Tube Amp Archive

Yes the original has that first dropping resistor before the plates. I`ve seen gut shots of three or four of them and they were all like that. Gets very very hot though, anything less than 10watts tends to catch fire !! If you`re using 6v6 you would be better off with a 250R cathode bias resistor in...

OK Phil I`ll send you my schematic of that with the one tube reverb.

Well personally if i wanted to keep the ac10 srt type reverb circuit I would take the component values from the Ampeg R 12 R schematic which Vox were obviously trying to emulate. On the other hand having built this amp a year or so ago (and having experimented with it a lot), if I wanted to add reve...

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Well it did cross my mind that this particular one tube reverb circuit was normally injected around a simple 100 - 200k mixer resistor. In this case Vox/Ampeg style there are two more gain stages involved relative to the dry signal. V2a on the way in and V2b on the way out. Whether that is causing t...

Well it may be preferable to ground the power amp components at the other end near the PT but if it`s working ok thats good. The main thing though is just make sure the earth ground from the ac inlet is on its own on a short wire from the inlet socket and very securely fixed to the chassis as the la...

I don`t know if this will help you but I quote something I heard a while back while adding reverb to an amp. "Fender grounded the RCA jacks at the jacks on the back of the chassis. Apparently this can cause ground loops in some amps.Solution is to isolate the reverb jacks from the chassis and ground...

I ground them where the center taps go next to the power transformer and everything preamp at the other end near the input jack. Never had any problems doing it like that.

As I pulled the filter caps in anticipation of installing new ones tomorrow, I realized that my grounding scheme may be to blame for some of the hum. My original layout connected all the filter cap grounds to a lug near the inputs. When I install new caps, I believe I should connect the ground of t...

There is a corrected version of the schematic labeled OS/026 which is included in the limited edition of the book Vox Amplifiers: The JMI Years I don't own the book, but I've seen the schematic. It is much easier to interpret. I didn`t know about that revised schematic. Had to make my own. In any c...

When I built this amp (no reverb) I definitely had to add a grid leak resistor on the triode before the phase inverter. Without it the amp made all kinds of howling noises. The original schematic doesn`t show one which always seemed strange to me. Don`t know if you added one. Mine also benefited a l...

Can you show us how this sits in your whole circuit relative to that Vox schematic. I made one of these a year ago and appreciate the idiosyncrasies of that schematic!!

Your schematic or layout would help. Hard To read the values from the photo.