Paolo Marshall JCM 800 2203 mods

This is a work in progress demo of the mods on my JCM 800. So far I've fitted it out with KT77s and done numerous gain and tone mods.
It's recorded using a digital camera and is heavily attenuated by a Hot Plate @ -16dB to avoid having the cops come around for a visit!!
Still working idea's for the additonal hole that was drilled by the previous owner, thinking of a PPIMV or resonance control.
Any comments, suggestions and/or critisisms are welcome.

Category:

Music

Tags:

• Marshall
• JCM
• 800
• 2203
• Les
• Paul
• KT77
• Mullard
• Brimar
• Electro
• Harmonix
• Metal
• Rock
• Slash

[BillMenchen]

It sounds good from what I can hear. I am in the process of doing some modifications to mine, and I have improved it but I don't think it sounds quite as good as yours. Would you care to reveal what you have done?

[PaoloJM]

@BillMenchen Hey man, send me a PM and I'll reply with detail.

[Vicejerri]

Has this mod 3 or 4 ECC83/803 ? I mean in the Preamp stage, not the ECC83 for a Tube FX Loop, if that is added, too...

Would like to get my JCM 800 modded, too, but i don't know which mod i should take :-).

[PaoloJM]

@Vicejerri Mine has no extra tubes, just releasing more of the gain the not used in the normal circuit. Adding valves is a pretty big, why not try the easy stuff first then see if you still need more?

[kakan147]

What scale are you using?

[AdamRainStopper]

@fuzzingaround Any type of power pentode or tetrode can be used in a cathode-biased circuit. It has nothing to do with EL84s or EL34s, it's a matter of circuit design. Others are fixed-bias, and you CAN'T rebias them, but a KT77 is so close in operational specs to an EL34 that you can usually swap them. The peavey windsor studio is cathode-biased and can use any octal without rebiasing (stock is EL34) including KT77, KT88, KT66, KT99, 6V6, 6L6, etc.

[fuzzingaround]

@AdamRainStopper of course not in a cathose bias based circuit but we are not talking el84 here, that amp on the clip was modify to a cathose biased head?? if so ok but they are usualy not with el34 nor kt77 you must ajust the bias each time you change el34 or kt77 etc... I didn't read the entire post here so I don't know if thid amp was modify for it's bias...

[AdamRainStopper]

@fuzzingaround Not in a cathode-biased circuit.

[fuzzingaround]

@AdamRainStopper you always have to rebias when you swap tubes...

[AdamRainStopper]

Damn, the palm-muted stuff sounds really tight and punchy. KT77s can just be dropped in to an EL34 circuit without rebiasing, right? I was thinking it would be cool to try KT77s in one of the new AC-50 heads. They used a pair of EL34s for the AC-50 Classic cCustom Plus or whatever it's called. The AC15 and AC30 still use EL84s so they will sound squishy and compressed no matter what, but the 50 watt has promise. They added the new high-gain channel and better equalization..... Nice 800 dude.

[Sarael72]

the neighbours won't be disappointed! xD

[theShowStopper321]

@PaoloJM What is the easy stuff? Id like to have some of the easy stuff done.

[biiiiirdman]

sweet!

[jeffdisario]

hello..what are you using as distortions?