Tube Driver build report

shredgd · April 30, 2006, 05:29:16 AM

Hi,

It's been ages since I first wanted to build a Tube Driver. I waited a lot for an update to cure the reported hum problem at General Guitar Gadgets, but lately I decided to see what the problem was and find a solution myself.

I read people wasn't getting many problems building the Shaka Tube, which is a very similar circuit, so the problem had to simply be a layout issue. So I did one myself, trying to separate the audio path from the power supply components the most, and I used an external 12v AC transformer.

I actually got a hum problem at first, but I only could hear it when using a high gain distortion after the pedal (which amplified that minimum hum I couldn't hear playing through the clean channel of my amp). I often use a high gain lead sound in my amp and, as the hum was there even with the Tube Driver bypassed, I had to find a solution.
So I used shielded cable to connect the jacks to the switch: this solved the problem 100%!
Then I also added shielded cable to connect the volume pot (i.e. the circuit output) to the switch just in case I will ever use the Tube Driver as a booster in front of a distorted sound. I should also shield the connection between the switch and the circuit input, but I simply don't want to disassembly everything to get access to the board (I used a 1590BB enclosure, so things are pretty tight in there, now). Even with this last "hum-bucking" procedure missing, I get a very minimal hum in front of a high gain distortion (and it is lower than the inevitable hiss associated). Of course I get no hum when using the clean channel of my amp or the Tube Driver alone.

Regarding the sound, this pedal has a lot of presence, I have to keep the hi pot at min. I still have to try it at loud volumes, so I'm wondering if I will have to add a low pass filter at the end of the circuit as Doug Hammond did with his Pentode Driver. I still wait before doing it because I want to keep this "original" (actually, Eric Johnson uses this pedal with the hi pot at min, too).
In my opinion, this pedal is best used to get a mild overdrive sound (as Eric Johnson and David Gilmour do), even if the gain pot is capable of delivering a good amount of distortion.
I used an EI Yugoslavia 12AX7 tube.

In conclusion, this project only needs care to avoid any close passage between the 12v AC wires and the signal ones, and shielding. In my opinion it doesn't have any circuit-related or valve-related hum, so I don't think experimenting with DC heated tube filaments is worth the hassle.
I don't have any webspace to post my layout, if some of you do and want to host it just tell me what email address I must send it to. It is a .pcb file.

Giulio

mojotron · April 30, 2006, 11:34:56 AM

You can send it to mike@mojotronics.com and I will host it.

petemoore · April 30, 2006, 12:17:39 PM

Very cool...thanks for sharing 1!
What are the 1n914 diodes up to at the input of the circuit in front of the +Oa input?
It looks like they'd be clipping diodes if the signal were big enough, but a HB pickup doesn't produce enough juice to meet their threshold, does it?

shredgd · May 01, 2006, 05:28:21 AM

I wondered about those diodes, too, but left them there because I saw them in other tube driver work-a-like pedals schematics as well.
I had planned to socket them, but I forgot to do it...!

mojotron · May 04, 2006, 11:36:31 AM

The pcbexpress file for his layout is at:

http://www.mojotronics.com/images/Tube_Driver.pcb

Thanks.

finkfloyd · May 04, 2006, 11:57:12 AM

Hi,

Thank you very much!

After my failed attempt on vero, I decided to purchase a laser printer, i bought a hewlett packard 2100 used.

How do you make this into a printable layout? In express PCB when I export as bmp it doesnt come out right with all the traces etc..

Thanks

Paul Marossy · May 04, 2006, 01:05:33 PM

That's good to hear. That GGG Tube Drive project looked good to go to me, but so many people reported having problems with hum. Shielded cables can make a big difference in a circuit like the Tube Driver, especially when there is any kind of 60Hz AC inside an enclosure.

Roobin · May 04, 2006, 02:55:01 PM

Sounds cool. I've always wanted to break into tubo overdrive/boost, and this one looked good. Now I know that noise can be solved, it's even more temptiing.

Any chance of converting to an image of PDF file?

psst · May 09, 2006, 03:30:08 PM

Finally I could install the program in a friend's computer (I use linux, so I can't run ExpressPCB).
How could I print just the PCB (after some experiments I could do it, but still the border line of the board is printed

...)
And should I guess what the pads are for with the schematic or there's an option that I could not find to show that info?

If there was a way to export it to PDF that'd be great...

Thank you for your work!!

finkfloyd · May 18, 2006, 04:12:39 PM

Hi,

I want to make sure I get this right pedal right, unlike my last failed vero attempt, So far I have populated the board, but i;ve noticed there dosent seem to be enough pads for ground and tube heater pins, can someone be kind enough to help me and verify the below text on the layout, and modify it if needed?

Also, there dosent seem to be a pad for negative power.

I would like to use a standard dpdt, not a 3pdt, the led function should still work?

It would be nice if this was all documented as the layout is quite a lot different to the "GGG" one at the bottom of this page.

Schematic :
http://www.generalguitargadgets.com/diagrams/tube_driver_sc.gif

Parts Layout: (Problematic GGG layout)
http://www.generalguitargadgets.com/diagrams/tube_driver_lo.gif

finkfloyd · May 20, 2006, 05:51:20 PM

nevermind, ive compared it again and it now makes sense, havent finished the pedal yet, ill post a soundclip when successful, need an ac supply yet.

EDIT, heres a layout diagram from shredg with the wiring explained:

Tube pin 4 goes to pwr+, and tube pin 5 goes to ground, refer to the general guitar gadgets layout and schematic for pot wiring.

finkfloyd · May 25, 2006, 03:42:55 PM

Hi,

Just completed it, though I'm getting a major volume drop though, though the sound is definately apparant, sounds very nice.

I used external wall power AC 12v output, and used a chinese Shuguang 12xa7b tube, and oh, i used for r18, a standard 10ohm 5% 1/4 watt resistor, instead of a 10ohm 1 watt resistor. and a couple of the caps are only rated at 16volts, but they should be ok.

I've checked for solder bridges, looks ok any ideas?

heres some pics of it :

finkfloyd · May 25, 2006, 05:22:07 PM

Ah Ah! I fixed it, i accidently cut a trace, bridged it and it works properly now!

Great pedal!

Ardric · May 25, 2006, 07:38:53 PM

I'm looking at the Tube Driver schematic and layout at GGG, and I think I see a problem with the power supply. If R3 and C3 are to filter V+ for IC1, then C3 is miswired. The positive end of C3 should connect to the other side of R3, at the junction of R3/D1/IC1 pin 8. As it's drawn now, C3 doesn't really do anything.

Aharon · May 25, 2006, 07:50:32 PM

Quote from: finkfloyd on May 04, 2006, 11:57:12 AM
Hi,

Thank you very much!

After my failed attempt on vero, I decided to purchase a laser printer, i bought a hewlett packard 2100 used.

How do you make this into a printable layout? In express PCB when I export as bmp it doesnt come out right with all the traces etc..

Thanks

Here's a link explaining a workaround for printing ExpressPCB layouts.
http://www.robotroom.com/PCB.html

Aharon

psst · June 20, 2006, 07:09:03 AM

I passed the PCB from ExpressPCB format to GIF, and I made the tracks wider.
Here it is:

el84 · June 20, 2006, 08:21:13 AM

Hello !
I have build the TubeDriver by JackOrman (I have make some mods to original project

) and it sound very very gooood !!

The project of GGG has problem of humm (or similar) and I don't have do it

This is my stomp:
http://www.viruweb.net/Public/Photos/IMG_2342.JPG
http://www.viruweb.net/Public/Photos/IMG_2343.JPG
http://www.viruweb.net/Public/Photos/IMG_2344.JPG

http://www.diyitalia.it/index.php?option=com_zoom&Itemid=37&page=view&catid=55&PageNo=1&key=8&hit=1

If you want see the tube amp you can see:
http://www.viruweb.net/
Menù : gallery/

.... or for demo-sound the page under
Menù: audio/video .... find the "TubeDriver-DemoSound"

Bye
Antonello

mat · June 20, 2006, 08:31:57 AM

Quote from: el84 on June 20, 2006, 08:21:13 AM
Hello !
I have build the TubeDriver by JackOrman (I have make some mods to original project ) and it sound very very gooood !!
The project of GGG has problem of humm (or similar) and I don't have do it

This is my stomp:
http://www.viruweb.net/Public/Photos/IMG_2342.JPG
http://www.viruweb.net/Public/Photos/IMG_2343.JPG
http://www.viruweb.net/Public/Photos/IMG_2344.JPG

http://www.diyitalia.it/index.php?option=com_zoom&Itemid=37&page=view&catid=55&PageNo=1&key=8&hit=1

If you want see the tube amp you can see:
http://www.viruweb.net/
Menù : gallery/

.... or for demo-sound the page under
Menù: audio/video .... find the "TubeDriver-DemoSound"

Bye
Antonello

Hi Antonello,

Very nice thick overdrive sounds ! Congratulations ! Now I just have to build me one

cheers,
mat

el84 · June 20, 2006, 08:46:07 AM

Quote from: mat on June 20, 2006, 08:31:57 AM
Hi Antonello,
Very nice thick overdrive sounds ! Congratulations ! Now I just have to build me one
cheers,
mat

If you use 'my' double PCB version the effect is ..... "very easy" !

Nashtir · December 30, 2006, 04:01:04 AM

Quote from: psst on June 20, 2006, 07:09:03 AM
I passed the PCB from ExpressPCB format to GIF, and I made the tracks wider.
Here it is:

Hi Guys, I just wanted to ask if the layout for this new tube driver pcb is the one up in the topic in the .pcb format and if the values of resistors and caps are the same of ggg because on that .pcb file there's only "R1" and "C1" and not the values..So R1 is ggg's R1 and so on?thanks

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Tube Driver build report