Aleph L PSU and 50V secondaries

[Stabist]

I just wonder - original AL has trannie with 60V secondaries - that gives around 85V after CRC filtering and before stack of 9V1 zeners - but I have a 50V trannie at hand - so I'll have "only" around 65-70V after CRC ...
But that should be still enough for desired 60V or is there some other catch and I'll have to recalculate some more values???

[wuffwaff]

Hi,

50V will be a bit low. You loose voltage in the bridges and because of the Vgs of the fet. Then you still need some margin to regulate the voltage.
What you could do is to go for 55V regulated, the amp will work fine this way.

William

[steenoe]

so I'll have "only" around 65-70V after CRC ...

Thats a bit too close to the regulated voltage, as your main supply (The 220v) will drift at least +/- 10%. Just swap out one 9,1v zener with a, say 4v or there about, and you should be fine.
A starving Zenerstring is not supposed to sound pretty

Steen

BTW. To be sure you dont starve the Zener value, you could just jumper one of them. That would net you some 50V supplies.

[Stabist]

55V idea sounds great

Thanks to both for tips!

Probably I'll do as steenoe sugested - I'll replace one 9V1 zener with 4V one and so get 55V - and then see what will I get out and if there are any major corrections needed in preamp circuitry ...

THANKS again!

[steenoe]

Probably I'll do as steenoe sugested - I'll replace one 9V1 zener with 4V one and so get 55V - and then see what will I get out and if there are any major corrections needed in preamp circuitry ...

If your mains supply is steady enough, that should do the trick If not, jumper the 4V Zener

Steen

[Stabist]

Well, I'll see what will be put together in this chassis afterall - original idea was the MiniA + BoZ - so that's why 50V secondaries ....

But in last days I'm thinking of making p2p AL instead ...

Btw - which solution should be better - more simple is to put trannie at the back, than PSU caps and preamp on the front panel - so pot is mounted directly to front plate, etc .... But then again - if trannie at the back - it's probably too close to RCA connectors, etc??? BUT OK, the trannie itself has a shield!

Any ideas or even better - experiences with possible troubles when trannie is mounted at the back ???

[Stabist]

So this is "another version"

[Stabist]

The copper is added to improve a bit heatsink's thickness ... They have only 5mm thick "meat" ...

[Stabist]

The finnal look will be - heatsinks silver (I've got them as 2nd hand and were allready eloxated in sliver ...) and the rest black ...

Not so OK considering heat dissipation - but for MiniA I think more than enough ...

Btw - I plan to have +/-15 to 16V (trannie is 12V) and around 1,4A bias - I need highest power at 5R - and those are the numbers that suits me fine ...

[Stabist]

Hi,

I just wonder - the PSU for AL - "the bottom half" in the schematic - that is one irf 610 and irf 9610, relay and some resistors is there only because of that relay? I don't intend to use delay - so I can easilly left the whole thing out.

Btw - would AL make any thumps during powering ON or why was that relay implemented??