George saw Ed's amp? Spill some beans Mr. Velvet!

[N3m0 7h3 Fi5h]

Is there any idea or any particular reason .. why does in the past he was using these 2 variacs..? For back-up units purposes ? Why does then.. he put tape, to cover body and input section variac on the right...?

Http://www.halen.com/images/uploads/EVHP-2_8006001.jpg" onclick="window.open(this.href);return false;

[efraser68]

This could be a second variac ran *in between* the amp and a cab.

[Strat78]

tubelife is also better if you get power supply sag.instead of seeing 450v or so, the power tube plate voltage is often around 390v when cranked

That seems to be another pluss, thanks Roe. Anybody compare the Marstran T2562 to the Magnetic Components Classic Tone version? Seems like there are some here who realy dislike Magnetic Comp, why?

[rgorke]

Is there any idea or any particular reason .. why does in the past he was using these 2 variacs..? For back-up units purposes ? Why does then.. he put tape, to cover body and input section variac on the right...?

Http://www.halen.com/images/uploads/EVHP-2_8006001.jpg" onclick="window.open(this.href);return false;

My guess, is that the gear is falling apart and they taped it because the cables were being strained. Here is a picture taken from further back. Although the variac between amp and cab is a feasible response, this is where volume is not an issue. My guess is that it is just a variac for one of the other amps.

[N3m0 7h3 Fi5h]

-edited message- ....

[sixpakldp]

Any idea what kind of pre amp tubes he was using and position?

[EddyInChicago]

Sylvania 12AX7WA

[vanhalen5150]

Interesting the dials were always pointed upwards. Secret.

[pfrischmann]

These specs George ???

Split cathode V1a 250uF/820,V1b .68/820
All coupling caps are 0.022uF,Bright channel coupling cap is 0.0022uF

470k mixer resistors
500pf [red out of 69 amp] mixer bypass cap
Bypass cap on V2a is .68uF and a 220uf to 470uf
33k/560pF lemco tone stack combo
100k NFB resistor at 4 ohm tap
220k bias splitter resistors
0.1 uF cap on presence control
.022uf output couplers

filtering is
2] 100uf's f&t in series mains
2] 32uf's f&t in series screens
1]100uf lcr phase inverter
1] dual 33 x 33 f&t preamp

I've never understood something...
V2a is a .68 AND a 220,330 or 470uf?
I can barely keep the base on 3 with just a 330..am I missing something?

[Tone Slinger]

I think we are missing picture PROOF of Ed's circuit in the pre 1980 days. Based on what George M. and original old pics of 12xxx plexi's, I'd say that the straight Metro 12xxx circuit spec is about what Ed's was on the first couple VH albums, 16 ohm tap and all. After Van Halen started making a little money (by the end of the second tour I'd say), then Ed's amp was raped by who knows how many techs.

[dirtycooter]

I dunno but the pic of those TWO ECHOPLEXES IN SERIES just solved another thread I started.
Concrete evidence for my "anti reverb use delay only" shtick.
Two tap delay before the term "two tap" was ever coined
Set just right it adds to the feel factor x10 for some things.
Remember he wasn't haulin sunset behind him on a trailer or a plate reverb.
Crafty bastard
Note the EQ in there... in the echo area
I think he was w/d before w/d was even invented. S O a B!!!!!!!!

[stef]

I agree - stock 12000 spec and couple of ep3's, phase90 and flanger.. EQ

[N3m0 7h3 Fi5h]

1. TWO ECHOPLEXES IN SERIES :
Two tap delay before the term "two tap" was ever coined.
2. Note the EQ in there... in the echo area.
3. He was w/d before w/d was even invented.
4. S O a B!!!!!!!!

Good Eye Dirtycooter..!
Indeed.. S O a B!!!!!!!!

[fivecoyote]

I dunno but the pic of those TWO ECHOPLEXES IN SERIES just solved another thread I started.
Concrete evidence for my "anti reverb use delay only" shtick.
Two tap delay before the term "two tap" was ever coined
Set just right it adds to the feel factor x10 for some things.
Remember he wasn't haulin sunset behind him on a trailer or a plate reverb.
Crafty bastard
Note the EQ in there... in the echo area
I think he was w/d before w/d was even invented. S O a B!!!!!!!!

That is a frickin' tremendous observation. Wow! Thanks DC!

[erigm]

Hey guys,

Just to clarify this variac between amp and speaker thing ... I got the idea from Chris ******, and I think it was on a thread at the plexi palace BB. He never said that Ed used this technique, but was just pointing out that it was a way that you can use a variac as an attenuator. Running a load in parallel with it keeps it from squealing/oscillating, because as you turn the variac down the load the amp sees goes towards infinity, so the load in parallel keeps the load the amps sees never higher than that. It works really well! I wish I had two variacs, one for 90V out of the wall, and the other between amp and speaker. I may just get a 120V -> 90V stepdown transformer for my wall socket, and then use the variac as an attenuator. Try it! You have to get an extension cord , cut it in half, and put 1/4" ends on it, but it's pretty cool.