Separate power supply chassis- with a difference!

[SHiFTY]

I am building the loftin-white 6a3 SET amp as seen here,
mainly out of scavenged components. I have a 380-0-380 transformer, a dual 6V/3A transformer, and a 5V 2A transformer. As well as this, I will be using a 12V 300mA tranny for the 12SL7s i have.

To avoid giving myself serious back pain (!) and any hum problems, I was thinking about utilising a dual chassis arrangement, with a difference.

Would it be a good idea to have one large box that contains all the power transformers, and then a separate chassis with all the glassware, choke and o/ps on it? I have a nice new CV729 (5V4G) which I would like on the main amp chassis, rather than on the power supply.

That way, the power supply chassis would be indestructible, and could happily live on the ground as a footrest/footwarmer in a metal box..

Anyone done this? Am I crazy? How would I make an umbilical?

[Colt45]

I'd put the caps/rectifier/choke on the power supply chassis as well, if it were me. otherwise there is no real point to put the power trafos on a different chassis (other than the weight factor).

Just use an octal umbilical or something like that, I guess..

[Joel]

I agree... Why would you bother build a seperate PSU box, and then put the rectifier and filtering in the amplifier box?

[SY]

Because transformers radiate, unless they're shielded well or toroidal. E-Is put out a humungous field.

And because you can shorten the connection between the low-Z output of the supply and the feed to the amp.

[fdegrove]

Hi,

And because you can shorten the connection between the low-Z output of the supply and the feed to the amp.

And carry all the AC in an umbilical?

Wouldn't it be wiser to do the rectification in the PSU block?

Cheers,

[SY]

What, and carry all that ripply DC in the umbilical?

[Joel]

Originally posted by SY
Because transformers radiate, unless they're shielded well or toroidal. E-Is put out a humungous field.

That may be true Sy, but it's a non-issue from a practical point of view. I've never had transformer induced hum in any of my amps. A little planning is all that's required.

[analog_sa]

Your idea seems fine to me. If you have rectifiers and filter caps in the PS box a good star-earthing scheme becomes a nightmare. Especially if you have multiple plate transformers. Another plus is that not having capacitors in the PS box will really make construction and placement so much easier as you won't have to worry about microphonics at all. Having the rectifiers in the PS box as Frank suggested, will likely bring no degradation at all, but will deprive you of the pretty lights and will make PS physical construction more difficult.


cheers

peter

[misok]

sorry for resurrecting this 9 year mummy, but i'm just making 2 wooden boxes for a SET integrated and i have to finally consider my division line.. my point with separation of 2 mains transformers is to gain a little distance from signal circuitry, as well as eliminating possible vibrations because of quite microphonic 6n6p-s.

so where to cut - opinions doesn't seem united here. is it benefical to have B+ caps near the tubes? is it better to carry ripply AC or ripply DC or filtered DC in 0.5m cord ..?

thanks

[prairieboy]

Just an observation .... in the ham radio world, separate chassis were common, and they always seemed to put trannies/regulator/filter caps/chokes etc. on one chassis and everything else on the other. Of course, in many cases, they ran AC through the umbilical as well so they could put a power switch on the radio unit.