Mark III "Stripes" - What was done on the circuit board..?

[Neptical]

Hey Guys!

Does anyone know what made each "stripe" variation of the Mark III differ from one another as far as tweaking the circuit board (starting at the black thru the green)? Just curious.

 

[lesterpaul]

have you seen this already?
http://homepage.mac.com/mesaboogie/dot.html
-doesnt go into the actual tweaks...more of a general description...

 

[Neptical]

Thanks, Mike. Yeah, I've seen that page more times that I can count. :lol:

I'm looking for the tweaaaks.

 

[JOEY B.]

Thanks, Mike. Yeah, I've seen that page more times that I can count. :lol:

I'm looking for the tweaaaks.

You already have the best Mark III, in my opinion, in stock condition. Are you chasing the "Mark series dragon"? If so, I know where you will end up. :wink: I have been on that hunt a few times myself.

 

[Neptical]

You already have the best Mark III, in my opinion, in stock condition. Are you chasing the "Mark series dragon"? If so, I know where you will end up. :wink: I have been on that hunt a few times myself.

:lol: .....Not at all, Joey! I absolutely love my III's. As a matter of fact, including my other gear (guitars & cabs), I think it's the best tone I've ever had. Seriously, these amps have cured my quest. I'm still going to purchase an early black stripe and I think that might be it. LOL.

It was just something I thought of and was curious about, that's all. I'm really interested to know what they actually did as far as tweaking the circuits.

 

[Neptical]

I thought some of the hardcore Boogie heads would know. I can't find any information except some schematics and I'm not even sure which version it applies to.

 

[kdorsey]

I might have some of the info you're looking for, but it was gathered from scattered locations and I don't always trust those sources.

 

[McBarry]

Nep,
I reckon yr up against the wall..
I mean, the schematics varied, the production adherence to same varied, and mods were/are common..
The only remotely definitive way would be inspect enough of each to see a pattern and document same..

Alternatively, folks like Ed (BoogieBabies), Andy (Monstatone) and others might had the info - would be worth a PM I'm sure..
Dave

 

[Neptical]

It's fine, guys.

If someone knows, that's cool. If no one knows, that's cool too. It just happened to dawn on me reading through some of the threads and piqued my curiosity; so I asked.

If anyone else wants to chime in, go for it. If not, it's cool too.

 

[Restless Rocks]

Just going from memory, as I have not documented any of this stuff on paper;

The "no stripe" black dot black plus: This is the one with the original CP-30 PCB ( this is by memory remember so I may get some of the numbers a little wrong) which is pretty much like the published schematic. The major differences in the stripes concern the R2 circuit. The R2 circuit in the black dot is just like the schematic. and C30 was 500pf in the lead circuit.

The "Purple stipe" Saw a redesigned PCB, the CP-31 (I think) Here were the major changes to the R2 circuit: There was another LDR added which switched in a .47uf cap on the cathode of V2a giving it more gain. The tone stack was lifted, via the relay, (this is unique only to the purple stripe and reminesent of the original MkI "pull boost") this also adds a little more gain hitting V1b but gives the R2 of the purple stripe more of a blurry feel. C30 was also 500pf in the purple.

The "Red Stripe" saw C30 return to the 1000pf cap like the C+. The R2 was restructured basically by using the relay leg to kick in the 750uf cap on top of the tone stack instead of "lifting" the stack by un-grounding the mid control. This is like the "pull shift" of the lead circuit kick in automatically for the R2 giving it a much more focused mid feel.

The "Blue Stripe" remove the C30 cap altogether, giving it the most raw and aggressive lead. IIRC the 120pf was put across the grid and cathode of V2b (ala C+) to tame some of this. The power supply voltages to the preamp stages were manipulated on some by changing the resistors between nodes A, B and C.

The "Green Stripe" of course is "basically" a Blue with Pentode wiring on the simul output pair. A few very subtle changes in cathode caps and tone bleed caps which are becoming esoteric at this point. Mostly to compensate for the also subtle variation in production tubes available at given times.

Hope this is of some help, again this is all from memory and subject to error.

 

[Neptical]

Hey, RR...wow, thanks!! That's some pretty knowledegable material, even if some of it may be off. That's exactly what I was looking for, though. Reading all that material makes it look like the tonal variations of the Mark III would be alot different from each other even though many claim they pretty much all sound the same. Not the case with my red and purple as the red seems quite a bit 'hotter' then the purple (which is more laid back,softer sounding). I'd love to put up an early black and a/b it with one of the last greens..just out of curiosity. I'd like to hear for myself. Anyways, thanks again for this info. I'll have to save this one. It feels nice to know a bit about the history of what made the difference inside the amps.

 

[Facelift]

would be cool to have each one for a month solid.

 

[chipaudette]

Cool info. I'm always down with some good circuit talk.

Chip

 

[Restless Rocks]

I agree , each stripe is great in it's own right with subtle variations. As everybody knows, tubes and speaker combinations make huge differences to any amp. I will have to add that if you get a chance to grab a black stripe/no stripe, do it. Especially the no stripe with the 105 tranny. This is of course the next step of evolution from the infamous IIC+ with the addition of the wonderful R2, which I happen to love. This amp sounds the closest to a raw natural souped up Fender and I could possibly say I like the original R2 circuit better than the later, hotter versions. Unfortunatly I don't have the time to sit and check each and every Mk III circuit for cap value differences and so forth but I listed above the most obvious changes I've noticed. All I can say is I've never seen a mark III that I've not liked or would not own and play, well maybe with the exception of a couple very very sad instances of hack jobs by folks who had no business trying to mod one of these circuit boards. Again I have to say freinds that if you don't have a LOT of experience as an electronics tech please don't try this stuff at home. They don't make anymore Mark III's.

 

[Neptical]

Thanks again, RR! Your definitely right as speakers and tubes can make a world a difference in amps. I had to do some tube swapping with my red and purple to make sure my ears were hearing right on the differences; and both used the same cab/guitar as well. My next stop is of course the black stripe/no stripe (preferably w/ 105 tranny) that I've been after for some months now. But as you mentioned, there's no Mark III that sounds bad at all. It's just fun and entertaining to hear and know about even the subtle differences that these amps had. And I guess I'm willing to pay the price to find out.

:lol:

 

[kdorsey]

Many seem to be attempting to make MkIII sound like a MkIIC+ when the MkIII stands on its own respectfully. Hetfield would kill to have MY tone! :wink:

Nice dissertation, Restless. 8)

 

[Neptical]

KDorsey, funny thing is I seem to have no problem spending $$ on gear. :lol: ...so really if I wanted a IIC+ it would just require some of my funds and then finding one; which I haven't even thought of doing at all. Maybe I'm a black sheep, I don't know...but the Mark III has been very fitting for what I play and has piqued my interest in the history of the amp. That's it in a nutshell.

 

[Facelift]

Cant agree more about not really needing to stray away from the III. I have went through alot of amps, and my search has pretty much ended with the III. Saves alot of time and money of buying up amps.

 

[boogiemon]

Just a couple data points for those interested.

i've got no-stripe & a black dot: both 60 watts, no 105 xformer in either one. The no-stripe also has reverb.
Tubes & speakers are the same in each.

The "dot" is somewhat more articulate & clear, the no-stripe is darker, rounder, smoother.
C30 in the no-stripe is a *stock* 2000; i don't know what the C30 value is for the dot.

both are monsters of course. The no-stripe is going in for the "+" mod tomorrow.

 

[Neptical]

Thanks for the addition of that information, Boogiemon. That's certainly interesting to know! I'm looking forward to picking up one of those with the 105 PT sometime.