Should I mod my JCM 800?

keano12

New member
Thinking of modding my JCM800 has a great sound as is on 10. I add a OD and that gets crazy but for low gain classic stuff as I back of the pre amp knob the tone gets thin.

Thinking of a Splawn mod $$$ tho'.
 
Re: Should I mod my JCM 800?

If it's vintage - don't. Just get a hack job of ebay and do the Splawn.

I am shocked it doesn't do it at lower volumes - Robin Trower uses 800s.
Have you tried changing caps or resistors? Sozos are great! Also, KT77's might do the trick EL CHEAPO! FREDs also cream up the tone a bit. Talk to Don Butler in LA.
 
Re: Should I mod my JCM 800?

Just get a Soldano Hot-Mod. Cheap and effective. I had one in my plexi, killer.
 
Re: Should I mod my JCM 800?

Can you please elaborate more on Soldano Mod? how is it different for a Vodoo mod, and is it more expensive if your amp has already been moded and is Soldano Mod availble for Laney AOR?
 
Re: Should I mod my JCM 800?

I believe the Soldano Hot rod mod is a device that you plug into one of your pre-amp tube sockets and has the same effect as adding another gain stage. I could be wrong though, it's been awhile since I've even seen one.

As for modding the JCM 800, I wouldn't do anything too drastic. I run a 2204 (the 50W version) with KT66's in the power amp, a hotplate to get the tubes cooking and a Keeley SD-1 for a boost. Killer tone, if I need something a little more low gain in nature I've adopted the habit of working my volume and tone on my guitar.
 
Re: Should I mod my JCM 800?

Brewtone said:
I believe the Soldano Hot rod mod is a device that you plug into one of your pre-amp tube sockets and has the same effect as adding another gain stage. I could be wrong though, it's been awhile since I've even seen one.

Yup I believe this is correct. But I believe they are hard to find nowadays.

As for modding the JCM 800, I wouldn't do anything too drastic. I run a 2204 (the 50W version) with KT66's in the power amp, a hotplate to get the tubes cooking and a Keeley SD-1 for a boost. Killer tone, if I need something a little more low gain in nature I've adopted the habit of working my volume and tone on my guitar.

Yup...agreed....learn to use the guitars vol/tone...thats how I've always done it.
 
Re: Should I mod my JCM 800?

Brewtone said:
As for modding the JCM 800, I wouldn't do anything too drastic. I run a 2204 (the 50W version) with KT66's in the power amp, a hotplate to get the tubes cooking and a Keeley SD-1 for a boost. Killer tone, if I need something a little more low gain in nature I've adopted the habit of working my volume and tone on my guitar.
i agree. i wouldn't mod a jcm 800. my jcm 800 cranked had more nuts than my 5150...all with no effects.

do you lose any tone with the hot plate? i hear that you lose some high end.
 
Re: Should I mod my JCM 800?

My JCM 800 has a bad gain mod and just seems to be extra noisy... i'm getting it yanked out of there as soon as i get some money... money has been tight this year!!!!!
 
Re: Should I mod my JCM 800?

esandes said:
do you lose any tone with the hot plate? i hear that you lose some high end.

You lose a little at extreme levels of attentuation (-16db) but, there are frequency compensation switches on it that help alot.

I tend to use it at the (-8db) which really doesn't effect the tone at all. I may have to adjust my eQ slightly. However, it's not a huge deal when you take into account how ballsy the tone is.
:banana:
 
Re: Should I mod my JCM 800?

Brewtone said:
You lose a little at extreme levels of attentuation (-16db) but, there are frequency compensation switches on it that help alot.

I tend to use it at the (-8db) which really doesn't effect the tone at all. I may have to adjust my eQ slightly. However, it's not a huge deal when you take into account how ballsy the tone is.
:banana:
boss. i think i'll get one.
 
Re: Should I mod my JCM 800?

My local music shop has one of those Soldano mods sitting in the display case collecting dust. I live in a small town so nobody really knows what it is.:27:
 
Re: Should I mod my JCM 800?

Ok you guys bring up some good points. first I was thinking of using a hot plate because I can't crank the amp as it is so loud.
What can I expect tonally by using the hot plate heating up the Power tubes more?

I was also thinking of a Lee Jackson mod, he is the guy that started the whole mod thing in the 80's. His mod actually has a button on the
front of the amp that acts as a hot plate. there is a place nearby in Los Angeles that does this mod also. http://www.ampcrazy.com/web/mods.html
Same price as a hot plate used almost.

Voodoo mod not familiar at all. Splawn does sound good expensive though with new tubes AND shipping. Actually too much.

Soldano Mod is basically just added gain then?
 
Re: Should I mod my JCM 800?

FRTBZZ if you wanna buy that Hot Mod and sell it to me, I am game. Find out how much? THERe HAs TO BE A TUBE WITH IT - those tubes are hell to find on the HOt Mods.
 
Re: Should I mod my JCM 800?

How old is your amp? Is it a reissue? If it's an early to mid 80's amp, I'd say "NO", don't mod it. You'd prolly lose money in the long run. IMO
 
Re: Should I mod my JCM 800?

New 2203 reissue dont' get wrong it sounds good. but I want DeMartini meets Vh
 
Re: Should I mod my JCM 800?

last i heard scott splawn isn't doing mods anymore. he's being overwhelmed with orders for this own amp line. bummer, but at the same time cool.
 
Re: Should I mod my JCM 800?

I don't know about the new ones, but the old Marshall JCM800s have a capacitor on the gain pot that acts as a BRITE switch. At lower settings of the GAIN control it adds treble (or cuts bass, if you want to look at it that way).

I had a tech simply clip this cap off the control--that kept the tone more consistent throughout the range of the GAIN control on my JCM800 4010 50-watt 112 combo. It made a world of difference in that amp, especially in the middle range of the GAIN control.

A tech could easily do this in a way that would be easily reversible, and anyone who KNOWS Marshalls would be able to advise you on this; it is a common, inexpensive, and totally reversible mod.

Bill
 
Re: Should I mod my JCM 800?

Bill good idea also. Power tube distortion is supposed to be sweet, so do any of you use a hot plate while playing live? Is it a smoother distortion?

Also the place in Los Angeles told me no mod for Lee Jackson. Any of you know a good place/perosn in L.A.?

Asfor Splawn I think your right he isn't taking Marshall anymore.
 
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