EVH Chassis Layout

awangotango · Post by **awangotango** » Tue Dec 26, 2006 5:08 am

wasn't that screw a simple bias adjustment, not a gain mod or MV.

rockstah · Post by **rockstah** » Tue Dec 26, 2006 10:24 am

a bias ajustment... so when he used the variac he had easy access to adjust, by ear, the bias... its a real good possibility.

darrell · Post by **darrell** » Fri Mar 09, 2007 8:03 am

Are some these mods feisable for a jtm45??Let me redo this question can i use some of thes to give me a sother distortion Im not after the V H thing I have the wrong amp for that. just trying to smoth it out a little.Thanks .I will not hold no one responsable or blame them for me f^cking up my amp so if you know a few tweeks or a link in the forum lay it on me I have looked and looked and looked..Does no one mod these?..The pre amp is dam near dead on of the 100 watt, that I can see,,Thanks Darrell

MarkCameron · Post by **MarkCameron** » Fri Mar 09, 2007 10:21 am

awangotango wrote:wasn't that screw a simple bias adjustment, not a gain mod or MV.

Master volume... not a bias or line out. Iv seen and worked on a few Jose's with the master in that spot. Its not one of Jose's normal mods, just a simple master no push pull.

nitro · Post by **nitro** » Mon Apr 16, 2007 3:35 pm

I agree with you mark,i have said this in some of my threads about the van halen 1 sound, i use to talk to jose a couple times a month in the 80s, jose was a very nice man to talk to, jose explained to me that on van halen 1 there was no mods performed i will quote jose again " there was a overdrive-distortion pedal used i just dont know what kind it was"mods were performed on the second album a master volume was added to eds marshall plexi. Van halen 1 was more aggressive then the rest of the van halen recordings if you listen to van halen 2 that sounds more like a marshall with a master volume then van halen 1, it sounds like something was taken way with the van halen 2 recordings, less aggressive, in my opinion the thing that was taken away was a overdrive-distortion pedal.

rockstah · Post by **rockstah** » Mon Apr 16, 2007 5:09 pm

MarkCameron wrote:
awangotango wrote:wasn't that screw a simple bias adjustment, not a gain mod or MV.
Master volume... not a bias or line out. Iv seen and worked on a few Jose's with the master in that spot. Its not one of Jose's normal mods, just a simple master no push pull.

so jose turned ed's amp into a 2203 then.

MarkCameron · Post by **MarkCameron** » Mon Apr 16, 2007 8:50 pm

rockstah wrote:
MarkCameron wrote:
awangotango wrote:wasn't that screw a simple bias adjustment, not a gain mod or MV.
Master volume... not a bias or line out. Iv seen and worked on a few Jose's with the master in that spot. Its not one of Jose's normal mods, just a simple master no push pull.
so jose turned ed's amp into a 2203 then.

No

MarkCameron · Post by **MarkCameron** » Mon Apr 16, 2007 9:11 pm

nitro wrote:I agree with you mark,i have said this in some of my threads about the van halen 1 sound, i use to talk to jose a couple times a month in the 80s, jose was a very nice man to talk to, jose explained to me that on van halen 1 there was no mods performed i will quote jose again " there was a overdrive-distortion pedal used i just dont know what kind it was"mods were performed on the second album a master volume was added to eds marshall plexi. Van halen 1 was more aggressive then the rest of the van halen recordings if you listen to van halen 2 that sounds more like a marshall with a master volume then van halen 1, it sounds like something was taken way with the van halen 2 recordings, less aggressive, in my opinion the thing that was taken away was a overdrive-distortion pedal.

VH1 is the 2 marshalls(1 as a preamp 1as poweramp this was the live set up) VH2 is just the main amp cranked up. Jose's master was there from the club days. I think it was taken out around FW tour. Jose would tell people different things too.Ill be at the amp show, Ill bring the old Jose load box. Lets hook up some Metropoulos Super Leads and... Univox echo,echoplex, MXR flanger, Phase90

rockstah · Post by **rockstah** » Tue Apr 17, 2007 1:29 am

MarkCameron wrote:
rockstah wrote:
MarkCameron wrote: Master volume... not a bias or line out. Iv seen and worked on a few Jose's with the master in that spot. Its not one of Jose's normal mods, just a simple master no push pull.
so jose turned ed's amp into a 2203 then.
No

doubtful this was post phase inverter master volume in this position.
so if he added a master volume to the plexi circuit what else would it be other than prephase, cascaded ala 2203 master volume?

Ricky Lee · Post by **Ricky Lee** » Tue Feb 12, 2008 11:41 am

Anyone seen this before? Would not the chassis be aluminum if it were from the 66 era. 67 era steel chassis?

Mats A · Post by **Mats A** » Wed Feb 27, 2008 5:28 pm

MarkCameron wrote:
awangotango wrote:wasn't that screw a simple bias adjustment, not a gain mod or MV.
Master volume... not a bias or line out. Iv seen and worked on a few Jose's with the master in that spot. Its not one of Jose's normal mods, just a simple master no push pull.

Mark where is that master in the amps signal chain? Before or after PI

Grosh_Guitars · Post by **Grosh_Guitars** » Wed Feb 27, 2008 6:37 pm

has anyone tried this mod? replacing the 820's with 1.1k resistors?

BTW those 820 ohm resistors were carbon-comp and drifted in value up about 1.1K and make the amp much more gainy and warmer, since these re-bias the 12AX7 valves in a bit more non-linear region..

rockstah · Post by **rockstah** » Wed Feb 27, 2008 6:43 pm

yes i have - changing from an 820 to 1k on v2 will yeild less gain - thus what he saying - browning out the sound.

Grosh_Guitars · Post by **Grosh_Guitars** » Wed Feb 27, 2008 6:54 pm

rockstah wrote:yes i have - changing from an 820 to 1k on v2 will yeild less gain - thus what he saying - browning out the sound.

really? it says. 1.1K and make the amp much more gainy and warmer, since these re-bias the 12AX7 valves in a bit more non-linear

so your saying less gain?

rockstah · Post by **rockstah** » Wed Feb 27, 2008 7:17 pm

Grosh_Guitars wrote:
rockstah wrote:yes i have - changing from an 820 to 1k on v2 will yeild less gain - thus what he saying - browning out the sound.
really? it says. 1.1K and make the amp much more gainy and warmer, since these re-bias the 12AX7 valves in a bit more non-linear

so your saying less gain?

try it tell me what u hear.
if he means means gainy as in it gets fatter yes... but i dont hear that as gain. infact i hear less gain when upping the value here.