GTFO - Full tube high-gain pedal (2x 12AX7)

gtudoran · September 25, 2011, 02:44:59 AM

Hey guys,

After some time i've managed to finish this project. It's based on Soldano GTO SUpercharger (the only thing that is like GTO - the main topology) - Some modes ware done. So this is it

Building instructions: http://dl.dropbox.com/u/15275178/Pictures/GTFO_Distortion.pdf

And sound clips: http://soundcloud.com/analog-sound/gtfo-and-amp

Best regards,
Gabriel Tudoran
Analog Sound

zambo · September 25, 2011, 03:23:55 AM

Great sounding pedal! What is the power supply situation? Are you running the whole pedal in starved plate mode at 12 volts? Again, great sounding pedal! Thanks for sharing

deadastronaut · September 25, 2011, 04:14:21 AM

sounds nice n chunky...is that into a clean amp?....

gut shot?..

frequencycentral · September 25, 2011, 05:25:35 AM

I spy Gabriel's take on the 555 nixie smps on the pdf, so this is high voltage. Very nice.

gtudoran · September 25, 2011, 08:03:41 AM

Thank you for your feedback guys! The PSU is a 555 Nixie SMPS with some additions - i will post an update ASAP. The anode voltage is 400V and the heaters are running in 12v mode for 12AX7. I will also post some guts pictures tonight. The upgrated version (it will be the samme tone matters) will have a SMPS with an ATMEL controller and variable duty cyrcle - this version use a hack for 555 to be used as PWM controller (you can google 555 pwm and at the pictures tab you will find the schematics).

Best regards,
Gabriel Tudoran
Analog Sound

PS: The recording was made using the clean channel of a Reason amp and a 1x12" Celestion V30 cab and a SM57 - nothing fancy.

Skruffyhound · September 25, 2011, 11:05:11 AM

That does sound good. Impressed

zambo · September 25, 2011, 12:27:21 PM

are some of the pots missing values? and there is a 1m between pot 2 and ground? I am not very familiar with soldano stuff ( but I would like to be ) so sorry for the ignorance.

I love the 39k cold clipper.

gtudoran · September 25, 2011, 12:53:02 PM

Quote from: zambo on September 25, 2011, 12:27:21 PM
are some of the pots missing values? and there is a 1m between pot 2 and ground? I am not very familiar with soldano stuff ( but I would like to be ) so sorry for the ignorance. I love the 39k cold clipper.

Bahhh.... $$#@$ indeed i will post an update later.

Best regards,
Gabriel Tudoran
Analog Sound

waltk · September 25, 2011, 01:27:51 PM

QuoteBahhh.... $$#@$ indeed i will post an update later.

Very nice! Not to be too pushy, but can you include a schematic for the pwm PS?

(I've been acquiring the parts to build 555-based power suppplies. Also have the tubes/sockets - I definitely want to build this!)

gtudoran · September 25, 2011, 02:45:51 PM

Quote from: waltk on September 25, 2011, 01:27:51 PM
QuoteBahhh.... $$#@$ indeed i will post an update later.

Very nice! Not to be too pushy, but can you include a schematic for the pwm PS?

(I've been acquiring the parts to build 555-based power suppplies. Also have the tubes/sockets - I definitely want to build this!)

There there

this is the main way to use a 555 like a PWM controller. You can also use a uC as a PWM controller

i will do that in the near future.

Best regards,
Gabriel Tudoran
Analog Sound

PS: I will not have the time to make correction on scematic but i will post the values here:

- POT1 - 1M Log - i used 500k as i found it more usefull on the range
- POT2 - 500k - or you can replace it with a 470k rezistor and the grid will take signal from the juction of the 470k rezistor and 1M rezistor
- C1 and C2 ajust them by taste - 1u with 680n or 1u with 1u - just a matter of taste
- if you find it too bright you can decouple R6 with a 470p/600v

And that is about it

waltk · October 02, 2011, 06:27:15 PM

The PDF linked to at the top looks kind of fishy. The the layout and PCB images all have stripes - very difficult to make out what is there, and the PCB images are not usable. Is anyone else having this problem?

deadastronaut · October 02, 2011, 06:54:08 PM

Quote from: waltk on October 02, 2011, 06:27:15 PM
The PDF linked to at the top looks kind of fishy. The the layout and PCB images all have stripes - very difficult to make out what is there, and the PCB images are not usable. Is anyone else having this problem?

yep, me too.

gtudoran · October 03, 2011, 06:23:33 AM

Quote from: deadastronaut on October 02, 2011, 06:54:08 PM
Quote from: waltk on October 02, 2011, 06:27:15 PM
The PDF linked to at the top looks kind of fishy. The the layout and PCB images all have stripes - very difficult to make out what is there, and the PCB images are not usable. Is anyone else having this problem?

yep, me too.

Sorry for this guys... my EAGLE is acting strange...i will export another PCB and schematic with the last modifications and i will post it again here. Sorry for this.

Best regards,
Gabriel Tudoran
Analog Sound

gtudoran · October 04, 2011, 06:05:28 AM

Ok... had some problems with this little p.o.s but i've managed to solve them - so now i can have a solid copper pour no matter what. I've used a ULP from cadsoft site that would export PCB and SCH (visible layers or not) to a SVG file ... and that was the solution.

I'll give you guys the SVG files as it's easyer to work with them (i use Inkscape and i can export them in any format - pdf, bmp etc.)

Links:

PCB: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_PCB.svg

Layout: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_TOP.svg

Schematic: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_SCH.svg

SMPS Schematic: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_SMPS.svg

ULP file: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/eagle2svg-1.2.ulp

You get all the info how to use it if you look inside ULP - the only thing you should do is to copy in ULP dir. from you Eagle installation.

Hope now is better

and i'm waiting for someone to build it

Best regards,
Gabriel Tudoran
Analog Sound

gtudoran · October 05, 2011, 09:11:57 AM

Hello guys,

With the help of our colleague Walt (thank you for your help) - he made a pdf with this project and i have added some text to it. This is the link http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/GTFO.pdf

Best regards,
Gabriel Tudoran
Analog Sound

PS: you can post it on any site/blog you like; posting is not forbiden.

gtudoran · October 10, 2011, 10:49:44 AM

This is a video made by a friend of mine (is in Romanian but the thing that is important is the sound so...), you will see that he use 3 different guitars. Enjoy!

Best regards,
Gabriel Tudoran
Analog Sound

RickL · October 10, 2011, 01:09:43 PM

There appears to be a small error on the PCB layout in the most recent PDF. R25 is shorted by a trace under it.

The schematic is also a bit confusing. Based on the layout it seems that the power supply connects to the circuit at the junction of R24 and R25 and that the output of the PS is from the junction of R22 and C11. It might not hurt to clarify this on the schematic.

pravudh · October 17, 2011, 08:57:16 AM

I use ac heater sound better than dc heater. any idea to get more gain

gtudoran · October 17, 2011, 09:55:13 AM

AC heaters sounds different from DC?!?!.... strange, i didn't notice that. What schematic did you use? One way to boost up the gain is to modify the interstage attenuation networks.

Best regards,
Gabriel Tudoran
Analog Sound

runmikeyrun · October 17, 2011, 07:24:08 PM

any chance for a sound sample on bass? Also, how/what do I adjust pot 5 to on the PS?

Thanks! I will build this sometime this winter once the snow flies and the motorcycles are put away

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GTFO - Full tube high-gain pedal (2x 12AX7)