Tube Driver Mods???

[jasonober]

recently built the tube driver from  GGG:
http://www.generalguitargadgets.com/diagrams/tube_driver_sc.gif

http://www.generalguitargadgets.com/diagrams/tube_driver_lo.gif

using a 12au7   and TL082 rather than the 4558.  I'd like to reduce the treble and increase the bass response as it's range is a little harsh for my taste/setup.   To me it seems as if the hi and lo pots could be more responsive.  I've tried it with a several different cap values at C1,C6, C7, & C8 with some results but still not what i'm looking for.   Any suggestions?

[Aharon]

You already tried tweaking basically every cap that cap that could have an effect on the tone of the circuit.
To change the way the tone pots react you could change the slope resistor(22K) in the stack.
The TL072 in my experience is brighter sounding than the 4558 but the caps have more weight on the sound I guess.
Aharon

[sean k]

You wanna try Duncans Amps and get the tone stack calculator.You want something that allows a low pass effect...I quite like the tone controls hanging off the end of the insanity box as your able to swing between a high pass and a low pass.And when you have Duncans lttle program you'll need to know the impedance you're coming from and thats the plate resistor in parallel with the 12AU7's internal impedance which is about 6.5k at 100 volts on the plate and 7.7k at 250 volts so god knows what it is at 12 volts...but mid boosts are what you really need and you need inductors over caps to ground to get that.

[sean k]

http://www.duncanamps.com/software.html
and its actually a big muff tone stack on the end of the insanity and if you check it out on the tone stack calculator and change the top leg values you'll see it move around a mid boost which moves up or down.Very Cool and only one knob.

[mojotron]

I have a tubeworks version of this - and I'm in the middle of making one - substituting J201 FETs with some caps to warm up the sound for the 12ax7 tube.... If I have an observation I'll let you know...

I do remember on the tubeworks version (same as the tube driver from chandler...) - if I plugged it into a Traynor the tone was really trebelly and edgy... just plain harsh... but on other amps it sounded great with all of the bass in the world...

So, I would try this. Try the pedal on a different amp... a different kind of amp and see if it sounds better..... it should have a TON of low and hi end. If the tone does sound right on a different amp, or maybe just try this...

Get some breadboard and substitute the TS9 output stage (with the volume resistor isolated from the output) at the end of the circuit.

Specifically, what I would do is to add C10, R12, Q2 , R14, R15 C11 R13 from the Tube Screamer schematic http://www.generalguitargadgets.com/diagrams/ts-808_sc.gif
following the volume pot (R17 from the Tube Driver schematic)

this would isolate the caps....

[jasonober]

so i'm spending a lot of time with this circuit trying to fine tune it to my tastes and i think i'm making some progress.  One question i have is what purpose does the 220K resistor from lug 1 to 2 on the Hi pot serve  wouldn't this increase the resistance of this dramatically?

[sean k]

Because the treble pot is linear then a resistor across it makes it kinda logarithmic.Do a bunch of parallel resistance calcs and you'll be able to graph out the slope...it won't be logarithmic but it won't be linear either.

[Doug_H]

so i'm spending a lot of time with this circuit trying to fine tune it to my tastes and i think i'm making some progress.  One question i have is what purpose does the 220K resistor from lug 1 to 2 on the Hi pot serve  wouldn't this increase the resistance of this dramatically?

I read an interview/email with BK Butler somewhere where he stated it was because he could not source the correct value pot at the time.

My pentode driver is based on this circuit and I had a similar problem with harshness. I added a 10k/950p low pass filter on the treble wiper. That smoothed it out fine. YMMV, so if you try this tune it to your own taste.

Doug

[mojotron]

...I read an interview/email with BK Butler somewhere where he stated it was because he could not source the correct value pot at the time.

My pentode driver is based on this circuit and I had a similar problem with harshness. I added a 10k/950p low pass filter on the treble wiper. That smoothed it out fine. YMMV, so if you try this tune it to your own taste.

Doug

Doug, the last couple of years I have wanted to build the Pentode Driver because I like the Tube driver so much with Trides... thought I would start getting to this project. But, I seem to run into a lot of dead links when I look for your projects at http://home.cfl.rr.com/dbhammond/..... Have they moved?

[Doug_H]

Here's my site:

http://home.cfl.rr.com/dbhammond/doug.htm

Here's the pentode driver:

http://home.cfl.rr.com/dbhammond/pdriver_sch.gif

I've gotten really lazy about web page maintenance of that site...

Doug

[mojotron]

Here's my site:
...

Awesome! Thanks... !!!