Man O' War DX - Calibration

[benny_profane]

Damn... well my final idea without a scope is that I see some 'nichion' caps by the compander, are they from Tayda? Not unheard of to get bad caps from them.

All the passives are from mouser. I've rechecked all the cap values visually and they are correct, should I start swapping the caps around the compander with replacements?

[Scruffie]

No, if they're from mouser don't worry about it.

Go through the problem one more time and tell me exactly what you hear and where, please.

It should be along the lines of... Q1 Emitter - Dry Signal, IC1 pin-1 - high passed signal, Compander Pin 7 - compressed signal, Q2 emitter - compressed and low passed signal, IC3 balance output - delayed signal (noisy, whiny and crunchy), IC5 balance output - further delayed, Q3 & 4 emitters - low passed delay signal (less noisy, whiny & crunchy), Compander pin 10 - bright clean delay output.

[benny_profane]

I went back to the board to note the signal at each point you suggested. I'm now getting different behavior. Q1, IC1.1, compander pin 7, and Q2 emitter are all as described. I'm getting signal at IC3.7 and no oscillation as IC3.3/4—but I'm also getting no repeats. Also, the signal at IC3.3/4 sometimes is absent. I have six clocks and four BBDs—each permutation is the same now. I don't know what is going on (I doubt I've fried every part) each replacement has been done without power in the circuit, safe handling, etc. I'm thinking I might build another board up to if even just to have something for comparison. Other than that, I'm truly stumped.

[benny_profane]

UPDATE: I built a new board and got redundant ICs.

What I learned: This was my first BBD delay and these are a little strange to bias if you're unfamiliar with them. The new build was exhibiting the same behavior as the initial while biasing. I kept moving forward with the process even though I was getting odd results (i.e., clock oscillation/ramping of repeats). The trimmers are all highly interactive, and the default setup was giving me issues. So, I now have two viable builds.

New developments: I'm getting an almost 'ring-mod' sound on the repeats with the delay control close to max. I know that is is a biasing issue, so I'm still trying to dial it in. Is there any advice beyond 'try to get the cleanest delay at each BBD output' without an oscilloscope?

[Scruffie]

Ring mod sound suggests aliasing noise, a normal part of analog delay in some respects but it suggests either your minimum clock frequency is too low (too long a delay) or your filters aren't cutting the highs as much as they should be.

The cancel trims can help a little with removing this, probe the outputs with no input signal connected when adjusting them.

[benny_profane]

Ring mod sound suggests aliasing noise, a normal part of analog delay in some respects but it suggests either your minimum clock frequency is too low (too long a delay) or your filters aren't cutting the highs as much as they should be.

The cancel trims can help a little with removing this, probe the outputs with no input signal connected when adjusting them.

Pins 3 and 4 of the MN3005 ICs? Thanks for the quick response! I appreciate it.

[Scruffie]

Not on the BBD output pins, you have to actually probe the output of the trimmer (balance in this case).

[benny_profane]

Not on the BBD output pins, you have to actually probe the output of the trimmer (balance in this case).

Ah, got it. Thanks! I'll report back afterward.

[half_smith]

Hey Benny, any luck?
I'm in a similar stuck point on my MOW, signal into the first XVIVE3005 pin7 but only clock or silence out pins3,4

I'm getting so used to probing this circuit, I'm kinda gonna miss it when it's fixed!

[benny_profane]

Hey Benny, any luck?
I'm in a similar stuck point on my MOW, signal into the first XVIVE3005 pin7 but only clock or silence out pins3,4

I'm getting so used to probing this circuit, I'm kinda gonna miss it when it's fixed!

I should've posted a final note to this thread and a link to the build report. Scruffie's advice about the clock and the filters is key. Noise is inherent to any BBD circuit. Also, the calibration is very interactive. The MoW seemed to be a little more sensitive to biasing and trim calibrations than some other BBD projects I've built.

Here's a link to the build report.

I'm not sure if your issues are the same as this one, but I'll respond to your tech help thread.