|
Title: JCM 800 2204 - JMP 2204 QUESTION Post by: hotguit on August 27, 2009, 04:03:16 PM Hi
I've noticed that in my 1985 JCM 800 2204 (horizzontal inputs) there are two 10K 1 W res. while in my 1978 JMP 2204 only one (the circuit is the same, one with pcb mounted pots, the other with chasis mounted pots) SEE PICTURE Why? how does it affect the tone? Is it a good idea remove it and put a jumper (on jcm 800?) thank you hot Title: Re: JCM 800 2204 - JMP 2204 QUESTION Post by: cmoore on August 27, 2009, 07:38:54 PM Does one amp have a choke, and the other does not?
Title: Re: JCM 800 2204 - JMP 2204 QUESTION Post by: hotguit on August 28, 2009, 08:58:23 AM both have choke.
Same circuit, different layout hot Title: Re: JCM 800 2204 - JMP 2204 QUESTION Post by: DanLurie on September 15, 2009, 10:28:40 AM It's an extra decoupled stage in the high voltage line. It provides more filtering to the preamp. I believe it's part of the original circuit. The filtering is a good thing in a higher gain amplifier. No need to jump it.
How do the two amps compare in sound?? Title: Re: JCM 800 2204 - JMP 2204 QUESTION Post by: hotguit on October 15, 2009, 01:41:17 PM jmp has a warmer and creamier tone and starts overdriving at about 12 o clock (preamp pot)
jcm is harsher and les compressed; it starts overdriving at about 14 o clock bye hot Title: Re: JCM 800 2204 - JMP 2204 QUESTION Post by: Kitarist on October 18, 2009, 11:33:25 PM What kind of mod do you need to do to transform a JCM into a JMP?
Thanks!!! |