Introducing "Mr Mostorto" ( not a magician ! )

[MartyMart]

Schematic :

http://aronnelson.com/gallery/Martys-layouts-and-photos/MrMostorto?full=1

Sound sample at full bore :

http://aronnelson.com/gallery/albums/album72/Mr_Mostorto_V1_1.mp3

"A High gain Mosfet/Jfet Distortion circuit with low noise performance"

The circuit uses a Mosfet stage, biased in a similar way to Jake nagy's blue magic, the "Pre-gain" control
provides an additional gain/tone adjustment for what hits the second stage, along with the 500k gain control
from the BS170's drain. ( this can be a 5k pot, 10k was all I had and is too large to make a difference past 50% )
The drain bias resistor can be either 3k9 or 4k7, please set this up to have approx 6.5v at the drain

The second stage is an SRPP "MU amp" stage providing LOTS of gain ! ( see RG's MU article at GEOFEX )
The top J201's drain should read approx battery voltage and the top of the lower J201 should be approx 4.5 to 5.5v

Then there's a final stage/tone shaping to output pot, this J201 should be biased with the trim pot to approx
4.5-5.0v at the drain ( this was not a problem, so if it's "twitchy" try a few different J201's )

If you build this, try to keep the caps "exact" as these were socketted and experimented with a LOT to get
this specific tone, the 6n8's can be made with a pair of 3n3's in parallel and be close enough, at 6n6.
I had a tone control on mine, added in after the final stage coupling cap (47n) which was just rolling off
high end, I found that I left it wide open- so it was pointless, the circuit has been setup to give a good
amount of mid/high end and should work "as is" into all but the brightest of amps !.
Add one in if you like.
I also have a switchable pair of zener diodes to ground, just before the output filter (12k/2n2) which are 3v1's and
I like the extra "grit" they provide, though they are probably not neccesary.
MODS:
If you find you still have too much low end, reduce the final 47n cap to 22n and slightly reduce the 4u7's and 2u2
bypass caps, 2u2's and a 1uf may be nice, this will reduce gain a touch too.

Thanks to RG Keen, Jack Orman, Jake Nagy and Ed Guidry for all the components that made this circuit work
It can be subtle, dial back the pre-gain and gain pots for "almost clean" tones and of course lots inbetween.

Marty.

[KerryF]

Nice Marty!  Glad to see the schematic.

Would you mind if later I drew up a cleaner version of the schematic on a program?  That is unless you or someone else does it, or you dont want it.  It might be a little easier to follow through and stuff 

Kerry

[brad]

Freakin' heck!  Sounds amazing Marty!  That's gotta be one of the best crunch tones I've heard in ages.  I love how you kept things simple and left out the tone control too.  Good job!

[MartyMart]

Nice Marty!  Glad to see the schematic.

Would you mind if later I drew up a cleaner version of the schematic on a program?  That is unless you or someone else does it, or you dont want it.  It might be a little easier to follow through and stuff 

Kerry

That would be very nice Kerry, PM me so we can email and I'll check it out and upload it to my gallery

Sorry ... I'm "oldschool" with schems at the 'mo !!

Marty.

[KerryF]

Sure Marty.  I will do it a little later and email it to ya cause im at school at the moment  .

[darron]

i think that hand-drawn one is better. it's more personal and gives you a bit of scope inside the creator's mind. it's easy enough to read also.

[MartyMart]

Is this getting lost in a sea of posts, or just not too anyone else's taste ??
It's about the best sounding high gainer that I have ! ....

MM

[JimRayden]

Well it does have it's own ring to it. Also very crunchy. Perhaps too crunchy for my tastes, as I'm more of a soft high gainer type.

Then again, it might just be the recording... how would you compare it to a BSIAB2?

---------
Jimbo

[slacker]

Sounds great Marty, I like the hand drawn schemo as well.
I think I'll have a crack at this over Christmas.

[KerryF]

Heres the computer drawn schematic:

http://i14.photobucket.com/albums/a303/call1800ksmyazz/MrMostorto.jpg

If you need it bigger, let me know.

It sounds great still! 

[Rafa]

Cool
Thanks a lot Marty
Cheers
Rafa

[WGTP]

Looks cool Marty.  Have you tried it flipped around with the Mosfet at the output and Jfet at the input?  I'm sort of off into Mosfets as the final stage and they seem to have a nice smooth robust manly tone.   

[MartyMart]

Thanks very much Kerry, though the first bypass cap should be 4u7 ( 4.7uf ) not a pf value 

Well it does have it's own ring to it. Also very crunchy. Perhaps too crunchy for my tastes, as I'm more of a soft high gainer type.

Then again, it might just be the recording... how would you compare it to a BSIAB2?

---------
Jimbo

It's a little thicker sounding than a bsiab, I'll post a couple of lower gain clips tomorrow, perhaps the "maxed out" version
is a bit much !
There's several lower gain tones, even quite mellow when backed off, it retains good mids & highs though and
cuts through very well with plenty of personality

MM.

[markm]

Marty,
This looks and sounds like it's a cool circuit.
I'm interested......but that don't sound like Country? 

[MartyMart]

Marty,
This looks and sounds like it's a cool circuit.
I'm interested......but that don't sound like Country? 

Perhaps "heavy country-rock" !!   
I'll try some cleaner "licks" tomorrow .....

MM

[KerryF]

No problem Marty.  I fixed the problem:

http://i14.photobucket.com/albums/a303/call1800ksmyazz/MrMostorto.jpg

Kerry 

[mydementia]

How about a layout file?
http://aronnelson.com/gallery/album89/MrMOStortoV1_0_Layout?full=1
Let me know if I screwed something up.

Marty - what's the 100nF cap immediately following the 100uF cap doing?

Mike

[KerryF]

Thanks for the layout!  I was hopeing for one soon 

[MartyMart]

How about a layout file?
http://aronnelson.com/gallery/album89/MrMOStortoV1_0_Layout?full=1
Let me know if I screwed something up.

Marty - what's the 100nF cap immediately following the 100uF cap doing?

Mike

That's perfect Mike - MANY thanks
The extra 100nf filter is an RG tip, if I remember correctly - faster ESR helps to smooth the power faster than the
large 100uf, when used in conjunction with it.
I use them often on higher gain circuits - then again, I could be talking absolute rubbish !!

I hope someone builds one soon and lets me know what they think ..... more samples soon..

MM

[John Lyons]

So much to build, so little time.
Sounds good marty! I'd love to hear more.

John