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

J0K3RX · October 27, 2012, 01:26:00 AM

WOW nice Hilli!!!

Hilli · October 27, 2012, 09:48:48 AM

Hey Jim. Thanks man. I have changed a few values and now he sounds even better.

gtudoran · October 28, 2012, 10:00:33 AM

Nice work

i think would be nice to tell us waht have you changed

Best regards,
Gabriel Tudoran
Analog Sound

Hilli · October 29, 2012, 02:45:31 AM

Hi gtudoran,

this is my current schematic. Now I have a very nice sounding clean channel, and he is much louder than the f*cking

true bypass.

gtudoran · October 29, 2012, 03:15:54 AM

That is normal, as far as i can see you don't have a volume pot for the clean sound (afer the first triode) and the only load that it's see is that 1M in series with 1M resistor (if i'm not mistaken) and also the load from the next pedal input... so that is going to be very loud if you don't stick a volume pot there.

Best regards,
Gabriel Tudoran
Analog Sound

Hilli · October 29, 2012, 03:37:07 AM

No, the clean chanel is perfect. He is a little quieter than the overdrive chanel, but clear, no distortion. It sounds very very nice. The volume difference comparison with the true bypass is enormous. Try it out.
But in the next pedal I will insert a 1Meg log clean volume pot.

Greetings, Bernd

Hilli · October 29, 2012, 03:33:06 PM

Have made a short video. In reality it sounds better, I used a cheap microphone. $:-\$

Greets, Hilli

Germanium_Boy · October 30, 2012, 01:32:39 PM

What a great project! I think that I'm going to pick all the pieces as soon as I can,... In your videos sounds so good!

By the way... Can this beast be used as a preamp? Maybe thru a DI to a sound card, for direct recording?

Hilli · October 30, 2012, 01:36:22 PM

Quote from: Germaniun_Boy on October 30, 2012, 01:32:39 PM
Can this beast be used as a preamp? Maybe thru a DI to a sound card, for direct recording?

I think yes. Maybe thru a speaker simulation.

Germanium_Boy · October 30, 2012, 01:50:06 PM

Thanks for that quick response! yeah, I have a great soft-simulation for cabs. Maybe, one day, I'll build a good cab simulator, but it's a project that I have started a hundred of times, but I've never decided what schematic is the best...

Hilli · October 30, 2012, 08:30:19 PM

Does anyone found really good working coils? I have tried hundreds but ALL of them run hot. More or less.

Germanium_Boy · November 01, 2012, 04:01:38 PM

Quote from: Hilli on October 30, 2012, 08:30:19 PM
Does anyone found really good working coils? I have tried hundreds but ALL of them run hot. More or less.

Hilli, I think that you live in Europe, like me (because you use to buy in Banzai and Tube-Town). Have you tried the coils at Farnell? I think I'll buy them there, there is a wide catalogue, and I have seen Panasonic and Wortech inductors (100uH, more than 2A) with a very good apparence...

By the way... I suppose there is no problem in using UF4007 instead xxx4, isn't it? Because I have a pair of them in "stock",...

Hilli · November 01, 2012, 10:35:42 PM

Hi,
Banzai and TT don't sell coils, I didn't tried the Farnell coils yet. I have tested 2,1A coils - they runs hot. Now I have ordered 3A types on ebay. Hope they works better and will fix my heat problem. Do you have no problems?

UF4007 works fine (1000V 1A).

Greetings

PS: I have updated the schematic, there was an error.

Germanium_Boy · November 03, 2012, 10:40:35 AM

Hilli, thanks again for the new schematic. I have not started tu build this little beast yet, but I'll report any troubles about heating. I think I'll try Farnell coils, let's see if they work so good as they seem to do it...

Germanium_Boy · November 03, 2012, 11:21:47 AM

By the way... Hilli, what is the box that you used for your project? It has the perfect fit, and I'm not sure about what model is... Thanks in advance!

ghostsauce · November 03, 2012, 12:53:54 PM

Be still my metal heart.. this thing is AMAZING! I am SO FREAKIN' building one.

Hilli · November 03, 2012, 04:32:45 PM

Quote from: Germaniun_Boy on November 03, 2012, 11:21:47 AM
By the way... Hilli, what is the box that you used for your project? It has the perfect fit, and I'm not sure about what model is... Thanks in advance!

Hi, the enclosure I used is from Musikding. It is al ittle bigger than a BB, but perfect if you build a full tone stack in it.

All the small coils will have problems with heat. Now I have ordered 4 Ampere!!! coils from Digikey. (The same are available from Farnell & Mouser).

Yesterday I tried THESE 7.8A types, the Coil and the IRF740 (no heatsink) remain ice cold. But they are gigantic, I would need a extra box for it.

I currently mounted 2x220µH in parallel under the footswitch with 2 little PCB's. But they run hot too after an half hour.

Germanium_Boy · November 04, 2012, 01:42:34 AM

Thanks, Hilli... Great info! I think I'll try with 5A coils, to be sure of avoiding any heating issue.

Hilli, is this the correct schematic?:

http://dl.dropbox.com/u/44238774/Bilder/DIY/Schematics/Redraw%20Plan%20GTFO.jpg

I'm collecting all the items... In a few days I hope being at work with it!

gtudoran · November 04, 2012, 05:55:13 AM

Waw Hilli - very nice, rilly nice builds you have there. This project of mine i see that had a lot of sucess... i would not expect that. I'm rilly sorry that i couldn't reply on this topic as often as i would like but in the last year had a lot of work with my digital projects (not musical). I will start another research on this project regarding the SMPS optimisation (maybe i could find some solutions - i would like to use a uC so the parts count would be lower, but that i will have to experiment).

Best regards,
Gabriel Tudoran
Analog Sound

sst4270 · November 04, 2012, 11:15:43 AM

Hi, I'm trying source parts for this project. While searching for IRF740... I'm finding lots of different ones... can someone post a link to the exact one they used? Much appreciated. Regards, Stev

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