Mosfet Drive (BK Butler Tube Driver - w/Mosfets)

MichaelW

MichaelW

Well-known member
Build Rating
5.00 star(s)
So when I built the Cattle Driver I had no clue what it was. It was a purely impulse buy after learning it was a clone of the Buffalo FX TDX, which is a solid state clone of the BK Butler Tube Driver.

Little did I know the rabbit hole that pedal would send me down......and I'm still working my way out hahaha.

I've become fascinated with the TD-X, the Tube Driver-like overdrives.
Since building the Cattle Driver, I've built the Grover Drive, the Cowpoker, and now adding this to my list. The PedalPCB Mosfet Drive, @Robert's take on emulating the BK Butler Tube Driver. But this Mosfet Drive board has been out stock for a while now. @Robert knew I was waiting for it come back and so he sent me one when they arrived. WOOOHOO!

It came in the mail today and it just so happens that I had an enclosure already drilled for it (from my failed 4 Knob Celestial Drive build.....)
So barely was it out of the hot little vacuum pack before I started putting together the parts to build it out.

It's a fairly simple build and went together quickly.
So does it sound like a BK Butler Tube Driver? mmmmmmmmmmmno....not really, but it's a GREAT sounding pedal!
(To be fair neither do any of the other Tube Driver emulations I've built heh.)

So I was chatting a little bit with Robert about the biasing, I thought that the trimmers were to bias Q1 and Q2 (I mean I think the build doc actually says "BIAS"). I had originally biased the Drain legs of the BS170's to 4.82v. Well turns out according to Robert that they're really mini gain trimmers, as opposed to bias trims. So he recommended to start at zero then dial up to taste. WOW that changed the whole nature of the pedal for me! The way I had it originally set it was an aggressive trebly distortion. (Not unlike the CowPoker, they have the same philosophical roots). But dialing the trimmers back to zero then cracking them up a wee bit at a time (they effect different frequencies) I have them "maybe a skootch less than 1/4 way open" and now the gain is warmer, fuller, more organic and LESS. hahah, I like that about the Cattle Drive that while it can get pretty gainy, it also sounds great low gain. The Mosfet is shaping up to be similar.

All of the Mosfet based pedals are pretty awesome in their own right and have their own thing going on. All great pedals.
On deck in this series I have the Finale Overdrive (Fulltone Hi-Mu), The Cliffhanger (not really a Mosfet drive but I'm counting it because it's supposed to emulate the pedal that emulates the Tube driver :p, the MBP Mysterioso. I "thought" this was a Mosfet based drive but now I'm not so so sure, I need to go look over the build docs again. And I have the MBP Archibald, an actual TUBE version of a Butler clone. So that will be interesting.

Anyway, great sounding pedal, treat the Bias trimmers as gain trimmers and you dial a really nice sounding medium high gain overdrive.

IMG_3862.JPG

IMG_3860.JPG
 
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It's me again
Which one of the Tube Driver circuits did you like the most?
I've built the Cattle drive which I mainly use with drive between 9-10, but I may do another one
 
As always I appreciate the in-depth write up. This is an interesting circuit looking at the schematic. Did you end up populating that 470k after the photos?
 
howas said:
It's me again
Which one of the Tube Driver circuits did you like the most?
I've built the Cattle drive which I mainly use with drive between 9-10, but I may do another one
Click to expand...
Hey Mark, I'll tell you after I go and quietly populate the missing 470k resistor...... :ROFLMAO:
 
ok fixed it......it definitely seemed to have tamed what I originally called "trebly and aggressive". It's now smoother.
I had to reset the Q1 trimmer, and while I was at it I also reset the Q2 trimmer, they're both at around noon right now and the pedal sounds even better! Thanks for the catch @swyse !

IMG_3863.JPG


@howas, couldn't say which one I like the best, they all sound a little different. The Cattle Driver has that big bass-y-ness that the Tube Driver is known for, none of the other pedals do. I would say the Cattle Driver sounds the most "amp-like" where the others are more "pedal-ish" (not necessarily a bad thing). I think the Cattle Driver might be a bit hard to lift up in a mix where the Grover (Dover) would be the easiest since it's the most narrow and focused sounding. The CowPoke is it's own animal altogether, a LOT more gain than the others.

Edit: Also the Grover Drive (LovePedal Dover), while it tries to emulate the Tube Driver, it's not a Mosfet drive (where tube gain stages are replaced with Mosfet transistors) but rather a completely different topology. It's actually a silicon fuzz going into a Zen drive, where the Zen circuit has the gain fixed at 50% and the fuzz has a bias trimmer to make it more spitty/gatey or more smooth.
 
After looking at the schematic some more and thinking about it (with my wee little non electronics brain) that missing 470k resistor (R17) was pretty significant. If I'm understanding it correctly, it works in tandem with the 470p cap (C15) as sort of a "treble bleed" for lack of a better or more proper term after the OpAmp and before Q1. So without the resistor it was probably filtering out too much bass?

@swyse thoughts?
 
This has been on my list forever. I was very excited to see it back in stock the other day. I am embarking on a “fuzz drive” quest: tweed-style OD, Blues Driver, Tube Driver, etc…
 
Update:

Ok after mucking about with the drive a bit more (with all the parts populated now.... :rolleyes: ) I want to amend what I said earlier about some of the differences to the Cattle Driver. I am able to pretty much get both dialed to the same sounds now, although the Mosfet Drive has Hi and Lo passive cut knobs. So it's a little bit different adjusting the EQ to the Cattle Driver.

They can be very close in sound in the "mid gain" region. The Cattle Driver still sounds better in the low gain, edge of breakup region but I I bet I can dial the Mosfet drive pretty close with some fiddling.

So here's one thing I've noticed. As some of you may have read my posts before, 99% of my pedal testing is on a Fender-y clean amp model.
It's the clean channel of the Fuchs Overdrive Supreme, basically a 6L6 based Bassman style amp. I like this amp model on my UAD Apollo because it levels the playing field and lets me hear what the pedal is doing as opposed to the amp.

But I've found that some pedals seem to really shine when paired with more Marshally based amps. My 2 favorites being the Friedman Buxom Betty, an EL34 based amp, and the Friedman Dirty Shirley, a JTM45 based amp. I have a number of clean to semi-clean presets for these two amps and the Cattle Driver and Mosfet Drive both really shine when using this type of amp as opposed to the more scooped mids Blackface clean amp model.

Just a tidbit of FYI for those interested.
 
MichaelW said:
After looking at the schematic some more and thinking about it (with my wee little non electronics brain) that missing 470k resistor (R17) was pretty significant. If I'm understanding it correctly, it works in tandem with the 470p cap (C15) as sort of a "treble bleed" for lack of a better or more proper term after the OpAmp and before Q1. So without the resistor it was probably filtering out too much bass?

@swyse thoughts?
Click to expand...
That’s what I was thinking, less bass and more gain, your thinking trebly and aggressive was exactly right. It’s kinda funny that it still worked, usually omitting a part has more of an impact! Glad to hear you’re liking it better.
 
I have 2 of the old black and yellow 5 knob tube works Real Tube pedals. I used them on my pedal board all through the '90s. They do a great low gain sound. The internal transformer makes it too noisy for high settings without using a noise gate in my opinion. I hade one for guitar and one for a lap steel on a stand. They have a wide range eq. It is an interesting circuit. I have put different tubes in it but in the end, the stock tube performs the best for what it does. I worked at a used instrument and repair shop. One came in and I picked it up for $80. I later gave a guy $100 for the second one so I could have it one the lap steel.
Is the eq pretty broad on this version?
 

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The Gator said:
I have 2 of the old black and yellow 5 knob tube works Real Tube pedals. I used them on my pedal board all through the '90s. They do a great low gain sound. The internal transformer makes it too noisy for high settings without using a noise gate in my opinion. I hade one for guitar and one for a lap steel on a stand. They have a wide range eq. It is an interesting circuit. I have put different tubes in it but in the end, the stock tube performs the best for what it does. I worked at a used instrument and repair shop. One came in and I picked it up for $80. I later gave a guy $100 for the second one so I could have it one the lap steel.
Is the eq pretty broad on this version?
Click to expand...
Well keeping in mind that this is a Mosfet emulation of the Butler, I would not say it's a "broad" eq range, but they are laid out as passive Hi and Low cuts. So full CCW is no cut. There's enough range to dial in and compensate for different guitar/pickup/amp combinations. I would not say theses solid state versions are ideal for low gain, edge of break up type sounds. They're all pretty high gain. But out of the bunch I've built so far the "Cattle Driver" probably does the best for the low gain thing.

I used it in my P90 comparison tests on the neck pickup.

 
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The Gator said:
I have 2 of the old black and yellow 5 knob tube works Real Tube pedals. I used them on my pedal board all through the '90s. They do a great low gain sound. The internal transformer makes it too noisy for high settings without using a noise gate in my opinion. I hade one for guitar and one for a lap steel on a stand. They have a wide range eq. It is an interesting circuit. I have put different tubes in it but in the end, the stock tube performs the best for what it does. I worked at a used instrument and repair shop. One came in and I picked it up for $80. I later gave a guy $100 for the second one so I could have it one the lap steel.
Is the eq pretty broad on this version?
Click to expand...
They only run at 12v starve plate.
I converted the 110v Black & Yellow & a 110v Blue & Yellow to a 500Ma -12v AC Wall Wart as I live in Australia which is 240v.
I had a stepdown Transformer but I found them hissy also with Stock Internal Transformer!
Since the Conversion, they are my favorite Butler pedals & Quiet, I also own the 240v cream 4 knob with Bias knob on the back but prefer the Black & Yellow version with 3 band EQ!
 
Thanks for all the info. I just built this pedal and I have a question. If I plug in to it directly from the guitar, then to other pedals or the amp directly, it sounds great, preforms as it should. If I run it after my phaser or OD, with either of them turned on, the sound gets very high-end treble/crispy. Have you noticed this? I have read one thing somewhere on the internet that the Tube Driver circuit likes to see a fairly high impedance input. So, if it is getting a signal from a device with lower output impedance it may not operate properly. Where do you have it in your signal chain?
 
allanshookphoto said:
Thanks for all the info. I just built this pedal and I have a question. If I plug in to it directly from the guitar, then to other pedals or the amp directly, it sounds great, preforms as it should. If I run it after my phaser or OD, with either of them turned on, the sound gets very high-end treble/crispy. Have you noticed this? I have read one thing somewhere on the internet that the Tube Driver circuit likes to see a fairly high impedance input. So, if it is getting a signal from a device with lower output impedance it may not operate properly. Where do you have it in your signal chain?
Click to expand...
I'll try it and let you know.
 
@allanshookphoto,

I just tried mine a coupe of different ways.
Guitar=>Mosfet=>Apollo interface=>amp model + IR
Guitar=>Mosfet=>Phase II=>interface
Guitar=>Phase II=>interface
Guitar=>my whole pedal chain with about 12 pedals in it=>Mosfet=>interface.

No issues at all. The only difference in sound is the last configuration where I have an always on compressor providing a slight bit of boost, light compression.

I'm wondering if maybe you have the wrong input cap value? Did you check C1 on your build and verify it's a 33n?
 
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