Debate on Eddie's Plexi

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leadguy
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Re: Debate on Eddie's Plexi

Post by leadguy » Wed Jul 21, 2010 3:00 am

Now, let me see if I've got this straight:
a) 820/.86uf on first stage instead of 2.7k/.68uf
b) VH1 is recorded with this circuit
c) Something like this circuit is added before VH2 is recorded
d) Pics of the "amp" that show a 250uf or 330uf cathode cap on the cathode follower AND a ~1000pf coupling cap, areof a different amp entirely...
Basically yes.
It doesn't come from my opinion or whatever, it's from John Suhr bits about Ed's white knob Plexi circuit and a comparison to a Plexi circuit that is 34 serial numbers away from Ed's that just so happens to match.

a) 820/.68uf on the first stage and a .68uf on the second stage
b) good chance that it was
c) seems like a bass mod was added at some time, maybe after VH1
d) that doesn't seem to be the white knob Plexi
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Re: Debate on Eddie's Plexi

Post by bob barcus » Wed Jul 21, 2010 5:22 pm

I found the secret,Resonance,Thats why its on the first 5150 PV In a GW from 1985 it says what it does to give the bottom more headroom ect.Now we can all get a life :roll:

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Re: Debate on Eddie's Plexi

Post by vh junkie » Wed Jul 21, 2010 5:30 pm

I always thought resonance controls were to make the bass fuller at lower volumes... so much of the VH sound seems to be about the whole amp working hard... I had thought about adding one, but always thought it would just make the bass flubby with amp dimed.
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plexified
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Re: Debate on Eddie's Plexi

Post by plexified » Wed Jul 21, 2010 8:37 pm

a few things ....

Eds pickup had the front coil shorted from fan picking and the high e getting stuck with deep dives

Suhr claims a jack on the back panel was to 'lift the power tube cathodes' ? WTF :shock:

Whats a few stock Marshall parts amongst friends 8)

Actually , my origional 12 series has been from stock clean and mean to full blown Harry Kolbe modfest . It sounded killer to start but the mod was for EVH . He added a separate high voltage power supply . Mostly the later 69 set up , but leaving the existing filters . So 50uf cans . And put the preamp on high voltage too . He had a stock input and his preamp mod . It consisted of a bi fet pre amp and the mod leadguy just outlined . Hey it sounded very versitile . It also had the Jose Mod cause Kolbe knew the guy . I thought it was bullshit cause I heard the same mod in a perfectly good sounding JCM800 and it ruined it .

My 12 series however , just sounded killer . One day I went to buy a 69 Super Trem from a guy who didn't have stock Marshall Cabs . He plugged into mine and it was the best tone ever . Imagine Dirty Movies through two cabs just dancing on the floor . He wouldn't sell it . He kept it . Fucker .

I say that because I restored the Plexi to stock specs and then to Cerrum specs and it kills no matter what. Not as much variation as you would think . Even with the variac . Food for thought though .

I do hear Ed using a second variac . I've said it before . I've used it in between the amp and the speaker and it gives a volume reduction and a shimmer that is just like 'Push come shove' . NO harminizer . It may have been a factor turning him on to the harmonizer . He just used it initially at 10ms for a fatness and early stereo testing with the RIPLEY ! woo hoo

BUT , you guys miss the most important fact I have been talking about for years now .

The transformer Ed prefers is the later BIG 69 OUTPUT . He favors it for the volume the grind and the harmonics galore !

In the 12 series the magnetics are now completely a factor . Affecting the caps under it and the circuit becomes more of an enigma . Oh and don't forget the choke ! For a reason .

All the mods you guys are talking of are cool and standard mod tweaks , but all of which can be tweaked with an EQ up front .

What year did Jose Die ? Thats a big deal on the timeline .

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Re: Debate on Eddie's Plexi

Post by bob barcus » Wed Jul 21, 2010 9:14 pm

mid 90's Why did he use a SD-1 with his 5150

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Tone Slinger
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Re: Debate on Eddie's Plexi

Post by Tone Slinger » Wed Jul 21, 2010 9:35 pm

I think we ALL need to back up our words with some clips (I KNOW I am).
Rip Ben Wise (StuntDouble) & Mark Abrahamian (Rockstah)

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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 2:33 am

John Suhr doesn't really know what the white knob was for because it wasn't there when he saw the amp in the early 1990s. He's just guessing like the rest of us. It could be a more bass, a standby switch, a master, a resonance, a bias, a half power, a etc etc.

What John Suhr knows is the circuit values and what original solder joints have been resoldered.

Apparently from the solder joints, Ed did not have a cascade or anything like that because there was only one place in the preamp where the solder joints are not original and that was for a more bass mod and the cathode resistors and capacitors are still original so the bass mod seems to be in the treble peaking (or mixer) circuit 470k/470pf. The treble peaking 470k/470pf circuit is a common place to mod as a on/off bright/less bright (more bass) switch or just a permanent less bright/more bass mod. The white knob was possibly connected to the more bass mod.

So we know what circuit the white knob Plexi is and that it's had some sort of simple bass mod by the time John Suhr saw it.

If anyones got a Plexi modded to Ed's white knob Plexi values and a Echoplex and a vintage style cabinet and a variac etc etc then post a clip otherwise there is no real point in just posting a clip of a generic Plexi with say a bass circuit, there are many of those.
Last edited by leadguy on Thu Jul 22, 2010 6:38 am, edited 5 times in total.
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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 3:01 am

Steve Fryette, owner president of VHT amps basically says the same things as John Suhr about Ed's amp

"but I recall that the circuit was actually closer to a 70 JMP than it was to a plexi, something I attributed to this possibly being a transition model, seeing as how it had a plexi panel, but apparently the newer input and feedback configuration."

===============================================

"Having worked on the supposed IT amp on more than one occasion, I can speak first hand on some of this.

First of all, hate to blow anyone’s bubbles, but there’s not a thing especially outstanding or unique about this amp. Matt Bruck brought what he said was Eds main amp to me in 1990/1 to “bring it back to life” He said Ed felt it just wasn’t the same as it once was and thought the output transformer was “getting weak”. I told him OT’s don’t get weak, but went ahead and checked it out from top to bottom and found not a thing wrong with it at all. In fact it was bone stock and rather clean inside. It sounded like a stock Marshall, put out full power and all of the caps were in good shape. I might add, and this is just from memory, but I recall that the circuit was actually closer to a 70 JMP than it was to a plexi, something I attributed to this possibly being a transition model, seeing as how it had a plexi panel, but apparently the newer input and feedback configuration. All that aside, Matt insisted that something needed to be done so I gave it a complete once-over and I then took the liberty of installing a Pittbull Classic output transformer into it to see if anyone would notice. Upon getting it back, Matt told me that they noticed no difference in sound and they still thought it sounded weak. I just presumed that something else was amiss or had changed and thought no more about it. I still have the receipt and copy of the check for the work signed by Ed, in case anyone wants to try to discredit this claim. I don’t usually talk about it, because frankly Scarlett…but since you went to the effort of posting this here, I though it might be fun to respond to some of the idiots history items:
"When your swinging, Swing some MORE" ~Monk

leadguy
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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 3:28 am

I think what this dude says in the reply makes a lot of sense

http://www.thegearpage.net/board/showth ... 79&page=40" onclick="window.open(this.href);return false;

Quote:
where did blix dime his plexi, I mean apart from a football stadium, you simply could not dime a plexi , which is probably pushing out 125 watts +


I dime mine all the time. I also dime my 100w and 200w HIWATT's!! You cannot make an assesment with the amp on "2". You have to get to jet engine volume levels to really hear what the amps will do. I agree that there are other factors involved in getting that sound...specifically, and I mean DEAD ON EXACT VH1....you simply have to take into account EVH, the signal chain from guitar to amp, the speakers...the # of speakers, the room, and the recording process. You cannot just look at the amp. Ralle posted some very convincing clips with his modded amp. Blix and Peter posted some great ones also with the stock circuit. The one person in this whole thread that has actually been inside the amp, played thru the amp, and heard Ed play thru the amp in person has said the sound was there. He also said that the amp was for all intentional purposes stock. Although it had and extra component for added bass in the bright channel and there were a few oddball , but stock, parts that would have an effect on the gain. Maybe the reason that no one can really figure out the big mystery is that there simply isnt one..you had a really great and unique player, a really great Marahall, and a really great producer and engineer using some great recording equipment. None of us were there in the studio when the album was being recorded. So all we can really do is speculate. But it has been a very interesting discussion and I have learned a few things from it.
"When your swinging, Swing some MORE" ~Monk

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Tone Slinger
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Re: Debate on Eddie's Plexi

Post by Tone Slinger » Thu Jul 22, 2010 9:04 am

The filter caps being of lower values was the key to these late '67/early '68 Marshall Super Leads. Obviously that (filtering) along with having the split cathode and higher preamp gain, which was stabalized by mid '69 .

To dime an amp (Metro's 12xxx or original) like this would obviously make a later model ('69-'73 ptp or '74 to now pcb) super lead sound a bit stiff and harsh in comparison, on AVERAGE that is.

I DO think that it is important here for players to post clips of 1959/1987 circuit amps. I mean, nothing is 100 % substantiated here from the Horse/s mouths (namely Ed and Jose, who is obviously ascended). A solder joint from '67 that was resoldered in '77, would possibly be hard to tell.

The EXACT circumstances of getting the first Van Halen albums guitar sound will NEVER happen again. Equipment aside, that time is long gone. The air is different, the electric current,etc,etc.

REALITY NEVER REPEATS ITSELF !



Having said this, I think I'd like to hear as many 'ATTEMPTS' at this elusive sound as possible. The only starting point should be that a 1959/1987 circuit amp, along with the use of greenbacks, should be the platform, and even this may be speculative to some.


Lets get the clips going again !
Rip Ben Wise (StuntDouble) & Mark Abrahamian (Rockstah)

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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 10:13 am

I believe John Suhr because too many things add up like a circuit 34 serial numbers away being identical and Steve Fryette saying it's a split cathode as well.

One of the differences from the Metro 12 series if this is the 12 series layout http://metroamp.com/wiki/index.php/Metr ... _'68_specs" onclick="window.open(this.href);return false; is the first treble channel tube stage has a 820 ohm resistor instead of a 2.7k resistor and the 820 ohm resistor/.68uf capacitor combo produces more gain and the gain is at higher mid frequencies than the 2.7k resistor/.68uf capacitor combo, so the amp is really EQ'd up pretty high in the mids and the mids are further accentuated by the .68uf capacitor on the second stage tube just before the cathode follower/tonestack and there is the treble peaking 470k/470pf combo as well accentuating the highs so that adds up to a bright amp and a bass mod would be a thing that quite a few players would have done with a circuit like this.

The 820 ohm resistor/.68uf capacitor combo starts rolling off the bass at around 431 Hz and the 2.7k resistor/.68uf capacitor combo starts rolling off the bass at 232 Hz and has less gain.

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

The 2.7k resistor/.68uf capacitor combo starts rolling off the bass around the open B string and the 820 ohm resistor/.68uf capacitor combo starts rolling off the bass quite a bit above the open E string, say around A on the 1st string 5th fret.

So John Suhrs 820 ohm resistor/.68uf capacitor combo Ed circuit starts rolling off the bass at a higher mid frequency and with more gain which means more mids and less bass.

For comparison a bass circuit with just a 330uf cathode bypass capacitor would start rolling off the bass at 10 Hz or lower and the bass rolloff starts lower than the low E string which is 82.4 Hz so there is a lot of bass in the bass circuit.
"When your swinging, Swing some MORE" ~Monk

leadguy
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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 12:17 pm

Getting back to what Steve Fryette says he saw, John Suhr says this

“The only change, besides the minor tweaks when I saw it, was the VHT transformer [Steve Fryette, founder and former owner of VHT, worked on the head at one point and replaced the output transformer]. My job was to replace that transformer with a donor from another plexi with a similar circuit and close serial number that belonged to Matt [Bruck, Ed's former tech and now assistant].

Steve Fryette says this

"I might add, and this is just from memory, but I recall that the circuit was actually closer to a 70 JMP than it was to a plexi, something I attributed to this possibly being a transition model, seeing as how it had a plexi panel, but apparently the newer input (ie split cathode) and feedback configuration."

and this

"All that aside, Matt insisted that something needed to be done so I gave it a complete once-over and I then took the liberty of installing a Pittbull Classic output transformer into it to see if anyone would notice."

and then after John Suhr the amp went to Peter Van Wheelden that was also mentioned by Ed in an interview

John Suhr says

"After me [the amp] went to Europe [presumably to Peter Van Wheelden, documented in an old issue of one the guitar mags]and everything was rewired and became a mess he [Ed? Matt?] wasn’t happy with. I believe Dave [Friedman] has the amp right now and is trying to breath life back in to it…."

So the amp goes to Steve Fryette who replaced the output transformer and then to John Suhr who did the same thing and then to Peter Van Wheelden.

Now it's pretty obvious that John Suhr and Steve Fryette are basically saying the same thing, so chances are there is no BS involved.
"When your swinging, Swing some MORE" ~Monk

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vanhalen5150
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Re: Debate on Eddie's Plexi

Post by vanhalen5150 » Thu Jul 22, 2010 12:49 pm

There could be a dozen "minor tweaks". Filters, Screens, numerous value changes etc.

I wouldn't call that a stock amp myself.
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leadguy
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Re: Debate on Eddie's Plexi

Post by leadguy » Thu Jul 22, 2010 1:13 pm

If the Filter caps are replaced by the same values and the screens are replaced by the same values, then what?

One of the stock oddball transitional parts that John Suhr mentioned that produces more gain is the 820 ohm resistor on the first stage in the treble channel.

I've already listed the circuit parts of a Plexi that is 34 serial numbers away from Ed's that syncs in with the John Suhr Ed circuit values, so compare those parts with earlier and later Plexi parts to find the stock oddball transitional parts that can produce more gain and a different EQ.
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plexified
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Re: Debate on Eddie's Plexi

Post by plexified » Thu Jul 22, 2010 1:21 pm

Helloooooo McFly ? what part of the explanation involving the output transformer being replaced and the choke being replaced does not register ? You guys are bantering about the innards of a stock circuit , but neglect the impact of massive voltage altering effects let alone magnetic effects on the tone hence the changed otx & choke . I spoon fed this obvious elephant to you all years ago , still . still you walk right past it :roll:

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