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Hi all, I'm building the U-boat using the layout from the blog. Only changes I have made from the posted layout are:
- NE5532 in place of LM833
- TL084 in place of TL074
Everything else is identical. I made a lot of mistakes in my initial build, but I believe I fixed them all and have been over my build many times carefully. The problem is I'm not getting a lower octave. With the mix all the way to the octave side I get a dull, fuzzy unison tone. The DPDT switch doesn't seem to make any audible difference in tone, and the tracking pot has no effect on the results.
Here are the voltages from my chips & transistor:
4013:
1: 8.9
2: 0.016
3: 0.016
4: 1.387
5: 0.016
6: ~8.3
7: 0.016
8: 0.016
9: 1.748
10: 0.016
11: 8.822
12: ~8.7
13: 0.064
14: ~8.7
5532:
1: 8.09
2: 4.37
3: 4.38
4: 0.016
5: 4.4
6: 4.42
7: 1.38
8: ~8.7
tl072:
1: 4.434
2: 4.37
3: 4.44
4: 0.013
5: 4.43
6: 4.44
7: ~4.5
8: 8.9
tl084:
1: 4.38
2: 4.5
3: ~3.3
4: 8.9
5: 4.34
6: 4.33
7: 4.5
8: ~4.5
9: 4.5
10: 4.4
11: ~0.2
12: 4.5
13: 4.44
14: 4.41
J112:
D: ~4.4
S: 4.3
G: 0.62
The tilde (~) means the voltage was fluctuating a lot, so the value is an average. Nothing was fluctuating more than a few tenths of a volt, though.
If I'm audio probing this, at what point should I expect to encounter an octave down? Is it after the flip-flops or after the JFET? I read through Valve Wizards description of how the circuit works, so I'm thinking the latter, maybe? Anything else I can check with the probe?
PS -- I Have also tried the 10M resistor from pin 5 to pin 8 of the 5532, it made no discernable difference.
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