Tech21 - XXL

invictus · Post by **invictus** » 16 Aug 2007, 03:51

;

gut shot of the Tech21 XXL:

http://www.axiomdrift.com/schematics/xxlboard.jpg

schematic:

http://www.axiomdrift.com/schematics/XXLpn.gif

.

soulsonic · Post by **soulsonic** » 16 Aug 2007, 09:44

Thanks.
It's actually pretty simple when you disregard the electronic switching circuit.
I'll have to give it a try.

GatesofDawn67 · Post by **GatesofDawn67** » 23 Apr 2008, 03:33

This link has disappeared. Can the XXL schematic be reposted?

FXFXFX · Post by **FXFXFX** » 23 Apr 2008, 10:24

it's peanut butter jelly time!!!

FXFXFX · Post by **FXFXFX** » 23 Apr 2008, 10:27

my virus scanner detects a virus in the link above (first post) - be carefull!!

bighud · Post by **bighud** » 23 Apr 2008, 16:58

FXFXFX wrote:my virus scanner detects a virus in the link above (first post) - be carefull!!

I checked it out...cause I was curious and on a linux box. I am 99% sure there is no virus. Some sort of executable file would have to exist for this to be the case. Since there isn't anything but a blog, I am convinced it is clean. Maybe I am wrong though.

jrc4558 · Post by **jrc4558** » 24 Apr 2008, 15:02

I've built a "lite" version of it (minus the bias control). Awesome heavy distortion. With med-hot humbuckers its your simplest way to get the nu-metal sound.

FXFXFX · Post by **FXFXFX** » 24 Apr 2008, 16:08

A friend of mine got the original and loves it..it's his main pedal. Not really nu metal i think but i like the fuzziness...

patafix · Post by **patafix** » 25 Apr 2008, 07:47

What's noticeable with T21 designs is that there are no clipping diodes... Barta seems to prefer the sound of overloaded Opamps...

I think I'm going to give it a try too... without the electronic bypass system... and with a single dualopamp...

FXFXFX · Post by **FXFXFX** » 25 Apr 2008, 08:39

The whole upper part of the schematic is just for switching?? What are these "CLK labeled" parts for?

patafix · Post by **patafix** » 25 Apr 2008, 08:47

I think so... as in Boss and other Fet switching stompboxes, they provide a current to the FETs so that one or another conducts the signal between the drain and source...

rocklander · Post by **rocklander** » 25 Apr 2008, 09:05

bighud wrote:
FXFXFX wrote:my virus scanner detects a virus in the link above (first post) - be carefull!!
I checked it out...cause I was curious and on a linux box. I am 99% sure there is no virus. Some sort of executable file would have to exist for this to be the case. Since there isn't anything but a blog, I am convinced it is clean. Maybe I am wrong though.

likely malware, which doesn't need to be an executible.. internet exploder needs not much at all for a site to have negative effetcs

soulsonic · Post by **soulsonic** » 29 Apr 2008, 03:21

patafix wrote:What's noticeable with T21 designs is that there are no clipping diodes... Barta seems to prefer the sound of overloaded Opamps...

I think I'm going to give it a try too... without the electronic bypass system... and with a single dualopamp...

I just looked up the TLC2262 chip. It's a CMOS opamp, the internal schematic is nothing but a bunch of MOSFETs! That likely is a key ingredient to the sound; not just opamp overdriving, but essentially a bunch of MOSFETs overdriving.

I see a similar concept in the Ibanez Mostortion, which also uses a CMOS opamp.

patafix · Post by **patafix** » 30 Apr 2008, 16:54

OK !

So I think I'll have to use Both a TL072 And A 2262.

I'll certainly use the first opamp of the TL072 for buffering the input...

Otherwise, I might use only one 2262 for both gain stages...

It wouldn't be an original XXL anymore, but it will distort anyway !

Bernardduur · Post by **Bernardduur** » 19 Nov 2008, 09:18

Anyone knows how the bass version differs from the one posted here?

Silent Fly · Post by **Silent Fly** » 19 Nov 2008, 10:49

Lite version edit.

Post by **audioguy** » 19 Nov 2008, 18:00

Torchy did a strip layout a few years ago- was cool.

mfgobbi · Post by **mfgobbi** » 22 Nov 2008, 22:51

Not that it means much but this box was reviewed in the 90s by GP magazine as the most authentic amplike overdrive in the market.

diegoribba · Post by **diegoribba** » 17 Apr 2011, 01:17

Hi folks! im just wondering if there's any posibilitie to turn this pedal into the xxl bass version! thanks a lot! regards!

DrNomis · Post by **DrNomis** » 17 Apr 2011, 01:27

diegoribba wrote:Hi folks! im just wondering if there's any posibilitie to turn this pedal into the xxl bass version! thanks a lot! regards!

Shouldn't be that hard, just increase the value of the coupling caps, the tone control should work okay as is, hope that helps....