The secret EVH amp part

[jnew]

Guess I need to be a bit careful about this one but I know many here know what it is I'm talking about. Has anyone tried going the other way with this? Talking about the value of that secret part. Does killer wonders on the low end. Thoughts?

[bobtec]

I did n't know we keep things a secret here,even Mark A gave up alot and Dave F too The secrets kept hidden here at MA are overwheming ,can't get a word out of anyone lol...Free Masons

[jnew]

This is the only thing I've ever kept quiet about and that's just because I gave my word. Truthfully though, even if it's true (and there are lots of supporting hints and facts) it won't be for every amp. Every amp is different and for some, it won't be right or even good for that matter. My amp is one of them but it did open my eyes (and ears) to different possibilities.

[Tone Slinger]

I think that what you described in the first post about the secret part is a great thing to try. Scooping things seems to always tighten up the bottom end by default. The inherent tone and voice of the amp wouldnt be drastically altered.

This leads me to wonder what the other 2's value could do if raised/ lowered.

[jnew]

Yes. I've thought about that too. I've actually begun to seriously consider that ALOT of magic EQ shaping can be effectively tweaked in these areas. Therefore a completely stock value circuit board can more easily be made to get "THE SOUND". I received a PM the other day from someone who's secret part measured quite far off what the stock value should have been. (considerably lower in fact) As we know, those parts from back in the day had mucho drift going on. Some would have by default, found that awesome EQ shape while others would have not worked out so nice but I believe this will be the area I will focus on for a while. When I built my amps, I just put in those stock values and assumed that was that and that there wasn't much of anything to monkey with. DOH!

Hey, while I've got you guys, what material were those chicklet .68's. Were they polypropylene? Polystyrene? I've got some vintage WIMA's but I think those are metallized.

[Tone Slinger]

You talkin bout the yellow box looking Phillips .68's on alot of the '70's era Marshalls ? If so, I think they are metalized film/polyester like the Sozo's or Mallory 150's.

[jnew]

Those are metalized? Could have fooled me. They look like little blocks of yellow plastic. lol. Was just curious.

[motrock]

Secret part huh? LOL I really don't think there are any secrets left. Hell, Dave F posted the specs some years ago. If everyone just stuck to those specs they would nail it. Thats why I am having my Plexi tweaked to those specs. Just had a friend that changed 3-4 parts and he nailed it on his VariPlex. I think the big "secret"; of which really isn't a secret, is that people are getting half the gain out of there amp due to the Negative Feedback. I see a lot of folks doing 47k 8ohm tap. Which is like half the gain you could be getting. Eddie's amp was 100k 4ohm tap. My friend just did this to his amp is he said it has all the gain you could ever need. Plus the other weird thing.... the big 330uF cap on the cathode. I think thats what the location is called! LOL Can't remember off hand. Anyway; my buddy had the same thing in his amp and they switched it out to .68uF; which is standard in Plexi's. That takes care of the awesome upper mids that you hear in Eddie's tone. Another issue; v1b needs to be a .0022uF cap. Last issue; there has to be a bright cap. If your amp does not have a bright cap.... WTF? LOL

You just have to stick with standard Plexi specs with the 100k 4ohm tap on the NFB. Variac the amp down to 90volts with Sylvania 6CA7s and you have it nailed. My buddy up in Chicago did these specs a week ago and he nailed it. As a matter of fact he had a music store in downtown Chicago floored by it.

My issue is that a lot of builders out there will do what they like to hear. Not what the amp really is. They will have there own opinion on what would make the amp sound great to there ears and there style of playing. Maybe the Van Halen tone doesn't work for them then!

No mysteries.... it just is what it is! No secret parts what so ever. Lots of crazy bullshit out there.

[jnew]

Nah man, I hear you. In fact, my amp has everything you just mentioned. Variac at 85VAC (except my 100K is on the 8 ohm because it's a self lead trannie) and yeah, gain is not an issue whatsoever. In fact, my volume is only on like 5 or so. You've heard the clips. Nothing but the guitar and an EP-3 pre-amp (which is not boosting anything, trust me) But this so called secret is more about the EQ shaping to get that sound than it is about getting the gain and distortion. Yeah, I have a 330uF on V2 also but that just allows boosting of more lows than a .68 but the boosting is roughly the same amount of gain as the .68. The 5000pF on CH I is a must. No questions there. Everything pretty much stock.

[motrock]

Nah man, I hear you. In fact, my amp has everything you just mentioned. Variac at 85VAC (except my 100K is on the 8 ohm because it's a self lead trannie) and yeah, gain is not an issue whatsoever. In fact, my volume is only on like 5 or so. You've heard the clips. Nothing but the guitar and an EP-3 pre-amp (which is not boosting anything, trust me) But this so called secret is more about the EQ shaping to get that sound than it is about getting the gain and distortion. Yeah, I have a 330uF on V2 also but that just allows boosting of more lows than a .68 but the boosting is roughly the same amount of gain as the .68. The 5000pF on CH I is a must. No questions there. Everything pretty much stock.

Oh yeah, cool! What I wrote above are some of the obvious points that most people do not stick with. My buddy is going to do the 100k 4ohm Tap on my amp. Can't wait to hear it. My buddy from Chicago told me the difference was huge! Said that the gain was incredible! I am going to stick with the .68uF; not because of the gain, but because of the mids. I was told that made a huge difference with my friends amp also! The EP-3 is really interesting. I hear a little bit of boosting; but its more of a thickening effect.

[jnew]

Yes it is (on the EP-3) Really no boosting. When I turn it off, the amp still has all the gain it needs. The EP-3 just colors and imposes a sort of thickening focus. Actually cuts away some amp hiss too. 100K NFB does make nice hairy gains stand out. Some amps get flabby on the bottom but that can be dealt with with other parts of the circuit.

[stef]

Judging by my old marshall SL (and this amp only), the secret part does not sound good with anything bigger than .68uf on V2a cathode, 2n2 plate coupler and 2k7 (v1b cathode). A 250uf (v2a) - flabby messy, 820r (v1b) the same thing, 1k same shit etc....
27k/8ohm for the NFB sounds good, 47k so so, anything bigger again makes the low end and tone flub out....

[jnew]

My amp is guilty in all those areas. 820/.68uF on V1B, 330uF on V2, 100K on 8 ohm. But when I put in that secret, There wasn't any issues with loose or flabby low end. It moved the EQ ing towards a honking, nasally mid emphasis that I definitely didn't like. Like it wasn't a thick balanced tone anymore but hard, rigid mid peak. But that's just my amp. Some amps may need that mid boost. Early EVH tone definitely needs those mids to be right and it's an art.

[stef]

I guess the bass stays tight because of the 2 tubes pulled...in fact VH1 does sound something like that!!!
I agree about the nasally HONK especially with all the values you mentioned

The "EQ" is hiding everywhere in the circuit - cathodes, plates, couplers, NFB, potentiometers, trannys, tubes etc etc....
Changing some resistors and capacitors anywhere in the circuit changes the EQ of the entire amp - the tone is really sum of all parts

[jnew]

That's a true statement if I've ever hear one. No doubts about it. I just put a 2.7K back on V1B but it's too late here for me to crank it up. Will see how I like it tomorrow. Been a while since I've had that value there.