6K6 Reverb Driver Issue

[W5FH]

I just finished a 50 watt "Wonderland" build based on the information on The Tone Geek's site for the "Fairfield County Signature". Mine is point to point on SR size chassis. The amp is working fine except for the reverb drive to the 8 ohm tank. During my study on this amp I read a number of comments stating the reverb level was low to some player's tastes. I built this amp carbon-copy of write-up, matched all voltage nodes, EXCEPT I made these changes:
1. Used 6K6GT for V3 reverb tank driver with 1K cathode R, bypassed with 20 uFd and 300 vdc to transf pri.
2. Used Edcor CXSE5-7K-8 driver transf (5 watt, 7K pri, 8 ohm sec)
3. Used 250KA pot for R-31 (dwell control) to get a little more drive to 6K6
I did use mixer resistor values of 68K for R-27 and 120K for R-42 as shown in this particular version.
I had the Fender outboard reverb circuit with 6K6 in my mind as a solution to get more tank drive. Dumb me did not realize that the 6K6GT with 22 vdc on cathode would be harder to drive than parallel 12AT7. My drive from 6K6GT to the 4AB3C1B tank is low. Am using NOS RCA and tried other good 6K6's. The recovery portion of reverb is OK, when I tap on the tank a little I get a loud response. The amp appears to me to need more tank drive from sound.
I connected an 8 ohm speaker in place of pan and listened to tone from audio gen into amp. With the Send control (Dwell) at 100% and a 0.1 volt RMS 1 khz signal feeding in I could barely hear the tone until I got to around 4 on preamp volume control. Had to back master volume way back as the amp is loud. Played with tone controls to observe effects on reverb sound/level. The fact of the matter is that playing tests indicate drive to pan is low.
I am wanting to avoid pulling Edcor transf and octal socket. Also thought about increasing gain of V2-A stage but trying to avoid changing the amp circuit. Am considering other octal tubes that have less drive requirement. Plus, I don't relish having all the heat from more plate current flow as I lower cathode R; plus only 5 watt transf. I did try a 6V6 with 470 ohm cathode R and same 300 vdc to transf pri. Was only minor improvement with 19-20 volts on cathode.
Am considering rewiring octal socket to use a triodes-paralleled 6SN7GTB going into same Edcor transf. I studied a headphone amplifier circuit that used the 6SN7 paralleled however it states the correct transf pri imp should be 12K at 300 vdc. I am wanting to try this with 7K transf and suspect loss of bass but in this case it should not matter too much, but is there other issues with the mis-match? In this circuit there will be 9.2 VDC on cathode and should be easier to drive.
I am open to suggestions. Have been studying various octal tubes that may work here before I change out transf and patch in 9 pin socket.
Thanks,
Byron W5FH

[lonote]

Pretty interesting project.

Looking at the schematic, & a disclaimer that I am not an expert, it looks to me like you are shunting a good bit of signal to ground, right at the 6K6 grid with only a 250K dwell pot.

I have built a 6G15 w/a 6K6 driver (works great), as well as added a dwell control to many AB763s. With the 6G16, the dwell pot is the same value that you used, but it has an entire gain stage after that pot before it gets to the 6K6.

With the AB763s, I have always just replaced the 1M grid leak with a 1M pot & have had good results.

In your instance, I would be tempted to first try a larger value dwell pot, but maybe you would have better luck moving the dwell pot to the input of the preceding stage. Maybe a 1M to ground, with the wiper connected to r28/68K input to V2a.

I will be interested in the insights of those more knowledgeable.

[W5FH]

Thank you lonote-
That is a good suggestion. The original circuit of Wonderland used a 100K dwell pot. In some builds a 250K dwell pot was used to try and increase the dwell. I believe I will try this.
Thank you