce, and more efficient for a given size.

Changing the regulator is a very small improvement compared to getting the transformer and the mains AC out of the chassis. It's worth doing, but that is not where the big improvements to the TT are to be found. Also the 338 is much bigger than you need, generally speaking regulators work better when they have a bit of load.

I'm a huge fan of the -1200, with just a few easy changes it builds on it rhythm, drive, power, precision and accuracy, shakes away the slight 'darkness' that is attributed it in it's stock form, and turns it into the most musical, soulful, and smile-inducing music machine - it's a wonderful TT, a few mods and it is as good as anything out there.

(Which are, in a nutshell; mat, feet, PSU, and if a Mk2, tonearm wire)

 

[JZatopa]

One other idea, though I haven't tried it myself, is to replace the transformer with a SMPS.

 

[6L6]

Sure! Completely worth a try.

 

[kodabmx]

Here's a Canadian take on why toroidal transformers are superior:
http://www.bryston.com/PDF/newsletters/Bryston_Newsletter_V8_4.pdf
http://www.bryston.com/PDF/newsletters/Bryston_Newsletter_V8_5.pdf