6Y6GT/6922 Bias supply and anode load CCS

Posted by jyourison (A) on March 28, 2015 at 11:31:35

In Reply to: A 6Y6GT/6922 P-P Amp with MOSFET Concertina Splitter posted by jyourison on March 28, 2015 at 10:32:15:

Here are the bias supply and anode load CCS as built. I used twelve turn cermet pots from Mouser (1/2 watt is fine), and they give just enough control when using a screwdriver to adjust to the third digit on my DMMs.

The bias supply is a tripler using a handy, cheap Radio Shack transformer. The tripler topology is slightly sensitive to the value of the capacitance -- more capacitance will keep the voltage losses down to some degree. The 4K and 10K Ohm fixed resistors put the pots in the middle of the desired bias range. Watch the polarity of the caps, and be sure to ground the supply loop.

The idea is to attain a good bias point for each 6Y6GT tube that also provides a current match across the cathode resistors. Those resistors should be matched per tube pair and be spot on 10 Ohms for ease of math conversion from Volts to mA. (E.g., a 0.07 Volt reading means 7 mA, since I = E/R, and 7 mA = .07/10)

Of the four 6Y6GTs I started with, the final bias point for three of them in nearly the same, while one needs almost an extra 0.5V. It's nice to have a granular level of adjustment. I'm not sure one would hear that level of mismatch, but I haven't played with that at all on the bench.

The CCS is modeled after the LTP in Eli's El Cheapo, but built for anode use.

At least the "top" MOSFET in the CCS should have a small heatsink attached. Same for the phase splitter IRFBC20s. I have a small sink on all the MOSFETs, mainly to keep it all cool in the final casing up.

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Follow Ups Full Thread

Topic - A 6Y6GT/6922 P-P Amp with MOSFET Concertina Splitter - jyourison 10:32:15 03/28/15 (26)

6Y6GT - FenderLover 06:55:02 03/30/15 (3)

RE: 6Y6GT - jyourison 10:55:28 03/30/15 (2)

6Y6G coke bottles - FenderLover 06:48:44 03/31/15 (1)

RE: 6Y6G coke bottles - jyourison 07:34:41 03/31/15 (0)

RE: A 6Y6GT/6922 P-P Amp with MOSFET Concertina Splitter - drlowmu 22:57:04 03/28/15 (2)

RE: A 6Y6GT/6922 P-P Amp with MOSFET Concertina Splitter - Eli Duttman 08:08:14 03/29/15 (0)

RE: A 6Y6GT/6922 P-P Amp with MOSFET Concertina Splitter - jyourison 06:49:48 03/29/15 (0)

6Y6GT/6922 Link to larger schematics and PDF file - jyourison 11:52:01 03/28/15 (14)

RE: 6Y6GT/6922 Link to larger schematics and PDF file - jyourison 12:06:26 05/14/15 (0)

RE: 6Y6GT/6922 Link to larger schematics and PDF file - Tom Bavis 11:00:33 03/30/15 (12)

Results with lower current in the 6922 (6.5mA) - jyourison 21:17:46 03/30/15 (0)

Could you expand on this statement? - jyourison 14:04:40 03/30/15 (4)

RE: Could you expand on this statement? - Eli Duttman 17:09:31 03/30/15 (3)

RE: Could you expand on this statement? - jyourison 17:37:13 04/01/15 (2)

RE: Could you expand on this statement? - Eli Duttman 19:02:16 04/01/15 (1)

RE: Could you expand on this statement? - jyourison 20:16:46 04/01/15 (0)

RE: 6Y6GT/6922 Link to larger schematics and PDF file - Eli Duttman 13:05:43 03/30/15 (5)

I plumb forgot the larger decoupling capacitors on the schematic - jyourison 14:21:58 03/31/15 (0)

Effects of Source to Ground adjustment - jyourison 14:32:43 03/30/15 (3)

RE: Effects of Source to Ground adjustment - Eli Duttman 17:15:10 03/30/15 (2)

Reduced 6922 Current (6.5 mA) results are good! - jyourison 21:05:11 03/30/15 (1)

RE: Reduced 6922 Current (6.5 mA) results are good! - Eli Duttman 08:12:53 03/31/15 (0)

6Y6GT/6922 Bias supply and anode load CCS - jyourison 11:31:35 03/28/15 (0)

6Y6GT/6922 Power Supply Option 2 - jyourison 11:09:41 03/28/15 (0)

6Y6GT/6922 Power Supply Option 1 - jyourison 10:59:02 03/28/15 (0)

6Y6GT/6922 Amp Channel - jyourison 10:42:05 03/28/15 (0)

Follow Ups

6Y6GT/6922 Bias supply and anode load CCS - jyourison 11:31:35 03/28/15 (0)

6Y6GT/6922 Bias supply and anode load CCS

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