I've designed a Filter Pedal for Bass

[snk]

Hello.
I built it today (nearly twice) :
First, I followed the layout i made (adding a booster in front of the original circuit) : it didn't work
I checked two, three times, and spent a couple hours trying to debug, without luck...

Then, i wanted to try a more "barebones" version, to see if my layout or my build is buggy, so i built the original layout (just adding a 100µF input capacitor, and omitting the output volume knob) : it works.
However, I only get a distorsion, without any filtering effect 
I had socketed the 4.7K capacitor and the diode, so i wanted to try different sonic flavours : removing the cap didn't change the sound, swapping the 4.7K for a 2.2K or for a 6.8K didn't produce any change either...
The filter knob doesn't seem to affect the sound either.
Changing the diodes change the sound a little bit (with a Germanium, the sound is a bit softer, less harsh in the bass range. With a 5mm red led, you have to push the input level a lot to hear some changes).

I am using a "regular' lm567cn (not a LMC567CN : does it matter ?)

I like the "core" sound i am getting out of it, but i am wondering why the filter knob and the capacitor doesn't produce any change in sound ?

[snk]

[edit]
- I changed the Germanium diode by the recommended 1N4148 : it helps taming the sound a lot.
- Also, I was using a 25K pot for the filter, and a 10K is really mandatory (maybe 5K is even better ?) : the "filter" knob acts more like a "fuzz amount" pot, and with 10K it comes from "no fuzz" to "a lot of fuzz" very quickly.
- But, I am still not getting the nice filtersweep effect i can hear in the demo, and changing capacitor values doesn't seem to affect the filter sound...

[FUZZZZzzzz]

Hello.
I built it today (nearly twice) :
First, I followed the layout i made (adding a booster in front of the original circuit) : it didn't work
I checked two, three times, and spent a couple hours trying to debug, without luck...

Then, i wanted to try a more "barebones" version, to see if my layout or my build is buggy, so i built the original layout (just adding a 100µF input capacitor, and omitting the output volume knob) : it works.
However, I only get a distorsion, without any filtering effect 
I had socketed the 4.7K capacitor and the diode, so i wanted to try different sonic flavours : removing the cap didn't change the sound, swapping the 4.7K for a 2.2K or for a 6.8K didn't produce any change either...
The filter knob doesn't seem to affect the sound either.
Changing the diodes change the sound a little bit (with a Germanium, the sound is a bit softer, less harsh in the bass range. With a 5mm red led, you have to push the input level a lot to hear some changes).

I am using a "regular' lm567cn (not a LMC567CN : does it matter ?)

I like the "core" sound i am getting out of it, but i am wondering why the filter knob and the capacitor doesn't produce any change in sound ?

I hope you mean 4,7 nf instead of 4,7 k??

also, can you include a picture of your build. might be easier to check since its such a small print.

[snk]

I hope you mean 4,7 nf instead of 4,7 k?

Yes, sorry for the typo 

also, can you include a picture of your build. might be easier to check since its such a small print.

I will, later tonight (at the moment the light is pretty bad and the picture are not clear enough).
But the "barebones" build is very rough (with big green caps and sockets)...

[snk]

Ok, I managed to get not-too-fuzzy, not-too-blurry, not-too-dark pictures of the "small" build (without booster, switch or output volume pot).
I hope that helps ?

With this build, i get distorsion, the filter pot action is rather audible, but i don't hear filtering effect, nor any filter sweep (filter env).

https://imgur.com/a/0Z9aaiz

[snk]

And an album with the "big" version (following the layout i posted above, including a booster).
I think something might be wrong with the layout (or I made mistakes in the build), as i don't get sound out of it.
I have set the trimmer so i get 4.5-4.8V for the transistor bias.


https://imgur.com/a/ZLiOxuG

[FUZZZZzzzz]

I'm looking at the small 'bass filter only' version. It seems like your diode is upside down. Im checking as far as I can see. Make sure all the cuts are really cut. Maybe by using a Multimeter to check continuity.

[FUZZZZzzzz]

what type of 567 chip are you using?

[snk]

Thank you, Fuzzzz 

It seems like your diode is upside down.

Yes indeed : i tried with the diode in both ways, and i think i took the picture with the diode upside down.
But i have tried with the diode in the right orientation, of course

Make sure all the cuts are really cut. Maybe by using a Multimeter to check continuity.

I checked (on the "small" version, not on the bigger version).
I will check continuity again.

what type of 567 chip are you using?

I am using a "regular' lm567cn (not a LMC567CN).
I also tried with 2 different 567 chips (to rule out a bad one, as i have a bundle of 10 chips).

[FUZZZZzzzz]

After checking continuity, could you also check for solder bridges between paths. Also, if you would like to check that the ground wire (middle lug of the voltage regulator) is connected tot pin 7 of the 567 chip?

[FUZZZZzzzz]

are you using a bassguitar for testing? if so, a passive one?

[snk]

are you using a bassguitar for testing? if so, a passive one?

I am using it with a synthesizer (i am not guitarist or bassist).

After checking continuity, could you also check for solder bridges between paths.

I will.

[FUZZZZzzzz]

i dont know if its going to sound great with a synth signal, yet. i will have to try this myself. I designed this for bass guitar. when using with bass the filter pot doesnt need to be bigger then 10k.

[snk]

i dont know if its going to sound great with a synth signal, yet. i will have to try this myself. I designed this for bass guitar. when using with bass the filter pot doesnt need to be bigger then 10k.

Do you mean because of possible impedance issue, or about frequency content (if the latter, i was making the test with a monophonic bassline. In fact, a sound and a phrase very close to the one you play in your video).

[duck_arse]

from "LMC567 Low-Power Tone Decoder" datasheet by TI:

Code Select Expand

The LMC567 can be directly substituted in most LM567 applications with the following provisions:
1. Oscillator timing capacitor Ct must be halved to double the oscillator frequency relative to the input frequency
(see Oscillator).
2. Filter capacitors C1 and C2 must be reduced by a factor of 8 to maintain the same filter time constants.


[FUZZZZzzzz]

i dont know if its going to sound great with a synth signal, yet. i will have to try this myself. I designed this for bass guitar. when using with bass the filter pot doesnt need to be bigger then 10k.

Do you mean because of possible impedance issue, or about frequency content (if the latter, i was making the test with a monophonic bassline. In fact, a sound and a phrase very close to the one you play in your video).

yes.. thats what I meant. But, to be honest I havent tried it yet. Will try some drummachines as well. and maybe some other noise makers. Did you find anything out of the ordinary yet?

[snk]

from "LMC567 Low-Power Tone Decoder" datasheet by TI:

Code Select Expand

The LMC567 can be directly substituted in most LM567 applications with the following provisions:
1. Oscillator timing capacitor Ct must be halved to double the oscillator frequency relative to the input frequency
(see Oscillator).
2. Filter capacitors C1 and C2 must be reduced by a factor of 8 to maintain the same filter time constants.


Thank you, Duck Arse, this might be very good to know 
I will adjust the values accordingly.
If i understand correctly, i should try to swap the 4.7nF cap by a 560pF, and leave the rest untouched ?

@FUzzzzz, did you use LMC567CN in your builds, or "regular" LM567 ?

[snk]

Little update :
I didn't yet made a continuity test, but i swapped the 4.7nF cap with a 560pF : the sound is the same. Whatever cap value i throw in, the sound doesn't change (even without any cap, it's the same).

Also, I noticed that with the negative side of the diode towards the bottom (as indicated in the schematic), the sound stays the same. If i put the diode (1N4148) with the cathode up, the "filter" knob acts somewhat as a lowpass filter, but without any frequency sweeping (or a fuzz dry/wet mix, ruling out the fuzz's high harmonics).

I still don't hear any filter sweep effect, and the sound reminds me a distorsion effect, without any obvious filtering.

What puzzles me is that the circuit is such an easy build with low part counts, I really can't see what i have done wrong  (both times -with or without booster- it didn't work as expected)

[FUZZZZzzzz]

this design has been succesfully build by at least a couple of people, so it should work according to the layout.

I've used the 'normal' 567 (KA567) for this build. i hope the answer is in the continuity test. can you unsolder the 100 uF cap. Thats the only thing different from my original design.

[duck_arse]

arum-ah, sorry for confusing anyone with my confusion. I seem to be thinking of a something else, that actually specs an LMC ...... sorry about that, chief!