Sustain Issue with Colorsound One Knob Fuzz

[GambitBandit]

Hello All,

I'm attempting my first circuit, so any help is appreciated!

I was breadboarding a Colorsound One Knob Fuzz following the Beavis Audio schematic

Link Here: http://beavisaudio.com/schematics/Colorsound-One-Knob-Fuzz-Schematic.htm

I followed the schematic exactly and I don't have any modifications I've made to it.

Pic of the breadboard:


There are no parts substitutions (I'll include my full parts list at the end of the post), but I did use a non-polarized aluminum capacitor for the 10uf (C4) capacitor.  I didn't think that would affect anything, but who knows I could be wrong.

This circuit isn't a Positive Ground Circuit

I've been having issues with general volume and sustain of the fuzz.  When louder more aggressive notes are played the circuit performs pretty decently, but when a single quiet note is played the fuzz sort of fizzles out, and when quieter notes are played there's no fuzz at all. 

My problem seems remarkably similar to this forum post:
https://www.diystompboxes.com/smfforum/index.php?topic=114587.msg1063976#msg1063976

but I didn't have any substitutions and I'm already using 9v. Unless it actually would be that I used a non-polarized capacitor for the 10uf (C4).

Power Supply which is a 9v battery is giving 9.48V

Q1 First Transistors Values:
C - 1.59V
B - 0.62V
E - 0.00V

Q2 Second Transistor Values:
C - 7.28V
B - 1.59V
E - 0.97V

Any help would be really appreciated!  Thanks in advance!

Parts List and Links:

Resistors https://stompboxparts.com/resistors/1-4w-metal-film-resistor-10-pack/
    R1: 10K Ohm
    R2: 82 Ohm
    R3: 2.2K Ohm
    R4: 150K Ohm
    R5: 1K Ohm https://www.amazon.com/dp/B07QG1V4YL?ref=ppx_yo2ov_dt_b_product_details&th=1

Capacitors
     C1: 100nF https://stompboxparts.com/capacitors/mlcc-capacitor/
     C2: 220pF https://stompboxparts.com/capacitors/mlcc-capacitor/
     C3: 220nF https://stompboxparts.com/capacitors/box-film-capacitors-10-pack/
     C4: 10uF https://stompboxparts.com/capacitors/aluminum-electrolytic-capacitor-non-polarized-10-pack/

Transistors
    Q1: BC109 https://stompboxparts.com/semiconductors/bc109-npn-transistor-metal-can-njs/
    Q2: BC108 https://stompboxparts.com/semiconductors/bc108b-npn-transistor-metal-can/

Variable Resistors
    VR2: A500k Ohm https://stompboxparts.com/pots/16mm-potentiometer-short-pcb-leg/ 

[antonis]

Hi & Welcome..

First of all, 10μF non-polarized cap makes no difference, compared to a polarized one..
(furthermore, it allows you to place it as you like..)

About Q2 Collector bias: 7.28V call for about 1mA working current (calculated either from (9.48-7.28) / 2282 or from 0.97 /1000) which, in turn, calls for a voltage on R2/R3 junction (stage's output) of about 82mV..
The above sets waveform's positive limit..!!
(very low amplitude for half of the output..)

For lowering Q2 Collector voltage, you can tweak R2 value (upwards), R3 value (downwards) or R5 value (downwards)..
Personally, I'd procced to the later one..
(for retaining Q2 stage gain..)

P.S.
Of course, feel free to lower R1 value for raising Q2 Emitter voltage hence Q2 working current..

[drdn0]

Hello All,

I'm attempting my first circuit, so any help is appreciated!

I was breadboarding a Colorsound One Knob Fuzz following the Beavis Audio schematic

Link Here: http://beavisaudio.com/schematics/Colorsound-One-Knob-Fuzz-Schematic.htm

I followed the schematic exactly and I don't have any modifications I've made to it.

Pic of the breadboard:


There are no parts substitutions (I'll include my full parts list at the end of the post), but I did use a non-polarized aluminum capacitor for the 10uf (C4) capacitor.  I didn't think that would affect anything, but who knows I could be wrong.

This circuit isn't a Positive Ground Circuit

I've been having issues with general volume and sustain of the fuzz.  When louder more aggressive notes are played the circuit performs pretty decently, but when a single quiet note is played the fuzz sort of fizzles out, and when quieter notes are played there's no fuzz at all. 

My problem seems remarkably similar to this forum post:
https://www.diystompboxes.com/smfforum/index.php?topic=114587.msg1063976#msg1063976

but I didn't have any substitutions and I'm already using 9v. Unless it actually would be that I used a non-polarized capacitor for the 10uf (C4).

Power Supply which is a 9v battery is giving 9.48V

Q1 First Transistors Values:
C - 1.59V
B - 0.62V
E - 0.00V

Q2 Second Transistor Values:
C - 7.28V
B - 1.59V
E - 0.97V

Any help would be really appreciated!  Thanks in advance!

Parts List and Links:

Resistors https://stompboxparts.com/resistors/1-4w-metal-film-resistor-10-pack/
    R1: 10K Ohm
    R2: 82 Ohm
    R3: 2.2K Ohm
    R4: 150K Ohm
    R5: 1K Ohm https://www.amazon.com/dp/B07QG1V4YL?ref=ppx_yo2ov_dt_b_product_details&th=1

Capacitors
     C1: 100nF https://stompboxparts.com/capacitors/mlcc-capacitor/
     C2: 220pF https://stompboxparts.com/capacitors/mlcc-capacitor/
     C3: 220nF https://stompboxparts.com/capacitors/box-film-capacitors-10-pack/
     C4: 10uF https://stompboxparts.com/capacitors/aluminum-electrolytic-capacitor-non-polarized-10-pack/

Transistors
    Q1: BC109 https://stompboxparts.com/semiconductors/bc109-npn-transistor-metal-can-njs/
    Q2: BC108 https://stompboxparts.com/semiconductors/bc108b-npn-transistor-metal-can/

Variable Resistors
    VR2: A500k Ohm https://stompboxparts.com/pots/16mm-potentiometer-short-pcb-leg/ 

Iirc there's a mistake on this schematic - R2 is meant to be 820R.

Refer to the One Knobber Project

[duck_arse]

Hello All,

I'm attempting my first circuit, so any help is appreciated!

I was breadboarding a Colorsound One Knob Fuzz following the Beavis Audio schematic

.....

Pic of the breadboard:

also welcome. we do want to see that breadboard pic. I notice your links have un-needed trailing spaces showing, they might stuff up the image displaying. where did you have that/those image/s posted, interwebswise?

[GambitBandit]

Hello again!

Here are a couple of photos of my breadboard in its current state.





I went ahead and swapped the R2 from 82 to 820 as suggested to correct for the type.  It seemed like it cleared up a lot of the volume issues.  However I'm getting this weird fizzle out with the fuzz on lower volume notes where it seems to cut out still.  I've uploaded a video here with some audio samples of what I'm talking about.

Would lowering the resistance on the R3 and/or R5 resistors possibly help correct this?


Here are the new values after swapping out R2:
Q1:
C 1.63
B .64
E 0

Q2
C 6.37
B 1.63
E 1.00

Thanks in advance ya'll!

[antonis]

Try to make R5 820R or so..
(by lowering R3 you lower Q2 stage's gain..)

[GambitBandit]

So I tried swapping the 1K R out for a 820 R and its didn't seem to make a significant difference in the sound.

Wondering if using a trim pot in the R3 and R5 positions would help me out?

Re uploaded the video of what the fuzz sounds like at high and low guitar volume:

https://streamable.com/tg8awd

[antonis]

You (we all) are dealing with a Fuzz circuit, yes..??

If so, there is no room for "good design practice" implementation..

P.S.
I'm not fond of fuzz circuits but I do understand (and recognize/respect) each circuit's distinctiveness..

[GambitBandit]

So I messed around and swapped out the R1 and R3 on the original schematic for some Trim pots and increased them until I got 1.5V off the Q1 Collector and 4.5V off the Q2 Collector.  That seems to have cleared up a lot of the issue!  It definitely increased the sustain of the fuzz altogether.

Cheers!