who needs 2 killewatts for passive subAwesome. Congratulations. It's been fun following your build process.
So.... What's next? 2x 833 in push-pull? Because, clearly, 200 W SET is not enough.
~Tom
Open baffle on mids and highs. Sealed cabinet with two 10" woofers in series for the bass.
PS: Still planning to do YouTube but had a delay due to unavoidable factors. Soon.
It's all in this thread already. Amp schematic, power supplies, component values, etc.
Thanks for sharing the power draw - its much less power consumption then I had imagined.
I wonder if you can offer any advice on the idea of doing a similar build but minus the output transformers for direct driving electrostatics with 3kV of DHT goodness. Do you think the build would be any easier and cheaper going OTL?
It would certainly be cheaper; the OPTs cost $2500 each! You'd need to add another series PS cap or two and series rectifier diode to handle 3kV, a higher voltage power transformer (or cap input supply) and be sure your wire, chokes, etc. can handle the voltage.
As always, this thread is not to be seen as an endorsement of anyone playing with HV willy-nilly. There is a real danger of death if all precautions are not taken.
I recall someone posting about directly driving e-stats with high voltage, but exactly where I saw it I can't say...maybe do a search here?
As always, this thread is not to be seen as an endorsement of anyone playing with HV willy-nilly. There is a real danger of death if all precautions are not taken.
I recall someone posting about directly driving e-stats with high voltage, but exactly where I saw it I can't say...maybe do a search here?
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holy crap, that IS a midlife crisis. Actually, a midlife crisis is less expensive. I knew this was an expensive set of amps, but I had no idea.
Try this handbook from bunkerofdoom.com
It's 268MB PDF, but in the power supply section there are tube regulators for low and high voltages. The HV ones are 'only' for 1200 and 2000V, but are easily adaptable to any voltage and current and illustrate the techniques involved. If +/-10V regulation over a 0-240mA current variation is OK. If it's not enough current, just add more tubes in parallel.
Since you only have to make up a small amount of voltage, anything will do if it is properly insulated. -or - put it 'under' the B- of the existing power transformer's rectifier. If you only need +/-50V, it's super simple.
http://bunkerofdoom.com/kb/goth/AGH-AM-027p.pdf
Great to know for future builds! Given that the Hammond 733A multiplies the line voltage by 21X, a sag or surge in the line of 10V would correspond to a change in B+ of +/-210V, quite a bit more than 50V.
Currently, I'm simply regulating the AC line voltage to the amps at 117VAC (the voltage rating of the 733A) using two AC regenerators. The bias is rock solid this way. I also get surge protection, DC rejection and line noise reduction out of the regenerators as a bonus.
I saw and heard it live at the European Triode Festival a few years ago. Scary, but it sounded great.
Thanks. Regarding the Youtube video...it's on hold after one of the Pyrex cylinders around the tube developed a crack - talking with the supplier, Greatglas, located in Delaware, they say that can happen occasionally when stresses develop from the holes being drilled in them.
They offered to replace it free of charge (great service!), so I sent it off to them last night. This time they will melt the holes in the glass instead of drilling them, and that should avoid any stresses being developed.
Here's a pic of the crack. Obviously I didn't want to run the amps like that and risk the glass shattering from the thermal cycling.
They offered to replace it free of charge (great service!), so I sent it off to them last night. This time they will melt the holes in the glass instead of drilling them, and that should avoid any stresses being developed.
Here's a pic of the crack. Obviously I didn't want to run the amps like that and risk the glass shattering from the thermal cycling.
Attachments
Bummer about the crack. Glad they're going to replace it (might as well do both).
The dog doesn't look too upset about it though. He's just monitoring the situation making sure you don't hurt yourself.
You do realize he's actually an alien and all of your activities are being reported back to the mother ship don't you?
The dog doesn't look too upset about it though. He's just monitoring the situation making sure you don't hurt yourself.
You do realize he's actually an alien and all of your activities are being reported back to the mother ship don't you?
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