Kay Fuzztone build

[Jackie Treehorn]

Over the weekend I did a vero layout of the Kay Fuzztone and put one together.  I tried a bunch of different transistors.  Initially, I used all the transistors I purchased from Small Bear for the Foxx Tone Machine.  They ranged from around 170 to 360.  I ended up with a 2N4401 from Radio Shack as Q1, one of the transistors I had pulled from my Vox V847 Q2, and 2 of the Foxx transistors (3565?) in the octave portion.  Incidentily, it sounds pretty nice when you pull one of the octave transistors, too.  Anyway, I trimmed the 100k on the octave transistors' collectors to 86k.  I also tried a couple different capacitors in the output section, .001, .0047, and finally .0022.  I like the .001 because as you rotate the tone pot, there's not much volume loss.  However, it sounds overly crispy, too. So, I'm at .0022 at the moment.

The other thing I noticed, is that slightly mismatched transistors in the octave section sound a bit better to me.  The ones I settled on are 250 and 210 approximately in gain.  I don't think I've quite hit the Sling Blade sound, but it's definitely interesting.

One thing that has me puzzled is that I seem to have a bit of volume loss.  If I jump around the network at the output, it's very loud.  What can I adjust to get to unity gain?  Any other Kay mods?

[MartyMart]

When I built mine, I found three different schematic "versions" of the output section, which all
looked kinda "wierd" to me !
I think I used the one with a 50k pot and 200k from lug 1 to ground, but omitted the following
100k to ground just before the out jack.
That seemed to get my volume back up some
( I may have changed that more, check in the search for my fuzztone post )
I also replaced all the 10uf electro's with 1uf NP poly's ( MMK's )
Output section cap was socketted, ended up as a .0047uf ( 4n7 )

Great sounding octave fuzz !

Marty.

[Sir H C]

Sorry for the crappy image, will have to take another picture, but this is the schematic from the inside of the fuzz:



I never really liked the sound of these, much prefer the Univox super fuzzes.

[Jackie Treehorn]

Sir H C, thanks for the picture!  I'd be curious to see a clearer one, too, to make out the values.

Marty, thanks for the suggestions.  I actually tried removing the 100k at the output and got no increase in volume.  I swapped the 22k at the input with a 9k carbon comp and the 22k in the output section with a carbon comp resistor that was around 16k.  I don't think I got much more volume, but it sounds fuller and less harsh.  There's no piercing tones at any tone control settings.  I did the 250k pot, by the way.  I may try .001 again, or I may be done.  I love all the weird noises this thing makes between notes.  It's more organic sounding than my Foxx Tone Machine, but doesn't seem to be articulate fast runs well at all.  Is yours like that?

I'm looking forward to finding a wah enclosure so I can manipulate that tone control more.

[Sir H C]

Until I can get that one up, here is the circuit:

[octafish]

In the octave section there are two identical resistors coming off the bases of the trannies to ground. In the superfuzz they are 22k's don't know about the kay. Anyway in some versions of the SF they connect to  pins 1 and 3 of a 10k trimpot with the wiper going to ground. You can dial in a better octave with this mod, but as you say missmatched trannies in the octave section can be good too.

[mrsage]

The schematic inside is "wrong." Someone traced the circuit and found that a few of the values were off.

I used the version on www.ustomp.com

The only change was that I had to play with the value of the 100k resistor coming off of Q3 and Q4. I think I ended up going all the way down to 10k for that (using, I believe, 2N5088 transistors).

[finetuned]

I'm going to build this fuzz pedal as well. Any word on what transistors I should use? (can anyone check the original one, Sir H C I see you have pics, could you check the transitor types?)

I'm looking at the UStomp shematic.

I'm sorry to reply to an old thread, so if anyone has a problem with this I'll start a new one.

Thanks

Stan.

[BRingoC]

I built this off the uStomp layout, I used, I think, BC549, whatever is used in the GEO Great Cheddar build.  Sounds great, havn't boxed it yet though.

[finetuned]

Thanks a lot.

I see there are two diodes in the circuit. I have a bunch of 1N914 diodes, can I use those? In general, what's the difference between different types of diodes?

Thanks

[petemoore]

I see there are two diodes in the circuit. I have a bunch of 1N914 diodes, can I use those? In general, what's the difference between different types of diodes?
  Higher or lower voltage threshold, Ge Would be lower voltage threshold.
  Looking up the diode part #20a90 [Ustomp Schematic], comes up Germanium diode...silicon substitutes will allow more output..and 'change' sound other ways...probly cool'.
  Since Ge's are lower threshold, Si's could be put in, then Ge's across'em, and the si's would see no voltage to clip because the Ge's would have shunted it all...making for easy 'addition' and possibly simple switching....'adding to' the si's some Ge's would functionally be the same as 'opting' to them.

[smallbearelec]

If you would like to try them, the 2SC828 named in the original schem is now in stock, my SKU 2021D

Regards
SD

[Dan N]

If you would like to try them, the 2SC828 named in the original schem is now in stock, my SKU 2021D

Regards
SD

Nice! As with some of the BC transistors, many Japanese trannies used a letter to denote a gain range. It would be nice to know if yours are Q, R, S, or T's. Same with your 2SK30A's (R, O, Y, GR).

Thanks for stocking cool parts!

Back on topic, the Kay circuit is not going the be very gainy. It lacks the tone recovery stage of it's bigger siblings. Run it into a simple booster.

Silicon diodes will increase the volume. No diodes will be even louder than that.

[smallbearelec]

On inspection, most of these are 2SC828A-R. The 2SK30A are -GR

Regards
SD

[finetuned]

Hi,

Small Bear Elec, that's very nice, but unfortunately I'm in the Netherlands so ordering would be a little complicated.
I've got BC549B and BC549C. What is the difference between them, and would there be a big sound difference between those and the 2SC828A-R? Which should I choose?

Is there a place in the Netherlands / Europe where I would be able to find these transistors? I've tried www.musikding.de and www.newtone-online.nl, but no luck so far.

smallbearelec, I guess the postage rates would be very high to the Netherlands?

And for the diodes: I think the Ge diodes would sound significantly different than the Si diodes, would they not? I will try both and see what I like better.

Thanks a lot for your help, everyone!
Stan.

[smallbearelec]

Ordering from Europe is very easy IF you have a PayPal account. If you don't, set one up at www.payapl.com. My shipping charge for a bag up to 120 graqms to Europe is $6.25. Other NPN silicon types will work (see the other posts here), but you may have to may have to re-bias the circuit to accommodate different gains. That means building on a breadboard first. Yes, germanium diodes will definitely sound different.

[analogguru]

The Kay Fuzztone uses originally for  the first two transistors 2 SC 644 S and for the other two 2 SC 828 R.

2 SC 644 S:   25V/100mA/150mW   ß: 260-520/2mA   F<3dB   Fg: 150 Mhz
you can use: BC 239 B, BC 549 B, BC 550 B

2 SC 828 R:   25V/100mA/250mW   ß: 180-360/2mA   F: 6dB   Fg:  220 Mhz
nothing special only a little bit less gain and more noise - you could use any junk here
BC 239 B, BC 549B and BC 550 B will work fine here, take the examples with the lowest gain.

analogguru