SL-1200 DC Power Supply DIY

[golana]

Wow! I don't know wether to thank you or be mad. This opens a whole can of worms I've been planning.
What are your plans for the regulator? Super job!

[6L6]

Mike - Thank me. I like single malt...

What is the can of worms you mention? Maybe a plan of some sort can be devised.

As for regulator I will do a LM317 first, (as I have all the bits on hand) and then likely something discrete like a Dexa UWB.

[golana]

First purchased my 1200M3D, about 5 or 6 years ago. It came to me newer, but with scratches and a small gouge on top.
I've done wires, gel trough, and TA mods, I've been wanting to do PS, and this looks like the time. Can of worms are bearing
and refinishing the top of the plinth. Money and time consuming. Don't get near Single Malts much, but love a good bourbon.

[6L6]

I have had a chance to listen to the turntable enough in the last few days for the sound of the modification to make itself apparent - there is no doubt that the noise floor is lowered, the background is blacker, and the entire presentation is cleaner. But that is the sound...

The startling thing is the musicality - after the mod it is much more difficult to listen to the turntable objectively... I sit down wanting to figure out what the differences sound like, and find myself needing to get up and pick the needle out of the run-out groove after listening to a really great side of an album.

I've done plenty of builds and modifications to lots of equipment over the years. In general the ones where the sonic differences are very obvious are actually not a step forward, although they might sound good. Usually the beneficial mods sound pretty relaxed, in a good way. Nothing stands out. (Although a circuit or the like getting quieter is always beneficial.) The real gains are noticed when you get wonderfully distracted by the music.

Musically this mod is fantastic.

I am not very far into the modification process of the Technics, but I'm quite pleased with how much gain can be made to such a competent deck. It's DNA is pure, and I am very interested into seeing where this adventure leads.

[MartinT]

Now you're starting to hear what the Technics is capable of, Jim. Insight and Musicality are both to be had in spades.

[Frankyc2003]

Good evening everyone,

I am putting together 6L6's design with a new traffo...

The one I got is rated at 100VA - 30V x 2
this one from Farnell
RK100/30 - BLOCK - TRANSFORMER, 100VA, 2 X 30V | Farnell United Kingdom

When connected to the mains (230V in UK), instead of 30VDC at the output of the capacitor's bank, I get around 44.5VDC?


I have tried with the secondaries in parallel, and with just a single secondary...

Same result...

Am I missing something?
(Please don't be too harsh in case I did, as it is my first serious foray into PSUs.)

Thanks for your enlightened help everyone!

Cheers

Francois

[MartinT]

Hi Francois, the DC voltage resulting from bridge (full wave) rectified and smoothed AC is sqrt(2) x VAC, so you would expect 30VAC x 1.414 = 42.4VDC. Now allow for the fact that the PSU is essentially unloaded (the transformer spec would be for fully loaded) and 44.5VDC is as expected.

[Canetoad]

The rectification to DC increases the voltage by a factor of about 1.4. I can't tell you exactly why this is but, perhaps, somebody with an electronics background could.

[Frankyc2003]

Cheers Martin and Bernie,
Indeed, it does make sense now... And I should have revised my theory...

https://en.wikipedia.org/wiki/Rectif..._rectification

[Canetoad]

Hi Francois, the DC voltage resulting from bridge (full wave) rectified and smoothed AC is sqrt(2) x VAC, so you would expect 30VAC x 1.414 = 42.4VDC. Now allow for the fact that the PSU is essentially unloaded (the transformer spec would be for fully loaded) and 44.5VDC is as expected.

There you go!