Cauldron of Gain Schematic and PCB

[ragtime8922]

This is the Cauldron of Gain revision 3 (final revision) schematic:

NEW LINK ON NEXT PAGE


This is a layout/PCB made by Nikolay. I haven't tested it but Nikolay assures me that he did. It is for revision 2 but the only difference is that rev 2 showed an extra 100K resistor between the 100K trimmer and +18v for Q2 and Q3. Just replace these 2 resistors with a jumper so that you can properly bias the JFETS.

NEW LINK ON NEXT PAGE

This is an 18-volt project. It is a high gain metal fire breather. Do not use 9V. I tried it with 9volts and it is absolutely horrible. 18v sounds great.

[nelson]

Cool, any chance of a PnP graphic?

[ragtime8922]

Cool, any chance of a PnP graphic?

At the risk of sounding stupid:
                                   What is a PnP graphic?

[nelson]

a transfer graphic, you know just the trace side of the board in black. For Press n Peel blue use.

Sorry, should have made it clearer.

[Connoisseur of Distortion]

i second that request for a transfer!  i am always up to building another high gain pedal, if it comes closer to finding "the sound" i am looking for. next build is looking like BSIAB, even though i am not really a marshall fan... but you never know...

(so far, an interesting sound discovered was a Metal Master pushing my Dr. Boogey... the boogey really smoothed out the sound, made it more natural, but the oscillations and difficulty of getting back to a clean channel were ridiculous!)

[ragtime8922]

Duh, Press-n-Peel is my favorite and yet I couldn't put together the PnP reference...LOL. Well, Nikolay did the layout and hopefully he'll chime in with that PCB layout.

[troubledtom]

cool,
 - tt :wink:

[Nikolay]

Hi guys
here are PDF files of ver.2 of PCB borad
http://hnikolov.hit.bg/razni/pcb.pdf     (ready to transfer file)
http://hnikolov.hit.bg/razni/print.pdf  (pcb with elements)

Here is picture how looks this drive


PS: I must make next version of PCB, because this is too small, and the distance between pots, and all elements are less

PS: Thanks to ragtime8922 to this distortion
PS2: I don't have time yet to make some records, but soon (as possible) I will

Good luck

[ketchup]

could we possibly hear some sound samples, to see just how high the gain can really get.. it would be nice

[kusi]

This is the Cauldron of Gain revision 3 (final revision) schematic:

http://tinypic.com/6oh8k2.gif

hi ragtime,

sorry, this link doesnt work! can you send me the schematic?

thanks a lot,
khe

edit, now it works.... thanks

[5150]

i must be missing something important, I can't get the link to work either.  Someone have the file saved?

[burnt fingers]

linky no workyhere either.   Please post somewhere that we can get to.  Thanks. 

Scott

[Connoisseur of Distortion]

another grave disturbed... 

[The Tone God]

Well I doubt those links will work when it is almost a year old and originally went to a temp pic site.

Andrew

[MetalGuy]

The links are not working.

[ragtime8922]

Hi guys. Sorry I've been away for a while. I saw the re-interest in this circuit yesterday and yes, I still have the schematic and I also found the layout that Nikolay made. I'll post them here.

I also made a horrible discovery. I had years of research and amp/effects design mostly saved in bitmap format before converting some of it to PDF and/or gif/jpeg. All of the bitmap stuff is corrupt and some of the gif stuff is corrupt as well. Lost forever. So today's tip would be to convert everything to PDF for safe keeping. You can also save as bitmap/gif/jpeg but use pdf as your back up.

Schematic:
http://i2.tinypic.com/t82kp4.gif

Layout:
http://i2.tinypic.com/t82mbb.gif

The PCB is one of the corrupt files mentioned above. Hopefully Nikolay still has it on his hard drive.

The circuit is a really nice, fire-breathing gain monster that can be toned down to get a nice, tube-ish reacting crunch. Tweaking the 2 noted bias voltages give the circuit different reactions to touch sensitivity and a difference in feel from a silicon rectofier to a tube recto (Sag). DO NOT TRY THIS CIRCUIT WITH 9V. USE THE RECCOMENDED 18V....AT LEAST.

ENJOY!

[Gus]

You should read up on fet biasing and gain math
IMO biasing in the drain leg is a bad design your gain in will be diffferent, work out the math.
your source Rs are not bypassed  a little hint

Fets are not easy to design with if you want to build more than than one effect and have them work the same.

FWIW when I build a FET microphone circuit I might get 2 to 4 FETs per hundred I test that will work the way I want.

Google, ASK, Yahoo  there are a few good sites with FET circuit design info.

[TELEFUNKON]

biasing in the drain leg is a bad design

but that`s the "law" right here

[MetalUpYerEye]

coud you repost the PnP again?

[ragtime8922]

So Gus, lets just name a few circuits that you'd consider a bad design:

Dr. Boogie
Boogeyman
The English Channel
Fetzer Valve
Umble
Thunderchief
Uno

Consider the above circuits (great FX pedals) and the fact that they are all original designs of the greatest guitar amps of all time. Now factor in the fact that the Cauldron of Gain is basically the exact circuit used in the Soldano SLO-100 preamp section. This should give everyone an idea of Gus' credibility. Hey Gus, you need to Google: Runoffgrove, Marshall, Vox, Dumble and Electronics.