Unclean Klone

[AntKnee]

I'm having trouble with a couple of klones I just built. They are the tagboard ones, and they both have the same problem. I don't know, maybe they just sound this way. Its strange that it would happen to two of them. Anyway, the problem is that with the gain off, and volume at any position, the sound is still very dirty. I assume it should be clean and clear with the gain off. At least thats how the actual Centaur sounds. I've been over the values and solder joints and knifed the gaps again and again just to make sure I haven't made a simple error, but I can't find anything obvious.

I would also like to know if it should cut low end, because it is doing that, too.

Here are the voltages:
IC1:
1. 4.53
2. 4.53
3. 1.23
4. 0.00
5. 4.42
6. 4.53
7. 4.59
8. 9.05

IC2:
1. 4.60
2. 4.53
3. 4.47
4. -8.48
5. 4.47
6. 4.53
7. 4.45
8. 17.14

IC3:
1. 9.05
2. 3.93
3. 0.00
4. -4.79
5. -8.48
6. 4.48
7. 3.80
8. 9.05

As a side note, I also built the Bare Bones version of this build,without the charge pump, and it sounds great. Clean when it should be with great gain when its turned up. It also doesn't cut the low end.

Any thoughts or advice is very welcome and appreciated.

[GrindCustoms]

I would suggest to remove the wires on the gain dual gang pot and measure each pot taper to see if they work properly, seems like the clean portion is'nt blending in.

[AntKnee]

I would suggest to remove the wires on the gain dual gang pot and measure each pot taper to see if they work properly, seems like the clean portion is'nt blending in.

Rej,

Just gave that a shot, both sets measure 0 at off and about 92k at full turn, each way, on 100k linear pot. They are within 10%.tolerance.

Good to rule that out, I now know the gain pot is shutting completely off.

Could a bad op amp cause this?

[GrindCustoms]

All the voltage reading are relatively good, some differ a bit from the reference ones, so i'd presume that they are good. Have you socketed them? If yes swap with known working to verify that part.

A simple short could make this happen, since it's a vero i would double and triple check that there's no unwanted solder bridge or whatever between the copper strips and pass a razor blade between the strips to make sure, magnifying glass is highly recommended here.

And see what happens!

[midwayfair]

Could a bad op amp cause this?

Bad parts are one of the last things you should expect, after you've exhausted everything else. Rather, since you have the same problem on two different vero builds, I'd sooner suspect that you've got a wrong value part somewhere, and you've used the same wrong value on both builds.

Get out the audio probe. Where does the distortion first appear? Is it distorted after the buffer, for instance? Does it appear at the input of any particular opamp, and then at the output (in which case, check the gain resistors).

Use your multimeter for continuity on the traces and parts -- not your eyes. Check against the schematic.

[AntKnee]

This is something that I kind of suspected also. Since I also built the bare bones version and it sounds correct, I'm suspecting I may have a wrong value in the buffer or charge pump area. I've also dreaded this process because its the first pedal I've had to troubleshoot to this degree. I'm glad to learn it, but not looking forward to it. I dont know how to check it against the schematic, but I do know how to use a probe, so I'll start there and see if I can find where it distorts.

[midwayfair]

I dont know how to check it against the schematic

Reading a schematic is a necessary skill to develop.
http://www.beavisaudio.com/techpages/SchematicToReality/

A layout is not a schematic, and there is no substitute. Now's a good time to learn. Break the schematic down into very small sections. If you get stuck, I and many others here will be happy to help. (But I think you have to try on your own first!)

[AntKnee]

Reading a schematic is a necessary skill to develop.
http://www.beavisaudio.com/techpages/SchematicToReality/

A layout is not a schematic, and there is no substitute. Now's a good time to learn. Break the schematic down into very small sections. If you get stuck, I and many others here will be happy to help. (But I think you have to try on your own first!)

Okay, I've been probing around, using the schematic to map may way through the circuit layout. I am at a point where I need some direction. I am probing to find where the signal is picking up its gain, looking for a wrong part or something. I can follow it (using the sunking schematic) up through the first IC and have some understanding of that part. Everything I probe anywhere connected to IC2 is high gain. I don't understand if that is the way the circuit works, or if something (like the gain control) interrupts and sends clean signal elsewhere for times when the gain is off. Does that make sense? I guess I am asking where I need to probe next... start at which component and follow what path?

Thanks for the help, Jon and others. I am trying to learn this the right way.

[AntKnee]

bump for help!

[AntKnee]

Well, still no progress. I've quadruple checked all the values and solder joints, I've checked for bridges. I've gone throught the schematic and labelled all the resistors and caps on my layout with their component number hoping to learn something along the way.

I'm beginning to think the pedal just sounds this way. Is it supposed to be totally clean with the gain turned all the way down? I thought the klon was supposed to boost very cleanly without the gain on.

I'm at a point where I don't know what to do next. I have a very basic understanding what the schematic says but I don't know how to use it to find the problem. I don't know what to do next.

Would the slightly low voltage at pin 3 be related to there being gain on when the knob is off? And there is still the mystery of why two pedals have the same problem.

I'm just completely perplexed.

[hoodoo]

You've probably considered this, but, would a reverse taper pot or a linear pot wired backwards, have this effect, does it clean up past the midway point.

[AntKnee]

You've probably considered this, but, would a reverse taper pot or a linear pot wired backwards, have this effect, does it clean up past the midway point.

Yes, actually this was something I suspected. I verified my wiring is correct and that I do have the proper pots and that they do function correctly. My original suspicion was that it was a problem with off board parts or wiring, but I don't see any.

The more I fiddle with it, I think I might just be expecting something that the pedal doesn't do. I expected to get a clean boosted signal, but with the gain down and the volume up, there is still some gain to it, and I suppose there just will be when you boost the signal. Its not all out distorted, but its not clean. I was expecting the pedal to be clean, just louder, but that apparently isn't the case. With the gain up, it gets a great crunchy distortion, but I wanted it to sound cleaner when the gain was down, with the volume up. That apparently just isn't the case. I think the pedal functions propertly, I just need to adjust my expectations of the pedal.

Someone feel free to correct me if they think otherwise.

[AntKnee]

Just figured out, as I was building the new Sunking II, that I used 0.68uF caps instead of 0.068uF caps. Would this affect the clean sound? I haven't tried swapping them out yet, I need to order some asap.