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Last time Phil came over from Hoboken to the homeland, he brought the last of his hurricane Sandy flood damaged pedals with him, a Mesa V-Twin.  This one is beyond repair   Corroded component legs, and pads, it would need everything pulling, and it's a nightmare to get the oxidised solder to melt,  only a pair of vactrols have been salvaged.  The board is still lying around in the corner somewhere , so if anyone wants it for the cost of shipping let me know , but I wouldn't bother to be honest.

Luckily the case is mostly stainless steel and survived ok, but the tread plate panel has suffered pitting corrosion, so has been painted.

Anyway,  the guts are now a JCM800 preamp circuit, with the second stomp acting as the lo and high input on the real amp.  The slider switch on the top switches a parallel 10k resistor on one of the existing 10k cathode resistors to give a little volume boost.

Phil wasn't bothered about some of the text being rubbed off, and said leave it as is, otherwise Haberdasher would have  been called upon to etch a face plate.

Somehow the Mesa 12AX7s survived with no ill effects, and are working well at the 190V the vero SMPS is supplying,  the best sounding tube pedal built by me or John.

Not good.




Lots of wiring.




JCM800 preamp.


9V in, 190V out.


A little repainting.

The caps are these 1uf multilayer ceramics
http://www.newark.com/multicomp/mcmlr50v105kx7r/capacitor-ceramic-1uf-50v-x7r-10/dp/97M4165?Ntt=MCMLR50V105KX7R

They are more expensive in the USA than over here.

On-on-on dpdt works, wiring is in this thread.

http://www.madbeanpedals.com/forum/index.php?topic=6759.0

RG Keen posted this on DIY.

"There are two ways to get "diode connected out of a MOSFET.

One is to use the substrate diode, which always allows current to flow backwards to the way it flows from drain to source. This diode is a normal silicon diode characteristic, consisting as it does of just the substrate isolation tubs.

The second is the one we usually want from MOSFETs. It consists of connecting the gate to the drain, and then using the drain-source as the diode in the normal current flow direction. Connecting the control node to the incoming power node (as in base to collector in bipolars) is the way to get the "diode characteristic" of the control node. It's done in bipolars to get a more-ideal diode characteristic than you get from either of the normal junctions. But this is the connection you want: gate to drain, then drain and source as the diode. Don't clip any leads off the MOSFET.

There is a problem here; the reverse/substrate diode prevents this "diode" from blocking in the reverse direction. In one direction it electronically looks like the amplified-diode MOSFET you want, and in the other it's an ordinary silicon diode. You can use an external diode in series with the drain or source to block the substrate diode from conducting, or if you're using two MOSFETs, you can connect them so the substrate diodes themselves are what allow current flow in the "right" directions each way."

Found this when building a Zendrive, that didnt connect them correctly either, might as well use a silicon diode.

i need to try the real mosfet clipping method, it will clip at the mosfets gate threshold voltage, higher than a LED for some mosfets.

TC1044S works fine if you jumper pins 1 and 8 under the board.

Definately a manufacturing defect there, you can check using the build document.

Contact Brian by pm and let him know.

Run it at twice the speed.

Try biasing at around 7-8V on Q3, its not correct at 4.5V, this seems to be a carry over from biasing a fuzz face.  Dave Main of DAM has tested loads of vintage Mk2s, and the good ones are in this range.  My OC75/OC76/OC75 Mk2 has a 4.7K resistor where on the stock circuit is a 8.2K, and it sounds great.  I assume the BYOC has a trimmer.

To make that circuit work with silicon still requires a germanium in Q1,  it needs the leakage to bias Q1 correctly.  the other two can be PNP silicon, but wont sound as good as germaniums.

If its using a 12A?7 tube, then it will pulling either 150mA, or 300mA depending on how the heaters are wired.

When you paint the box, do it a face at a time, and stipple it with the brush after each face, helps to hide the brush marks.  This doesn't work with normal paint just hammered.  A couple of coats helps too.

Had a play with the GB-83 today. Swap the resistor from Q1 base to ground to something from the 39-47k sort of range. We stuck a pot on and turned sustain to max which squealed like hell, then adjusted the pot until the squeal went. Ours ended up at 42.4k. Sounds great!

I'll get it boxed up tomorrow.

Juan on Cleggy's iPad.

I'm looking for a chorus for bass,I have an angel now,would this one be a deeper chorus effect?

Just tested it.  It sounds amazing!  I don't think I'm losing any low end with a 4 string.  Turning it off and everything sounds kinda flat.

I can imagine all the real goth bands in the 1980s using it.

None more clean!

I really like what Brian did with that layout...must get one now...

It's such an easy build despite the amount of parts, just like your Chimaera.

Very similar to one made the other day.

Being made second resulted in the invisible wiring,  jacks the other way up means I can put the wires underneath and its hidden in the 45 degree cutout on the jacks.

Are you running it out of an enclosure?

Its very noisy out of the box, and ths results in it being hard to set the trimmers.