Debate on Eddie's Plexi

vh junkie · Post by **vh junkie** » Thu Jul 22, 2010 7:37 pm

vanhalen5150 wrote:
StuntDouble wrote:ahhhh....Dude! You guys just need to use your ears...F***k photos and timelines. Bump 820 up to 1k on V1 and it's perfect. Try this; it's all there!
I'm with you!

My apologies for being terse... I just want the timeline of the JS observations verses the MC pics... it would give us insight...

I always wondered why folks thought the fact that the 820 had drifted to 1K were even important... the 820 would have been on the unused normal channel??? Was it known before this that it was a 820, not the the 2.7k on the bright (used) channel before this? If it is right that both channels have drifted 820 to 1K, then that would make sense...

I'm sure the values you describe sound cool in your setup! ... but right now I'm trying to logically equate the JS observations to the MC pic... I don't think they are even the same amp... the timeline would help... if the MC pics were taken after the JS observations, that would make sense...

vanhalen5150 · Post by **vanhalen5150** » Thu Jul 22, 2010 7:50 pm

Didn't D.Friedman say this pic was it?

vh junkie · Post by **vh junkie** » Thu Jul 22, 2010 8:10 pm

vanhalen5150 wrote:Didn't D.Friedman say this pic was it?

Maybe it was IT... but when! Twenty... thirty... years after the late seventies? If JS saw it after this pic then his ability to suss solder joints is suspect, and everything else you attribute to him... this amp has been through so much... we gotta have timeline...

... I am not discounting that StuntDouble's setup was the one used in the golden years... I just wanna make sense of all of this...

Good Guest · Post by **Good Guest** » Thu Jul 22, 2010 8:57 pm

Your going to have to ask Mark C. for any info on when those pics were taken....perhaps there is a date on the back of them. He is the owner of Jose's tech shop...Wouldn't that place be a gold mine of info.

I wonder what he's got on the "golden amp" (JoseEVH joint venture) ..of which there were a few prototypes made.

Sometimes the forumites get too heady and they scare all the good sources away.

Hey Stuntdouble...can't wait to try those specs out ..The vibe of your posts are contagious..I can feel your excitement.

Good Guest · Post by **Good Guest** » Thu Jul 22, 2010 10:50 pm

Pics of caps manufactured in the last 20 years aren't going to cut it when trying to cross referance an old pic...the chocolate (yum yum cap) was probably a sprague...

Nowadays they call them "chocolate drop" ya know like sprague orange drop...used in plenty of old fenders...maybe Eddie swapped it out of his bandmaster.

All this chololate talk has got me craving a "dirty monkey"..on this hot summer night.

Talk about "brown sound"...

StuntDouble · Post by **StuntDouble** » Thu Jul 22, 2010 11:12 pm

RACKSYSTEMS · Post by **RACKSYSTEMS** » Fri Jul 23, 2010 1:12 am

Jeez the pic was taken some how after I got my hands on it. This is the state it is in now. V1 820/.68 v2 820 330uf. Originally v2 .68 and 470uf supposedly. Stop all this silly stuff it was a stock 12 series amp with 2 changes the 470uf on v2 with a .68. Filtering of that era and a slight change in the feedback circuit. I won't say anymore. Remember you are trying to recreate a recorded tone. Its not how the amp sounded in the room period. Add the signal chain and the bias turned all the way hot and then dropped with the variac and also remember it had a latter jmp output transformer and choke installed at some point.

StuntDouble · Post by **StuntDouble** » Fri Jul 23, 2010 1:20 am

leadguy · Post by **leadguy** » Fri Jul 23, 2010 2:09 am

By the time these pictures were taken (if they are it), then I assume it would have been through a few techs like Peter Van Wheelden and who knows who else and who knows what they did to it.

I would say that there is a good chance that the amp started out like the amp 34 serial numbers away.
Maybe VH1 is the amp in the original state (ie 34 serial numbers away).

Try it and if it doesn't work for someone then ditch it.

The amp 34 serial numbers away is not magic or anything like that, but it does have a very mids/upper mids based gain EQ.

leadguy · Post by **leadguy** » Fri Jul 23, 2010 4:20 am

There is an old Sesame Street song about

"One of these things is not like the others,
One of these things just doesn't belong,
Can you tell which thing is not like the others
By the time I finish my song?"

spaceace76 · Post by **spaceace76** » Fri Jul 23, 2010 4:31 am

there's a really large electrolytic where there should be a .68µF. that's pretty weird

leadguy · Post by **leadguy** » Fri Jul 23, 2010 6:57 am

Yeah, it looks like a 330uf capacitor across V2's 820 ohm cathode resistor.
When it was added, who knows?

The 820 ohm resistor/.68uf capacitor combo on V1 starts rolling off the bass at around 431 Hz and the 820 ohm resistor/330uf capacitor combo on V2 starts rolling off the bass at 10 Hz or less and has all frequency gain including bass gain.

The 820 ohm resistor/.68uf capacitor combo on V1 starts rolling off the bass around the 5th fret on the 1st string and the 820 ohm resistor/330uf capacitor combo on V2 starts rolling off the bass below the low E string so there is a lot more bass in this circuit.

So the 820 ohm resistor/.68uf capacitor combo on V1 gives a mids/upper mids boost and the 820 ohm resistor/330uf capacitor combo on V2 gives a more bass boost. So there is a fair amount of bass in this circuit.

The original 820 ohm resistor/.68uf capacitor combo on V1 and 820 ohm resistor/.68uf capacitor combo on V2 gives a double mids/upper mids boost with the bass rolloff starting around the 5th fret on the 1st string for both V1 and V2, producing much more mids/upper mids and not a lot of bass. FWIW, this .68uf capacitor on V2 is closer to VH1 IMO and the 330uf capacitor on V2 would be closer to later Ed.

Guitar open string frequencies

E - 82.4
A - 110
D - 146.8
G - 196
B - 246.9
E - 329.6

A 5th fret on 1st string - 440
E 12th fret on 1st string - 659.2

vanhalen5150 · Post by **vanhalen5150** » Fri Jul 23, 2010 7:10 am

spaceace76 wrote:there's a really large electrolytic where there should be a .68µF. that's pretty weird

I kept thinking the same thing......

leadguy · Post by **leadguy** » Fri Jul 23, 2010 10:13 am

Jeez the pic was taken some how after I got my hands on it. This is the state it is in now. V1 820/.68 v2 820 330uf. Originally v2 .68 and 470uf supposedly. Stop all this silly stuff it was a stock 12 series amp with 2 changes the 470uf on v2 with a .68. Filtering of that era and a slight change in the feedback circuit. I won't say anymore. Remember you are trying to recreate a recorded tone. Its not how the amp sounded in the room period. Add the signal chain and the bias turned all the way hot and then dropped with the variac and also remember it had a latter jmp output transformer and choke installed at some point.

Thanks Dave.

So as I read it, Ed's amp started with a 820/.68uf on V1 and a 820/.68uf on V2 and then Ed had a 470uf cap in parallel? with the V2 .68uf cap (which would basically be the same as a single 470uf, ie 470.68uf, parallel cap values add together) and this is John Suhr's more bass mod that he saw in the early 1990s and then both V2 caps were removed (470uf and .68uf) and now there is a 330uf cap on V2.

http://forum.metroamp.com/viewtopic.php ... &view=next" onclick="window.open(this.href);return false;

I would also say that if Ed had a 470uf and .68uf in parallel on V2, that it points to the 470uf cap not being totally permanent and the white knob might have possibly been involved in this as well.

So basically a stock transitional Plexi in one form or another and the variac/bias and Echoplex Phase etc do matter in the rig and so does Ed's playing.

joejoegun · Post by **joejoegun** » Fri Jul 23, 2010 11:37 am

So... does anyone have a guess as to what these big brown caps. are?? I have some old sprague orange drops that are pretty close to that size that are .1uf.. however i dont see the point in swapping out that one brownie in the first stage of the normal channel, since Ed never used this channel anyways, unless it was cascaded...

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