Wolfshirt 2015 no octave effect?

[sjaustin]

Either there is no octave effect, or there is, and it's subtle, and the toggle switch doesn't disengage it. At any rate, the switch does not change the sound one bit. All other controls work as expected.

[sjaustin]

Bump

[Betty Wont]

If everything else works then it could be the switch has a solder bridge or the switch itself is bad. You should notice a difference in the modes. The noise floor disappears in octave mode.

[sjaustin]

If everything else works then it could be the switch has a solder bridge or the switch itself is bad. You should notice a difference in the modes. The noise floor disappears in octave mode.

By "the noise floor disappears", I assume you mean it gets Real Noisy? 

I removed the switch and tested it with the continuity setting on my meter. Appears to be working properly.

[Betty Wont]

If everything else works then it could be the switch has a solder bridge or the switch itself is bad. You should notice a difference in the modes. The noise floor disappears in octave mode.

By "the noise floor disappears", I assume you mean it gets Real Noisy? 

I removed the switch and tested it with the continuity setting on my meter. Appears to be working properly.

No, it gets super quiet in octave mode. In non-octave there is background noise like a big muff. If its not the switch, then it could be what is being switched. If something is wrong with the octave diodes, the switch might not do anything.

[jimilee]

Sounds like it's time for an audio probe. Did you check the diodes before hand?
I love beans BOMs. The audio path is traced out. In thin lines. I know what you've done build wise, so the audio probe may ferret out a bad trace maybe?


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[sjaustin]

If something is wrong with the octave diodes, the switch might not do anything.

Did you check the diodes before hand?

I didn't test the diodes beforehand, but they came from Small Bear, so I'm fairly confident they were good when I received them last week.

I love beans BOMs. The audio path is traced out. In thin lines. I know what you've done build wise, so the audio probe may ferret out a bad trace maybe?

I had no idea the BOMs had that feature—very helpful! Would you believe that in over 100 builds and nearly a decade, I've never used an audio probe? Maybe today really is the day? Hmm. PS: You're probably overestimating my abilities, but thanks. 

[jimilee]

If something is wrong with the octave diodes, the switch might not do anything.

Did you check the diodes before hand?

I didn't test the diodes beforehand, but they came from Small Bear, so I'm fairly confident they were good when I received them last week.

I love beans BOMs. The audio path is traced out. In thin lines. I know what you've done build wise, so the audio probe may ferret out a bad trace maybe?

I had no idea the BOMs had that feature—very helpful! Would you believe that in over 100 builds and nearly a decade, I've never used an audio probe? Maybe today really is the day? Hmm. PS: You're probably overestimating my abilities, but thanks. 

Bean published a guide to his BOMs at some point. It's been a life saver. I built a Foxx time machine last month. I had some diodes with high forward voltage that didn't work nearly as good as ones with lower forward voltage.


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[madbean]

If I had gotten to this thread sooner I would have suggested audio probing D1 and D2 before removing anything from the PCB. The audio probe is the second best tool for building pedals (after a multimeter). I use it nearly every time I have a problem build.

[sjaustin]

If I had gotten to this thread sooner I would have suggested audio probing D1 and D2 before removing anything from the PCB. The audio probe is the second best tool for building pedals (after a multimeter). I use it nearly every time I have a problem build.

OK, you win, I tried it. 

Except I'm not sure exactly what I'm listening for. I'm fairly certain it's doing what it's supposed to do; connecting the probe to output gives me the same thing I get when it's just connected to my basic breakout box. I put the probe on all four pads for D1 and D2. They all sound pretty much the same: kinda muffled, still fuzzy but somewhat under a blanket. Toggle switch doesn't change this.

[sjaustin]

Any suggestions for what to do with the probe to troubleshoot the octave portion of the circuit specifically?

[madbean]

Any suggestions for what to do with the probe to troubleshoot the octave portion of the circuit specifically?

Sorry I should have been more specific. If the switch is already removed you need to probe the cathodes of D1 and D2 simultaneously. You can do this by adding a temporary jumper between the two and probing the jumper. D1 and D2 mix the two out of phase audio paths to create the octave effect. The goal here is to verify if that's the case (so we know the switch is the problem) or if the problem is with the diodes themselves or along those audio paths.

[sjaustin]

Thanks Brian. The switch is back on the board now. Checking for continuity on the pins, it seems to function as expected. (Switches from 1-2 to 3-2 opposite the angle of the switch's bat.)

I'm looking at the schematic and the signal path on the build doc, and it makes some sense, but I feel like it's just beyond my grasp to make a sensible next step. Sorry for being a bit dense on this.

[madbean]

Thanks Brian. The switch is back on the board now. Checking for continuity on the pins, it seems to function as expected. (Switches from 1-2 to 3-2 opposite the angle of the switch's bat.)

I'm looking at the schematic and the signal path on the build doc, and it makes some sense, but I feel like it's just beyond my grasp to make a sensible next step. Sorry for being a bit dense on this.

Actually, correction to what I said before - you need to probe the conjunction of the anodes, not the cathodes. I typed that from memory of the schematic and D1 and D2 are reversed from what I thought.

Anyway, nothing dense to feel about here. The way the octave effect works is by splitting the signal coming into the base of Q2 into two separate paths. The path from the collector is phase inverted from Q2 base. The path from the emitter is in phase with Q2 base. D1 and D2 serve as rectifiers so instead of the two signals cancelling out when they are mixed, the octave harmonic is reinforced...producing the octave effect. So, what we need to determine is are these two signals mixing properly to make the octave effect? If not, it could be one of several potential issues: the switch doesn't work right, the diodes are not rectifying the signal properly or something is wrong with Q2 (or some problem with soldering/bridges.)

These types of problems never have clear cut answers until you start investigating. Knowing what to look for is just a matter of gaining experience in understanding how the effect itself is supposed to work. It just takes time and practice.

[sjaustin]

I tried a couple things:

1. I swapped Q1 and Q2. No change. So I think we can rule out a faulty Q2?

2. I jumpered the anodes (round holes, right?) of D1 and D2 and probed the jumper. This was hard to do without soldering something there, but I think I got it. Probing the jumper killed the signal. Would this indicate a bad diode?