Tone Vendor MKI Attack pot not much effect.

Matopotato

New member
Hi,
I just managed to finish MKI and there is a lot of fuzz in it. I modded it by setting a trimpot (20k) for R7. Lowering it gives a sort of dying battery sputter, and 75%+ makes it less fuzzy almost like a boost.
First question/issue is that it has a high noise floor (?), but I was sort of expecting that with fuzzes. But reading other posts it seems to be possible to adjust.
The second issue is that the Attack knob does not do very much. When off or almost off it kills/turns effect off like close to 0 on volume knob. (Which is good and expected) But above 15% it does not do much all the way tTo the top.
I checked the thread by @Coda (MKII issue) but the fix there seems not to be my case at a first glance. Also checked the thread on MKII by @TSReppe .
The transistors from Das Musikding were 1 OC75 and AC125F and AC125U. I tried to compare the hfe on the AC125s but they were very close as I remember.
No idea how to check for leakage and if that would have effect. Musikding are good at sending matched and appropriate transistors imho.
Thanks in advance.
PS I like the casing (from Tayda, long transport...) and knobs combination, will try some decal printing later on.
 

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Big Monk

Well-known member
I have not built many MK I Benders but I am more than familiar with the MK II Bender. Let ma take a crack at some specific concerns:

First question/issue is that it has a high noise floor (?), but I was sort of expecting that with fuzzes. But reading other posts it seems to be possible to adjust.

These circuits are terribly hissy and generally noisy. You are dealing with a ton of gain from the added third stage. The MK II is no different. What I usually do is breadboard the circuit into it's final form before loading it up.

The best way I have found to quiet down the hiss and any other extraneous noise is to use base to collector caps in the pf range on all three transistors. This cuts some of the top-end out of the frequency spectrum depending on the sizes, so you'll have to tweak some of the other caps in the circuits to compensate but I've been able to make nearly whisper quiet MK II units with this as my MO.

The second issue is that the Attack knob does not do very much. When off or almost off it kills/turns effect off like close to 0 on volume knob. (Which is good and expected) But above 15% it does not do much all the way tTo the top.

This seems to be the name of the game for the MK I. Most people run that all the way up most of the time. Sola Sound fixed this in a major way when they re-designed for the MK II, as that control is much more useful.
 

Matopotato

New member
I have not built many MK I Benders but I am more than familiar with the MK II Bender. Let ma take a crack at some specific concerns:



These circuits are terribly hissy and generally noisy. You are dealing with a ton of gain from the added third stage. The MK II is no different. What I usually do is breadboard the circuit into it's final form before loading it up.

The best way I have found to quiet down the hiss and any other extraneous noise is to use base to collector caps in the pf range on all three transistors. This cuts some of the top-end out of the frequency spectrum depending on the sizes, so you'll have to tweak some of the other caps in the circuits to compensate but I've been able to make nearly whisper quiet MK II units with this as my MO.



This seems to be the name of the game for the MK I. Most people run that all the way up most of the time. Sola Sound fixed this in a major way when they re-designed for the MK II, as that control is much more useful.
Many thanks, will try not to worry about the Attack so much then, although you'd think it would serve a purpose.
Pre-breadboarding is a great tip, thanks!
I am working on a Fuzzrite diy from guitarpcb, and they added slots for 220pF caps (or less) on the board already. Now in hindsight it would have been good for MKI as well, although I was not sure where to put them in the schema until you explained.
 

danfrank

Well-known member
This seems to be the name of the game for the MK I. Most people run that all the way up most of the time. Sola Sound fixed this in a major way when they re-designed for the MK II, as that control is much more useful.
This has been my experience also. I guess it depends what sound the builder wants. On mine, I finally ended up with a MK1 build where the first half of the "attack" knob offers varying degrees of sputter/gating and the second half of the pot is solid fuzz but the sound doesn't vary much in the second half of that control where the fuzz is solid and full on. Like Big Monk said, this is the nature of the MK1. So ideally, the "attack" knob should be mostly varying degrees of sputter/gating with the last 1/4 turn full on solid fuzz.

Here's a post I did a while back with my observations. Hope it helps you with yours:

 

Matopotato

New member
Thanks a bunch. I will check my 2 AC125 one U one F (???) And figure out how to measure leaky. hFe I managed on my breadboard although it seems to ve more of relative values. The OC75N that came with I can check too although I think it is the right for Q1. I have some ACs leftovers from a Rangemaster build. Here variation of transistor did not have much impact.
Right now the Attack makes a difference first 1/4 -ish. And if I can get it to 3/4 I'm happy. Resolder a pot is what ruined another build I made so I will pass that until experience and any left annoyances tip the scales...
 

danfrank

Well-known member
Using a log or audio taper pot instead of a linear pot for the "attack" control will help greatly to give you more variance when turning that knob.
 

Matopotato

New member
Using a log or audio taper pot instead of a linear pot for the "attack" control will help greatly to give you more variance when turning that knob.
Thanks I appreciate the tip, I will consider it.
I was building a Fuzzrite and the predrilled casing made me rotate the pots 180. So when I tried to correct by desoldering (instead of cutting and cross-wiring) it all went south. So that is why I am not super keen on swapping out the B pot for an A. But I'll try some transistor shuffling first and then possibly swap for a log/audio one instead.
 

danfrank

Well-known member
I wouldn't swap the pot in your already built PCB, too much trouble. If you end up liking the sound of this pedal after tweaking it, I'm sure you will build another in the future. Lol! Like I said, the audio pot will give you more variance in the gated sputtering sound, once that adjustment gets to full solid fuzz, the sound doesn't change much.
 

Matopotato

New member
I wouldn't swap the pot in your already built PCB, too much trouble. If you end up liking the sound of this pedal after tweaking it, I'm sure you will build another in the future. Lol! Like I said, the audio pot will give you more variance in the gated sputtering sound, once that adjustment gets to full solid fuzz, the sound doesn't change much.
Thanks. Well, after sleeping on it I think I will go through the transistors I have and see if I can optimize somehow. If it still bothers me, cutting and swapping the pot using wires should be possible without desoldering it.
But it is good to know what expectations that are realistic to have.
 

Dan0h

Well-known member
:The best way I have found to quiet down the hiss and any other extraneous noise is to use base to collector caps in the pf range on all three transistors. This cuts some of the top-end out of the frequency spectrum depending on the sizes, so you'll have to tweak some of the other caps in the circuits to compensate but I've been able to make nearly whisper quiet MK II units with this as my MO.
Big Monk, can you share an example of values you used for this fix? Same Pf on all three trannies? Or literally just pop in and out different caps until the hiss disappears? I will be building the MkII soon and any starting point would be a huge help. I really like the idea of breadboarding first to tweak out changes before putting them in the pcb ( insanely great idea, why didn’t I think about that before!)
 
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Big Monk

Well-known member
Big Monk, can you share an example of values you used for this fix? Same Pf on all three trannies? Or literally just pop in and out different caps until the hiss disappears? I will be building the MkII soon and any starting point would be a huge help. I really like the idea of breadboarding first to tweak out changes before putting them in the pcb ( insanely great idea, why didn’t I think about that before!)

For the MK II, I’ll usually start with a rough draft set of 100 pf, 82 pf and 82 pf for Q1, Q2 and Q3, respectively. It’s important to listen and mentally log the difference between this initial set and the sound with no caps installed.

With the Attack pot all the way up and volume at unity, increase the caps until the pedal is pretty quiet. Don’t try to find balance between noise and treble content. Kill the noise completely first.

When the noise has been addressed, compare the tone with the sound without caps installed. Now use a combination of the treble bleed cap (cap to ground on input), the input cap and emitter cap to tweak the circuit for the proper frequency response. “Proper” in this case is driven by personal taste.

I like to start with the bog standard cap set for the MK II at the outset: 0.01 uf, 4.7 uf and 4.7 uf for Treble Bleed, Input and Emitter caps, respectively. I find the treble bleed and Emitter caps most effective here. If the pedal is quiet but a bit muffled or muted after base to collector caps have been installed, tweak the treble bleed between 0.0047-0.0082 uf if need be and the emitter cap between 1 uf-3.3 uf.

Keep in mind, you may hit a point where the tone cuts well but is a little ragged. Also, lowering the treble bleed too much can bring on uncontrolled, high pitched, i.e. non-musical, feedback.

Conversely, you can go the Supafuzz route and ditch the treble bleed cap altogether while raising the input cap.

Many, many options. This is a circuit, much like the Fuzz Face, that IMHO requires breadboard tuning. It’s almost criminal to sell someone a cookie cutter kit or anything similar for these pedals.
 

Dan0h

Well-known member
For the MK II, I’ll usually start with a rough draft set of 100 pf, 82 pf and 82 pf for Q1, Q2 and Q3, respectively. It’s important to listen and mentally log the difference between this initial set and the sound with no caps installed.

With the Attack pot all the way up and volume at unity, increase the caps until the pedal is pretty quiet. Don’t try to find balance between noise and treble content. Kill the noise completely first.

When the noise has been addressed, compare the tone with the sound without caps installed. Now use a combination of the treble bleed cap (cap to ground on input), the input cap and emitter cap to tweak the circuit for the proper frequency response. “Proper” in this case is driven by personal taste.

I like to start with the bog standard cap set for the MK II at the outset: 0.01 uf, 4.7 uf and 4.7 uf for Treble Bleed, Input and Emitter caps, respectively. I find the treble bleed and Emitter caps most effective here. If the pedal is quiet but a bit muffled or muted after base to collector caps have been installed, tweak the treble bleed between 0.0047-0.0082 uf if need be and the emitter cap between 1 uf-3.3 uf.

Keep in mind, you may hit a point where the tone cuts well but is a little ragged. Also, lowering the treble bleed too much can bring on uncontrolled, high pitched, i.e. non-musical, feedback.

Conversely, you can go the Supafuzz route and ditch the treble bleed cap altogether while raising the input cap.

Many, many options. This is a circuit, much like the Fuzz Face, that IMHO requires breadboard tuning. It’s almost criminal to sell someone a cookie cutter kit or anything similar for these pedals.
Dude, this is so helpful thank you. Pretty sure this is going to make the difference of a pedal collecting dust on the shelf vs being used. I remember when I built the Powersound pedal I ran into similar issues but my buddy, who I built it for was happy with it as it was. I will report back after the build is complete. Parts should arrive next week.
 

Big Monk

Well-known member
Dude, this is so helpful thank you. Pretty sure this is going to make the difference of a pedal collecting dust on the shelf vs being used. I remember when I built the Powersound pedal I ran into similar issues but my buddy, who I built it for was happy with it as it was. I will report back after the build is complete. Parts should arrive next week.

The powersound should NOT be noisy like a Tonebender MK II.

The MK II is one of noisiest pedals going. Like rom-com movies that end with the fairy tale wedding, demos for high end fuzzes very rarely show you how much damn noise there is in the background.
 

Matopotato

New member
For the MK II, I’ll usually start with a rough draft set of 100 pf, 82 pf and 82 pf for Q1, Q2 and Q3, respectively. It’s important to listen and mentally log the difference between this initial set and the sound with no caps installed.

With the Attack pot all the way up and volume at unity, increase the caps until the pedal is pretty quiet. Don’t try to find balance between noise and treble content. Kill the noise completely first.

When the noise has been addressed, compare the tone with the sound without caps installed. Now use a combination of the treble bleed cap (cap to ground on input), the input cap and emitter cap to tweak the circuit for the proper frequency response. “Proper” in this case is driven by personal taste.

I like to start with the bog standard cap set for the MK II at the outset: 0.01 uf, 4.7 uf and 4.7 uf for Treble Bleed, Input and Emitter caps, respectively. I find the treble bleed and Emitter caps most effective here. If the pedal is quiet but a bit muffled or muted after base to collector caps have been installed, tweak the treble bleed between 0.0047-0.0082 uf if need be and the emitter cap between 1 uf-3.3 uf.

Keep in mind, you may hit a point where the tone cuts well but is a little ragged. Also, lowering the treble bleed too much can bring on uncontrolled, high pitched, i.e. non-musical, feedback.

Conversely, you can go the Supafuzz route and ditch the treble bleed cap altogether while raising the input cap.

Many, many options. This is a circuit, much like the Fuzz Face, that IMHO requires breadboard tuning. It’s almost criminal to sell someone a cookie cutter kit or anything similar for these pedals.
I understand that the values differ between MKI and MKII, but would the principle be worth applying to MKI or is it so inherent already with MKI build that trying to silence it is a somewhat wasted effort? I mean I have some good tips on how to bring the noise down, bit perhaps I should not hope on getting it as quiet as with your MKIIs?
 

Big Monk

Well-known member
I understand that the values differ between MKI and MKII, but would the principle be worth applying to MKI or is it so inherent already with MKI build that trying to silence it is a somewhat wasted effort? I mean I have some good tips on how to bring the noise down, bit perhaps I should not hope on getting it as quiet as with your MKIIs?

You could do the same thing. I’m just not as well versed in the circuit architecture of the MK I so I can’t say how changing frequency shaping components will affect the overall tone.

You can absolutely use what I described to clamp down on noise though. That is circuit independent.
 
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Matopotato

New member
You could do the same thing. I’m just not as well versed in the circuit architecture of the MK I so I can’t say how changing frequency shaping components will affect the overall tone.

You can absolutely use what I described to clamp down on mouse though. That is circuit independent.
Thanks! (I am guessing "mouse" is autocorrect of "noise"...)
 

andare

Active member
The powersound should NOT be noisy like a Tonebender MK II.

The MK II is one of noisiest pedals going. Like rom-com movies that end with the fairy tale wedding, demos for high end fuzzes very rarely show you how much damn noise there is in the background.
When Dunlop issued the JHW1 Fuzz Face (a Si/Ge mini pedal with switchable buffer and Jimi Hendrix licensed art), almost every demo featured the incredible hiss of the Ge side, which makes it unusable on cleanup. I stupidly bought it, thinking it wouldn't bother me. Sold it.

Another one like that is the Pedal Pawn fuzz. It's advertised as having the SRV "glassy cleans" and sure enough, even the official demos have a ton of hiss in the background.
I believe any fuzz face with the volume all the way up accomplishes the same effect.

This thread is gold. Sorry for derailing it but I suppose the base to collector caps can be implemented in a Fuzz Face circuit as well?
 

Matopotato

New member
Derailing is fine by me. A lot of good tips tricks and discussion surfacing. Only minor worry is if MKI title will hinder MKII searches from finding this. Feel free to clone if anyone feels the need for it.
For me, the cap analysis with first lowering the noise and the compensating the treble loss, with a different circuit (MKI) already soldered puts me in a sort of "best effort" approach of what I might be able to try. I choose the MKI for it's rawness. And I plan to get a noise
gate for various other purposes so it might end well in my case. Also some hiss might be part of the vintage "feel" that could add a little bit to authenticity. A completely silent fuzz would be great, but perhaps also a bit if a "contradiction in terms".
 

Big Monk

Well-known member
This thread is gold. Sorry for derailing it but I suppose the base to collector caps can be implemented in a Fuzz Face circuit as well?

Yup. Same exact methodology but with a few quirks of its own. With a MK II/Supa, you’ll probably start low and end up with higher values for the base to collector caps. That circuit typically requires higher values to really clamp down on the hiss.

The Fuzz Face is a little different. For starters, the Fuzz Face has the oscillation issues that the MK II/Supa does not. Eliminating this should be the first order of business.

Let me start a new thread in a bit after I get my kids rocking and rolling for school. Stay tuned.
 
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