Revised Kay Fuzz Tone schematic

[g3rmanium]

Hello,

I've promised over and over again () to trace the schematic of my Kay Fuzz Tone, so here it is:



From the schematics published here, the 0.0022 cap is missing and the pot is 250 K instead of 50 K. There are some other changes to the tone stack, I think.

[Sir H C]

Some guts shots (the schematic here I think has been debunked several times over)

[g3rmanium]

Some guts shots (the schematic here I think has been debunked several times over)

Yeah, gut shots!  Just made these:

[Meanderthal]

 I just noticed it's a wah type control for the gain. Interesting!

[g3rmanium]

I just noticed it's a wah type control for the gain. Interesting!

Hm? Gain is fixed, the treadle just blends between two different sounds.

[puretube]

 

[Meanderthal]

 Ummm. Oh! Makes much more sense now! From the perspective of a foot control being useful mid-song anyway...

[Dan N]

Thanks for the nice photos!

Interesting about that .0022 cap being gone. It was used on one we saw here a while back.

I'm pretty sure you missed the big 0.1 cap on your drawing. It goes to ground from a 22K resistor. Bottom right corner of your drawing (next to the diodes).

How does yours sound? Losing that .0022 cap might make it raunchier.

[analogguru]

the schematic here I think has been debunked several times over

but never really good....

If the valu is 2n2, this cap can be seen on the picture from Sir H C  and also on the 2nd picture of g3rmanium.
this cap is located between the base and collector of the FIRST transistor.

On every schematic this is shown incorrect.  It´s the same with the collector resistor of the 3rd/4th transistor.  This is definitely a 10k and NOT a 100k.

also the 100n-cap can be seen on both pictures and it was on every picture I have seen before.
It doesn´t make any sense without that cap.

compare it with the Univox superfuzz, Royal Fuzz, Ace Tone FM-2, Ibanez standard-fuzz or any similar unit like the foxx tone-machine or fender blender.

The kay seems to be the PMS:  "poor-man´s superfuzz".

The schematic is also incorrect in the way, that there is not shown the true-bybass slider-switch.

so I wouldn´t trust the schematic shown.

analogguru

[analogguru]

Ok, here is the link to the:

"Revised" Kay F-1 Fuzz Tone schematic

enjoy !

analogguru

[g3rmanium]

Thanks for the nice photos!

No problem

I'm pretty sure you missed the big 0.1 cap on your drawing. It goes to ground from a 22K resistor. Bottom right corner of your drawing (next to the diodes).

Hm, I will check again but I went over the circuit and counted the parts and they matched the Photoshop drawing.

How does yours sound? Losing that .0022 cap might make it raunchier.

Mine doesn't have much sustain and also is not really loud, but the octave-up sound is cool. Not sure if the other ones are louder. There's this guy on TGP that has modded his Kay Fuzz Tone to sound incredible (Mr. Sage or so is his nick), he told me he put some Germanium diodes in it.

[g3rmanium]

If the valu is 2n2, this cap can be seen on the picture from Sir H C  and also on the 2nd picture of g3rmanium.
this cap is located between the base and collector of the FIRST transistor.

Ah, I guess I know now what you mean. It could be that I overlooked this cap. I will check this.

also the 100n-cap can be seen on both pictures and it was on every picture I have seen before.
It doesn´t make any sense without that cap.

Ok, I'll try to find this one as well.

[mattpocket]

I still dont get what the wah pot type set-up is for?

Is this pedal in a wah enclosure?! Does it have a stomp switch and a wah pedal?

EXPLAIN! I'm intrigued.

[Sir H C]

To switch it on and off, there is a slider switch on the top.  No stomp switch.  Kay put several things in different colored wah enclosures, tremolo, wah, and a bass booster.



Here is the wah circuit:

[mattpocket]

So the fuzz is controlled by the wah pedal?

[analogguru]

So the fuzz is controlled by the wah pedal?

@mattpocket
this is a pedal, not a "wah-pedal"... a wah-pedal is a pedal which produces a wah-sound.

The fuzz is not controlled by the pedal, only the output volume of the fuzz (and the tone-color a bit).

@Sir HC
you make me really curious:

you have close-up-pictures of the component-side of the wah ?

also you mention the bass-boost ? any guts ?

and a nice picture of the tremolo-components would be helpful to clear the question if the resistor which comes from the collector of the oszillator and feeds the to opposite-trannies is 68k or 10k.

analogguru

[Sir H C]

I am lacking a bass boost, I will have to dig out the trem to get some pictures of it, but here is one of the Wah:

[Mark Hammer]

Look at the schematics for the Foxx Tone Machine, Univox Superfuzz,  Honey Fuzz, Ace-Tone Fuzz, and a bunch of others and you'll see many similarities.  There is the phase splitter (transistor with equal-value emitter and collector resistors, providing two opposite-phase outputs), the  diode pair to ground, and the notch/scoop filter on the output.

The big differences between the Kay and these others lies in the input stage.  You will note the absence of any network linking the base of the input transistor and the emitter of the phase splitter (Q1 and Q2, respectively).  I don't know a lot about discrete circuits, but I take it that this network has the function of providing more boost for certain portions of the spectrum, and especially boosting the fundamentals that are likely to make up the doubled frequencies.  The Kay is a simpler circuit that omits this element, which, in principle ought to make for a thicker fuzz with a less obvious octave up (hence no means for selecting/deselecting it).

C9/C10, R14/R15 make up the traditional midscoop filter in these pedals.  The values are fairly similar to those seen on the Superfuzz except that the value of C9 is substantially larger, allowing more mids through to the output.  You will note that C9 sort of steps over the pot directly to the output, such that mid/treble content is generally uninfluenced by the setting of the pot.  I wouldn't say completely uninfluenced, since you will note that the output of C9 has two direct paths to ground: one through R16 and the other via the pot wiper through the ground leg of P1.  Place those two resistances in parallel and that resistance plus the value of C9 forms a kind of crude variable highpass filter.

At the same time, consider that R14/15/16 form a kind of fixed voltage divider, kind of like a 132k pot turned down partway (32k on one side, 100k on the other).  But whoops, once again we have this "other" path to ground that places the ground leg of P1 in parallel with R16. We also have another path whereby R14 and C10 form a lowpass filter with a corner frequency of 72hz and P1 simply attenuates that output.

So, P1 seems to play multiple roles that involve attenuating the bass, shifting the highpass corner frequency, and attenuating the overall signal level.  As noted, moving the pot around, whether by fingers or foot, will produce equal parts volume and tonal change.  Not having used one of these, I have no idea what the effect-vs-bypass volume shift is.  Given the complete absence of any post-filter gain recovery stage, such as found on both the Superfuzz and Tone Machine, my sense is that the output will be a bit louder than bypass, but not by much, making the pot more of a tonal change than anything else.  This is likely part of why it is situated in a treadle mechanism like a wah rather than a panel-mounted pot.  If the volume won't change much then the player won't get themselves into trouble by turning up too loud and risking feedback.

This pot is actually a nifty little control, and entirely capable of being implemented on many designs that use a gain recovery stage.  For instance, the Superfuzz has a 100k terminating resistor on the output stage.  That could easily be converted into a 100k log pot for volume control, and the volume pot normally situated before the output stage co-opted into functioning like this little-bit-of-this-n-that control found on the Kay.  It might actually make for a more interesting tone control than the stock one found on the Superfuzz.

[Jackie Treehorn]

Well, I'm not so sure about that 10k on the tied transistors.  When I built this circuit, I noticed that the best sounding value in that spot shifted a bit with the battery.  I ended up using a 50k pot and a 47k resistor to adjust between 47-97k and I think there's a sweet spot in there to get the Lanois style sound.  The initial output was less than the bypassed output, so I tried to reduce some resistors here and there.  I've got a .0022 in the tone section.  As I recall, smaller values tended to give a brighter/harsher tone but there was more volume loss heel down.  I ended up with a 100k pot, but with a 120k resistor between the ground connection.  The amount of sustain seemed to depend on the gain of the transistors.

Here is a movie I made of the pedal in action.... http://theinside.net/misc/Kay Fuzz/Kay Fuzz.MPG

I have a vero layout I did based on the old schematic, but maybe that would just lead to more confusion!

Oh and pulling one of the tied transistors gets a pretty nice straight fuzz, too...

[Mark Hammer]

Very nice tone, and nice demonstration of the effect of the pot.  The huge bottom is a consequence of the midscoop filter.  As expected, there was very little variation in volume.  The octave is more pronounced than I was expecting, but then the octave effects varies with the tone setting in the Superfuzz, so there is no reason to expect it not to vary with pot setting here.  And since you mentioned that the pot value was replaced by a pot/resistor combo that essentially restricted the pot's range of influence, I gather the pot has more effect in a stock unit.

You don't have to pull the transistor to get the fuzz.  I gather you can simply lift the connection between the 1uf cap and the base of the relevant transistor to do the same.  This is essentially what is used on the Foxx Tone Machine.