As i said in another thread, i changed my amp rather dramatically and loved the results. So i decided to throw the chassis back in the cab and hopefully be done with it. At least for a while. Anyways, i has a lot of slop from experimenting (even tho this build is only a month old !) and a number of the tweaks were just hanging there in a non permanent fashion. So i cleaned all that up and when i tried it to make sure all was the same, i found i now have issues with the gain cranked up. the sound will cut out completely like i've witnessed many times when i have too much gain. If i turn it down one notch to 4:00 instead of 5:00, it then is ok. But i don't have as much gain as before so i don't get why this is happening. i did make one change and this is one of my questions. I went from 60uf for the V1 filter to 20uf. So the question there is whether filtering can affect when a stage does that. the other question is blocking distortion and cut-off....are these two things just different degrees of the same thing, IE: too much gain?
I don't have my newly edited schematic here, so i can't check it against that for mistakes. but i'v gone over and over it and i can't see anything i have done any different aside from changing the V1 filter value. i don't want to add anymore grid blockers or raise the value of the one i now have for fear of darkening this tone that i'm extremely happy with right now.
The couplers shouldn't matter because i didn't change them and it was fine before and with even less gain that i had B4 i made all those major changes. the only thing i know changed because i changed it was the filtering. But i think i'll change that back and see. if it does it then, then i will really be lost wondering what it could be. Of course when i get home and look at the schematic then i can be sure it's not a mistake either.
EDIT: it's working now. i'm not exactly sure what the problem was, but the V2B plate wire at the pin was very close to the heater pin. It wasn't touching but maybe some sort of coupling was going on? Anyways, when i moved it the amp with a guitar plugged in just started screaming so i knew whatever was happening was right there. Juggled the wires around a bit and now it's fine with the gain on 10 as before. By the way, do any of the common vintage style fender circuits use filters as high as 60UF? The ones i looked at all had 20uf filters. Is that pretty much standard for all the common fender designs?
Anyway, there are three (at least) eras of Fender amps.
You have the tweed, blackface and CBS era amps.
The early ones of course used tube rectification and the later blackface tended to use SS rectification. Not all but most.
So there are design limitations to consider when filtering each type of rectifier.
Many tube rectifiers do not like anything above 40uF for the first filter.
For SS amps, it was common to use two 70uF in series for a total of 35uF for the first filter.
For many of the tube recitifier amps they used dual 16uF in parallel for 32uF.
Thanks. Yeah, it is. But i wanted it to sound more fendery. I felt if i could get a tone that had more in common with fender's dynamics and tonal balance but with more mids and the ability to have gain from the preamp i would be quite happy. I am ! I love the typical SRV style tone, but unless you have a good one with the right tubes and all that and play it at ear splitting levels you don't get the mids and distortion like SRV got. I knew i couldn't get that from preamp drive, but i wanted to get closer to that and by going from a CF driven stack to a plate driven one and changing a few other things to fender values i got closer than i thought i would. Now please pray for me that once i stuff it back into the combo cab i don't take it out again soon and start more mad experiments on it !
Anyways, i has a lot of slop from experimenting (even tho this build is only a month old !) and a number of the tweaks were just hanging there in a non permanent fashion. So i cleaned all that up and when i tried it to make sure all was the same, i found i now have issues with the gain cranked up. the sound will cut out completely like i've witnessed many times when i have too much gain. If i turn it down one notch to 4:00 instead of 5:00, it then is ok. But i don't have as much gain as before so i don't get why this is happening. i did make one change and this is one of my questions. I went from 60uf for the V1 filter to 20uf. So the question there is whether filtering can affect when a stage does that. the other question is blocking distortion and cut-off....are these two things just different degrees of the same thing, IE: too much gain?