freestompboxes.org

Is BK Butler really making these by himself? Has anybody opened one of these "limited production" models up?

https://www.ebay.com/itm/TUBE-DRIVER-NE ... 3f1ee449eb

Hey guys, just finished my BK Butler Tube Drive using
the info posted here.

Awsome booster!

Gilmourish violine sustein notes all the time boosting my proco Rat.

To add a bit of info here, check this tread at Vintage Amps Forum:

http://www.vintageamps.com/plexiboard/v ... p?p=608542

It shows pictures from other angles and one that shows a small diode
near the place to conect to the trainy.

Thanks a lot for the effort, I'm pleased with my new Tube Driver.

Hi Folks!

I've got two of these BK Butler Tube Drivers. One is an older (80s?) version with a black chassis and bright-yellow lettering and lines, and which requires powering by an external 12 VAC source. I wrote to Butler's company and a technician there verified it as a genuine Butler pedal, as opposed to the Chandler "fakes." The other is a newly made re-issue with bias knob and built-in transformer, as endorsed by Eric Johnson.

For years, I thought the older one I had was quite different and inferior to the new stuff. Then I bought the new re-issue version and had an A-B comparison. They're both just as good and the range of sounds available from each are pretty much identical, except that the knobs have to be set quite differently on each pedal to achieve the same sounds. I've got a 12au7 in the old one and a stock tube in the new one (no idea what it is). To my ears, to get the equivalent of an Eric Johnson setting (treble knob all the way down) on the new version, you have to set the older pedal at treble 4, mid 4, bass 5. Consequently, setting the drive knob at different levels impacts the tone controls so that they respond differently on each pedal. It's barely noticeable, but the older pedal tends to be somewhat more saturated on the mids and also has more hiss/hum, while the newer one is slightly more transparent and quieter. Apart from that, dynamic and tone responses from both are nearly identical.

Being pedantic about noise issues, I would prefer the newer one, except that it's really huge, way too big for my regular pedal board. My ambition is to someday rebuild the newer five-knob version into a smaller box. From what I understand, it's not one of the easier pedal projects to undertake.

So would anyone like to join me in my quest? Anyone want a peek at the innards of these pedals in order to create some schematics? Or are they already posted somewhere on this site? I searched but couldn't find anything here...

I made my own "smaller" version. It has a jfet on the front end and a footswitchable gain boost with a high pass.

JT

imaradiostar wrote:I made my own "smaller" version. It has a jfet on the front end and a footswitchable gain boost with a high pass.

Looks great! Which version of a BK Tube Driver is this based on? Is there a schematic on your build available somewhere? What are the dimensions of your chassis? I'm eager to get everything into as small a package as possible.

Thanks! It was fun to build. I use it every Sunday at church, mostly in front of a catalinbread DLS but occasionally by itself. It sounds every bit a tube driver, in fact it sounds quite a bit better than my old 4 knob one.

It's based mostly on the rackmount single tube version (with the black panel), but only loosely. It's powered by a 12vac wall-wart. There is a jfet out front, a 2n5457 I think, driving a gain pot, followed by the grid stopper on the first triode. There are no opamps. The jfet source bypass cap is in series with a trimpot with a footswitch across the trimpot. I set the trimpot internally for "low gain" mode and the footswitch shorts the pot for full boost and high pass. It works quite well and can be adjusted to be just a gain boost or to get louder and much gainier. I can't remember exactly which part values I used but there is a cathode pot mounted on the back face of the pedal, set up similarly to the Butler "bias" pot on the newest versions. There is clearly a "sweet spot" on the tube bias knob where it sounds right; other positions don't really work for me. I would be tempted to bring the internal off-boost source trim to the outside as it could make the gain boost more useful. Of course, then you'd end up wanting different EQ and volume settings for each and it would get out of control. Then again- switching from Gilmour to EJ mode on the fly would be gnarly. I should work that out...

I don't think I have any shots of the completed version but it got a little bit messier as I finished wiring it. The box is 4" wide and about 5" deep. I'm sure it could be done neater on a PC board but I love turret construction and I had quite a few of the tiny gold turrets. I used the PEM stud inserter at work and pressed in hard mounting points for the board so no screws show from the top of the pedal. It's plain aluminum with clear LED knobs, clear LED holders and bright blue and green leds. Switches came from BLMS.

Let it also be said- you could build one with a submini tube in a tiny chassis and it would be amazing. The submini tubes I've played with sounded great. I only used a 12ax7 in this because I wanted to be able to swap more easily. If you want a 9vdc powered version you can buy a tiny chinese dc-dc converter on ebay, power the tube from a 7806 or string of diodes and tube plates from the output of the dc-dc (around 36 to 40 volts). I bought a bunch but haven't yet experimented with them.

Jamie

I keep forgetting there is no edit button!

I don't have clear LED knobs. I have clear knobs, from BLMS. That is all.

JT

imaradiostar wrote:Thanks! It was fun to build. I use it every Sunday at church, mostly in front of a catalinbread DLS but occasionally by itself. It sounds every bit a tube driver, in fact it sounds quite a bit better than my old 4 knob one.

Any chance you could post some sound samples?

So nobody wants to see the innards of my two Butler tube drivers?
Someone called Bajaman seems cloned the reissue version, but I couldn't find any decent gut shots or schematics anywhere. Am I missing something?

I got a newer version in; owner thought it didn't sound right.

I changed the TL072 to a RC4558 and added a 12AT7 and now it screams and sounds just right.
The unit is a tad different compared to the other schematics I could find;

Bernardduur wrote:I got a newer version in; owner thought it didn't sound right.
I changed the TL072 to a RC4558 and added a 12AT7 and now it screams and sounds just right.
The unit is a tad different compared to the other schematics I could find;

Bernardduur, power supply is voltage doubler, what's the transformer's secondary voltage ?

karul wrote:

Bernardduur wrote:I got a newer version in; owner thought it didn't sound right.
I changed the TL072 to a RC4558 and added a 12AT7 and now it screams and sounds just right.
The unit is a tad different compared to the other schematics I could find;

Bernardduur, power supply is voltage doubler, what's the transformer's secondary voltage ?

Not a voltage doubler. Its half wave rectifying the positive and negative power rails for the split supply.

hmmm cant edit my last post...

The tube heaters are running off the secondary which at a guess means the secondary is 12 volts and the power supply is +12/-12 volt split supply.

Groovenut wrote:Not a voltage doubler.

Correct me if I'm wrong, but ain't that a Delon circuit ?
http://en.wikipedia.org/wiki/Voltage_do ... ge_circuit

Groovenut wrote:Its half wave rectifying the positive and negative power rails for the split supply.

True.

Groovenut wrote:The tube heaters are running off the secondary which at a guess means the secondary is 12 volts and the power supply is +12/-12 volt split supply.

My guess too, but I'd like Bernardduur to confirm that.

The most recent posted schematic appears to be more accurate than the previous ones based on my old tube driver.

Rectified voltage from the filament (12.6 vac) should be around +/- 17.8 volts.

I just noticed the post above that asked for clips - sorry I missed it previously. I'll try to record some soon.

Jamie

karul wrote:

Groovenut wrote:Not a voltage doubler.

Correct me if I'm wrong, but ain't that a Delon circuit ?
http://en.wikipedia.org/wiki/Voltage_do ... ge_circuit

If the V- was used as the ground for the circuit, then yes I would agree it's a voltage doubler, but since one half of the secondary is grounded and that same ground is used as signal ground, I would guess it's probably called something different. Potayto pahtahto. All depends on your perspective I suppose

imaradiostar wrote:The most recent posted schematic appears to be more accurate than the previous ones based on my old tube driver.

Rectified voltage from the filament (12.6 vac) should be around +/- 17.8 volts.

With that arrangement the power supply will yeild +12.6 -12.6 with about a 15mA load, not counting the supply sag from the heaters. IIRC some of the pedals I checked were +-15V

Oh, of course your mileage may vary. I just meant 12.6 rms times 1.414 means 17.8 volts peak. As I recall my original tube driver was around +-16v.

Jamie

karul wrote: My guess too, but I'd like Bernardduur to confirm that.

Sure, I'll add some voltages to the schematic when I get home!

While doing that, change either the triode symbols name to 12AT7 or the heaters name to 12AX7