Tube Amp Archive

I forgot why aned would appreciate a quick reviewof the following. Why does a 6v6 cathode biased amp use a 250 0hm resistor if both cathodes are biased but a 500 ohm resistor if they are wired independent of each other?

Friends, A few years back I bought a magnatone M7. It looks like something between a television and a portable room huimidifier. It was during the Estey period. Regardless I didn't like the sound of it and since it wasn't exactly a great vintage priceless jewel I Leo'd the circuit. I changed the pre...

Preliminary testing point to bummer power tubes. I'm not sure yet as it's hard to think it was such an easy fix. My dog was knawing on a bone but I'm pretty sure the noise was from him and not from the amp.

Friends, I finished another 5e3 and have been having some troubling sounds with adventitous white noise. The guitar sounds great but there is intermittent white noise that I haven't been able to figure out. It sounds a bit like hiss when you tune in a radio. It has no impact on the sound of the guit...

Thanks for the help. It is in fact a bad pan.

I've got a blues Jr here with a reverb circuit that isn't working. I resoldered 2 connections where the wires had snapped loose in the pan. Now I have spring noise when I wack on the pan, the classic sounding wap the side of a spring reverb sound, and this come and goes as it should when I dial up o...

First I thank the previous contributors for their help and insight. My understanding of grid bias has much increased in the last week. It seems that reading must be accompanied by bench time in order to gain understanding. Regardless, I am trying to create tremolo but I have not yet been able to do ...

It is the fender Vibrolux 5e11. I am using a diode instead of a selenium rectifier. My guess is that is why the voltage is so far off. I was applying no bias to the grids and had the cathodes grounded when making the measurements. I will adjust the resistor voltages to get to -31. Would I increase t...

I'm having issues with the power amp stage of my new fender build. I have the same voltage on the screen and the plates without the tubes in, but when I put the tubes in the one plate is 340 volts and the other is 360 volts with 360 volts on the center tap of the output transformer. The tube with th...

If the organ amp uses miniature preamp tubes then the transformer will work fine for a guitar amp. I have used the transformers with great success. If the tubes are all octal then you have the field coil speaker type and the voltages are too high.

Noise does ocur without cable plugged as well as with cable plugged in.

I walked into some real nice 15 inch speakers so I built a 5E3 to push one of them. It sounds great but I have some intermittent background noise, it sounds like hiss/white noise that goes for a few seconds then stops. Throughout this noise the guitar sounds rich and clear, no effect on output. Any ...

Picked up a Magnatone 421 today. It is a small amp from the Estey period. It has one 10 inch speaker. It also has the tremolo/vibrato circuit. The vibrato is the pitch changing that magnatone is famous for. That is why i bought it as I was curious and then sucked in by the cool sound. I got it for 2...

Friends,
I've got a bassman 10 and I am wondering what is the best way to modify this circuit to make it a good guitar amp. Any ideas?

Friends, I've got this amp I built using an old Hammond organ amp. It has 6sc7 for preamp and PI tube. It works fine but if I plug in my tuner with the input jack plugged in to the power supply while the amp is on, the amp cuts out completely. I then wait a short while and it starts working like not...