Something is bad with jack 3 that is stopping that 1 meg resistor from acting like the needed ground reference for the tubes input grid.
You don't need 3 inputs anyway so I would just wire it up like the two inputs on a Fender TR for example, and while you are at it change out those crazy 120k for 68ks.
I have the 1966 SS version of that which does not sound all that bad, even the reverb is ok.
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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!
I agree with Stevem. Something is messed up with the jacks.
I owned one of those for a few decades. That is one fine-sounding amp. It is the best-sounding amp that Thomas Organ ever made IMHO, and ranks up there with any amp. It's one flaw is that it's relatively low power.
"It's not what we don't know that gets us in trouble. It's what we know for sure that just ain't so"
Mark Twain
Juice isn't worth the squeeze. Leave the dummy plug where it is. If that solves the problem, I wouldn't mess with it. OTOH, some people just can't leave well enough alone. Just don't fix it until it's really broken.
I don't know about that leave it alone stuff with this one!
Having a jack in that 3rd input means it's working so with no signal going into to or having a shorted jack that you made to use there your asking for a higher and higher noise floor as you turn the amp up.
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!
R.G., your opinion on this amp is well-regarded from where I stand. Thanks for that.
If I'm understanding correctly, seems like there's some good and bad with changing the grid stoppers R1 and R2 from 120k to 68k:
Good:
May make the amp (a tad?) brighter
Bad:
May make the amp (a tad?) brighter
Overloads the input (too hot sounding/induce blocking distortion)
Potential for more RF hash getting into the input stage
For my own education/amusement: there must have been a reason why Thomas Organ used the values they did? Is it possibly due to the fact that there are 3 inputs here instead of the typical 2?
Those large value resistors must be a leftover from the small amps like the AC15 that used a Pentode for the first gain stage because every other tube amp in the Vox line up that was made in England uses a 68k value from my look see I just did.
Who knows, maybe when these where designed in CA back then there was a radio broadcast antenna 5 blocks away and they needed those 120K resistors in there?
Too much highs you ask, well you have a treble pot to cut back on that now don’t you!
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!
Stevem wrote: ↑Wed Apr 26, 2023 9:00 pm
Who knows, maybe when these where designed in CA back then there was a radio broadcast antenna 5 blocks away and they needed those 120K resistors in there?
Stevem wrote: ↑Wed Apr 26, 2023 9:00 pm
Too much highs you ask, well you have a treble pot to cut back on that now don’t you!
