Author Topic: MkII Tonebender  (Read 637 times)

Bret608

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MkII Tonebender
« on: October 28, 2019, 10:19:48 AM »
So...here is the MkII that I have been either planning or working on for quite some time now. I populated a board for one of these years ago, but didn't love the layout and also did not quite have a transistor stash robust enough to pull it off. I suppose I could have used a fabbed board with trimmers, but I wanted this to be a fully realized project in the sense that I cut and traced the vero, tested the transistors, painted the box, etc.

Anyway, this is the early Sola Sound MkII/Marshall Supa Fuzz. I pretty much just took the historical MkII layout and redid it to work better with the smaller-pitch vero we use these days (see attachment if interested). Also, I wanted it to fit in something no bigger than a 125b. The paint is good old Rustoleum gray hammered. For transistors, I did a lot of digging on other forums to see what transistor voltages were actually like on vintage units, rather than using the hfe as the main starting point. Using a mix of pretty leaky germaniums, I was able to nail the voltages that Electric Warrior reported on his vintage Supa Fuzz (most importantly, around 0.17v on Q2's collector and 8.5v or so on Q3). It does sound really cool! However, that was just bit too gated with my guitar and amp when turning down the guitar's volume knob, and I suspect those voltages may favor humbuckers (since the higher output could overcome the gating somewhat). So I went with a slightly lower-gain (but similar leakage) Q2 and that got me about 0.25-0.30v on Q2C, and 7.5-8v on Q3C (depending on room temperature). The end result is that it has some useful cleanup at lower gain settings, but still has that classic MkII gating. When you go even lower leakage on Q2, the cleanup is fantastic, but it ends up sounding more like a smooth, higher-gain Fuzz Face. By the way, I held Q3 constant with a very leaky AC125 (about 0.440mA of collector leakage). Anyway, this thing completely rips! I was also surprised at how much the noise and oscillation quieted down once I got the pedal boxed. I'll stop now because I could talk about these things all day...

Manc

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Re: MkII Tonebender
« Reply #1 on: October 28, 2019, 04:47:48 PM »
This really, really tasty.
The MKII is the very reason that got me into pedal building... such a great little circuit!
Ever since, and many pedals later, my dream is still to find a proper sloped sandcast enclosure.
I have three OC81D with the right specs that are just waiting for that elusive box...

Bret608

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Re: MkII Tonebender
« Reply #2 on: October 29, 2019, 08:30:52 AM »
I know, right? I would love to get hold of one of those enclosures. I am pretty sure Dave Main and Macari's have the market locked down on those. And maybe they should, but anyway...

harryklippton

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Re: MkII Tonebender
« Reply #3 on: October 29, 2019, 08:57:36 AM »
Not exactly the same but I've been seeing these make the rounds:

GAPco Vintage Pedal Enclosure Pressed Steel (ROTO-1) https://reverb.com/item/15153505-gapco-vintage-pedal-enclosure-pressed-steel-roto-1?utm_source=android-app&utm_medium=share

Bret608

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Re: MkII Tonebender
« Reply #4 on: October 29, 2019, 09:38:48 AM »
Cool! It looks like the old Rotosound fuzz. That would be seriously fun to use on a MkIII-type build.

Govmnt_Lacky

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Re: MkII Tonebender
« Reply #5 on: October 29, 2019, 09:50:14 AM »
Not exactly the same but I've been seeing these make the rounds:

GAPco Vintage Pedal Enclosure Pressed Steel (ROTO-1) https://reverb.com/item/15153505-gapco-vintage-pedal-enclosure-pressed-steel-roto-1?utm_source=android-app&utm_medium=share

3 words......

Sheet... Metal... Screws  :-\

jubal81

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Re: MkII Tonebender
« Reply #6 on: October 29, 2019, 12:26:36 PM »
So clean. So industrial. So fuzzalicious. Excellent execution all around. Really nice engineering on the battery space, too!
"If you put all the knobs on your amplifier on 10 you can get a much higher reaction-to-effort ratio with an electric guitar than you can with an acoustic."
- David Fair

Bret608

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Re: MkII Tonebender
« Reply #7 on: October 29, 2019, 01:17:59 PM »
Thanks! I know, I am really clever with my use of foam and batteries. ;) I have a couple of those metal battery retainer things but it looks like they have to be bolted on. I'll get over the lack of motivation on that at some point...