redshark wrote:prspastor, remove that 33k resistor until we confirm the value, V1pin7 and put the parallel cap(0.0022) leaving the 820 ohm resistor in V1pin2. I just did and I like it better.
Maybe I'm assuming that if the resistor in V1pin7 is a 1.2-1.8k it was there to supress an oscillation or maybe because the original owner of the amp played really hot pickups and Ken wanted some impedance matching or something. I don't know.
Very interesting development. I tried the above and the grainy/crushed glass distortion characteristic was introduced into the sound again. I returned the 33K resistor to V1 Pin 7. I wonder if my amp just needs that grid stopper because of oscillations I can't hear... It is still very touch responsive even with that resistor.
FWIW, I've also got NOS 5751s in V1 and V2 and they are known good tubes. Even with the 5751s, this thing has incredible gain. I'm typically playing it with volume around noon and the guitar rolled back to about 7.
Well, I thought I'd get in on the fun on this one too, so I tried a couple of these 'mods' on my Express.
First I tried a parallel .0015 ceramic capacitor across C8 (I didn't have a .0022) and it definitely added some high low end, or low mids. It sounded pretty cool, but I'm always rolling off the bass on my amps anyway, so I didn't keep this one.
Then I tried a 10k resistor on pin 7 of V1 and it reduced the gain too much for me. Next I tried a 2.2k resistor and it sounded really good. I then tried a 1.5k and it sounded awesome. Still had the gain and the character but sounded more 'barraaangy' if that's even a word! Letting a power chord ring out gave more of the steely ballsy thing kind of like a Marshall. But the main thing I noticed is it greatly helped pinch harmonics jump out!
I didn't try the 820R on pin 2 of V1, mainly because it sounded so good after I put the the 1k5R on pin 7!
I might add that I tested these changes in 2 ways; one with a loop I recorded with the guitar straight in to a Digitech JamMan and the other playing straight into the amp. Both with a Les Paul. The nice thing about the loop is you can get a more subjective opinion of the tone, although I think the JamMan colors the sound slightly...
I finally got around to adding that parallel .0022 cap in mine. It seemed to add more "fullness" to the sound. I liked it and I am running now with all the Ingrid Mods. Very happy.
John
