JCM 800 owners...public service announcement....

[Racerxrated]

Dudes(and ladies if you're here) check your solder joints on your boards. Or, if you have board mounted pots like I do with my 86 2210(4211) and 88 2205. I recently got that 4211 chassis that was for sale in the classifieds and it was pretty noisy, kinda muddy sounding which can be normal for these as they really varied by year and even models from the same year can be night/day different.

But, I was reading about re heating/flowing the solder on all the board mounted pots and how it made a difference for a dude on the Marshall forum, and man was he right! Night and day. Clear gain with hardly any buzz/noise now. I must've had some cold solder joints-the difference is astounding. So, if your 800 is noisy, or just doesn't sound that good, and your filter caps/tubes are good I highly suggest taking the knobs/washers off, pushing that board back and tilting it up so you can access those solder points for the pots. Huge difference.

2210/05 owners: Also, give these two mods a try.....find C20, a small cap between the gain and volume pots on the board. Clip one end. Then, move the purple NFB wire to the 16 ohm tap. Way less 'tubby' and the amp gets a little brighter, tighter but more clarity. This damn 4211 chassis (with my OD1X boosting) reminds me of my favorite Aldrich from long ago.

 

[Longo]

in my 89 jcm800 4104 the c20 is one of the bias caps..
I assume you mean c13?

 

[Exo-metal]

Dudes and bitches, this is still RT you dogs...btw that 2210 sounds killer bro!!
I know my stock 82 800 2204 is goes nowhere?

 

[Racerxrated]

in my 89 jcm800 4104 the c20 is one of the bias caps..
I assume you mean c13?

Possibly…it’s a tiny ceramic cap, in between the volume and gain pots. Thought in my 86 it’s C20 but I could be wrong…

 

[Racerxrated]

in my 89 jcm800 4104 the c20 is one of the bias caps..
I assume you mean c13?

Oops this is referring to a 2 channel 2210; not your 1 channel 4104

 

[Longo]

yes... I have seen that it is not the same.
c13, in the jcm combo, is between middle pot wiper to ground... i think it's some kind of compensation for the open back combo cab

 

[JackBootedThug]

Dudes(and ladies if you're here) check your solder joints on your boards. Or, if you have board mounted pots like I do with my 86 2210(4211) and 88 2205. I recently got that 4211 chassis that was for sale in the classifieds and it was pretty noisy, kinda muddy sounding which can be normal for these as they really varied by year and even models from the same year can be night/day different.

But, I was reading about re heating/flowing the solder on all the board mounted pots and how it made a difference for a dude on the Marshall forum, and man was he right! Night and day. Clear gain with hardly any buzz/noise now. I must've had some cold solder joints-the difference is astounding. So, if your 800 is noisy, or just doesn't sound that good, and your filter caps/tubes are good I highly suggest taking the knobs/washers off, pushing that board back and tilting it up so you can access those solder points for the pots. Huge difference.

2210/05 owners: Also, give these two mods a try.....find C20, a small cap between the gain and treble pots on the board. Clip on end. Then, move the purple NFB wire to the 16 ohm tap. Way less 'tubby' and the amp gets a little brighter, tighter but more clarity. This damn 4211 chassis (with my OD1X boosting) reminds me of my favorite Aldrich from long ago.

I was looking today for that and saw it sold....I was wondering who got it...awesome...

 

[gtrwun]

Dudes(and ladies if you're here) check your solder joints on your boards. Or, if you have board mounted pots like I do with my 86 2210(4211) and 88 2205. I recently got that 4211 chassis that was for sale in the classifieds and it was pretty noisy, kinda muddy sounding which can be normal for these as they really varied by year and even models from the same year can be night/day different.

But, I was reading about re heating/flowing the solder on all the board mounted pots and how it made a difference for a dude on the Marshall forum, and man was he right! Night and day. Clear gain with hardly any buzz/noise now. I must've had some cold solder joints-the difference is astounding. So, if your 800 is noisy, or just doesn't sound that good, and your filter caps/tubes are good I highly suggest taking the knobs/washers off, pushing that board back and tilting it up so you can access those solder points for the pots. Huge difference.

2210/05 owners: Also, give these two mods a try.....find C20, a small cap between the gain and treble pots on the board. Clip on end. Then, move the purple NFB wire to the 16 ohm tap. Way less 'tubby' and the amp gets a little brighter, tighter but more clarity. This damn 4211 chassis (with my OD1X boosting) reminds me of my favorite Aldrich from long ago.

Good timing on your post racer! Just about to tear into that 4 holer I bought last week. Thanks….
???

 

[Racerxrated]

yes... I have seen that it is not the same.
c13, in the jcm combo, is between middle pot wiper to ground... i think it's some kind of compensation for the open back combo cab

Yep that's also present in the 4010 I think? This one is in both my 2205 head and this 4211(2210) combo. I think C20 is a treble bleed cap, or so I've read.

 

[DanTravis62]

Based and 2210 pilled.

 

[thegame]

Can’t get a JCM 800 to sound brutal without a pedal? Try a testosterone booster.

 

[guitup too]

Thank you for the info. I wonder if this would apply to a JMP as well.

 

[Kapo_Polenton]

Thank you for the info. I wonder if this would apply to a JMP as well.

I'm guessing no. You won't have board mounted pots in an older JMP and you won't have that ceramic cap on the mid pot. He's referring to the combo amps as well. JMP should be good to go as is. You can still tweak small things here or there though.

 

[Racerxrated]

Thank you for the info. I wonder if this would apply to a JMP as well.

Unless you might have 'dry solder joints' which is what the pot joints looked like on mine? If the amp sounds healthy, you're probably fine. But if it doesn't sound that great, and tubes/filter caps are good then take a look and the solder points. Or have your tech...