Tube Amp Archive

I didn’t add the extra filter stage. Went with Robinettes minimal mods. I also undid the LNFB on the PI, 4.5k PI cathode bias and the 500 ohm v1 bias. Kept the 100k plate and tail resistors though. I don’t have my voltages. Next step is to measure this stuff. I’d like to ascertain what the PT is cap...

MJW Modified 5E3.gif There we go! I've omitted the VVR just for the sake of space. It only operates on the B+1 and B+2 voltage lines. One thing I do notice is just how little voltage dropping is going on. 1500 resistor and 8200 resistor, assuming I'm reading the values right. Any thoughts on this?

Thanks for all your input Stephen. I've managed to install a GNFB loop today. 56k resistance with presence pot (10k with 0.1uF on centre lug to ground). My word. What a difference! Also reduced the noise floor enormously. Had to swap the OT primaries around and undo some lead dressing to get them lo...

Evening sir, Current features The VVR, PPIMV and triode/pentode switch were features on the original Bantam model. The idea behind them was the player could shift overdrive to pre- and/or power-amp with any of those controls. I'm also working on the schematic, but not sure I'm competent enough to in...

Thanks Stephen, I'll see what I can do. Regarding the power scaling, that came installed when I ordered it. I had it on the original model, so I asked for it on this. I don't know too much about how it had been configured, but when you turn it down, you also have to pull the MV down to avoid fizzine...

Thanks Stephen I believe you are correct the original WEM was a LTPI, and the first Bantam I had was wired this one. But with this Tweed variant, the builder had indeed used a cathodyne PI, per the 5E3 circuit. So I didn't have to change this over. However the output stage uses EL84 tubes like the W...

Evening folks I've been lurking for a few weeks, soaking up the info for both amp mods and a cabinet build. Just completed a first foray into one of my amp setups thanks to all the resources here, so thought I'd share. The Amp Photo 31-05-2024, 17 27 26.jpg This was originally a small 18W EL84 head ...