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Re: Question to Carl
 4/15/2000 4:27 PM |
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Bruce | Re: Question to Carl
Not worth the hassle to change them, plus, you'll alter the response of the lower gain If you decide to try this, replace the two jacks and install the combination you want on the new jacks. Install a 27k to 33k resistor right to the tube's socket and leave the 68K resistors where they are.
OK but maybe try 5uF on the first triode and 10uF on the second after the tone stack. Or, you might like it the other way around.
OK, you understand the difference between grid stopper resistors and grid load resistors, right? If you're playing the amp loud enough to cause bass farting, reducing the PI/driver couping caps to a lower value, like .022uF-.047uF and changing the 220K grid load to 100k-150k is a decent way to get some of that in control. I think you'd find that using a grid stopper resistor of 47K instead of 1k5 might start to roll off the high freqs but I doubt many could prove to me they can hear the difference between 1k5 and 4k7.
If you mean replace the .1uF caps to .047uF, yes, see above.
I don't care for this mod too much. I've had amps come in for repairs where someone had used a .022uF there. More urban legend crap... actually suburban basement band legend... ha ha . Unless you play in your bedroom at low volume 95% of the time you might find the lower frequencies of the amp (at higher volumes) caving in the power section. I seldom use anything larger then .0047uF here and I try to use the best cap I can find for this job.
The 4k7 resistor will slightly lessen the overall gain of the PI driver tube and that 22k/4k7 combination actually allows a little more NF then a stock Fender and lowers the gain of the PI/driver so more. So, IMO, that one's no good either... well, that was a little harsh... maybe it was a suggestion from somone who did it once to one amp and they like it based on their personal taste. If you want to loosen up the NFB loop a little, try changing the 820 ohm resistor to 1k2 to 1k5. Too much resistance here will create a very mushy/woofy tone and I wouldn't think of using anyting larger then 4k7. OK if you like bluesy slide guitar at reasonable volume levels.
OK. I've gotten away with using as high as 500pF here with virtually no major difference in tone. If you notice the amp has lost it's top end "air", then reduce it's value. As a matter of course I use a small pF 500v silver mica cap on all my amps in this position. Bruce | |||||||
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| Replies: |
| Carl Z Wow Bruce, that was harsh! Trace q{I think you'd find that using a g... -- 4/18/2000 2:39 PM |