You could try an 833a amp
Wow!
The beauty ot this one seems to be that it doesn't need forced air cooling (at reasonable powers).
This thing can take as much grid current (75mA) than the usuals can take though their anode (plate).
I wonder what the Ra (Rp) is. I notice that the linked company makes OPT's with 30k primaries, so perhaps it's about 10k.
If this is the case, it might be difficult to equal the performance (other than power) of the commoner 211, 845, 572 etc, without very special attention to transformer design.
Thanks for the link!
Wow!
The beauty ot this one seems to be that it doesn't need forced air cooling (at reasonable powers).
This thing can take as much grid current (75mA) than the usuals can take though their anode (plate).
I wonder what the Ra (Rp) is. I notice that the linked company makes OPT's with 30k primaries, so perhaps it's about 10k.
If this is the case, it might be difficult to equal the performance (other than power) of the commoner 211, 845, 572 etc, without very special attention to transformer design.
Thanks for the link!
833A
Look at Lancroft tramsformers site. They have trannies, and at least 2 designs for the beast there. Supplies are up in the 1500V+ range which makes it a heck of an expensive amp on parts.
http://www.users.bigpond.com/triode/833A1.html
Then there's always the GM70, which AudioXpress has an article on about a year ago, and iirc, it was 30W. They are $US50 new from KW Tubes (he's on holidays till end of July).
http://kwtubes.s5.com/
Or the GM100. Now this is a man size tube. Almost literally.
http://www.vt52.com/diy/myprojects/amps/gm100/gm100.htm
Makes the 833A look like a pokemon
Look at Lancroft tramsformers site. They have trannies, and at least 2 designs for the beast there. Supplies are up in the 1500V+ range which makes it a heck of an expensive amp on parts.
http://www.users.bigpond.com/triode/833A1.html
Then there's always the GM70, which AudioXpress has an article on about a year ago, and iirc, it was 30W. They are $US50 new from KW Tubes (he's on holidays till end of July).
http://kwtubes.s5.com/
Or the GM100. Now this is a man size tube. Almost literally.
http://www.vt52.com/diy/myprojects/amps/gm100/gm100.htm
Makes the 833A look like a pokemon
Attachments
GM70
Let the boasting about size end here!
Yes I know and love the GM70. I'm currently building an SE amp that will run with 845's or GM70's.
The trouble with these biggun's is the heater power. Makes hum reduction a "non trivial" problem in SE. Still, it's lucky my speakers are not too efficient.
Let the boasting about size end here!
Yes I know and love the GM70. I'm currently building an SE amp that will run with 845's or GM70's.
The trouble with these biggun's is the heater power. Makes hum reduction a "non trivial" problem in SE. Still, it's lucky my speakers are not too efficient.
Take a look at this:
http://www.expresslighting.com/eltran24.html
An 11.6V/5A@>20khz version was posted on the TubeDIY Asylum, by Par.
I haven't tried 'em yet (probably have to choke filter the output switching noise), but hum should be non-existant with ultrasonic AC heating. And you could throttle/trim the output voltage with a dimmer.
http://www.expresslighting.com/eltran24.html
An 11.6V/5A@>20khz version was posted on the TubeDIY Asylum, by Par.
I haven't tried 'em yet (probably have to choke filter the output switching noise), but hum should be non-existant with ultrasonic AC heating. And you could throttle/trim the output voltage with a dimmer.
Re: GM70
My transmitter tubes are not compensating for anything. <i>Really</i> they're not. I'm going to build a 6S45 spud amp just to prove it.
I'm going to use either DC current source heaters in the 813PP (10V, 5A each) or high frequency regenerated linear supplies. The lighting controller is a nice turn-key idea, but I wonder how much RF garbage will end up in the amp (DHTs remember) or put out into the mains. Think of what the average household LV dimmer can do, and these are designed for a much less sensitive environment. However Par is usually pretty good, so....
HF AC heaters were also discussed on Tube -DIY a bit recently.
Cheers
dhaen said:
My transmitter tubes are not compensating for anything. <i>Really</i> they're not. I'm going to build a 6S45 spud amp just to prove it.
I'm going to use either DC current source heaters in the 813PP (10V, 5A each) or high frequency regenerated linear supplies. The lighting controller is a nice turn-key idea, but I wonder how much RF garbage will end up in the amp (DHTs remember) or put out into the mains. Think of what the average household LV dimmer can do, and these are designed for a much less sensitive environment. However Par is usually pretty good, so....
HF AC heaters were also discussed on Tube -DIY a bit recently.
Cheers
VT52.com
I ordered some valves (tubes) from Jim de Korts other company http://www.triodes.nl/.
After 2 months and many emails (mostly mine), they eventually turned up.
I do not know who's fault the delay was, but it was not delayed in the UK because the package had a Dutch postmark of 2 days previous.
Those are the facts.
I ordered some valves (tubes) from Jim de Korts other company http://www.triodes.nl/.
After 2 months and many emails (mostly mine), they eventually turned up.
I do not know who's fault the delay was, but it was not delayed in the UK because the package had a Dutch postmark of 2 days previous.
Those are the facts.
Hi Bas,
I'm still waiting for clarification from AE about frequency reponse and shipping.
Have been in touch with Triode Dick, who gives a glowing report on the AE product, so as soon as I get clarification I shall order from them: OPT's and driver transf..
Thanks again for the recommendation, I'll pass it on once I have first hand experience.
dhaen AKA JD
I'm still waiting for clarification from AE about frequency reponse and shipping.
Have been in touch with Triode Dick, who gives a glowing report on the AE product, so as soon as I get clarification I shall order from them: OPT's and driver transf..
Thanks again for the recommendation, I'll pass it on once I have first hand experience.
dhaen AKA JD
steve jones said:
Have you ever looked at the output waveform of one of these?
I looked at one a couple of years ago (that was causing interference). That one's waveform looked like 20KHz (ish) square wave - modulated between 0 and 100% by 100Hz.
Now I don't know whether they all use the same principle, but this one just looked like a bridge rectifier into an oscillator and a ferrite transformer.
If they are all the same, it's a no-go'er.
BTW I would love to be proved wrong on this one!
, Dave ..
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