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

[gtudoran]

Holly crap Jim way to go - 3x GTFO (try to cascade them  )

Best regards,
Gabriel Tudoran
Analog Sound

[Keeb]

So I'm thinking about building this and unlike Hilli I'd build only one... For starters.

Which tube socket works best?

http://www.musikding.de/product_info.php/info/p1196_Socket-noval-print.html

or

http://www.musikding.de/product_info.php/info/p3252_Socket-noval-print-small.html

[Hilli]

I have used the small sockets. They are perfect.

Hilli

[fair.child]

Dear friends who have been made GTFO,

Here mine, I built this today, but I will test this maybe next week, because I'll go out of my town

Here, the board before I soldered up all of the component


IMG_0602 by DIY Parts + PCB Center, on Flickr


IMG_0603 by DIY Parts + PCB Center, on Flickr

After few hours,

Taddaaaaaaaa


IMG_0604 by DIY Parts + PCB Center, on Flickr

I luv it

IMG_0605 by DIY Parts + PCB Center, on Flickr

I have keep in my mind for Hili Mods, so here, I made a MOD out for 10N caps for it


IMG_0609 by DIY Parts + PCB Center, on Flickr

I also tried to make IRF transistor socketed, so I can swap it easily if it misconfigured or broken


IMG_0606 by DIY Parts + PCB Center, on Flickr

Finally, back of the board


IMG_0607 by DIY Parts + PCB Center, on Flickr

I haven't finished this yet, probably I will try the Hili mods in my board after I have GTFO basic result

Please give me any advice about my works, it would be my pleasure if heard suggestion from Jim or Hili (both of you guys)

Cheers all

[J0K3RX]

Damn! That board looks great!! Keep in mind that the caps are high and Q1 the IRF740 is sitting high. Might want to get a larger box/enclosure to put it in! If not you will have to lay the caps down on their side so you can fit it in the box without them hitting the pots. Hilli (Bernd's) box looks to be a perfect size!  Looks great man!

Remember to do all of this like Gabriel Tudoran told me!!

- Input is from R2 and GND (any point from ground plane will do)
- Output is from R17 and R18 junction
- 12V input is on the positive side of the 470uF cap C9 on the layout

You will have to make the following checks before you put the tubes in the sockets:

- you have to have 12V @ pin 4 and 8 of the 555 timer
- you will have to have 90v at the positive side of C11 (4.7u) - is the HV out
- you will have to have almost the same voltage like above to the sockets V1 and V2 (pin 1 and pin 6 of the sockets) take your mesurment on the pin directly
- you will have to have 12V @ pin 5 of both sockets - there heaters voltage

After that, if everything is in place and good to go, disconect from the 12V supply, put the tubes in the sockets, reconnect the 12V supply and you should see the heaters glowing. You should take the messurments again (the ones from above) - and @ point 3 from above you should have smaller voltage readings then the first ones. Only after that you should hear something... and btw keep the volume low and pay attention to your fingers - do not touch FET's metal tab or the back side of the board!

[fair.child]

Damn! That board looks great!! Keep in mind that the caps are high and Q1 the IRF740 is sitting high. Might want to get a larger box/enclosure to put it in! If not you will have to lay the caps down on their side so you can fit it in the box without them hitting the pots. Hilli (Bernd's) box looks to be a perfect size!  Looks great man!

Remember to do all of this like Gabriel Tudoran told me!!

- Input is from R2 and GND (any point from ground plane will do)
- Output is from R17 and R18 junction
- 12V input is on the positive side of the 470uF cap C9 on the layout

You will have to make the following checks before you put the tubes in the sockets:

- you have to have 12V @ pin 4 and 8 of the 555 timer
- you will have to have 90v at the positive side of C11 (4.7u) - is the HV out
- you will have to have almost the same voltage like above to the sockets V1 and V2 (pin 1 and pin 6 of the sockets) take your mesurment on the pin directly
- you will have to have 12V @ pin 5 of both sockets - there heaters voltage

After that, if everything is in place and good to go, disconect from the 12V supply, put the tubes in the sockets, reconnect the 12V supply and you should see the heaters glowing. You should take the messurments again (the ones from above) - and @ point 3 from above you should have smaller voltage readings then the first ones. Only after that you should hear something... and btw keep the volume low and pay attention to your fingers - do not touch FET's metal tab or the back side of the board!

First of all, I would say thank you jim, you have been followed my several project and help me debugging. Yesterday before I've left for out of my town, I tried to power it up with 12VDC and tried to see the result

I'm curious with what I've done

1. I always keep in my mind that my GTFO is high voltage pedal, regarding that I embraced myself to put an old 12ax7 to see the result

Seems fine but weirdo I didn't see the heater light on them, but they're getting hot when I connected 12ax7, so please give me your assumption Jim about my problem? Maybe bad 12ax7? Or my wiring?

2. I didn't have much time to check dmm, but I remembered that I touched the IRF metal, nothing happen Jim, tell me what happend if I haf touched it ? Maybe I would get killed or something ? And I realized that I need to bias 5k trim in proper way, so what is the best value for 5k trim? Where I should put my red pin DMM to see the adjusment? Because I got my GTFO result when I pulled left the trimmer, but it doesn't seem the proper way to bias/adjust 5k trimmer

3. I saw that my GTFO build doesn't give me hi gain result like Jim GTFO or maybe Hili GTFO because I tried to compare it with jim soundclip and mine. My gtfo sounds like a vintage overdrive, can you give me the signal chain when you tested your GTFO, Jim? Let me know what kind of amp channel did you use to test it.

About your warning, yes Jim , I've been carefully with this build, wearing slippers, etc. And maybe I would try to Check the voltages after I come back from out of town. Just to make I was doing right with my GTFO, my last question this built is categorized to amp or a OD pesto ? I'm curious to know it, Jim

At the end, gabriel, you are the one who deserved a medal because you had shared it,

cheers all

[fair.child]

Hey Jim,

Holy crap,

This pedal is really amazed me a lot....

Metal Rules, I guess, today I will try Hili mods, I discovered everything was right, instead I should change my old tubes

This pedal, really rawk, I will catch the demo soon


Cheers all

[zambo]

Anybody build one with a nixie supply or a power transformer yet?  I did something kind of similar but different schematic layout etc. ( questioning the wisdom of this now....) but using the smps. still tweaking it.

A metal enclosure would be sweet. quieter too lol. I have been quieting down the smps by loading it down with a resistor from b+ to ground of around 33k. It hasnt blown up yet.

[J0K3RX]

Anybody build one with a nixie supply or a power transformer yet?  I did something kind of similar but different schematic layout etc. ( questioning the wisdom of this now....) but using the smps. still tweaking it.

A metal enclosure would be sweet. quieter too lol. I have been quieting down the smps by loading it down with a resistor from b+ to ground of around 33k. It hasnt blown up yet.

Greg, that sounds good man and great playing!! interested to see the schematic you used, care to share? Also, what kind of amp are you running into? btw - The gtfo has a nixie in it.

[zambo]

I used a typical preamp of 4 gainstages gs>1meg pot>gs>1meg pot>gs>tone stack ( british style)gs> 1meg pot. Plate R is 220 on first 3 and 47 on 4 . Cathode R is 1k5, 2k2 , 10 , 4k7 with the first 2 bypassed with 22uf caps. running at 200 volts from taylor 1363 smps. I may change to the gtfo schematic if I cant get this one sounding right. Its sounds ok but still tweaking it. Amp is a peavey bandit 112 on the clean channel with the bass and treble up around 7 and mids around 3 or 4. I was trying to set it at levels I see other guys play so I could adjust the pedals voicing right. Thanks for the kind words and watching.

[fair.child]

Now I can play my guitar in peace...


IMG_0617 by DIY Parts + PCB Center, on Flickr

I'm still asking what is the exact value for the 5k Trimpot ? I'm tweaking and still working on it. I got a whine when I boxing GTFO, but suddenly I remembered about the 5k Trim, so I started to tweak it. My question is how to adjust this 5k Trim and what is the exact output value ?

Here's what I've got,

http://soundcloud.com/andrewraharjo/gto-supercharger-smps-method

Sorry for sloppy playing, I'm too excited with this Hi-Gain pedal

Cheers all

[Ripthorn]

Alright guys, need just a little help here.  I just put mine together, but I used the old PCB artwork (post 66 or something).  I wired it according to the schematic (near as I can tell, I needed to make one or two small adjustments).  I just plugged in power to it and it smoked my LM7812 in no time flat.  I am wondering if my 1A 12V power supply is too weak.  I don't have a more powerful power supply currently, so I can't just check that out.  What current rating do all of you have for your power supplies?  Thanks.

[Ripthorn]

I have a question about the schematic.  It shows R24 and R25 in series between the 2nd and 3rd gain stages.  Why wouldn't we just replace that with a 33k resistor?  I am thinking the schem is problem not quite correct, as I would think that R24 would be on the right, therefore making the HV come through R24 to get to pin 1 of V2, then through R25 to get to pin 6 of V1.  Is this correct?  That is how I wired it.

As a note, I found my first issue, I had a short from +12V to GND.  However, I still don't have any HV and my IRF740 gets blazing hot in a relatively short amount of time.  I've never done one of these PWM power supplies, so I really don't know what I am doing.  My pot 5 is a 1k multi turn trimmer set to about half (about 500R per side).  Any ideas? 

[fair.child]

Alright guys, need just a little help here.  I just put mine together, but I used the old PCB artwork (post 66 or something).  I wired it according to the schematic (near as I can tell, I needed to make one or two small adjustments).  I just plugged in power to it and it smoked my LM7812 in no time flat.  I am wondering if my 1A 12V power supply is too weak.  I don't have a more powerful power supply currently, so I can't just check that out.  What current rating do all of you have for your power supplies?  Thanks.

I used 12AV 500mA DC, it's fine, hey you've got 66 PCB artwork, hmm I look like you got the wrong PCB artwork

here quoted from Gabriel

Hello Minion,

Ahhhh %#$%#, you have missed the post #83 ( http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_brd_ok.svg ) this is the last PCB for GTFO (i've made a mistake: i've overwritten the general instruction PDF but i didn't erase the PCB PDF) i think that it will be the best practive to redo the PCB or you can use the schematic to populate the board it will be a little bit more complicated but you will not loose it  really sorry for this mistake. I will also modify the #66 post to have all the latest data.

UPDATE! USE THIS! DO NOT USE POST No. 66:

General Instructions: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/GTFO.pdf
Bom: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/bom.txt
PCB SVGfile: http://dl.dropbox.com/u/15275178/blast%20from%20the%20past/BFTP_brd_new.svg

Thank you again for pointing that mistake, 1000x excuses for this.

Best regards,
Gabriel Tudoran
Analog Sound

PS: @guitarrob - yes there are 2 x superbright blue leds under the tubes just for design

Hi , I etched my board and I drilled the holes and then went to install some components and realized that the Layout that shows the parts placement does not match up with the PCB ........ The traces and parts placements in the PSU don"t match up and also in other places ......

I"m using the layout and pcb from post #66 ....... Is there an updated layout ??

Thanx

[fair.child]

I have a question about the schematic.  It shows R24 and R25 in series between the 2nd and 3rd gain stages.  Why wouldn't we just replace that with a 33k resistor?  I am thinking the schem is problem not quite correct, as I would think that R24 would be on the right, therefore making the HV come through R24 to get to pin 1 of V2, then through R25 to get to pin 6 of V1.  Is this correct?  That is how I wired it.

As a note, I found my first issue, I had a short from +12V to GND.  However, I still don't have any HV and my IRF740 gets blazing hot in a relatively short amount of time.  I've never done one of these PWM power supplies, so I really don't know what I am doing.  My pot 5 is a 1k multi turn trimmer set to about half (about 500R per side).  Any ideas? 

Try to etch new PCB Artwork then you'll have something to successful pesto photo post here. And yes from the schem 33, there was an errata on it. HV pin out 1 from the tubes should be more likely on pin out 6 from tubes (above 400V ), and make sure tube heater are on. Also try to put extra ground to make your wiring become easier

Cheers

[Ripthorn]

I have a question about the schematic.  It shows R24 and R25 in series between the 2nd and 3rd gain stages.  Why wouldn't we just replace that with a 33k resistor?  I am thinking the schem is problem not quite correct, as I would think that R24 would be on the right, therefore making the HV come through R24 to get to pin 1 of V2, then through R25 to get to pin 6 of V1.  Is this correct?  That is how I wired it.

As a note, I found my first issue, I had a short from +12V to GND.  However, I still don't have any HV and my IRF740 gets blazing hot in a relatively short amount of time.  I've never done one of these PWM power supplies, so I really don't know what I am doing.  My pot 5 is a 1k multi turn trimmer set to about half (about 500R per side).  Any ideas? 

Try to etch new PCB Artwork then you'll have something to successful pesto photo post here. And yes from the schem 33, there was an errata on it. HV pin out 1 from the tubes should be more likely on pin out 6 from tubes (above 400V ), and make sure tube heater are on. Also try to put extra ground to make your wiring become easier

Cheers

I know that the pcb artwork is not the latest nor correct, but I had already etched the board and started populating it before I realized it.  So I have just been carrying on and primarily working from the schematic.  I have isolated the power supply section to try to get that squared away first, but I get nothing.  I am just wondering if there are common pitfalls with the power supply section that some have run into.  I will check it out again tonight after work.

As for the schem, on the signal portion of it (first page), where exactly should the HV connect?  Should it connect between R24 and R25?

[fair.child]

R24 goes to C11 and C13
R25 goes to R24 and  C12

Have you tried to check the SMPS Voltage ? I mean, did you try to turning your 1k-5k trim ? in my opinion, HV connect comes from the SMPS.
Try to upload some pictures of your build. Probably, Jim, Gabriel or Hili can figure something, in case solving your problem.

Cheers

[Hilli]

I had the same problem first, the IRF was overheated and destroyed in a very short time. The reason was that I used a toroidal inductor. They are unsuitable for this project.
Please upload pictures.

[Hilli]

@fair.child: Wow, very nice PCB. That looks professional !!!

[Groovenut]

Just finished populating my version of this build. Will post pics soon.

Just a reminder, the inductor needs to be rated at 1A and non-torroidal. Also this little guy pulls ~250mA completely unloaded (according to my bench PSU). Figure in heaters @ 300mA and anode current @ ~15mA and we have eaten up the better part of 1A, so the wall wart needs to be rated at least 1A.