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I completed my ESV 2 Knob Fuzz. This has got to be the simplest BYOC build ever!

But now that it's done, I'm not sure exactly what the deal is with dialling it in. I had built the previous (non ESV) version a few years ago and was never really satisfied with it, so I sold it. I changed my tune when I listed to someone's clip of an ESV version they'd built that sounded spectacular. Specifically, it sounded really good and responsive to rolling back the guitar's volume. That convinced me to give the improved ESV version a chance.

Like I said, I built it and installed the transistors. I meticulously went back and forth trying every freaking micro angle of the trim pot. I'm still at a loss. For one thing, I do believe that this thing actually sounds pretty damn nice with my guitar at full volume. For reference, I used a home-built Tele with a pair of Duncan P-Rails, so I can get single coil, P90, parallel humbucker or series humbucker out of each pickup. At every setting, the thing sounds like a big, beefy Mk II fuzz. Nice!

But things get tricky when I do any rolling back of the guitar volume. Unlike that other guy's clip in which the thing actually cleaned up a bit, mine doesn't do that. Insted, it gets all spitty, buzzy and "gate-y", for lack of a better word. I noticed today that a guy posted a problem he had with his ESV due to a resistor error he made. I don't have that error, and I don't have that awful sound with my guitar at full volume. But with the volume rolled way back, I do kind of get that sort of tone, but to a lesser degree.

Here's the link to his video http://s187.photobucket.com/albums/x130/Jerrocity/?action=view&current=esv2khelp_0002.mp4
in this thread: http://www.buildyourownclone.com/board/viewtopic.php?f=51&t=36072

Mine doesn't sound that bad, but it does give the idea of what I get with the volume back. What to do? Should I rotatle the transistors to new locations? Is one spot more important than the other two?

Site was wigging out on my the longer my post got, so I'll continue here.

Full counterclockwise (CCS) on the trim post yields by far the loudest tone with what seems to be the least fuzz breakup at full guitar volume. Oddly enough, it gets extra spitty and bad with the guitar volume rolled back.

Spinning clockwise (CW) seems to cause it to distort more (i.e. more fuzz and less output volume) the furhter I go. The first quarter turn or so seems to have a humongous difference. The next eighth or so does more, then the rest of the final two quarters (post seems to turn basically 270°) are just overkill. Curious where most people dial theirs in.

Also curious how everyone does it. I know we do it by ear, but how? In other words, is it best to have the fuzz knob itself fully dialled back for the cleanest (relatively speaking) tone for setting the bias, or is it better to go crazy and fuzz it out? Or is halfway the best?

The longer I monkey with it, the more disheartening it becomes. I just can't believe that I can't make any guitar volume roll backs without getting unusable tone. Gotta be something...

Anyone have any input to the above questions?

Saw your post & thought I’d offer my experience – probably won’t be much help, but who knows… I had this issue as well as have others on the forum. Nothing wrong with the product as far as I can tell, for me it turned out to be related to – I think – temperature. Really. Mine went together fast, only a minor issue with the LED, then killer super fuzz.

Then I picked it up to play last month – splatty, nasty, gated weirdness. However, after I played for a bit & rolled up the guitar volume it was OK. Rolling volume back down, not so much. Put it aside awhile after fruitless trouble-shooting, then came back to it & the wonderful fuzz I had originally came back.

What changed? The weather, only thing I can think of. When I had the problem, we had temp’s in the 80’s – very odd for March in Chi. Significant humidity, too & this was a rather sudden change. When it passed and temp’s cooled back down, the Bender was just fine.

I’ve toyed with the idea of putting it in a wine fridge for a bit if I’m going to use it when it’s particularly warm/humid, but we’ll see.

As far as how to bias, I just plugged in & played using the ax I’ll use mostly with it & set the trim accordingly – I kinda like the saturated, higher voltage, tone. YMMV.

Tom

Just so we are on the same page, that's at the clockwise end of the trim pot, right?



I'm still curious about the questions I posted above. Hope somebody chimes in.

Since you haven't posted any pictures you aren't giving anyone on the forum the opportunity to eyeball your build for possible problems.

As I understand it a good fuzz face cleans up as you roll back the guitar volume because the circuit does not have a huge amount of gain on hand. At some point the signal from the guitar is not sufficient to drive the circuit hard into distortion.

The odd thing about the circuit is that has a fairly low input impedance which loads the guitar signal (tone sucking as it is often referred to) and this loading effect actually contributes to the sound because the loss of treble at the input results in a less harsh tone at the output. The other odd thing about the circuit is that it appears the guitar electronics act as part of the feedback circuit to the first transistor. However they only do that when the Fuzz control is dialled back. With the Fuzz control at full clockwise for AC signals the feedback resistor R2 and the emitter of Q2 are effectively grounded by C2 and there is no AC feedback reaching the base of Q1. Since there is no AC feedback under those conditions, feedback cannot be affected by the guitar controls. This would indicate that if you want the fuzz to interact a lot with the guitar controls you should try to keep the Fuzz control backed off as low as you can.

Personally as far as adjusting the trimmer is concerned I would try adjusting it for DC conditions, the position of the Fuzz and Volume knobs have no effect on the DC conditions. I would connect a multimeter to the collector of Q2 (positive lead the the collector, negative lead to circuit ground) and adjust the trimmer for around +4.5V.

Yeah, clockwise - I have mine right around 3/4 CW.

Temperature will definitely be an issue if you have the germanium version. I believe rebiasing (via the trimmer) will help, but if you plan to use the pedal in a variety of live situations (indoors, outdoors, etc. meaning hot, cold, and in between), you might consider doing what I did and putting the bias on an external pot.

(Not sure this is your issue, just adding what little knowledge I have.)

A further thought on my previous comment - "As I understand it a good fuzz face cleans up as you roll back the guitar volume because the circuit does not have a huge amount of gain on hand. At some point the signal from the guitar is not sufficient to drive the circuit hard into distortion."

Which transistors did you get with the kit and which transistors do you have in the PCB?

I see that BYOC have run out of the germanium transistors and now only ship the silicon version of the kit. This may mean the finished kit does not respond as you expect if it is the classic germanium sound you are after.

Thanks for the reply. As far as pictures go, it's such a simple circuit and I don't really believe the pedal is working "wrong" or I made mistakes, that I didn't bother snapping any. With my guitar volume all the way up, the thing sounds pretty much like you'd expect it to sound. There's not weirdness with regard to gain or lack thereof. My questions were completely with regard to biasing properly in an attempt to make the pedal as friendly as possible to turning down guitar volume. Right now, at just about any bias setting, a decent sound is attainable with the guitar cranked wide open, but not so much with the volume dialled back.

I do see some interesting nuggets there that I will attempt to use in my further bias journey. Thanks! One, I'll continue to focus on setting the bias with the peda'l's fuzz knob rolled back. Two, I'll attempt to take those DC measurements and see what I get.

Part of the thing I'm sort of wondering is if there's some way of determining which of the three transistors should go in which spot - assuming they aren't exactly equivalent to each other.

Interesting. Based on my travels on that trim pot, that's major saturation city. Do you find the pedal reacts well to any guitar volume changes at that bias setting?

Just realized you wrote fuzz face there.

This thread is about the ESV Two Knob Fuzz (Tone Bender Mk II clone), not the ESV Fuzz (Fuzz Face). Do your other comments apply to the Mk II as well as the Fuzz Face (especially the DC voltage you suggest)?

Mine is the Two Knob, so I don't think there is (or even was) a silicone version. I think that germanium vs. silicone thing is a Fuzz Face issue, not a Tone Bender issue.


But yeah, just checked the site. Interesting that they are out of the germanium transistor for the ESV Fuzz (AC127) as well as the germanium transistor for the ESV Two Knob Bender (OC75).

Aaah! right sorry, I have the fuzz face on my mind at the moment.

As far as I can see the ESV 2 Knob Bender is almost exactly a fuzz face, but with an extra single transistor buffer in front of it, so many of my comments still apply. The difference is that the extra buffer does two things - it isolates the guitar from the fuzz face portion of the circuit (without BTW any increase in input impedance, so it still loads the guitar) so there is less guitar controls / fuzz face interaction and it adds more gain so the sound is actually less likely to clean up as you roll back the guitar volume. That is how it seems to me anyway.

Also - in my opinion - all that vintage carbon composition resistor/capacitor nonsense, is exactly that - nonsense! There is absolutely no advantage to the use of 'vintage' components in this circuit, apart from the germanium transistors, which BYOC now don't supply. All these old fuzz circuits rely on the same thing - low gain transistors - to get that 'sweet' tone.

So what transistors do you have? I had a quick look at the instructions and the BYOC Bender page just seems to say - NO MORE OC75s. So are they not selling the kit, selling without the transistors, or selling it with substitute transistors??

I bought the kit months ago when everything was in stock. I'm guessing they offered it with just the OC75, and now that it's not available, the kit is also not available. At least that's how I interpret the page on the website.

Are you sure that the clip you heard was the 2-Knob Bender? While this pedal will clean up some with the guitar volume rolled back, it's not nearly as sensitive to input level as the ESV Fuzz (which, BTW, also has 2 knobs, hence the confusion created when you referred to the pedal as "Fuzz" rather than "Bender"). Also, it retains some fuzz character (at least mine does) even with the volume control on my Strat down around 5. With the ESV Fuzz, it loses almost all the fuzz character by the time the volume is between 8 and 7. The extra transistor stage makes a big difference in this regard.

Also, the pedal retains a pretty reasonable balance of volume vs. fuzz/sustain over a wide range of that trimpot's sweep. If we assume that mid-sweep is 12 noon, then anything between about 9 and 3 o'clock still sounds reasonably good--you're just trading off volume for fuzz/sustain. Too far one way and you'll lose almost all of the fuzz, and too far to the other side starts getting splatty and gated sounding. If you just set it in the middle of the sweep, you should be in pretty good shape. Further optimizing can be done by ear.

As Tark has suggested, a couple of photos couldn't hurt. You wouldn't be the first to miss/overlook something that was obvious to a different set of eyes....

Nice one DVM - that backs up my assumptions about the 2 knob bender with actual experience of what it does.

I suppose I could be wrong. Maybe it was the ESV Fuzz and not the ESV Bender. That would explain a lot. If so, I'm making the entire bias operation harder than it needs to be.




Thanks for this bit. You are the first to put it in a way I can compare with my own findings. Great stuff!
This is prety much in line with exactly what I'm seeing in my bias attempts. Using your clock model, with 12 noon as the center point, I suppose the pot itself goes from mayb 7 o'clock at minimum to around 5 o'clock at maximum. There does seem to be a lot of "action" between 7 and 9 0'clock - basically going form almost no fuzz (and a pretty bad sound with the guitar volume rolled back) to boom!, fuzz! in that range. Things do remain reasonably constant from 9 to 3 o'clock. At the top end, from 3 to 5 0'clock, it's pretty much as you describe. The fuzz just becomes a bit over the top and sort of useless (makes the pedal's fuzz knob almost a waste of time).
Knowing this, I think I'll focus my efforts on that 9 to 3 o'clock range. From the other day, I do recall that there were some points in there where adjustments at the top range of the guitar's volume (7-10) did affect the fuzz tone. Didn't clean up, but I could reduce some fuzz for a bit of a dirty rhythm tone and then crank for over the to fuzz. I'll focus on that instead of some elusive point where the fuzz is gone (ala a tube amp or even a Fuzz FACE).




If I still think I have problems after trying what I described above, then I'll be sure to post some pics. Heck, I should probably post some anyway. Can't hurt.

You could convert this circuit to a fuzz face if you did want the extra interactivity with the guitar. All you have to do is bypass that first transistor stage, you could even fit a DPDT toggle switch to make it an option.

I figure I'll build a Fuzz Face type pedal some day, so I have no interest in modding this one.

After all the posts above, and some thought, I played around with it a bunch last night think I'm done with monkeying with the bias. Using the midpoint = 12 noon model, I ended up just a shade below that. Call it 11:30! Seems to work really well for what I want it to do.

Once I got past the notion that I could get it to clean up with the volume knob, I dialled it to where the fuzz sounded good/right to my ears at full bore guitar volume. Around that 11:30 or so mark, it even seems that you can crack the guitar volume down to 9 or even 8 and get a sort of rhythm tone.

For some reason, I used a Strat and my Allen Old Flame (BFSR type amp) for most of the experimenting. For the heck of it, at the very end, I unplugged from that amp and plugged into my Marshall-clone Trinity 18. OMG! Now that's what I'm talkign about. It sounded even more "right" to my ears. People have often said that Jimmy Page used a Tone Bender Mk II for the first Zeppelin album, but I could never really hear it. A decade and a half ago I bought a Prescription Yardbox to get that tone, but was using it with a Fender Twin Rerverb. Ended up selling it a few years later. Last night, with my Strat and that 18, I started to finally hear that Led Zeppelin I vibe. With a nice Tele and some studio tricks (EQ, compression, delay), I can easily see how to naile "Communication Breakdown", "You Shook Me", "Dazed and Confused" and "How Many More Times". The tone was RIGHT THERE!

I suppose this pedal is sort of a one trick pony. But I'm starting to understand that trick now. Should be fun to occasionally ride that pony.