SOLVED Muzzle (Classic) and low threshold settings

[m1nl]

Hi everyone, hi first, as this is my first post here!

A few months ago, I built a Muzzle (Classic) pedal from a Musikding kit. I believe the circuit works as intended. I really like it and agree it's one of the best noise gates I've ever used!

What bothers me is whether the pedal behaves correctly when the threshold is set low (below approximately 1/3; high sensitivity setting for range switch). When the input signal is zero (input jack tip connected to the ground), the LED indicator suggests that the pedal is never gating. Given the way the threshold pot works (its setting also affects the dynamics of the noise gate), I cannot say if the gate really works, as the output level difference is subtle. I took a few measurements, and indeed, the red LED indicator starts working when there is at least 0.6V at pin 18 of the IC - this is expected as lower values won't turn on the Q3 transistor. When the threshold knob is set to lower than 1/3, there is less than 0.6V even when the input is grounded, so the LED won't turn at all. The voltage sets at around -100mV when the threshold is further lowered to its minimum.

I don't know whether this works as intended and the LED indicator won't turn on when the threshold is set low by design, or there is something wrong with my circuit. Can somebody please tell me how your build behaves?

I took some other measurements, and the only thing I found strange is output voltage from LT1054 - instead of -8.4V on pin 5 (9V minus voltage drop on D1), I only get around -8V. Because of the voltage drop over Q2, I have around -7.4V as the negative power supply for the circuit. I am unsure if it matters and can affect threshold control.

My build uses THAT4301 retrofit module. A few photos attached:
- red LED indicator on when threshold is set just to the point when voltage equals 0.6V
- red LED indicator off even there is no input signal
- general gut shot of my build

 

[guitarbruno76]

Also read this topic as it looks Mattallica75 experienced very similar issue to yours:

Indeed our friend Mattalica75 has a pedalboard , looking like a "wasps factory", it's worse than me !

 

[guitarbruno76]

Another day brings another idea.
Actually, to eliminate the most I can the squeal/whistle, it is enough to adjust some knobs , decreasing the "treble" one, increasing the "tight" one, decreasing the "drive" one...
It needs to experiment our effects to compromise...

 

[m1nl]

Hey, sorry for the late reply.

1. I don't see a single ground connection between the PCB and the input/output jacks—blue cables are not connected to the jacks on the top of the pedal. I believe exactly one of them has to be connected. I recommend connecting the PCB ground to the input jack only. The output jack should get its ground connection through the aluminium enclosure.

2. It looks like the key input to the GND connection is still there. Was the photo taken before modification? If yes, did you connect the ground to the input jack?

3. Can you try to use separate power supplies for the OD pedal and Muzzle so we can narrow down the issue to a possible ground loop?

Mateusz

 

[guitarbruno76]

Hi Mateusz, thx to reply.

1. I don't see a single ground connection between the PCB and the input/output jacks—blue cables are not connected to the jacks on the top of the pedal. I believe exactly one of them has to be connected. I recommend connecting the PCB ground to the input jack only. The output jack should get its ground connection through the aluminium enclosure.

Done, but it doesn't work better...
We have to notice that if we disconnect both of the blue cables, the default option to use the noise gate , I mean with no side chain won' t work.
Meanwhile, I went back to solder these 2 blue cables to the ground of the in/out jacks.

2. It looks like the key input to the GND connection is still there. Was the photo taken before modification? If yes, did you connect the ground to the input jack?

Not sure to understand....you maybe mean the ground connection between the key 1 and 2 on the PCB. I have to recall that if I disconnect this point, the side chain won't work.

3. Can you try to use separate power supplies for the OD pedal and Muzzle so we can narrow down the issue to a possible ground loop?

Done with 2 9 volts batteries, but it doesn't work better.

Edit, after some tries and many more:

I decide to not use the side chain, so the noise gate is used with first option, guitar=>all noisy pedals (wah, comp, OD, dist) =>in/out Muzzle => all mod and space pedals ( flange, chorus, rev, delay) => amp

I can adjust the knob at 14 o clock with " high range" option, chaining my Brown Eye OD with Nux Cerberus dist stops squealing, sustain is saved whenever I am on clean sound.

Indeed, if the side chain is used, the sustain is less, in spite of I claimed, the squeal is annoying.

I think the option of using side chain is for playing some styles like djent or thrash metal and so on, I am in a soul pop rock band, i need to have some "elasticity" of the sound.

However, all along the august month, I didn't have some gig or rehearsal with band fellows, I could try 4 cables method, but it begins to be a too long story about this "damned" Muzzle.