Debate on Eddie's Plexi

[motrock]

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.

And there you have it!

[rgorke]

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.

And there you have it!

Agreed, and we keep forgetting or ignoring that simple, yet significant fact.

So, what do we talk (argue) about now?

[Good Guest]

a slight change in the feedback circuit. I won't say anymore.

And there you have it!

So, what do we talk (argue) about now?

Resonace circuits Actually this thread has been pretty darn helpful and just finding out that it was 820 ohm/.68uf cathode combo platter has made my summer....No question this is the forum of forums when it comes to EVH...and the thread was reasonably civil to boot...

I do think tho that plexified is onto something regarding power transformers and inductors (chokes)...The same with variac tests regarding harmonics that leadguy pointed us too...

I remember reading an interview when marshall reissued there hand wired series on how they couldn't get the original tones because of electrical codes and materials regarding transformers and how all they could really shoot for were ballpark specs...

This same problem affected wahs if you remember the fuss about fasel inductors...when tests were done it was shown that more even order harmonics(warmer and richer) were created from the older materials than the present ones ..this is a problem that plagues the music industry as parts are made for performance characteristics as opposed to tonal characteristics.. we should be thankful that metro and racksystems are around addressing these issues. and grab them amps while we can...

[rgorke]

a slight change in the feedback circuit. I won't say anymore.

So, what do we talk (argue) about now?

Resonace circuits Actually this thread has been pretty darn helpful and just finding out that it was 820 ohm/.68uf cathode combo platter has made my summer....No question this is the forum of forums when it comes to EVH...and the thread was reasonably civil to boot...

I do think tho that plexified is onto something regarding power transformers and inductors (chokes)...The same with variac tests regarding harmonics that leadguy pointed us too...

I remember reading an interview when marshall reissued there hand wired series on how they couldn't get the original tones because of electrical codes and materials regarding transformers and how all they could really shoot for were ballpark specs...

This same problem affected wahs if you remember the fuss about fasel inductors...when tests were done it was shown that more even order harmonics(warmer and richer) were created from the older materials than the present ones ..this is a problem that plagues the music industry as parts are made for performance characteristics as opposed to tonal characteristics.. we should be thankful that metro and racksystems are around addressing these issues. and grab them amps while we can...

I fully agree as well. I find it very interesting that "we" got pretty darn close - based on the "Calling Rockstah Thread" and others - using ears and some detective work to get the spec that John, Dave and others have confirmed. I think Ed did the same thing vis a vis varciac and tone changes.

[vanhalen5150]

Time to mod those plexi's and try all this stuff out. If you can't hear it, it's nothing. Anything else is just talk now, just like most other internet sites and forums.

[rgorke]

Time to mod those plexi's and try all this stuff out. If you can't hear it, it's nothing. Anything else is just talk now, just like most other internet sites and forums.

"Nut up or shut up"

46 pages and counting over at the Gear Pages...

[StuntDouble]

...

[rgorke]

At this point, I could care less what Ed did; my search is over. I'm lowering the value of my filter caps down to 33uf, closing it up and calling it good...this thing is bad!

I'm with you. I have been very ver happy with my tone since I lowered my filtering.

[StuntDouble]

...

[pfrischmann]

So based on Dave's post, is the amp shared cathode in VI or is it just assumed V1-A is 250/820?

[vh junkie]

So based on Dave's post, is the amp shared cathode in VI or is it just assumed V1-A is 250/820?

Split cathode... 820/.68uf in v1 lead channel instead of 2.7k/.68uf

Also 820/.68uf on V2, though at some pint it may have been upped to a larger value.

[vh junkie]

Last time I'll say it, then I'll shut up about it. If you haven't tried a .68uf/2.7k combo on V2...assuming that the rest of your amp is setup like Ed's...basically what Mark layed out for us, then you're missing out.

OK! OK!
So 820/.68uf in v1 lead channel instead of 2.7k/.68uf
.68uf/2.7k combo on V2
.1 ufs in and out of the PI
.022, .039 or .047 lead channel coupling caps!

Right?

basically what Mark layed out for us

Can you show us where?

[redozzman]

Last time I'll say it, then I'll shut up about it. If you haven't tried a .68uf/2.7k combo on V2...assuming that the rest of your amp is setup like Ed's...basically what Mark layed out for us, then you're missing out.

OK! OK!
So 820/.68uf in v1 lead channel instead of 2.7k/.68uf
.68uf/2.7k combo on V2
.1 ufs in and out of the PI
.022, .039 or .047 lead channel coupling caps!

Right?

basically what Mark layed out for us

Can you show us where?

Here ya go:

Here is what our very own Rockstah says in the second post:

check list to evh:

330u/820 - .68u/820 split cathode
.0022u bright channel coupling cap
330u/820 v2a
33k/500p tone stack - 500p on the bright channel mix resistor
.1u in the phase inverter ( output coupling caps)
47k feedback resistor on the speaker tap ( 16 ohm feedback )

dual 16u preamp
32u PI cap
16u screens
50u mains

with everything on ten this is a real good start in evoking the dutch treat

Mark

Then on page 19 you get to the fifth modification (.68 on V2A):

viewtopic.php?f=3&t=11549&st=0&sk=t&sd=a&start=270

[StuntDouble]

...

[vh junkie]

yes, everything in my amp is now setup just like Mark described, with the exception of .68/2.7k on V2; you might not like it, but I find it to be nastier, meaner with some of that VHI goodness that the 330uf/820k combo lacks. You will have to dime the bass, or at least put it at 3 O'clock; I think that's a good clue that this is closer to Ed's early setup.

So let me get this stright, Dave is saying that there was a 440uf cap paralleled with the .68uf/820 prior to being setup with the 330uf/820 on V2?

Sounds like we are saying the 820/.68uf was there originally, so a larger resistor was added parallel (essentially swamping out the .68uf) to see if the additional bass was the way to go... eventually a larger cap was substituted for the .68uf all together.

I have started out by putting a 1k(instead of 2.7k) across the .68uf on v1. While I like the idea of putting a pot here (and may do it!), I don't think it was done on the amp in the picture (the joints in that area all look untouched). Immediately I noticed more string noise, was enticed to push the base side of the 1k frown curve on the EQ up to be more even with the right side.

When I initially started, I had the tone stack lifted, (as you said) returning the tone stack removed a lot of harshness.

Here is where I am now:
1k/.68uf on v1
.0022 coupler
820/330uf on v2
.0022 PI input coupler
.1uf output couplers
I always run all the tone controls dimed (sometimes turn the presence down a bit)