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-   -   stereo push pull amp one heater supply for power tubes (http://www.diyaudio.com/forums/tubes-valves/95559-stereo-push-pull-amp-one-heater-supply-power-tubes.html)

nhuwar 2nd February 2007 09:35 PM

stereo push pull amp one heater supply for power tubes
 
Has anyone ever encountered a problem with using 1 power supply for there stereo push pull amp output tube's heaters.

Nick

Wavebourn 2nd February 2007 09:54 PM

Re: stereo push pull amp one heater supply for power tubes
 
Quote:

Originally posted by nhuwar
Has anyone ever encountered a problem with using 1 power supply for there stereo push pull amp output tube's heaters.

Nick

No. Why?

nhuwar 2nd February 2007 10:30 PM

ok just checking

Nick

frank754 2nd February 2007 11:12 PM

My impression, and I'm no expert here, is that as long as all your tubes' filaments combined don't exceed the amp rating of the transformer's heater supply, you should be ok. On the pre-amp sensitive stages, though, some people prefer DC, or some sort of hum-bucking circuit, as that's where you are likely to pick up more noise.
If you do have a larger circuit pull, I would get a separate trafo for just the power tube filaments.

On the other hand, my question would be that if you were making a 2-channel (stereo) unit, would it be better (considering that you have all bases covered for the filaments) to get a huge 200-300 ma HV secondary xfmr for the HV, or better off and more economical to use a separate one for each channel, thus perhaps also avoiding the extra heater supply.

If you do use a bigger one, can you get by with just one choke and dual electrolytic caps, etc., for the HV to both channels if you have enough ma to start with?

ray_moth 2nd February 2007 11:52 PM

It has been said that a separate heater transformer is a good idea. Of course, you might need more than one heater winding if you have some tubes with elevated cathodes (e.g. in direct-coulped stages), so you can bias their heaters above ground to avoid exceeding cathode-heater voltage limits. Separate heater circuits for left and right channels is unnecessary - unless you're talking directly heated tubes, which is a whole 'nother story.

nhuwar 3rd February 2007 02:32 AM

Well I think i will use 2 separate supplies luckly i've got a huge filament transformer that will put out 10 volt and it has 2 secondary's wound with square copper wire thats about 2 by 2 milimeters it's a monster.
I know that it's not normal to do this but I'm going to try runnig it wit a half wave rectifier into a 42000 mfd cap that should keep it fairly clean I think.
If I get hum though I will throw 2 more rec's on it.
I just dont want to put 2 of these transformers in the amp, there heavey like a 6" cube of metal thing weights about 25 pounds.


Nick


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