Kapo_Polenton
Well-known member
This subject comes up a lot on Rig talk and elsewhere.. you always hear about people complaining that they must not have the "right" JCM800 because theirs is harsh or thin at lower volume. Well, the fact of the matter is that yeah, some of these amps are just gonna be the cat's ass above the others. However, you definitely can even the playing field a little more if you find yours ratty. My 82 4140 combo is awesome.. my clone, not so much. So this weekend I took it out of the chassis and poked around to note some of the differences, here is what I found and what I propose for those of you who want to take the edge off the amp and make it more fun to play with pedals:
1. Treble peaking circuit. Right off the input jack. That 470k/470pf resistor/cap combo that feeds the preamp vol pot. It makes for a bright ass amp! You'll hear people point out that all you have to do is "cut the bright cap /end thread" but that comes at the expense of the crunch that makes these amps great. Drop the bright cap value to 500-1000 and drop the 470k/470pf combo down to 220k/470pf. What is this going to do? Allow the amp to sound WAY better with an OD on the front end. I noticed my 82' had a 300k resistor in this position so i just piggy backed a 220k over the 470k that is there now to end up with around 250k. Made a HUGE difference in how the amp sounds with a pedal at lower volumes. I couldn't stand how brittle the thing sounded before with anything goosing the front end.
2. my 4140 had a 4700pf cap on the mid pot. Not sure why this was done with the combos but it darkens up the amp big time. If you go this route, you can bring out more highs earlier in the preamp with bypass caps. This is nothing new, there is tons of info all over the net. Just mess around and see what you like. On the plus side, you'll also get a bit more gain but if you aren't careful, you'll also get some fizzies. This is why I would say, leave it out if you have the head and just stick with pedals.
3. NFR, negative feedback on a lot of these 800's is what, 100k to the 4 Ohm tap? I switched mine to a 47k to the 8 ohm tap. Robs you some gain but also smooths it out nicely and you end up with a bit more "give" feel wise.
4. Volume. lol. no $hit. probably the most important factor. These can be bright , tight, unforgiving bees in a can amps when played too low and at bedroom levels. Ya gotta open these bad boys up. Yes you'll get complaints from GF's or wives but if you want to be able to coax some smoothness or sponge out of these amps, you need to get the master up past 3 (preferably 4-6 i think is the sweet spot) which is loud as f-ck. Everything smooths out and fattens up and the pedals are actually useful to cut through and tighten. Right now I am using a hotplate set to 8db and I am only really up at 3. It's still complaint worthy loud. Not sure if a volume pedal in a loop (if yours has a loop) would be a useful idea to try but if you can't get that volume up, you'll most likely not get what these are about and flip em in the classifieds.
So there ya have it.. one mod that takes 1 minute to do and will make your amp more pleasing with pedals at lower volumes.. as for the rest, you are out of luck if you can't turn it up
Unfortunately , I imagine that these amps are probably too loud for use in smaller clubs as well which is why so many other amps do the lower volume thing much better.
Anyway, hope that helps some people out. After months of wondering why my clone sounded horrible , I now have two very usable 800's and didn't even have to resort to any drastic Tone Lizard changes!
1. Treble peaking circuit. Right off the input jack. That 470k/470pf resistor/cap combo that feeds the preamp vol pot. It makes for a bright ass amp! You'll hear people point out that all you have to do is "cut the bright cap /end thread" but that comes at the expense of the crunch that makes these amps great. Drop the bright cap value to 500-1000 and drop the 470k/470pf combo down to 220k/470pf. What is this going to do? Allow the amp to sound WAY better with an OD on the front end. I noticed my 82' had a 300k resistor in this position so i just piggy backed a 220k over the 470k that is there now to end up with around 250k. Made a HUGE difference in how the amp sounds with a pedal at lower volumes. I couldn't stand how brittle the thing sounded before with anything goosing the front end.
2. my 4140 had a 4700pf cap on the mid pot. Not sure why this was done with the combos but it darkens up the amp big time. If you go this route, you can bring out more highs earlier in the preamp with bypass caps. This is nothing new, there is tons of info all over the net. Just mess around and see what you like. On the plus side, you'll also get a bit more gain but if you aren't careful, you'll also get some fizzies. This is why I would say, leave it out if you have the head and just stick with pedals.
3. NFR, negative feedback on a lot of these 800's is what, 100k to the 4 Ohm tap? I switched mine to a 47k to the 8 ohm tap. Robs you some gain but also smooths it out nicely and you end up with a bit more "give" feel wise.
4. Volume. lol. no $hit. probably the most important factor. These can be bright , tight, unforgiving bees in a can amps when played too low and at bedroom levels. Ya gotta open these bad boys up. Yes you'll get complaints from GF's or wives but if you want to be able to coax some smoothness or sponge out of these amps, you need to get the master up past 3 (preferably 4-6 i think is the sweet spot) which is loud as f-ck. Everything smooths out and fattens up and the pedals are actually useful to cut through and tighten. Right now I am using a hotplate set to 8db and I am only really up at 3. It's still complaint worthy loud. Not sure if a volume pedal in a loop (if yours has a loop) would be a useful idea to try but if you can't get that volume up, you'll most likely not get what these are about and flip em in the classifieds.
So there ya have it.. one mod that takes 1 minute to do and will make your amp more pleasing with pedals at lower volumes.. as for the rest, you are out of luck if you can't turn it up
Unfortunately , I imagine that these amps are probably too loud for use in smaller clubs as well which is why so many other amps do the lower volume thing much better. Anyway, hope that helps some people out. After months of wondering why my clone sounded horrible , I now have two very usable 800's and didn't even have to resort to any drastic Tone Lizard changes!
