Carl Martin - PlexiTone

gnognofasciani · Post by **gnognofasciani** » 04 Dec 2007, 19:33

Does anybody have some info on this great sounding stomp?
I just have this pic:
https://img107.imageshack.us/img107/520 ... bd3.th.jpg
What I can see is a +/- supply (trasnformer + 2 little regulators) and a 4opamp ic used for Ts like stage (3 led for asym clipping) + the booster stage; If you know something else i would be very happy...

BTW I'm giving a try with a +/- 18v HeavyDrive based on the schematic I've found here

Thanks,

Paolo

analogguru · Post by **analogguru** » 04 Dec 2007, 20:13

I think that you are talking about the Carl Martin Plexitone:

http://www.digimart.net/images/1220/DS00181323.jpg

doesn´t look so complicated to trace....

analogguru

Bernardduur · Post by **Bernardduur** » 04 Dec 2007, 20:59

Wow, HUGE enclosure, so little parts

Can I guess.......

CMOS based pedal???

gnognofasciani · Post by **gnognofasciani** » 04 Dec 2007, 21:08

I don't think so, look at the carl martin heavy drive and you'll see that it (like the other stomp called "something drive", I assume) uses a MC33079, which is a 14pin 4opamp

Dirk_Hendrik · Post by **Dirk_Hendrik** » 05 Dec 2007, 08:57

For reference:
http://www.dirk-hendrik.com/cm_heavy_drive.pdf

JHS · Post by **JHS** » 05 Dec 2007, 10:50

Runs on +/-12V.

I-buffer, Gainster/Snapper like OD-circuit w LEDS, switchable IC-boost.
+ a bad buffered bypass.

JHS

gnognofasciani · Post by **gnognofasciani** » 05 Dec 2007, 15:59

Jhs thanks for your reply, it confirms my theory...

I just don't understand if it is a guess or a statement...
I'm gonna build the Heavy Drive (the pcb is already drilled) and tweak it beacuse it is pretty similar to what the Plexitone is supposed to be

picassochild · Post by **picassochild** » 08 Dec 2007, 02:58

I had Heavy Drive but didn't find that it was close to Plexitone. I tested BJF Dyna Red vs. Plexitone and they were almost identical... but BJF won bcos of much better balance in tone...and of course size of box.

picassochild · Post by **picassochild** » 08 Dec 2007, 03:01

gnognofasciani, let us know if you'll mod Heavy Drive to Plexitone sound and tone... could be Dyna Red for poor guys.

gnognofasciani · Post by **gnognofasciani** » 08 Dec 2007, 07:59

I think that the differences between the plexitone and the heavy drive are the power supply and tone control...but I think i'm gonna like the HD tonestack

Starting from the HD schematic it's pretty easy to have a double channel (2 gain pots) and the boost (pot instead of a fixed resistor in the last buffer stage) with 2 simple switches

I had to etch the pcb again because I found a mistake

, i'm gonna drill it today

Stay tuned

JHS · Post by **JHS** » 08 Dec 2007, 10:48

The circuits of the HD and the PT are complete different.

The HD is similar to the Xotic RC/AC drive + gain stage before the output.

JHS

Winther · Post by **Winther** » 24 Dec 2007, 13:24

PT is the same layout as a HDB...but filtered differently(several times)
+-12v powersupply.
3 5mm LEDS that makes the sound the way it is...(not gonna spill that one..sorry)
LF347 quad OP-Amp.
Originally it was a singlechannel od...did not wanted it to be so big in the first place, but I am not the one who calls the shots there....
The Heavey drive is also a TS style variant with a "hifi" tone circuit!
Makes alittle more noise than your normal tonestack.
But very flexible!!

gnognofasciani · Post by **gnognofasciani** » 07 Mar 2008, 11:08

A nice pic for you all!
I'm waiting for the pic of the other side, then I'll be ready for tracing

The pic was at an higher resolution but it was too big...
If you want the original just pm me your mail!

gnognofasciani · Post by **gnognofasciani** » 14 Mar 2008, 11:37

I'm tracing

gnognofasciani · Post by **gnognofasciani** » 14 Mar 2008, 15:05

Here you have the schem, if you see any mistake please let me know so that I can correct (tone control is pretty unusual to me for example)

Hope you enjoy!

I forgot to write on the image that c11 is 2,2u

P.s. Admin please change the title otherwise no one will know there's a schematic inside

, thanks

soulsonic · Post by **soulsonic** » 14 Mar 2008, 15:14

Grazie!

gnognofasciani · Post by **gnognofasciani** » 14 Mar 2008, 16:16

The other thing I dubt of is the 47 ohm resistor..I mean: with the cruch pot (100k) max gain would be 2127 and with the hi-gain pot (1M) 21276...
Isn't it way too much??maybe it's because of the leds

ik6gpy · Post by **ik6gpy** » 14 Mar 2008, 16:38

The active tone control in that configuration should affect frequencies above 1.2kHz approximately , acting as a sort of a treble boost if my ee reminiscence are still good . So the tone control section could be right if someone who tried a Plexitone can confirm this.
Matteo

ik6gpy · Post by **ik6gpy** » 14 Mar 2008, 16:42

Missing value on C11.

gnognofasciani · Post by **gnognofasciani** » 14 Mar 2008, 17:08

gnognofasciani wrote:Here you have the schem, if you see any mistake please let me know so that I can correct
I forgot to write on the image that c11 is 2,2u

Carl Martin - PlexiTone [traced]