Homebrew Mesa?

[Joelschaos]

I was just wondering if anyone has ever tried to wire up their own remake of a vintage Mesa before from scratch. I understand this could possibly be illegal (let me know if it is), I would think the amp design would be patented. I was just wondering if anyone has had any success wiring up something similar and if it sounded at all the same.

 

[aaronlyon]

(I am not a lawyer!) There's nothing stopping you from building your own amp using a MB schematic…you just can't sell it as a Mesa Boogie! Check out all these here schematics: http://tubefreak.com/fschema.htm

I just finished building my first tube amp--a one-watt Firefly, using two 12ax7 and one 12au7. Killer bedroom amp! http://ampgarage.com/forum/viewtopic.php?t=11248

 

[msi]

You could try the sloclone forum. There are a bunch of hi-gain amps that have been built there and they may have some information that could help you.

 

[zebpedersen]

For a Boogie it may not be illegal, but I do think it's a bit cheeky/immoral as they're a legit business - if you're trying to recreate an amp they no longer make, maybe that's fair enough, but if you're trying to build an Electra-dyne or something that's a bit naughty.

For something like a Trainwreck or a Dumble though, go right ahead - if Howie doesn't want to sell you an amp unless you're Mr Carlton/Ford/Santana then you're not doing him a disservice by building your own!

 

[Restless Rocks]

Back when I was a starving full time musician in 1982 I cloned a Mark IIb from the schematic and later upgraded it to a mark III from the schematic. I used that amp to make the cash to purchase the real deal. The amp still kicks ass. I was unable to make a PCB in a hotel room so it is totally point to point wired. The Mesa police dept has yet to find me.

 

[Joelschaos]

So what I'm guessing is that, since I would not be using exactly the same brands or types of parts, it would sound a bit different... but it probably would still sound awesome. Correct?

I'm thinking of playing around with some old tube amplifiers off ebay first, adding some eq's and small little things, and working my way up to a project like this.

Thanks for the input guys.

 

[zebpedersen]

I think there's a board member currently upgrading a Fender Hot Rod or Deluxe or something to Dumble-specs and there's certainly something to be said for giving it a go modding some other amps.

FWIW - I spoke to the guy who built my D-type and asked him if he'd considered doing a IIC+ clone, but he said that no matter what schematic he used, he never got the preamp sounding perfect, so your mileage may vary when doing a direct Boogie clone.

 

[Restless Rocks]

The schematic was only a guide; to get the amp to sound the way I liked required a bit of tweaking.

 

[CoG]

I hope this is, like, a "why not" project and not "I'm gonna teach myself to build my own amp because I'm broke." I hate hearing about those. Seriously, unless a guy is already a really good tech he would be better off just taking that spare time and delivering pizza at night for a couple months and just buying the damn amp :lol: Nobody who gets into heavy modding and ever actually finishes a project properly can say it's saved them much money, they did it because it was a neat thing to do!

 

[chipaudette]

Since the Mark series started as a deviation on the blackface-era Fenders, I modded by Fender Deluxe Reverb Re-issue to include the Mark IIC+ / Mark IV lead circuit. Let me tell you, the sound and feel of the overdrive is nothing like my Mark IIC+.

Based on this experience, I believe that the following items make a surprisingly big difference in the sound of an overdriven pre-amp:

1) B+ Voltage: The voltage applied to the pre-amp tubes (I feel) strongly affects the sound during overdrive. My Fender is designed to run with a B+ rail for the pre-amp tubes at around 260V. On my Mesa, I think that I measured around 360V in the pre-amp. This difference in supply voltage strongly affects the voltage at each tube's anode, which has substantial implications on the load lines, the self-bias points, and (as a result) the clipping behavior.

2) B+ Filtering: It's also likely that number and location of the filtering between pre-amp stages has a big impact. My fender has all the pre-amp stages hanging off the same B+ with no filtering between them. The Mesa has the pre-amp B+ separated into 2 or 3 sections with filtering between each. During non-linear operation (ie, overdrive) there are big swings in current being pulled through the overdriven tubes. I can't imagine that the addition (or absence) of isolation and filtering of the current source (ie, B+) doesn't affect the overdriven sound.

3) Length and Routing of Wiring: My Fender has longer runs of wires/traces as they go back-and-forth between the front panel controls and the tubes which hang toward the BACK of the chassis. My modifications then added yet more lengths of wire to jump from the unmodded to the modded parts of the circuit. I've found that length is a bad thing. By comparison, the wire runs / traces in the Mesa are fairly tight. For example, Mesa really helped themselves out by moving the pre-amp tubes to the front of the chassis. They now have less distance to cross when going between the tubes and the controls. I feel that this all matters because, when working on my Fender, I'd occasionally re-wire sections just to tighten up the lead dress...and I was often surprised at how strongly it affected the sound (not always...but sometimes). Long is generally bad...short is generally good.

4) Capacitor Type: My Fender uses quite different types of capacitors for the cathode bypass caps than the Mesa. I think that I've got differences in my coupling caps, too. Lots of folks think that the type of cap makes a pretty big difference. During overdrive, I can definitely see how any peculiar non-ideal response of a particular brand of cathode cap would suddenly have a big impact. I have less of a strong opinion on the coupling caps.

There are also a ton more issues once you step outside the early part of the pre-amp. The Mark IIC+, for example, does tone shaping with the return from the effects loop. That will affect the sound (though not being at overdrive voltages at that point, I'm not sure it'll affect the feel). Also, the uniqueness of the Mesa EQ, the contour of the presence circuit, and the fixed bias power amp (or simul-class) will all leave their imprint. Then there's the speaker...the sometimes-forgotten element that has one of the biggest effects on the sound of any component.

Finally, another rarely-mentioned issue is is how the Master Volume pot is wired. A lot of people don't think about this component. In my IIC+, the master volume pot is wired as a variable resistor to ground. A more typical configuration for a pot is to wire it as a voltage divider. With their method, no part of the pot is in series with the signal, which means they avoid the very typical problem with tube circuits...loss of high frequencies due to resistors in series. Their master volume configuration avoids that. But, as a trade-off, their method causes the low frequency cutoff of the preceding coupling cap to change as the pot is turned, which causes the resistance to ground to vary. It leads to a very complicated interaction between tone and volume. That's why a lot of IIC+ players talk about getting extra oomph by adjusting their volume settings to a "High Master Volume with a Low Lead Master" configuration. It affects the cutoff frequency of the last coupling cap.

Anyways...that's a lot of info. Sorry for the long post. I say, go ahead and build your own amp. It's loads of fun. You'll learn a ton. Just don't expect it to sound like a Mesa. If you're lucky, you may like the sound of your amp EVEN MORE!

Chip

 

[Boogiebabies]

I think there's a board member currently upgrading a Fender Hot Rod or Deluxe or something to Dumble-specs and there's certainly something to be said for giving it a go modding some other amps.

FWIW - I spoke to the guy who built my D-type and asked him if he'd considered doing a IIC+ clone, but he said that no matter what schematic he used, he never got the preamp sounding perfect, so your mileage may vary when doing a direct Boogie clone.

With the Dumble 0124 schematics around it was hard not to look into the mystique. That Fender will never be a Dumble, but it is WAY better
sounding than it was before using a few Dumble circuit ideas.

 

[Boogiebabies]

I hope this is, like, a "why not" project and not "I'm gonna teach myself to build my own amp because I'm broke." I hate hearing about those. Seriously, unless a guy is already a really good tech he would be better off just taking that spare time and delivering pizza at night for a couple months and just buying the damn amp :lol: Nobody who gets into heavy modding and ever actually finishes a project properly can say it's saved them much money, they did it because it was a neat thing to do!

Truer words have never been written.

Mike Soldano called me to talk about my 93' SLO-100. We talked about the amp and it's link in Soldano's LA period history and spent the next
hour talking about how many people have been ripping him off. First Mesa with the Dual Rectifier and now the SLO
Clone forum. He wryly said, they will never have my amp unless they buy one and pull the transformers out. Otherwise
they will never get their hands on the DeYoung transformers. The big difference between Mike and Randall Smith is patents
and copyrights. Mike had neither on his amp and Randall had the dual mode circuit, Simul-Class patents and a copyright on all PCB's as artwork.
As many tube geeks know, the layout of the trace and components can produce subtle magic and circuit interaction. Mike's layout was
used almost exactly and then sold by the SLO Clone members. Is that ethical? No, but it's also not illegal. I would beg to differ if someone
cloned the RP-11A and sold it. You can clone the circuit all you want, but since the MK V is out and your competing will Mesa I would not
be surprised if ol' Randall ran your ass to court. You'll have to wait 70 years after RCS has gone to Boogie heaven to clone that PCB.
If you produced one for yourself and your own personal consumption and it's actually correct, great !!! Now figure out the transformers.
If you have some extra time and money and enjoy the prospect of copying one of the most venerable tube amps of all time, then do it.
Just don't expect it to sound like an exact replica. Mesa could not even do than from C+ to C+.

Unless, you can sing a charming musical number..... Whenever........

 

[zebpedersen]

So basically when Boogie print "patented" and "magic" in the same sentence all over their brochure it's not total BS!

 

[Boogiebabies]

So basically when Boogie print "patented" and "magic" in the same sentence all over their brochure it's not total BS!

No just 90% fluff after 1992. I don't understand what they are doing today.

 

[zebpedersen]

Ha, well admittedly they normally crop up in the company history at the front...and then again on the Mark IV's product page. Haven't seen a catalog since the release of the V.

 

[Restless Rocks]

So basically when Boogie print "patented" and "magic" in the same sentence all over their brochure it's not total BS!

No just 90% fluff after 1992. I don't understand what they are doing today.

Me neither!! This cram every whistle and bell ever thought of into one amp thing is well,,,,,, after repairing several Road Kings I would be scared to death to rely on one on stage. Way too many vulnerabilities in something so complex. For that reason the Mark IV may well be my last Mesa amp.

 

[Boogiebabies]

So basically when Boogie print "patented" and "magic" in the same sentence all over their brochure it's not total BS!

No just 90% fluff after 1992. I don't understand what they are doing today.

Me neither!! This cram every whistle and bell ever thought of into one amp thing is well,,,,,, after repairing several Road Kings I would be scared to death to rely on one on stage. Way too many vulnerabilities in something so complex. For that reason the Mark IV may well be my last Mesa amp.

I went through three RK's... When I saw the schem on the MK V I could not believe it. I think RCS mention 43 or so relays.
I have a four channel amp with a loop for each channel, serial and parallel loops, switchable serial loop and midi control.
It has 9 relays in the preamp and 11 for the loops.

 

[Monsta-Tone]

This is an awesome thread!

I've always wondered about the SLO & Recto connection. Just because Randall is a better business man, does not mean that he makes a better or maybe even a comparable product. I love my Heartbreaker and Maverick, but my Lucky 13 is one of the best amps I have ever played!


As for cloning or building......
This is how I started fixing and modding amps. I made the mistake of trying to clone a Lee Jackson VL-502 head. I lost my ass and 6 months later, it still didn't sound right. I didn't make a PCB, it's all P to P, but it's noisy and generally a pain in the ass.
I still have it though!


I think it's an incredible learning experience, but like most have said here, save up and get the real thing if that is really the tone you are looking for. If you want to create your own tone, then a homebrew is the way to go!
Just the parts to build a great sounding amp will run you around $700-$900 if you purchase them separately.

A really great starting point is the Fender 75. It sounds like ****, but the transformers are huge and it's got a tag board for all of the parts. I've got one in my shop right now that I plan on building into a IIc.