GGG Tube Driver

[kurtlives]

http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=83&Itemid=26

First off what do you guys think of these project? I have always looked at it and wanted to try it. Has anyone built it, opinions and issues?

It says there is some issues with noise. I ways thinking use shielded wire (where needed), metal film resistors, power filtering, neat layout/wires and a voltage regulation with a LM7812.

Do you think that would cut back on noise?

Basically any info or advice on this effect would be appreciated.

[Krinor]

I asked J.D. about this project a while ago and he said he would have to improve the project somewhat before he'd sell any more pcb's for it.

There's Tube Driver for sale on ebay right now if you're interested: http://cgi.ebay.com/Tube-Works-Tube-Driver-Pedal-BK-Butler_W0QQitemZ330224242910QQihZ014QQcategoryZ41416QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[kurtlives]

How long ago did you ask him?

Do you know how bad the noise is?

[Mick Bailey]

I can heart-and-soul recommend Aron's Shaka Tube for this type of circuit and add a tone control as per my previous posting. I've also just replaced my LF351 IC with a 741 (I built mine to take a single op amp - should have used a dual) . Was playing about with different op-amps and was taken by surprise with the 741. Most people don't use them any more in favour of TL0xx family, but the richness and harmonic content they add to this design is worth considering.

I find this pedal to be quiet and very versatile, and my build was hasty point-to-point with a rats nest of wiring (twisted heater wires, though), as I was keen to get it built after hearing Aron's clip. I thought it would be noisier due to my poor layout. I did use screened cable for the in/out connections.

If you mount the socket on the outside you can swap valves all day long. It also has a useful bias control too.

[kurtlives]

Do you have PCB layout or project file for this build?

[shredgd]

Read here:

http://www.diystompboxes.com/smfforum/index.php?topic=44779.0

and here's my own layout:



Giulio

[Mick Bailey]

Just do a search for Shaka Tube on this forum. Various layouts and some useful background info too.

[Krinor]

How long ago did you ask him?

Do you know how bad the noise is?

Not so long ago.

I know you probably wanna build this thing because Gilmour used one etc. but honestly - there are better projects right here, so just pass on it and do a search in the forum. 

[kurtlives]

If I did build the GGG Tube Driver how would I add a bias knob?

[Mick Bailey]

Connect a 10k trim pot across your power supply V+ & V- then connect the wiper to R7 and R10 instead of the resistors connecting directly to V-

You need to note that the bias will be generally at the V- end of the pot, but some valves are much better slightly backed off.

[kurtlives]

Connect a 10k trim pot across your power supply V+ & V- then connect the wiper to R7 and R10 instead of the resistors connecting directly to V-

You need to note that the bias will be generally at the V- end of the pot, but some valves are much better slightly backed off.

Going by this layout... http://www.generalguitargadgets.com/diagrams/tube_driver_lo.gif

Lugs 1 and 3 go to 12V and ground. Do I disconnet the 10K resistor leads going to pin 2 and they go to the wiper?

[Mick Bailey]

The trimmer connects to V-, not to ground.

Referring to the layout, Probably the most straightforward way of doing this is to omit R7 & R10 from the board and hard wire one end of each resistor to pins 2 & 7 of the tube socket. Solder the 'free' ends together and wire them to the wiper of your 10k trim pot which will need mounting off-board.

Now you need to pick up V+ from the board which can be from the junction of R19 and R8. Wire this to one end of your trim pot.

Similarly, you need to pick up V-. There will be a free solder pad where R10 came from - the end which connected to R20. Wire this to the remaining lug of the trim pot.

If you study the schematic compared to the layout you'll understand.

BTW, the layout has an error - the supply shown is DC which will not work correctly. You need an AC adapter (suggest 300 - 400ma, no more) and pick up the LED + connection off V+ (you could use the V+ side of the trimmer, but you may need to increase the LED resistor value as V+ will be about 14v)

[kurtlives]

Does this look right? I think it's correct. My only concern is R9, how does it get to the tube socket?

[Mick Bailey]

Your diagram is correct, though you still need to wire the pad originally marked '2' to the tube base in order to connect R9. This is in addition to the 10k resistor connecting to pin 2 

[jpm83]

Paul Marossy have made a PCB layout for Shaka Tube. Just scroll down this page and you find layout for both the dual and single opamp versions. http://www.diyguitarist.com/DIYStompboxes/ST1590BB.htm

Janne

[Mick Bailey]

Since building (and subsequently modding) my Shaka tube I've built a number of distortions and canned every one. I've now decided to give up on drive/distortion circuits for the time being and look more at delays, modulation and other effects, it's that good.

FWIW I've ended up with a 741 op-amp after trying half a dozen types (richer harmonics, better drive characteristics, nicer saturation) and a modified BMP tone control (excellent range of tones from super-bass right through to fingers-on-blackboard treble) as well as a couple of other component changes.

[kurtlives]

Your diagram is correct, though you still need to wire the pad originally marked '2' to the tube base in order to connect R9. This is in addition to the 10k resistor connecting to pin 2 

I belive this is right....I just added one wire. Doesent pin 7 need to be connected?

[Mick Bailey]

Sorry, missed that.

It does, using the same method as pin 2.

[kurtlives]

Sorry one last question....

I am powering this pedal using an transformer. Should I have regulation and filtering before the "juice" hits the board?

Also LEDs can run on AC current?

[Grizz]

I take it the gray picture with the fat wire going to R8 is the transformer?