Ohhhhh Kay!!

[Mark Hammer]

Daniel Lanois is in town tomorrow, and that got me interested in the Kay fuzz.  The Kay is essentially a Superfuzz, with a simpler front end, no variable drive, no output level control, and no gain recovery stage after the mid scoop.

Looking at it, I thought it might benefit from a few things.  First, the emitter bypass cap on the input stage is kind of small at 100nf.  I installed a 3-way toggle that patched in a 680nf or 10uf in parallel with the 100nf.

Next, I stole a trick from ZVex and inserted a 10k Lin pot between the diodes and ground.

Next, I stuck a 10k pot between the 100nf cap in the mid scoop and ground.

The  50k foot treadle pot was replaced with 100k and the 200k ground resistor replaced with 150k.

The 3way toggle is KILLER.  Feel free to experiment with other values but there is no reason to go beyond 10uf.  And at  10uf, the octave blooms beautifully, like a feedback simulator.

The diode pot helps soften the clip and vary the degree of growl vs sizzle.  Useful.  Just note that reducing the clipping action raises the volume.

The variable scoop works as expected, but interacts with both the foot treadle control and the other installed options...in a good way.  Because these options alter the volume level, I'll swap out the 100k output resistor for a 100k volume pot.

The Kay fuzz is a very nice unit.  But this....this is better.  Much better.  Jimi, I hear your soldering iron calling.

[digi2t]

Jimi, I hear your soldering iron calling.

Phhhhhhttttt!!!

I can feel the heat, all the way over here! 

[Mark Hammer]

I just finished it before coming upstairs to watch 24, and it's too late now.  I'm home tomorrow so I'll try and put up a video so folks can decide if it's worth their while.

I used a pair of 2SC828s with HFE of 214 and 215, along with 1% resistors for the octaving part, and 644s with HFE of 375 and 415.

[Liquitone]

Most disappointing title of a thread ever!!

hehe no, actually I'm going to keep an eye on this thread because I just started working on a Fuzztone layout yesterday.
The client didn't ask for modifications, but I'm going to try these out for him to test. (and make sure you get the credits/part of the profit if these modes end up in the build.)



p.s. this is a layout in progress, there are mistakes and missing parts here.

[Blitz Krieg]

What schematic are you using?

[Liquitone]

The known incorrect schematic along with info about the wrong placement of the .022 and the missing 0.1 near the end. this layout has since been changed accordingly. This was just trying out how well this circuit would translate to a turret layout.

[Ben N]

Was expecting an ash blonde Strat with maple neck and gold hardware. This is good, too.

[drolo]

Daniel Lanois is in town tomorrow

If you see him, say hello and tell him to come visit us in Belgium :-)

[kaycee]

Interesting ideas there Mark. I've been messing with the SF of late, I tried a warp control on the diodes but not the resistance to ground version. On my v2 I have the SWTC v2  which is another of your ideas. I'd like to find a way to mix the octave with the raw fuzz as I don't always want the ping of the octave in the distortion. One nasty fuzz 

[Mark Hammer]

Thanks for the nod. 
The SF still distorts quite a bit, even without diode clipping.  Here's a kooky idea to try out.  Lift the ground end of the clipping diode pair.  Connect them to one outside lug of a 50k linear pot, and the pot wiper to ground.  Now connect a 22nf cap from the other outside lug to the other end of the diodes.  The pot will vary the path to ground of the diodes and a treble bleed cap in reciprocal fashion, so that the more intense the clipping, the more treble reaches the output.  Think of it as a warm-to-fried control.

I'm not sure ALL of the 50k is needed between the diodes and ground to produce a useful range of control, so consider sticking a 15k resistor in parallel with that leg of the pot.  If you try this out, let us know if you find it useful.

[Mark Hammer]

Daniel Lanois is in town tomorrow

If you see him, say hello and tell him to come visit us in Belgium :-)

I think I may have met him before, but can't be sure.  In the late 70's, I did a profile piece on the studio he established with his brother, for the local university newspaper.  Somebody greeted me at the door and gave me a great tour, but I have no idea if it was Dan or his brother Bob.  Neither of them were "famous" at that point, so I didn't really make a point of differentiating, though I think Dan had started collaborating with Brian Eno at that point.

Didn't go to the show.  I have never seen so much rain as seems to have fallen here in the last few hours, and it was an outdoor show.  Guess I'll find out tomorrow if it went ahead or not.

UPDATE on pedal:

So I quickly assembled a video - probably as quickly as I boxed the circuit up.  I like the red lettering, but I failed miserably in lining it up.  And as the video attests, I need to swap the output jack for a new one.  

Here's the schematic:


And here is the video: https://www.youtube.com/watch?v=us2kP17lyLY  Note that the demos you hear from Dan Lanois ae him pumping the Kay through an AC30.  I'm pumping it through 2W of mighty LM380 power into a 6.5" speaker.  I'm sure it'll souind bigger in a bigger amp.

[armdnrdy]

Wow..

Those harmonic overtones sound pretty cool!

Good job Mark!

[Liquitone]

Those modifications sound quite interesting and useful. It reminds me of that FY-2 you built in how it stays true to the original but being able to have it stand out more in a band mix.
It sounds like the increased emitter-cap values add gain and noise, or is the noise just the octave notes ringing through longer? I also like how the clipping knob acts, giving a louder,cleaner sound along with what sound like more bass and mids.

[kaycee]

Sounds good, particularly near the end where the octave almost sounds like feedback. Are you still using ge diodes? maybe try some 914's or 4148's?

Not that this hasn't enough knobs and switches......but, maybe change the emitter resistor on Q1 for a pot for a gain control? The interstage gain pot on the SF is crap, it's either raging or not enough signal to drive the next section with not much between IMHO.

Been messing with the SF for about a month and was just about to give it a rest, darn you Mark

[DDD]

Hmmmm...  Acetone Fuzz (Ace-tone Fuzzmaster FM-2)...   http://www.diystompboxes.com/smfforum/index.php?topic=90369.0

[Mark Hammer]

Sounds good, particularly near the end where the octave almost sounds like feedback. Are you still using ge diodes? maybe try some 914's or 4148's?

Not that this hasn't enough knobs and switches......but, maybe change the emitter resistor on Q1 for a pot for a gain control? The interstage gain pot on the SF is crap, it's either raging or not enough signal to drive the next section with not much between IMHO.

Been messing with the SF for about a month and was just about to give it a rest, darn you Mark

I used some unmarked chunky glass GEs that measured around 320mv Vf.  I did install a switch in a SF I sold off last year, that selected between GE, SI and no diodes.  SIs make the output louder, as you can imagine, and lifting the diodes makes it even louder, still.

I was set to use a 10uf emitter cap and a variable series resistance for Q1, much like the gain control on the AMZ MosFet booster, and the Stratoblaster, but thought that the soul of the Kay was largely varying the tone of an already "stressed" guitar sound.  So I opted for using the caps to alter where in the spectrum the added gain was applied.  The 100nf cap applies it to the higher mids and above, where the larger cap values move the gain downward to cover more mids and upper bass.  Because there tends to be more guitar signal in that region, it has the practical outcome of appearing to increase gain, although it doesn't really change gain.

I should note that I omitted some details in the drawing, because I didn't feel like drawing them.  For the additional emitter caps, I connected them to the emitter via individual 100k resistors.  I then use the toggle to shunt one, or the other, or neither, of those resistors.  This allows the caps to be in circuit in a manner that does not alter gain, but avoids audible popping, since they never have a floating free end.

Hmmmm...  Acetone Fuzz (Ace-tone Fuzzmaster FM-2)...   http://www.diystompboxes.com/smfforum/index.php?topic=90369.0

The FM-2 seems to be a sort of hybrid of the SF and Kay, doesn't it?  It has the output stages of the SF, but the simpler front end of the Kay.  I don't know how much more bass gets to pass through the Kay, given the 10uf caps I the signal path, but it CAN be a throbbing monster when it wants to.  But the absence of any emitter cap for Q1 on the FM-2 just cries out for experimentation, doesn't it?

The treadle control is interesting.  because of how it has been drawn in the various posted schematics, it took me the longest time to intuit just what it does.  But I finally get it, now.  The 4700pf cap, 22k and 10k resistors, along with the 100nf to ground, form the standard midscoop found on many of the Shin-Ei derivatives, be it the SF, or FY-2.  The SF and FM-2 use a switch to select between the midscoop filter and a simple passive attenuator that yields a full-bandwidth signal of approximately equal loudness/amplitude.

In the Kay, one leg of the treadle control pot is in parallel with the 10k resistor, when that parallel leg is reduced in resistance value, it essentially moves the 100nf to ground closer and closer to the output of the 4700pf cap.  When the 10k plus pot-leg resistance is nil, the 100nf cap serves as a treble cut for the entire signal, and not just the portion passing through the 22k resistor.  As you can tell from the video, the whole circuit seems to be designed to provide a bit of a boost over bypass - ostensibly for soloing purposes - but the only control on the original is really just a tone control, without any apparent need for a volume pot.  Of course, once you start monkeying around with parameters that DO change the level, a volume pot becomes necessary.

[kaycee]

I take your point about retaining some of the character traits of the original Kay and making a Kay Plus. I've not done the Kay yet, I have a vero printed off and next time I get to messing with the SF type circuit I was going to build one. For me I like the SF, but found the two tone selections limiting, and the way it runs flat out all of the time a bit limiting, so the tone control ideas are very interesting to me.

After I suggested the pot on Q1 emitter, i thought better of it and would probably go for a series resistance instead between stages. What I like about your caps idea is it changes the frqs before the rectifier stage so you can accentuate or maybe cut the octave effect to an extent.

One other thing, I got hold of one of those little Ditto looping pedals a while back. They are very handy for testing and demoing pedal circuits. Just play a riff into it and let it repeat it over and over while you fiddle with the circuit controls, gives you a much better idea of what if anything is changing.

[Mark Hammer]

One other thing, I got hold of one of those little Ditto looping pedals a while back. They are very handy for testing and demoing pedal circuits. Just play a riff into it and let it repeat it over and over while you fiddle with the circuit controls, gives you a much better idea of what if anything is changing.

That is one of the smartest ideas I've heard this week, in just about any walk of life.  Good on ya! 

[italianguy63]

[kaycee]

Something that's been bugging me a while with the SF type circuit? You can usually spot its a SF by the number of electros, building one always decimates my 10uf stash. So why the two caps either side of the diodes to ground? I don't see them on other diode to ground applications? Also 10uf seems overkill?   I see the Kay uses 1uf mostly, is it just standardisation for production perhaps.