The Amp Garage

About the resistor value, how much lower than 470k can I actually go, so I can have a range to make my mind around. I need to study this part of the design that is for sure. Kind of a tricky question. Someone with more expertice might want to chime in on it. Generally, grid leaks and resistance to ...

Thank you very much for these infos. New schematic. That looks better. I presume what looks like a resistor with no value next to the grid leak is a leftover from the previous version. You can make the 470k grid leak smaller if needed when you have figured out suitable ratios for the voltage divide...

I have revised the schematic. For the NFB, would you go for 25k or 50k? I m confused about the 470k resistor down the v4 grid, providing grounding has been mentioned. Also, that “C” on the v6b, what does it means? If you don't need to be able to cut off the NFB completely, 25k should be enough to g...

To vary the NFB, you should be looking at the 820R resistor (where it says "Feedback" on the schematic). IMO, a potentiometer in series with the 820R resistor is more flexible than a switch with set values.

Turn the high gain pre down until you are a couple of degrees below the blocking. Play for a while and make sure. Measure the pot. That will tell you what the splitter values need to be. Yeah, might do that or just put a grid stopper on the CF (which I guess is the prime suspect). But as mentioned,...

Hello, thank you. I actually didn t notice it, i took the original schematic and erased both tremolo and reverb and doing so i left the cap and cathode resistor out by mistake, the v4 is the reverb recovery tube and it has those two components but they just show up in the reverb circuit draw. It wa...

Anyway, why wouldn t it work? It is the same design but without tremolo and the reverb and for what i am learning here, using the third preamp tube for both channel shouldn t be a problem. You need to take another look at the 3rd gainstage V4B. On your schematic it has no cathode resistor, no grid ...

At a glance HOLY SHIT You need to do some interstage attenuation! Ok I see. And I will get a link to Rob's micro bassman that might help you develop your idea that won't cook the lil booger with 2x the gain required to drive the tail. Obviously not a high gain design but if you listen to the outcom...

Sounds like you're overdriving a tube grid into cutoff. As the level drops, the tube recovers and signal returns. OK! Cutoff...or clipping/grid current limiting? I looked it up in Merlin's book and it seems that hot biased gain stages are prone to grid clipping? I have two hot stages in a row with ...

It wasn t my intention, I understand how to adjust the gain now but I prefer to keep the schematic design as genuine as possible an maybe work from there. I did the opposite with my first amp and I had hard time understand what was going on untill I brought everything back to original. I will put i...

This is related to my amp build discussed in another thread, but I thought this might be worth its own thread. I know this phenomenon indicates a particular condition in a gain stage, but if I ever knew what it is, I've forgotten. It happens when I have the preamp gain turned up to "metal" amounts o...

WhopperPlate wrote: ↑Mon May 29, 2023 5:33 pm Us bootleggers and amp pirates don’t deserve to have it so easy .

The journey is the destination

Yeah, I think I get it. De-gooping the forum

Well, this might be it :wink: I pretty much did what Littlewyan suggested: less bass and more treble. I also changed the top treble cap in the James to a whopping 750pF for a mid hump around 300Hz. I did that because it dawned on me that the nasal and grating kind of "cheap Marshall pedal" sound was...

I have information on the following models (schematics or layouts, ...) : #04, #13, #33, #40, #60, #94, #101, #102, #121, #123, #124, #133, #148, # 183, #189(ripper), SSS , Bluesmaster, UltraPhoenix, ... ... and since the only site I consult for this kind of information is ... The Amp Garage: I thi...

They are not really hiding …with a little bit of sleuthing you can find it all Thanks! I was mainly wondering about ODS circuits, and that helped me find more of them. I guess I might have skipped over a few layouts inadvertendly while scanning threads for schematics. So about 7 all in all if I got...