Filter capacitor most likely , open her up and look for a cap puffed out on the ends .
The cap has a little cut in the ends to allow swelling to show a bad cap !
Make sure no hair or steel wool ect is on the tube sockets or boards causing a short !
Plug in and out your jacks - FX loop send...
I hear a bunch of Luv from Renegade owners and a lot less of any problems with that amp.
Im a Rebel 30 head owner with a date code bcc01 with no problems and reports of Channel 2 switching issues has occurred for some others unfortunately .
I think they upgraded the Transformer in those after they sold a bunch.
I think you can tell by the serial number but does anyone know how to find out .
I was considering buying one myself so I need to find the info!
You may just may find a great metal gain pedal like Bogner makes is exactly the cure , sounds like your pre amp needs some help but read reviews like Musician friends and get some metal forum help but it could just be you need a great pedal !
This may give some insight on what each tube does the effects the next tube ect:
V1 is the vital initial gain and tone for both channels .
V2 Is your cascade overdrive tube fed from v1 , this can be a challenge finding your crunch flavor .
V3 is the Equalizer recovery , use your ears turning...
I have had the Rebel 20 head 3 years and all the 12ax7 tubes did not get the tone i wanted.
Frankly the sound was shrill with highs and hateful and offended my senses .
3 years later i put a RCA 12ax7a long Black plate tube in the OD socket and what a great tone it has now !
I have been...
However if it is a cathode bias amp just plug the right type 6v6-el84 tubes in and play .
Funny fixed bias is different and needs adjustments , A DMM meter is a must !
I would google , bias tweaker amp but it is simple !
Careful so as not to touch the amp chassis bottom where capacitors can zap you.
I set my rebel 20-30 amps on the end with the transformer supported by a stack of books so I can access the component section.
Make it stable and find the test...
I wish I knew which ecc83 tube your talking about, I looked on tube maze and no unbranded ecc83 came up in the search.
It is important that you not, to get the highs over whelming your full chords as this will coverup the ringing individual notes in the chord .
I call this smearing which I did...
My opinion was re-tubing my rebel 20 & 30 amp heads and tubes I said were un-suitable for me may well work in your amp and the is not definitive good tube or bad tube due to various amp designs !
Your ears and your amp tone is for you to judge, my tone sucked but I have another tone now and it...
The gain channel was my nightmare too re-tube in my rebel 30 and 20 and after $$$$ and many new tubes none had that tone that sounded good to my picky ears.
I wanted a over-drive sound classic rock vibe and what I got was loud harsh lots of gain overly fat midrange that was bloated sounding...
I would turn the volume a few times and the watts control include the mix control because it is a component or tube socket contact glitch it seems.
Unplug the send & return and try it then re-install the FX cables and try they may be dirty contacts.
Eureke i found out the 3rd tube from the input does the EQ of the amp and whoa what a difference.
I thought this was just a OK amp but the tone stack responds like a really good amp when you get it tubed right.
I had the crunch gained abit and cut on a T-Rex Alberta OD pedal and i never could...
Are you refering to wizard amps ?
If so have they done jet city amp mods allready .
Theres plenty of room on the PCB to work on, its easily modded i think.
I put a 8 ohm eminence wizard in the 1-12" combo.
This is a 2 channel amp and it positively rocked with this speaker.
The stock eminence is a bright as crap speaker IMHO
It was 16 ohm so im running using the 8 ohm output now.
I considered this amp kinda bright but was wrong as could be.
If...
How the china 12ax7 tubes breakup is what i dont like,fizzy as it gets .
The best gain vs breakup are new sensor tubes and the russion gold lion also,NOS GE are very bright like EH tubes.
I do have 2 NOS mullard 12ax7 that flat out smoke with tone.
The surprize find recently is the EH gold...