Klon Centaur clone sounds weird

[DocBrown]

Hello everyone !

First pardon me the fact of being pretty noob. This build is my third pedal and I still got a lot to learn...

I build a centaur clone based on ther Aion electronics refractor : https://www.dropbox.com/s/4xhwadzx2rxbm8z/aion-refractor-centaur-documentation-v2.pdf?dl=1

Everything works but the pedal sounds weird :
- the sound is pretty harsh, and harshier when you increase gain, becoming a little thinner when the gain is at max
- the sound is really bright you can't really go over 10 o'clock on the "treble" pot

When I began this build I decided to use the Aion PCB (seems to be the same scematics as the original klon) but I made a few changes on the BOM, trying to be closer of the original klon. Here is  what I changed :

- C9 and C10 are polarized electrolytics (value is the same), instead of film caps on the Aion documentation
- D3 and D4 are 1N4001 instead of 1N4002 on the Aion documenation
- IC3 is a ICL7660SPCA instead of TC1044SCPA
- D1 and D2 (clipping diodes) are 1N34A

I don't think the 3 firsts points could cause any trouble.


[EDIT] here are the voltages with every pot at 12 o'clock battery at 9.00V

IC1 (TL072)
1 = 4.32V
2 = 4.33V
3 = 3.43V
4 = 0V
5 = 4.33V
6 = 4.33V
7 = 4.33V
8 = 8.63V

IC2 (TL072)
1 = 4.35V
2 = 4.23V
3 = 4.34V
4 = -7.95V
5 = 4.36V
6 = 4.36V
7 = 4.38V
8 = 14.77V


IC3 (ICL7660SPCA)
1 = 8.68V
2 = 4.15V
3 = 0V
4 = -3.95V
5 = -7.87V
6 = 3.96V
7 = 6.34V
8 = 8.30V

I made a test with my strymon bluesky power supply (9.20 V) and here are the voltages :

IC1 (TL072)
1 = 4.73V
2 = 4.70V
3 = 3.74V
4 = 0V
5 = 4.74V
6 = 4.76V
7 = 4.77V
8 = 9.19V

IC2 (TL072)
1 = 4.66V
2 = 4.69V
3 = 4.70V
4 = -8.74V
5 = 4.66V
6 = 4.62V
7 = 4.61V
8 = 16.40V


IC3 (ICL7660SPCA)
1 = 9.19V
2 = 4.55V
3 = 0V
4 = -3.39V
5 = -8.75V
6 = 4.83V
7 = 7.17V
8 = 9.20V


I think that the harsh sound is comming from the clipping diodes. I've read that those diodes are a big part or the sound of this pedal. But could they cause the treble pot problem too ?

What do you think ?

Thanks a lot.


EDIT :

new test with those matching diodes and with the pedal powered by a power supply instead of a "new" weak battery. Here is what I noticed :

- slight background white noise on power supply, dead silent on battery
- No problem with the treble pot
- the pedal seems to work well if used as a boost, with low gain value and high output value
- the sound is not as great if the pedal is used as an overdrive (output at 12 o'clock and gain at 12 o'clock or over)
- white noise when turning the gain pot
- pedal is sqealling if you go over 2 o'clock on the gain pot

BUT after a few minutes, no more squeal, but the sound is really crappy after 2 o' clock and gets crappier the more you encrease the gain. Verry difficult to describe, it's like if you were playing on a dead speaker.

[patrick398]

Voltages and pictures, otherwise it's guesswork

[DocBrown]

Hi !

sure ! what pics do you want, what voltage do you want ?

As I'm pretty noob I discovered the forward voltage notion yesterday. After test my 1N34A where mismatch, and don't have the recommended value (0,22v and 0,29v).

I bought somme NOS Russian D9E, maybe a better choice for this build.

Anyway, any thoughts is welcome.

[antonis]

Is there any moderator with gracious kindness to create a stand alone topic for those trillion Klon Centaur issues..??

[DocBrown]

Well... OK.

[DocBrown]

OK, sorry to have been such a noob, after search in the forum I understood what you mean in giving voltages. So, here are the voltages on IC1, 2 and 3 with every pot at 12 o'clock, battery at 9.00V :

IC1 (TL072)
1 = 4.32V
2 = 4.33V
3 = 3.43V
4 = 0V
5 = 4.33V
6 = 4.33V
7 = 4.33V
8 = 8.63V

IC2 (TL072)
1 = 4.35V
2 = 4.23V
3 = 4.34V
4 = -7.95V
5 = 4.36V
6 = 4.36V
7 = 4.38V
8 = 14.77V


IC3 (ICL7660SPCA)
1 = 8.68V
2 = 4.15V
3 = 0V
4 = -3.95V
5 = -7.87V
6 = 3.96V
7 = 6.34V
8 = 8.30V

[patrick398]

Hi !

sure ! what pics do you want, what voltage do you want ?

As I'm pretty noob I discovered the forward voltage notion yesterday. After test my 1N34A where mismatch, and don't have the recommended value (0,22v and 0,29v).

I bought somme NOS Russian D9E, maybe a better choice for this build.

Anyway, any thoughts is welcome.

I didn't mean to be flippant, there's just little point describing what's wrong with a circuit as it's usually impossible to diagnose anything from that. When i say voltages i mean voltages at certain points around the circuit which would tell us what is/isn't working correctly. Note down the voltages at your power supply input, every pin of your ICs and every pin of the transistors if there are any.
High res pictures of the top and bottom of the PCB so we can check for wrong components, wrong polarity of something, or bad solder joints.
Do you have a multimeter?

[DocBrown]

I didn't mean to be flippant, there's just little point describing what's wrong with a circuit as it's usually impossible to diagnose anything from that. When i say voltages i mean voltages at certain points around the circuit which would tell us what is/isn't working correctly. Note down the voltages at your power supply input, every pin of your ICs and every pin of the transistors if there are any.
High res pictures of the top and bottom of the PCB so we can check for wrong components, wrong polarity of something, or bad solder joints.
Do you have a multimeter?

No problem, I perfectly understand your point. It's just I didn't knew what voltages to give. I updated the post with the voltages on the IC pins. I'll try to post pics.

[italianguy63]

Here is a copy of "good" voltages for you to compare to:

[DocBrown]

Here is a copy of "good" voltages for you to compare to:

thanks, it's what I was looking for. As you can see my voltages are a bit under the reference (around 0.3 V, except for pin 8 of IC2 where I'm 1,46v under  )

What do you think ?

[Marcos - Munky]

0.3V difference means nothing. Maybe the person who measured those voltages had a power supply with 0.3V above yours.

But 1.46V difference isn't normal. It may be a resistor with the wrong value or something like that. We need pictures to be sure.

[DocBrown]

Ok, My (brand new) battery was delivering a weak 9v. I made a test with my strymon bluesky power supply (9.20 V) and here are the voltages :

IC1 (TL072)
1 = 4.73V
2 = 4.70V
3 = 3.74V
4 = 0V
5 = 4.74V
6 = 4.76V
7 = 4.77V
8 = 9.19V

IC2 (TL072)
1 = 4.66V
2 = 4.69V
3 = 4.70V
4 = -8.74V
5 = 4.66V
6 = 4.62V
7 = 4.61V
8 = 16.40V


IC3 (ICL7660SPCA)
1 = 9.19V
2 = 4.55V
3 = 0V
4 = -3.39V
5 = -8.75V
6 = 4.83V
7 = 7.17V
8 = 9.20V

With a proper power supply, everything looks normal, expect, pin7 of IC3 where I'm 1,58 higher and pin 6 with +0,74V... but, on the schematics, Pin 6 & 7 of IC3 seems unused so this higher voltage souldn't be a problem.

Maybe the problem are my germanium diodes. When I tryied the pedal yesterday Forward voltages where mismatch. I changed the diodes for a matched pair but the forward voltage is 0.29v instead of 0.35V. And the probability that my diodes sound like crap is real 


I'll try to take pics but it's not easy...

[Marcos - Munky]

Matched diodes doesn't matter here. And while they do influence on how the clipping sounds, they won't make the circuit sounds so harsh and bright.

[DocBrown]

Matched diodes doesn't matter here. And while they do influence on how the clipping sounds, they won't make the circuit sounds so harsh and bright.

Thanks for this info. So mismatch is not the problem. Could be bad sounding diodes ?

[Marcos - Munky]

It could be lots of stuff. We need pics to see if we can spot something wrong.

[italianguy63]

Probably not diodes...

[DocBrown]

OK here some pics. Sorry for bad quality, lots of wires here...

[DocBrown]

ok I made a new test with those matching diodes and with the pedal powered by a power supply instead of a "new" weak battery. Here is what I noticed :

- slight background white noise on power supply, dead silent on battery
- No problem with the treble pot
- the pedal seems to work well if used as a boost, with low gain value and high output value
- the sound is not as great if the pedal is used as an overdrive (output at 12 o'clock and gain at 12 o'clock or over)
- white noise when turning the gain pot
- pedal is sqealling if you go over 2 o'clock on the gain pot

BUT after a few minutes, no more squeal, but the sound is really crappy after 2 o' clock on gain pot and gets crappier the more you encrease the gain. Verry difficult to describe, it's like if you were playing on a dead speaker.

There is a problem, for sure 

Thanks again for your help.

[antonis]

There is a problem, for sure 

TRy to DC "isolate" GainA pot lug 3 & R10 ..

[DocBrown]

There is a problem, for sure 

TRy to DC "isolate" GainA pot lug 3 & R10 ..

thanks for your help.

what do you mean by "DC isolate" ? put some shrink isolant ? English is not my primary language...