New Build-Wonderland "Fairfield County Signature"
Moderators: pompeiisneaks, Colossal
New Build-Wonderland "Fairfield County Signature"
Just finished "Wonderland" build based on the info from The Tone Geek's "Fairfield County Signature" version. Built on Super Reverb chassis, 290-EX power, 2x6L6GC to an O/Netics A-431 output (not using UL), Edcor 5 watt 7K reverb driver, mil surplus sealed 8H choke. Subbed a 6K6GT for reverb driver. Had a few issues with low drive to reverb tank (4AB3C1B). Ended up increasing gain of stage driving the 6K6 and increasing dwell pot to 500K, plus increased voltage node supplying 6K6 to 300 vdc. Using 1K Ck bypassed with 20 uFD for 6K6. All cathode bypasses are film caps mostly Electrocube polyester. This is a very nice sounding amp. I added the Sluckey Trem-O-Nator using 250K intensity pot coming off master volume wiper. Also added a line-out feature, copied from Jensen application bulletin using JT-11 series matching transformer. The shielded cable runs (RG-316) are numerous but worthwhile I believe. The amp is very quiet and no cross coupling. The bias circuit I use has two pots, one to adjust voltage and the other to balance it between the two output tubes.
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Stevem
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Re: New Build-Wonderland "Fairfield County Signature"
Since you’re set up with a bias balance pot you can crank the amp and audition a balanced and not balanced output section and be able to hear the effects of more even or odd order harmonics in your overall sound.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: New Build-Wonderland "Fairfield County Signature"
Thanks Stevem-
Never have experimented with that but thank you for the info. Will see. I like that bias circuit because if I have a pot wiper connection go open, or even a pot track itself, the bias will rise to its peak value and not lose its path to tube grids. Am excited about this Wonderland circuitry and plan to do some experimenting as I research all of the similar designs.
Thank you,
Byron W5FH
Never have experimented with that but thank you for the info. Will see. I like that bias circuit because if I have a pot wiper connection go open, or even a pot track itself, the bias will rise to its peak value and not lose its path to tube grids. Am excited about this Wonderland circuitry and plan to do some experimenting as I research all of the similar designs.
Thank you,
Byron W5FH
Re: New Build-Wonderland "Fairfield County Signature"
Thought I would post this for info, a learning experience for me -
After a couple of days of testing/use the "Gain" pot R-14 got mildly scratchy when turning. Removed the LNF capacitor C-9 and scratchiness went away. I had originally installed a NOS Orange Drop 6PS 0.047 @ 600v cap for C-9. I replaced it with a MKT 630v polypropylene cap. This cured the scratchiness.
After a couple of days of testing/use the "Gain" pot R-14 got mildly scratchy when turning. Removed the LNF capacitor C-9 and scratchiness went away. I had originally installed a NOS Orange Drop 6PS 0.047 @ 600v cap for C-9. I replaced it with a MKT 630v polypropylene cap. This cured the scratchiness.