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I did a few mods to my Princeton, the Stokes mod to increase headroom in the phase inverter and changing some values in the tone stack. I'm really happy with the sound but would like to get a little more high end. I played around with the NFB, but could not quite get what I need. I don't necessarily need a presence control, just the way to cut the high end out of the NFB. If I disconnect it, the high end opens up nicely but the bass gets a little woofy. Also, I never use the vibrato, would there be any benefit to making that into a cathode follower?
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Princeton: no high end
You have not stated what mods you did to the tone stack. My Princeton lost high end when I changed the slope resistor from stock (100k) to 56k. Changing it back solved the problem.
Also if you changed the treble cap to be alrger than stock (250pf), this would also boost mids and kill highs. -
I changed the slope resistor to 50K, lowered the value of the mid cap (10n from 47n) and treble cap (100p from 250p) and increased the resistor to ground to 13.6K from 6.8K (no mid control). Now the midrange notch is centered at 1Khz instead of 200-400hz. The bass control reaches into the mids, previously, I felt it was centered too low. I'll probably put the treble cap back to stock values as it is centered too high now. I think I strung together some capacitors to achieve 5n, and this got me a little help in the upper frequencies. I'm seeking a strong clean smooth tone that has more "chime" than piercing brightness, and I've gotten a lot closer than I was. This has lowered the insertion loss by 8dB with the controls at 0 and with them dimed got me around 16dB more oomph at 300hz and lost about 7dB at 1200 hz (max differences).Comment
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