Current Lover – 15V- Noise issue. Pops and background

[Kinki fuzz]

Hi,

I'm in the process of biasing and adjusting the effect and I'm having 2 noise issues.
1-   In certain Range and Rate combinations, Range between 2 and 4 o'clock AND Rate between 11 and 1 more or less, there's a clearly audible POP-POP (2 pops!) every few seconds, the distance between them varies with the Rate, so I think this has something to do with the clock signal getting into the audio signal. You can clearly hear it even when you are playing, so is something I need to fix.
2-   When I'm not playing there's some background noise, like picking distant radio signals, not audible when playing and wonder if it is maybe normal or not.

Any tips to fix that?

Apart from that, the effect is working and I'm getting pretty sweet sounds from it, so I guess I'm close to finishing it.

Thanks guys,

[Govmnt_Lacky]

Do you happen to have access to an oscope or a DMM that has a frequency function?

Builds like these (BBD-based with LFOs) really need to be set up with an oscope. You can guess what the clocks are but, usually they are off from the frequencies that they should be. Im going to guess you have 2 issues...

- Your clock to the BBD and the BBD bias are not in the correct range.
- Check the locations of your off-board wiring. Make sure to seperate the power, grounds, and any offboard pots as much as possible. Also, try using shielded wiring from your input and output jacks to the 3PDT.

Also, what are you using to provide the 15V?

[Kinki fuzz]

Thanks for the help,

I'm using a Road Rage for the 15V.
I don't have an oscilloscope, but I could probably get a DMM with FQ function, how should I use it to fix this?

""Your clock to the BBD and the BBD bias are not in the correct range.""
How can I check/fix this?

[Govmnt_Lacky]

""Your clock to the BBD and the BBD bias are not in the correct range.""
How can I check/fix this?

To get the "perfect" BBD bias, you NEED an oscope. Other than that, you will have to dial it in by ear in accordance with the build doc.

As for the clock. You would set your DMM to read Frequency (KHz) and attach the Black probe to ground and the red probe would be on the BBD Pin 2 (or Pin 6.. either one). Next, set the switch to "Filter" mode. Set the Rate, Feedback and Volume pots fully CCW and set the Range pot fully CW.

Adjust the Clock trimmer until you see approximately 30-40KHz on your DMM.

Next, adjust the Bias and T1 trimmer according to the build doc.

Let us know how it goes! 

[LaceSensor]

Hi

This is a mis-bias issue, im 100% sure
Just turn back the bias trim a tiny bit from where it is set now, and you'll eliminate the popping on the sweep.

or use a scope, obvs

the second issue of background noise can be due to proximity of the road rage or other charge pump you are using to get the 15v supply.
try moving it around somewhere else in the box. if not using a roadrage or similar, ignore this advice, obvs

[Kinki fuzz]

Thanks guys for the help, really appreciate it, I'll do all that and let you know...

[Kinki fuzz]

So I finally got time to work in this project... but I still have the "pop" issue.

I used the DMM to adjust the clock which gave a great result, now the sound is sweeter, no doubt. Thank you very much for that tip.

But the pops are still there just the same, if I move the bias trim the pops disappear in the same point that the flange disappear, so no sucess in that area. Any other ideas?

About the background noise, you were absolutely right, a little wire movement and improves, so I'm not really worried, when I finally box it will be easy to get it right.

[dondougie]

I have exactly the same problem, noise at 15V with a road rage and LT1054.  I got rid of the popping with the clock trim, but i have noise and oscillation that can't be dialed out with the bias and t1.

Also, the bias trim only gives signal at the very end of the rotation, and I feel that there is still room to go. Should I change it for a 200k and see if that helps?

Sound wise, the sweep is very uneven with squealing and oscillation at the bottom of the sweep. Just like my Colossalus sounded with a 9V supply, but this is a 12V supply with a steady 15V going to the board via the RR. It feels like the calibration is out of range for the trimmers.

[LaceSensor]

you need to be careful the proximity of the wiring of the charge pump to the other circuit parts
or you will get cross talk / clock noise / "heterodyning" in your output

shielded cabling might help too.