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Old 8th December 2003, 04:08 AM   #1
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Default 6C45 211 Amp

I am thinking of building a new amp, something single ended.

What about a nice simple amp, 6C45 driving a 211?

Can I set the amp up with a 6C45 Cascade into the 211, with both driver and output having a grounded cathode with bypass cap?

Also can I use the same power B+ power for the 211, then a huge resistor before the 6C45? ie 1000v for the 211, about 190v for the 6C45?

Finally, where do I get 1000v capacitors??


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Old 8th December 2003, 06:51 AM   #2
dhaen is offline dhaen  Europe
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Default Sorry for the negativity...

Because of it's high Miller capacitance, you really need a low Z driver fir the 211. That is not really practical with a single supply arrangement, unless you waste 100's of watts.
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Old 8th December 2003, 07:14 AM   #3
agent.5 is offline agent.5  United States
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Use Gary Pimm's CCS to load the driver. For most drivers, you probably need separate power supplies for the driver and the output tubes, because of the difference in B+ requirement. But there are pentodes that can take some serious H+.


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Old 8th December 2003, 07:50 AM   #4
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Location: North Herts, UK
Hi Adam,

Stefano Perugini has a nice account of his design for just such an amplifier.6C45 into 211 .

I would drive it with 6C45s in PP like my 845SE amplifier shown here 6c45 pp it 845 . With the 211 replacing the 845. The bipolar psu allows one to use 'normal' ratings for caps etc. and helps reduce the chance for a full 1000V shock. Note: It doesn't remove the potential for a 1000V shock!

Hope this helps.


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Old 8th December 2003, 02:46 PM   #5
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Location: New Hampshire
Default 6C45 --> 211

I've build a 6C45 --> 211 based in no small part on Stefano Perugini's design.

I used a very different power supply, and run the 211's at a lower b+. My operating point is 825vdc/60ma for around 8wpc. More than enough for my Altec A-5's.

I used an old Acrosound power transformer (TP550), and 866jr's for the B+. I have a digital delay that pre-heats the mercury rectifier filaments before the B+ is supplied. I then use a damper diode for slow turn-on. I use a 5Y3 indirectly heated variant (Bendix 6106) for the 6C45 B+. Filter caps on the HV are vintage oil, output transformers are Magnequest FS-100's. Chokes for the 6C45 are also from Magnequest.

Click the image to open in full size.

I'm very pleased with the outcome.

A few caveats. The 6C45 likes to go RF, use ferrite beads on the filament leads, and a small carbon composition resistor (around 1K) as a grid-stopper.

Also, don't plan on moving your amp around often. I ended up around 80 pounds!

There are a few more pictures at http://www.the-planet.org/nnetg.html
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Old 22nd July 2011, 07:20 PM   #6
codyzox is offline codyzox  Serbia
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Greetings dude and to all...I am looking for low powered 211 tube rectified project to run my altecs and we speakers! I have interest in Your project. Can you please post shematics, part list and instructions, if You have will to share Your project with rest of world...Which 6C45 You use, i heard bad things about new Sovtek production, that in uper region sounds "metallic" somehow, is it truth, what is Your opinion? OPT in my case would be lundahl ll1620 (which current value is best in Your opinion to choose for this project?), also, is it possible to create direct coupled version or with Lundahl interstage trans instead of capacitor coupled??? Thanks...Any leads to similar concept beside this one welcomed!

Last edited by codyzox; 22nd July 2011 at 07:43 PM.
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