C*rr*m Mod?

[leadguy]

Look, to work out if the C e r r e m mod is BS or not, just trace the sources of where it came from.

The C e r r e m mod appeared on Plexi Palace by a post from this Dutch? Plaap weirdo.

C e r r e m said that Plaap ripped off the post from a C e r r e m post on Usenet ages ago.

So Plaaps is full of BS.

The C e r r e m mod is a C e r r e m invention ie

"The amp was either left stock into a load resistor or, a big Ohmite(or other) power resistor was placed somewhere in the circuit to cut the power of only the output stage meaning Sylvania 6CA7's were the only valves to hold up to this."

This is from a Usenet C e r r e m post.

C e r r e m''s Ed amp is wrong. It is not the right circuit for any of Ed's main amps according to what Dave Friedman has said about the wood plexi and the main white knob plexi circuits and other Ed amp circuits.
C e r r e m also wrote that stuff about the 20 ohm load resistor and H&H amps for VH1 which is all wrong and started the Ed VH1 slaving BS.
The load resistor and H&H's were published in a mid 80s guitar magazine and that's where C e r r e m got it and transposed it back to VH1 based on a feeling and no proof.

Jeez what BS.


(2) By ******. 1980.
To try to wrap up is ED thing...
His head was a 67/68 and he had the first stage valve with BOTH cathodes tied together sharing the same 820 ohm resistor that was bypassed with a 330uF blue cap...

His treble cap was a round shaped ceramic that was a 250pF that said MURATA ... With 56K on the tone circuit feed..

One of the 470K mixer resistors was bypassed with a round hollow tubular MURATA cap 500pF... If memory serves me right on the value, or it was a 330pF..I will check my notes....

The real kicker, his phase-inverter "get-rid-of-the-FIZZIES" cap was a 100pF instead of the normal 47pF ....and this my friends is how the "brown sound" with that added compression happens..

Oh, 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..

I am pretty sure the feedback resistor was a 47K ...I will have to check my notes...

The filter cap in the center of the board was a dual 16uF gray RS cap...

The screen filtering was 2 DALY 32uF light-blue caps in series... The voltage doubler were 2 100uF DALY royal-blue caps...

Rear cap on top of chassis was a royal-blue HUNTS 32uF or 16uF...need to check notes..

The value of the coupling cap between V1 and V2a....022uF.

At least that was what it was in 1980...


(3) Plaap (a friend of Peter Van Wheelden who restored Eddie's amp.)
Edwards amp's internal measurements were as follows:

1.The first 820 ohm resistor (carbon type) measured a little over 1K. It was bypassed with a blue 330uF resistor. can

2.His treble cap was a 250pF Murata flat ceramic one. The cap across his 470K was a Murata hollow round 330pF. cap

3.His second stage 820 ohm (which also measured a little over 1K, was also bypassed with the exact same type 330uF blue colored cap that was on the first cathode resistor.

4.The filtering caps for the middle of the board were gray colored RS caps that had dual 16uF values.

5.The screens were 2 blue caps in series (DALY 32uF's).

6.The voltage doubler were two big blue caps (100uF DALY's). The one on the outside was a blue Daly - and was a single 32uF.

7.The feedback resistor was a 47K of unknown origin.

8.His power transformer was the smaller one of that era. His OPT was also the smaller one with 1.5" stack.

The amp was either left stock into a load resistor or, a big Ohmite(or other) power resistor was placed somewhere in the circuit to cut the power of only the output stage meaning Sylvania 6CA7's were the only valves to hold up to this.

If this is true - doesent this kinda dispel the whole 'special' 67 slp 100 myth ...as almost all amps of that year had pretty much identical configurations (with the small exception of the 330uf cap on the second preamp stage?

Dankuwell !(dutch for many thanks)
Plaap

[rgorke]

Based on what Friedman has said, what Suhr has said, and many results e.g. Philip's Metro build it EVH's magic marshall was largely if not completely stock. All these fancy smancy mods and what have you are fun to fantasize about not in the realm of reality.

Can we move on to what Rockstah is up to?

[vh junkie]

... original post deleted ...

[vanhalen5150]

Based on what Friedman has said, what Suhr has said, and many results e.g. Philip's Metro build it EVH's magic marshall was largely if not completely stock. All these fancy smancy mods and what have you are fun to fantasize about not in the realm of reality.

Can we move on to what Rockstah is up to?

I agree, George's stock 12000 he sends you in pieces, is 98% EVH. The tweaks of that for the other 2% are really only noticable by the person that has put time on the amp playing it. Everyone else says "dont change a thing". I played a real 68 a few months ago. My metro was much better sounding. Guy was asking $4500.00. Neeeh.....I'll buy another kit from George before I'd ever do that.


If any one can tell me how to do the Kerrem mod to a 50 watt Sovtek with 6L6's in it I'll give it a go. I have a lot of different value resistors. Couple dynamite versions too. Pin 3 would be which pin on a 6L6? Perhaps it will shock my ass and give me some sort of superpowers.

Who is Rockstah?

[vanhalen5150]

Pin 3 seem to be the same. Any word on how this sounds with a 50 watt?

[vh junkie]

The resistor goes across the plates (HI voltage!)... which are connected to each side of the OT primary... so the resistor is in parallel with the OT primary.

Twisty was using 1300 ohms across a 1750 ohm primary. The relationship would be the same if you used 3k across your 3.5k primary (typical for a 50w). Might start with 4k and work your way down.

[vanhalen5150]

So it reduces the volume and adds distortion...hows that? I understand the volume but not the distortion part. Ill try to find a variable resistor. 25 watts?

I'm thinking this.

http://www.sourceresearch.com/store1/qu ... &do=detail" onclick="window.open(this.href);return false;

[vanhalen5150]

The resistor goes across the plates (HI voltage!)... which are connected to each side of the OT primary... so the resistor is in parallel with the OT primary.

Twisty was using 1300 ohms across a 1750 ohm primary. The relationship would be the same if you used 3k across your 3.5k primary (typical for a 50w). Might start with 4k and work your way down.

Wouldn't his primary be much higher than that?

[vh junkie]

The resistor goes across the plates (HI voltage!)... which are connected to each side of the OT primary... so the resistor is in parallel with the OT primary.

Twisty was using 1300 ohms across a 1750 ohm primary. The relationship would be the same if you used 3k across your 3.5k primary (typical for a 50w). Might start with 4k and work your way down.

Wouldn't his primary be much higher than that?[/quote]
A typical 100w amp has a 3.5k OT primary impedance, roughly double the 1.75k OT primary impedance of a 50w


[quote="vanhalen

So it reduces the volume and adds distortion...hows that? I understand the volume but not the distortion part. Ill try to find a variable resistor. 25 watts?
I'm thinking this.
http://www.sourceresearch.com/store1/qu ... &do=detail" onclick="window.open(this.href);return false;

5150"]
Twisty was using 50w resistors. If this resistor is 50w for the whole 5K, is it only 10w when adjusted to 1K?

As far as distortion goes, the tubes are working harder, and the NFB loop is beginning minimized...

[vanhalen5150]

OK, you said 3.5 was typical for a 50 watt though. I thought I read 100 w are around 6K?

[vanhalen5150]

The relationship would be the same if you used 3k across your 3.5k primary (typical for a 50w). Might start with 4k and work your way down.

[vh junkie]

I should start by saying Ed had really cool sounding basically stock plexi... I THINK he was looking for ways to make it quieter in the club days, and stumbled onto some interesting things. The variac was the first step... it reduced the volume and gave introduced the brown sound.

I think other things were tried... this MAY have been one of them... there is something is different between VH1 and VH2... VH2 sounds to me like the unadulterated head variaced... it has a intensity of grind that isn't there on VH1...

OK, you said 3.5 was typical for a 50 watt though. I thought I read 100 w are around 6K?

Nah... as one of my tests for possible ways to reduce volume, I ran my 100w head thru a 50w OT... you get the volume reduction, but the tubes aren't working hard enough... the 100w OT has half the primary impedance of the 50w OT...

Back to the witness statements about the amp:
How would any of these guys know if two tube socket pins had ever had an extra wire soldered to them... most ugly power tube failures require the sockets to be replaced because the arcing between pins leaves conductive carbon residue!

[vanhalen5150]

So your thinking a 50 watt resistor at about 4K first. I'm gonna give this a try when I get the resistors. 4,3,2,1, maybe a 470ohm.

[vh junkie]

So your thinking a 50 watt resistor at about 4K first. I'm gonna give this a try when I get the resistors. 4,3,2,1, maybe a 470ohm.

I'm not sure I would go below 3. Going lower is will get you sicker sounds at lower volumes, but what's the point? Just more likely to lose tubes and OTxs.

If I were you I wouldn't do this AT ALL!
I started this thread to see if anyone here had tried this, and what they thought of the tonal results... I have the resistors to do this now... but I'm still going to investigate more... look into fusing the individual tubes first, etc... I have a 2" core Drake clone ready to go to replace the 1.5" Dagnall clone OTx... hope it doesn't come to that!

[vanhalen5150]

It's an amp I'm thinking of gutting anyways. Besides there is a voice in my head saying "do it".