simple tube psu

[ioaudio]

this psu should feed two bottles (heaters 6,3v at 300ma+200ma=500ma)
ht unregulated
48v via voltage doubler/zener regulated.

did i miss something?

 

[Greg]

I've only built one piece of gear with tubes, and it was an LA-2A, and the 6.3V went to the heaters, but it was AC, not DC. I don't know that much about valves, so maybe some heaters want DC.

 

[ioaudio]

most (all?) tubes can be heated with either ac or dc, doesnt matter (Except hum issues)

i wonder if 15 va transformers would suit here.

 

[rodabod]

[quote author="Greg"]I don't know that much about valves, so maybe some heaters want DC.[/quote]

It's quieter to run them at DC if you think about it.

 

[moamps]

[quote author="ioaudio"]
did i miss something?[/quote]
Hi,
The sch looks good.
But, you should be carefull with the ground connection; you can't connect -point of the heaters PS to the ground and also the heater can't be elevated to the higher potential.

Regards,
Milan

 

[ioaudio]

thanks moamps,

what about referencing the 48v ground at the input xlr pin1?

regards, max

 

[moamps]

Of course. Phantom power must be referenced to the audio ground (pin 1).

 

[PRR]

> did i miss something?

The heater supply is probably the largest load, yet this is very inefficient.

You take only one of the two 12VAC windings, rectifiy to 17VDC, and then waste 2/3rd of your power in a regulator.

Low-volt regulated supplies ARE inefficient, but this might be rather a lot of heat.

 

[ioaudio]

[quote author="PRR"]Low-volt regulated supplies ARE inefficient, but this might be rather a lot of heat.[/quote]

yes, i know, but there must be one disadvantage feeding all three voltages from this two transformers...

hmm. this supply is supposed to power a mic pre with pentode (6,3v) and a triode (6,3v or 12,6v), so i could use another regulator for 12v and heat the ecc in series...?

 

[pstamler]

Only if the current draws of the two tubes are the same at 6.3V -- not only on the spec sheet, but for real.

Peace,
Paul

 

[ioaudio]

my english...
i didnt mean to take the heaters in series, but to heat the two bottles seperated ( pentode with 6,3v and triode with 12v) via two regulators.

 

[ioaudio]

ok, i powered up, everythings fine. also tryed using a 9v:220v transformer for getting higher ht voltage.

i´ll stick with one heater voltage for 6,3 volts, seems to work fine with lm317, about 4watts of heat are manageable with a heat sink. but i think its really suited for two bottles only.

regards, max

 

[CJ]

I always thoght that voltage doulblers should be restricted to cheap TV sets, but what the heck.

Buying the right transformer is the correct solution for minimum parts count in a power supply.

You guys should pester a few companies. I bet they would be glad to make a 6.3
48
and
250 volter.

And I know of at least 50 MB of server space could be saved on posts related to 48 volts dc.

 

[ioaudio]

[quote author="CJ"]You guys should pester a few companies. I bet they would be glad to make a 6.3
48
and
250 volter.

And I know of at least 50 MB of server space could be saved on posts related to 48 volts dc.[/quote]

i was really trying. but no one would make me an offer below 40-50 euro. this one´s really cheap.

 

[tk@halmi]

There is nothing wrong with diode multipliers. Phantom requirements are very simple. The fact that decent microphone outputs and half-decent preamp inputs have excellent comon mode rejection is sometimes overlooked.

 

[JanW]

CJ wrote:
You guys should pester a few companies. I bet they would be glad to make a 6.3
48
and
250 volter.

And I know of at least 50 MB of server space could be saved on posts related to 48 volts dc.


i was really trying. but no one would make me an offer below 40-50 euro. this one´s really cheap.

In Germany you can buy a transformer for 21euro with pri : 230V , sec: 230V/20V/6,3V
from www.die-wuestens.de/eindex.htm
I think you can get 48V easy from the 20V... and it is maybe cheaper than two transformers. I think they will ship to austria..
:guinness:

 

[ioaudio]

[quote author="JanW"]In Germany you can buy a transformer for 21euro with pri : 230V , sec: 230V/20V/6,3V
from www.die-wuestens.de/eindex.htm [/quote]

i build some projects with such (recycled from old wheel-to-wheels) but when it comes to micpre´s (especially in smaller housings) i prefer using toroids.

aside from that i always had troubles getting 6,3v dc from the 6,3v ac windings. when the transformer was oversized, i managed getting about 6v dc, sometimes less.

now, after some days of testing i am very pleased with this psu, maybe its a bit waste of power, but then a tube amp is a bit waste of power...