“The Fuzz”

[Big Monk]

Shout out to @JamieJ for making me reconsider the blend control. Did some surgery last night to expand the Q2 bias range and remove the Frequency switch circuitry. Added a temporary blend control. I’ll be revising the enclosure drill plan, art and board to accommodate an internal blend trim and use a smaller LED and then ordering final PCBs and enclosures.

Kind of a bass-ackwards build report but sometimes even the best laid plans (and enclosures and PCBs) require “field” changes.

 

[Big Monk]

Played around a little more today. Ended up ditching the blend control for a single cap. It really just acts as a switch anyway. I’ll go with a single cap for the input between 680 not and 1 uF.

I have to redesign the board slightly and I believe add a base to collector cap slot as well, as adding 470 pF seems to have helped the hiss issue too.

So I’ll be revising the art and Drill plan, as well as the PCB for the final run.

 

[fig]

Shout out to @JamieJ for making me reconsider the blend control.

Ended up ditching the blend control for a single cap.

Well Jamie, it nearly lasted a day.

Do you have a current schematic? Not that I could be any real help mind you, but I am curious about this hiss.

 

[Big Monk]

Well Jamie, it nearly lasted a day.

Do you have a current schematic? Not that I could be any real help mind you, but I am curious about this hiss.

Give me 10...

 

[fig]

Give me 10...

PayPal or Venmo?

( I paid to see the Sistine Chapel…this schematic better be worth it )

 

[Big Monk]

Do you have a current schematic? Not that I could be any real help mind you, but I am curious about this hiss.

So here is the "as-built" schematic:


For starters, I can't rule out with 100% certainty whether I'm chasing my tail or not, i.e. I can't remember for certain if this level of hiss was there on the breadboard and I just disregarded it because, well, breadboard!

From this breadboard demo though, I think I can hear what I'm hearing now:

So it becomes a case of having zero RF or oscillation and trying to simply squelch some of the hiss.

I believe the Gain pot may actually be contributing. Input/Series resistance can often be a culprit for excessive noise in pedal and tube amps so that is where my head is at right now.

Yesterday I tried some strategic cap placements. I used a 470 pF across the B-C of Q1, but that muted the tone too much and did not really help with the hiss. I currently have a 100 pF cap across the Volume control and that definitely helped so that may stay permanently. I may try the 100 pF across the Gain pot as well and see if that helps. \

Overall, not a huge issue but I had hoped for a fairly quiet pedal, which this is in the classic sense (no whale/dolphin in distress noises or spanish language radio stations/country stations).

 

[MichaelW]

I dunno, sounds fab to me, right around 2:17 mark. Killer sound.

 

[fig]

Have you considered audio probing to find where it is being injected or accentuated? My guess would be the area around the Q2 bias trimmer into the volume pot.
This is unrelated but a chance for me to learn something if you’ll indulge me (apologies for derailment)..coming off the emitter of Q2 are two polarized caps to ground (10u, 2.2u). Why two, and why those values? Thanks in advance.

 

[Big Monk]

Have you considered audio probing to find where it is being injected or accentuated? My guess would be the area around the Q2 bias trimmer into the volume pot.

If all else fails I will do just that. I’m going to try some “at volume” testing to see how effective the 100 pF across the volume control is, as well as 100 pF across the Gain pot and a cap at B-C for Q2 for completeness.

This is unrelated but a chance for me to learn something if you’ll indulge me (apologies for derailment)..coming off the emitter of Q2 are two polarized caps to ground (10u, 2.2u). Why two, and why those values? Thanks in advance.

That was a way for me to “‘tweener” cap values for the emitter cap. 10 uF just wasn’t cutting it and my next option was either 15 uF or 22 uF. So basically I can now get any value from in between standard values.

When I do a Silicon MK II, I’ll do the same to get values in between 4.7 uF and 10 uF, which is another no mans land.

 

[Big Monk]

“On this week’s episode of “Waste Not, Want Not”……..”

I was cleaning my bench a couple weeks ago and saw “The Fuzz” enclosures with the switch hole error in my enclosure bin.

So I whipped up a quick PCB that I could use in that enclosure:



Offboard wiring tomorrow then some sound clips and then these are going up on Reverb to fully fund the Giveaway fuzzes.

 

[Big Monk]

Got it all wired up:

 

[fig]

It looks great Derek!

 

[Coda]

And here we are with August right around the corner…

 

[Big Monk]

And here we are with August right around the corner…

Well, these are getting sold straight away so I can get on with the Big Show…

 

[Bricksnbeatles]

Ain’t never gonna do it without the fuzz on

 

[Big Monk]

I’m sick as a dog and the whites are in the laundry today so no socks: