Aquaboy deluxe help

[CDW]

So I have my aquaboy deluxe built and calibrated and it sounds great!

I built using the V3205 V3102 from small bear.

Only problem is I can't seem to get the max delay time to the advertised 550ms without a high pitch squeal. Best I've managed is to adjust the clock trim down to about 420ms. thats the highest delay time I can get with out the squeal in the background.

Ive consulted the troubleshooting section of the build guide with no luck. The troubleshoot part of the build guide said to replace the delay pot with one that came in closer to spec (rather than under) I canged mine to one that comes in at 1.06Mohm. Also per the guide I have changed the value of C33 (and re-biased the BBD when necessary) many times to different values with no luck.

I really don't need the full 550ms, but I have to have at least 460-470ms. Any help would be appreciated.

[madbean]

It might just be bad luck and you got a couple BBDs with shorter delay time. It's never exact, but 420ms is quite low. Only thing I can recommend is on your next parts order is maybe pick up a couple more v3205 and another clock and see if you get a better result. If you have a frequency measurement option on your multimeter, set the delay time to max and check the frequency reading on either CP1 or CP2. I forget what the target is exactly but it's somewhere between 6.4-6.8kHz. If that's what you are getting then it's your particular BBD set causing the shorter delay, IMO.

[Scruffie]

I've never, ever heard of a BBD not having the stated stages unless it was fake and who'd fake a v3205? Plus it came from smallbear so shouldn't be any concern there, unless a batch of v3208 got mislabelled at the factory as 3205 but that seems fairly unlikely and delay time would be more like 375ms max and wouldn't just be whiney but extremely aliased and crunchy at 550mS.

It sounds like one of four things;
a) A wire is bleeding the clock in to the audio signal.
b) A cap or resistor value in the filters is incorrect raising the cut off and allowing the clock to bleed in.
c) Poor adjustment of the cancel trimmer.
d) You haven't boxed it yet.

[CDW]

I appreciate the fast replies!

I have it working now!

I landed on C33 at 160pf. I also swap the BBD's with each other (of course I don't think that actually did anything). Re-biased and auto probed.

Finally mess with the cancel trim for a long time with the amp cranked to try to hear and cut down the noise as much as possible. I found a good setting almost 3/4 of the way up.

I'm guessing Scruffie was right and it was my poor adjustment of the cancel.

Thanks for help guys! Just got it boxed up.

[madbean]

Scruffie is pretty much the master of the BBD!