Ocelot Octave subtle distorted sound

[waarp]

Hello,

Having an issue after building two Ocelot pedals, The octaves are working 100% however there is a subtle fuzz/distorted signal coming through that is driving me mad.
This distorted signal only comes through while the pedal is on and when I play notes. It happens with both just clean signal and just octave -1, -2 or any combined, basically any setting.

Has anyone encountered this before? I did find this unresolved post from finebyfine as well with the same issues.
Thank you in advance!

here are some of my voltage settings with all pots set to off.

IC6-CD4013BE	IC7-CD4027BE	IC1-TL072	IC2-TL072	IC3-TL072	IC4-TL072	IC5-TL072	Q1-2n3904	Q2-2SK30A	Q3-2SK30A
1- 0	1- 0	1- 4.93v	1- 4.93v	1- 4.93v	1- 5.03v	1- 4.69	e- 4.21	s- 4.88	s- 4.93
2- 0	2- 9.07v	2- 4.93v	2- 4.93v	2- 4.93v	2- 4.94v	2- 4.96	b- 4.84	g- 0	g- 0
3- 9.06v	3- 9.08v	3- 4.48v	3- 4.93v	3- 4.61v	3- 4.91v	3- 4.93	c- 9.06	d- 4.93	d- 4.93
4- 0	4- 0	4- 0	4- 0	4- 0	4- 0v	4- 0
5- 0	5- 9.07v	5- 4.93v	5- 4.61v	5- 4.62v	5- 4.91v	5- 4.93v
6- 0	6- 9.08v	6- 4.93v	6- 4.93v	6- 4.94v	6- 4.94v	6- 4.93v
7- 0	7- 0	7- 4.93v	7- 4.93v	7- 4.94v	7- 4.84v	7- 1.52v
8- 5.0v	8- 0	8- 9.06v	8- 9.07v	8- 9.08v	8- 9.08v	8- 9.06v
9- 0	9- 0
10- 1.52v	10- 0
11- 0	11- 0
12- 0	12- 0
13- 9.06v	13- 0
14- 9.06v	14- 9.06v
	15- 0v
	16- 9.07v

Troubleshooting done:
1- replace all IC and transistors, no difference.
2- replace 1u electro in audio path with 1u film, no change
3- attempted audio probe to find where the fuzz starts but the probe is too noisy and everything has a bit of a white noise sound to it.

Thanks!

 

[music6000]

haha sorry been a super busy week, one pedal was posted up top but my other pedal looks like its getting a different reading on G of Q3

These are with nothing plugged in or out and all knobs set to full off.

Q2	Q3
S- 4.92v	S- 4.92v
G- 0v	G- 4.31v
D- 4.92v	D- 4.92v

Did you purchase the 2Sk30's from Tayda?

 

[waarp]

Did you purchase the 2Sk30's from Tayda?

I did, however I swapped them with 2N5457's and had the same result. Fun fact though it did boost the octave levels a bit having the 2N5457 in

 

[music6000]

You realize the pinout is different, D S G VS 2SK30 D G S !!!

 

[waarp]

You realize the pinout is different, D S G VS 2SK30 D G S !!!

yeah haha dont worry I checked and put them in the right way. I went back to the 2SK30 though since the distortion issue was still present. Saving those 5457s for another build.

 

[harmaes]

I just finished an Ocelot build and experienced noise/static like behavior only in the dry signal.
I had the PCB populated yesterday and quickly connected it to my breadboard to see if I build the circuit correctly.
Everything worked correctly but I noticed a little bit of noise/static on the dry signal with my P-Bass.
I boxed the pedal today and now it had noise/static constantly on the dry signal.
I experimented with the input and output wires and moved them away from the PCB and the static went away. When using the breadboard there were no wires going across the PCB.

So I replaced the single wires with shielded wire and the problem went away. Connected the mass to ground of the jacks and to the ground of the switch. Hope that this could solve your issues as well?

 

[Dan0h]

I just finished an Ocelot build and experienced noise/static like behavior only in the dry signal.
I had the PCB populated yesterday and quickly connected it to my breadboard to see if I build the circuit correctly.
Everything worked correctly but I noticed a little bit of noise/static on the dry signal with my P-Bass.
I boxed the pedal today and now it had noise/static constantly on the dry signal.
I experimented with the input and output wires and moved them away from the PCB and the static went away. When using the breadboard there were no wires going across the PCB.

So I replaced the single wires with shielded wire and the problem went away. Connected the mass to ground of the jacks and to the ground of the switch. Hope that this could solve your issues as well?

I will wrap my wires and see if it resolves the issue. Thanks for the idea.

 

[Nic]

Sorry to bring back this thread to life ... did anyone find the problem ? My build is now almost perfect, I had one bad IC from Tayda on the -2 side.
Now, the pedal sounds really good, except that I have the described static/buzzing sound.
1 - Only when engaged
2 - Only when strings are vibrating.
3 - Only when -1 is turned on.

So with the -1 knob turned all the way down, no buzzing.
Thanks all

 

[PJS]

If you are looking at parts of the circuit that are unique to -1, then on the schematic you are basically looking at R11 through Q2, IC 1.2 and through to IC2.2 I think. I am a bit hazy on it, but I think the purpose of that network is basically to buffer and filter what starts out as a square wave. I would check that part of the circuit for bad connections and wrong value components. An audio probe may be able to tell you more precisely where the buzz is coming from

 

[Nic]

Yes, I took voltages everywhere yesterday and will post the values when I have a chance... I've got 3 drastically different from values in the OP. I also thought that part of the circuit would be where the problem sould be, time to take out the probe... I wish santa would send me an auditorium pcb.

 

[Nic]

I marked in red the values that are really far from the original post values ... but those could be ok, just not sure. To me IC7 pin 3 at 0 correspond to the path linked to IC6 pins 2 and 5, so that should be normal.
Where do IC6, pin 1 go ?
IC5 pin 1 has a lot of current, is that normal ?

I also think probing and inspecting R11 to IC2.2 will be the key.

I will let you know my findings as soon as I hate time to probe it, might be during the week-end.

	IC1-TL072	IC2-TL072	IC3-TL072	IC4-TL072	IC5-TL072	IC6-CD4013BE	IC7-CD4027BE	Q1-2N3904	Q2-2SK30A	Q3-2SK30A
1	4.59	4.60	4.57	4.59	7.7	8.36	0	E: 3.83	S: 4.54	S: 4.53
2	4.57	4.60	4.58	4.57	4.54	0	8.33	B: 4.43	G: 0	G: 0
3	4.15	4.59	4.30	4.53	4.55	8.34	0	C: 8.33	D: 4.54	D: 4.51
4	0	0	0	0	0	0	0
5	4.59	4.30	4.27	4.53	4.54	0	8.33
6	4.60	4.59	4.57	4.56	4.56	0	8.33
7	4.60	4.59	4.57	4.58	1.54	0	0
8	8.43	8.42	8.39	8.37	8.36	7.69	0
9						0	0
10						1.54	0
11						0	0
12						0	0
13						8.33	0
14						8.33	8.33
15							0
16							8.33

 

[Nic]

Oh yeah, I get all my voltages values are relative to running this on an 9v battery that right now would output around 8.3 to 8.4 volts

 

[Nic]

Ok, after some probing and troubleshooting, the problem occurs around IC4. But there is a lot going on in this circuit.
I found out that when oct 1 AND 2 are full on or off, there is no buzzing, but any other setting will buzz.

Without IC4, no buzzing at all.
I swapped the IC around and troed new one from PPCB, the IC is not the problem. Could it be the diodes ?

 

[Nic]

Quick follow-up, I had a bad pot on OCT2. I had soldered/de-soldered/modified them quite a lot to fit. I hade only one spare, a lug type which was perfect. I still have a little buzz, but nothing that compares, I'll end up replacing the OCT1 as well when I reorder from Tayda... Maybe even the third one for good measure.

 

[waarp]

I was never able to completely remove the buzzing but a few things ended up making it hardly noticeable, one was to replace all internal wires with shielded wires, swap all the electrolytics in the signal path with tantalums , and the last was replace r9 and r18 with trim pots. I am not sure which of these helped the best but it became usable for me and I eventually gave it to a friend of mine.

 

[Nic]

With your last comment, I suppose it could be marked as solved ?

 

[waarp]

With your last comment, I suppose it could be marked as solved ?

if youd like! the buzzing never fully went away though i did abandon fixing it and just treat it as a feature.