no tone no top superlead

[darrens-66]

hi im new to this site so i hope i dont make any mistakes on my first thread. i have a weber superlead 100watt marshall clone i had it in the repair shop getting things checked over had a set of jj el34s put in and had it biased got it back and now it seems to have no top it has real deep tone almost muddy ive tryed every preamp tube i could get my hands on to try to get some treble out of it but nothing works. ive never had a marshall were you had to turn the treble past 5. any one no if there is a power tube out there that might bring back my tone there doesnt seem like there is any other issue with amp other than it dont like these jjs. the amp tech said to bring it back and try playing with caps but first do tubes and see if that fixes it. so if anybody nos a good tube that will give some good topend i thank you in advance.

[Robert M. Martinelli]

Hi, and welcome!

If the amp is really muddy and lacks highs to the extent you described, I don't think that changing the tubes' brand or searching tubes with a little bit more high end would help. The differences between the various brands, though audible, are rather subtle and not THAT pronounced. If you're unable to get the highs to be there even with the knob at "10" ( or "11" ), then I'd look somewhere else, as you've probably a bigger fish to fry.

Did the tech change any components ( capacitors/resistors)? Have you checked the components' values to comply with the amp's schematic?

( misreading a value is something that can happen to anyone, also, some component(s) could have drifted and both things sure as H&ll can alter/ruin an amp's tonal response ).

JM2CW

Hope this helps

Best regards

Bob

[bluesfreak]

The JJ EL34 are a bit more ballsy in tone then a similar russian valve. I would recommend to use Svetlana (Winged-C) to get a bit more top end. However, if your amp is similar to the weber 8cm100 kit then a more darker tone is normal as this copies very early marshalls. You can try some small mods to get a bit more mid/treble out of this amp:
- add another 10k R to the 10k cathode r (R37) of V1b to get 5k on the cathode
- if you use the Lo input replace R18 (470k) with 220k
- increase the slope resistor (R26) from 33k to 39k or 47k

[Robert M. Martinelli]

The JJ EL34 are a bit more ballsy in tone then a similar russian valve. I would recommend to use Svetlana (Winged-C) to get a bit more top end. However, if your amp is similar to the weber 8cm100 kit then a more darker tone is normal as this copies very early marshalls. You can try some small mods to get a bit more mid/treble out of this amp:
- add another 10k R to the 10k cathode r (R37) of V1b to get 5k on the cathode
- if you use the Lo input replace R18 (470k) with 220k
- increase the slope resistor (R26) from 33k to 39k or 47k

Hi bf,
you're "technically" correct about the mods, but that's not the point IMHO, as, in his "thread starting" post, he stated that the amp lost the highs after being for a while at the repair shop. This probably means that the amp tech did something wrong ( like misreading some cap's value or something similar ).

Mods are good only if a certain amp's design lacks something you want, and, clearly, this is not the case, as the amp had plenty of highs before being carried to the tech's shop.

Cheers

Bob

[pdf64]

What was it in the repair shop for? Who built the amp?
Have you tried your guitar and lead through another amp, ideally one you're familiar with, to check that it's not a problem with them?
Same with you speaker cab and cable.
Peter.

[bluesfreak]

Hi bf,
in the "thread starting" post, he stated that the amp lost the highs after being for a while at the repair shop.

you're right bob, thats something I overlooked in the initial post (a bit hard to read this one sentence post ). Best would be to know what exactly the amp tech tried to repair and also if he biased the tubes correctly...

[darrens-66]

hi guys thanks for all your input. was out of town a few days but any way the amp was in the shop because when you turned volume past 3 it just didnt get any louder. the tech fixed that and it was due for a set of tubes so they were changed and amp was biased. but it did have plenty of top before i took it in it just wouldnt get any louder past 3. not that i ever needed it to it was plenty loud but i knew it wasnt right. also it seemed to run real hot it had a bit of a oder after it sat for a while. tech said that was because it was biased to cold. the oder is gone the amps volume works now it seems to run cooler it just aint got no tone and god nos im no tech so i dont know what im gonna do. amp tech said bring it back and he would play around with caps. and yes i did play it threw a couple different cabs and a few guitars just to be sure. the other thing i did notice is the presence acts weird when you turn it all the way up amp wants to sqweel so their is something wrong for sure,and also the treble doesnt seem to start working until you hit 7 or 8 and bass seems same way. so i am starting to wonder if tech did something wrong infact he almost had to because it didnt have these problems before. now. the question is do i want to take it back to him or not. any way thanks again for all your input