Author Topic: More gain from JCM 800?? (Read 11300 times)

JakeLeigh1986 · « **on:** May 23, 2006, 08:30:32 PM »

Hi everyone,

does anyone know anywhere (In London) I could get another preamp valve installed on my JCM 800 for more gain.

I'm already running it with the power valves on full and pre amp maxed out (With a hotplate) and its still hasnt got enough gain for that John Sykes kinda sound. Definatly getting the Cold Sweats for one of my Les Pauls though.

Can different types of pre amp valve give more gain or is it all quite similar?

Thanks

Jake

Twinfan · « **Reply #1 on:** May 23, 2006, 08:44:31 PM »

OK. Take a step back.

LEAVE THE JCM800 ALONE!!!!

*pulse returns to normal*

If it's an original JCM800 then I'd add a stomp box, a clean boost or even an EQ pedal for more gain.

If you have to mod one, buy a modern re-issue and do it to that.

JakeLeigh1986 · « **Reply #2 on:** May 23, 2006, 08:54:23 PM »

haha alright, well i'm using 1960a cabs with it, maybe if i used vintage 30s?? yh it is an original early 80s 50watt. I'm using a SD-1 for overdrive, maybe I'll look into a tubescreamer?

Jake

steve · « **Reply #3 on:** May 23, 2006, 09:31:11 PM »

Quote from: JakeLeigh1986

haha alright, well i'm using 1960a cabs with it, maybe if i used vintage 30s?? yh it is an original early 80s 50watt. I'm using a SD-1 for overdrive, maybe I'll look into a tubescreamer?

Jake

Try the marshall guvnor plus pedal, it has gobs of gain a warm deep tone and sounds great boosting a valve amp.Oh and its quite inexpensive.

HTH AMPS · « **Reply #4 on:** May 23, 2006, 09:37:01 PM »

there are a few (reversable) preamp mods that can be done - I'm talking about changing the values of a few resistors and adding a couple of bypass caps - this will give you quite a bit more chunk. a modded SD-1 however will give you that extra kick in the pants - those two just work together SO well, it's a no brainer.

:twisted:

JakeLeigh1986 · « **Reply #5 on:** May 23, 2006, 09:38:09 PM »

where can i find more info on these reversable mods?? cheers

Jake

sambo · « **Reply #6 on:** May 23, 2006, 09:55:49 PM »

Quote from: Twinfan

OK. Take a step back.

LEAVE THE JCM800 ALONE!!!!

*pulse returns to normal*

HAHAHA!!! :lol: :lol: :lol: classic

Skybone · « **Reply #7 on:** May 23, 2006, 10:21:38 PM »

Add a nice stompbox to add some colour to your tone. RAT's add tons of graunch, fuzz boxes add a huge grin factor, OD's add OD... erm... :?

If you want more gain, sell the JCM800 and buy a high gain amp, if you want solid tone with some added colour, try out a few stompboxes with your rig, and buy some. You can never have enough pedals... ;)

JakeLeigh1986 · « **Reply #8 on:** May 23, 2006, 10:26:08 PM »

ah no i wouldnt sell it. I do really like it, just trying to improve it. My other amps a dual recto, and i'm sick of its sound. Also a JMP1 and 9100 rack system which i think sounds much better than the recto. But theres something about the 800. I prob need to find a new pickup really, prob the cold sweat. I'm just using Burstbuckers, hotrails, dragon 2s and invaders.

CaffeineJunkie · « **Reply #9 on:** May 23, 2006, 10:45:48 PM »

try the fuzz factory, works for everyone i know, just make sure the drive knob is AAAALLLLLLL the way around, and avoid the stability knob and you'll get great (normalish) distortion

chrisola · « **Reply #10 on:** May 24, 2006, 12:33:53 AM »

i used to nail slayers early tone and play In Flames type stuff on a JCM800.

Guitar > SD-1 > JCM800 head > Power Attenuator > Cab

EDIT ok so i didnt read you already had a Hot Plate lol.

New tubes maybe??

Bainzy · « **Reply #11 on:** May 24, 2006, 12:41:02 AM »

Although you can get a fantastic sound with an extra preamp tube, it shouldn't be necessary to get John Sykes style gain with a JCM800. If you can't get it by driving the amp hard with the preamp on 10 and using the hotplate, you still can mod the existing components in the preamp to squeeze more gain out of the amp.

FELINEGUITARS · « **Reply #12 on:** May 24, 2006, 01:01:21 AM »

You could put a Soldano Hotmod in as it is a single channel MV amp
The hotmod works by substituting the hot mod valve for one of the ECC83s
(the hotmod has an EF86 and some associated circuitry enclosed)
see an example here:
http://cgi.ebay.co.uk/Soldano-Original-Brass-Hot-Mod-Tube-Hotmod_W0QQitemZ7416323380QQcategoryZ38075QQssPageNameZWD2VQQrdZ1QQcmdZViewItem

Sykes got his 1987 album tones from a Boogie for riffs etc and a JCM 800 for lead tones. He may or may not have used pedals or outboard gear as well at the time but these days he seems to like to play direct into the amp

fps_dean · « **Reply #13 on:** May 24, 2006, 01:58:06 AM »

I don't know where to mod it, but before you get it modded may I suggest either a tube screamer or a treble booster.

I would recommend a Keeley Java Boost - www.robertkeeley.com which is a treble booster but may also be used as a mid or fullrange boost. That will increase your gain significantly - they provide a good amount of boost too. I ran it into a Marshall Major and it took that fairly clean amp into full blown overdrive, worthy of John Sykes but a whole lot meaner sounding.

The other option is a Tube Screamer. You can get a Keeley modded TS-9 which will have even more gain to it.

Boosts can increase your gain a lot!

indysmith · « **Reply #14 on:** May 24, 2006, 12:26:43 PM »

I'd considered the Java boost in the past, but the clips on the Keeley website sound really harsh, solid state, and cr@p. Kinda like if put a booster in front of my marshall microstack...
Can you confirm that the pedal sounds nothing like this in real life? :lol: