Tube Amp Archive

Thank you for very detailed response. I will be back to work tomorrow and will check all these suggestions.. I have been building and preparing amps since 2008, on and off , and, maybe, I have had this type of problem, but I forgot all about it and forgot what causes it, so the help of all those peo...

Hello everyone... I need some help from more experienced amp techs on this forum. A friend of mine asked me to help him with his Twin Amp that developed not so loud but annoying ghost sounds that are more pronounced on the lower notes and sounds like a hum but an octave or two lower. I recorded the ...

I am trying to find the time to start drilling the chassies, but in the meantime I found an excellent resource of info on 5F6A amps. https://robrobinette.com/5F6A_Modifications.htm
Do you think their schematic for PPIMV is a working one?
here is the shematic:

I have another question... I am putting together the list of all the parts for this amp and I saw this strange capacitor between the plates (anodes) of the PI tube. I circled it on the photo. It says 47 something, and on another schematic it said .00001. What is it for? Do I really need it (cause ot...

Thank you for your words of advise. Over the years I heard many stories and opinions on the "magic" of vintage tubes, but your reply gives a reasonable, well balanced overview of that topic. I found that the old tubes are more robust built. The new tubes do not show as good of a readings on my tube ...

I was out of town and missed a reply or two, but i am back and I have a semi off topic question. I heard over the years that the best tube for V1 (12ax7) is Mullard or Telefunken brand. Would anyone suggest to me what you would prefer and where should I buy (find) one, preferably NOS? Just the usual...

I see... I will have to do some research and see which circuit will be "better" for me. I always looked for more overdrive, but this time I look for more head room...

I'm getting ready to start building an iconic Bassman amp but I need help deciding on what schematic to use. I want to use the one with a rectifier tube and the long-tail pair phase inverter. Tweed 5F6-A 4x10 or Blonde 6G6 head? Both are excellent amps, but 6G6 uses diodes in the power supply circu...

My pick would be the 5F6-A. Stability comes from proper layout of the parts during construction. 3 things I would add during the build is (1) a hum balance pot for the filiments and (2) a bias adjustment set up such that if the adjustment pot goes open a resistor set up applies full bias voltage to...

Hello friends, I'm getting ready to start building an iconic Bassman amp but I need help deciding on what schematic to use. I want to use the one with a rectifiier tube and the long-tail pair phase inverter. Can anyone suggest a schematic with some modern modifications that improves the stability of...

Phil, thank you for your help. I am not an artist and, therefore, it is hard for me to tell the shades of a color... I thought the center of the guitar is a slightly different color than our good old Vintage amber. You suggest that it is, I just have to catch the intensity of it... Hmmm... I will ha...

Hi guys. I know that it is an AMP forum, but I also know that there are many pros here, that build guitars also. My go to forum called Reranch is down and I hope someone can help me here. One fellow asked me to help him to paint his guitar this tiger stripes design like on attached photo. Does anyon...

Your screen be pulling mad current, I'd look at replacing tubes. If only one of the two 1K 5 watt resistors is getting hot, switch tube positions and see if the issue stays in the same socket or follows the tube, and then dig deeper if needed. Thank you for your help. Yes, I also think the problem ...

bepone wrote: ↑Sat Oct 14, 2023 8:11 pm dont even try to diagnostic this cheap pcb type of amp, throw all out, ,keep the transformers and build any decent amp

I hear you bro! I build my own amp all from scratch (minus the transformers) and I love the tone of it. But this amp - it seems that the problem is one of the tubes.

Hello. I was asked to diagnose 3 year old Marshall DSC 40C. Problem is that after a few seconds going off standby, the sound becomes crackly and distorted, and you can smell like something is getting hot (no smoke though). I checked all the tubes on my tube tester and they all checked ok. Next, I pu...