The Amp Garage

Old topic, but I found it while searching the same question for a customer. There is a misprint on the schematic. R7 should be 47k, not 4.7k. That will correct the issue, for anyone interested.

It's hard to make out but you can see one positive lead of the internal f&t cap is wired to ground. The 470k won't affect the "balance" at all, it just drops the PI input impedance down to a bit less than 1M (from 2M), so it will move that corner freq up an octave and load down the preceding circuit...

Cut open the optocoupler and replace the bulb with a red LED. For me, when all else has failed, this has always fixed a noisy fender tremolo.

I've built and rebuilt a few majors, with original/rewound transformers, as well as new transformers from heyboer. On the first Major, I couldn't decide what to do after hearing all the horror stories. Should I run regulated screens, etc. I wanted to hear what a cranked stock major sounded like with...

I've repaired two dirty shirley amps in which the internal can caps were miswired. One of the anodes grounded, the other at HVDC, with a voltage divider built off it for a positive DC heater reference (but mistakenly wired to the cathode). Once wired correctly, both amps sounded VERY good, in my opi...

Some Bogner amps use a switching supply for the heaters

Maggie:

[IMG:263:406]http://img13.imageshack.us/img13/6351/37663133749509133616498.jpg[/img]

RJ, would you be interested in adding their iron to your store, especially if some good reports come back? I sure would like to try some, but I would much rather order through you.

JamesHealey wrote: Personally after trying them all my personal favourite is the Edcor using 5k2 tap.. but the Pacific 6k6 is by far and away the closest sounding to Glen Kuykendall's clips.

How would you describe the difference? Can't wait to hear those clips!

. . . AND halve the value of the Rs in the tone stack and double the value of the Cs.

In my experience, even compensating as such, the clean-to-mean potential of the amp is reduced. less clean range

My theory is that it's because the miller capacitance is doubled. The tone stack loads down the 1st stage enough to prevent loss of highs no matter where your guitar's volume control is set (because the gain is reduced, miller capacitance is reduced). Parallel the input stage, and a 500k pot, depend...

I've used the 6SJ7 (and 12SJ7) and the earlier 6J7 (w/grid cap) in several guitar amps, vox and tweed type circuits and even higher gain stuff. Always had good results.

a 6SN7 cascode can easily reach gain levels beyond 100, plenty for an input stage. I've also used them with success as DC-coupled cathode followers in 5f6a/marshall type circuits, where the reduced gain doesn't matter much and can easily be compensated for.

looks like a good low-medium gain stage. I usually use Rp 47k and Rk 470Ω, grid-leak biased liked yours. I have tried current boosting the lower triode with resistors from its plate to the B+ node, but the tone changes in a negative way IMO. Interesting bootstrap of the CF there

I've used 6SN7 cascode input in many in guitar amps. Go for it! They're very quiet and sound great but you can't get HUGE gain numbers like you can with a pentode, even when current-boosted. They make a good standard 12AX7 triode input sub though, almost no miller capacitance They don't sound the sa...