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Improve jcm800 sound, fuzzy tone and tonestack managment
Posted: Fri Dec 25, 2015 6:42 pm
by giordydiver
Hi guys,i came here because i want improve my amp sound. Amp is jcm800 2203 with some mod(schematic below). The sound is really good for be, good clean channel,good OD, but overdrive has a bit of fuzzy tone that i dont like, i prefer a sound more defined and granite. Other thing, tonestack has a very inexistend usable range and I want a tone more manageable and effective. What can i do do make this thing?
http://s11.postimg.org/el2c2zm6b/image.jpg
Re: Improve jcm800 sound, fuzzy tone and tonestack managment
Posted: Sat Dec 26, 2015 9:59 am
by RockinRocket
Do you need that much gain? Ive done basically what you did minus the last gain stage. The last two gain stages were hot rotroded with cathode bypass caps. MAybe remove the last cathode bypass cap and use more power amp volume.
Re: Improve jcm800 sound, fuzzy tone and tonestack managment
Posted: Sat Dec 26, 2015 12:06 pm
by giordydiver
So I try a lot of value today.... Remove 680n from 820r, less gain but thinner sound with much treble, remove 100n from second stage, less treble but less gain...so i put the 680n on 820r and i have a bigger sound and good gain, a 47k resistor second stage imput,and the sound is really good. I change also the 2.7k ok first stage to 820r and in my opinion the sound is better with natural overdrive....also the fuzzy tone is better.
For tonestack managment i use a 47k slope resistor and 500p.
For me now rhe sound is really good, better than original 2203 and better tha my original project(sir 34)
Re: Improve jcm800 sound, fuzzy tone and tonestack managment
Posted: Mon Dec 28, 2015 6:39 pm
by giordydiver
giordydiver wrote:So I try a lot of value today.... Remove 680n from 820r, less gain but thinner sound with much treble, remove 100n from second stage, less treble but less gain...so i put the 680n on 820r and i have a bigger sound and good gain, a 47k resistor second stage imput,and the sound is really good. I change also the 2.7k ok first stage to 820r and in my opinion the sound is better with natural overdrive....also the fuzzy tone is better.
For tonestack managment i use a 47k slope resistor and 500p.
For me now rhe sound is really good, better than original 2203 and better tha my original project(sir 34)
So i play today ad 2 master and cabinet 2x12 with v30... The sound is wow,overdrive is perfect the best i have ever hear, no fuzzy tone, right treble. The clean channal is good but is a bit dark,i thing to add 150k resistor from gain pot to gain to have more twang and a bright cap to have more treble and have a clean tone...
