Collosalus build finished: a few noise questions

[Bucksears]

I just finished my Collosalus build and it works (sounds like the flanger 'in my head' always has), but having noise issues and want to run a few things by you guys:

1) I'm using BC550C's instead of 549C's because that's what I had on hand. Are 550C's more noisy? What's a suitable direct replacement for a 549C?

2) I'm using wires to connect the pots to the board, rather than using PC-mount pots. I drilled the case before I really had a look at the way the leads are oriented on the PCB.

3) I've tried running it at 9V and 12V; either way, it sounds the same (lots of background noise, gets louder at the bottom of the sweep).

4) I tried swapping out the MN3007 with another one that I had on hand, but it was like a Star Wars gunfight when I switched it on; same flanging sound, but a repetitive high-pitched chirp that sounded like you were tuning in a radio station on a transistor radio.

5) The input/output jacks and footswitch are at the bottom of the case; no wiring going past the MN3007.

Think the most likely culprit is #1 or #2? (or any other ideas?)

Thanks!
- Buck

[Scruffie]

4) Sounds like heterodyning with the description in which case the most likely cause is 2) Your wiring is interfereing with the clocks, keep it as short as possible and don't let them cross over.

[Bucksears]

I updated my build with the following changes:

- Replaced the wired pots with PC-mount
- Replaced the BC550 transistors for the correct BC549's

I can provide a guts shot tonight, but there is no wiring crossing (or even near) the MN3007. Bottom line is that it still has the same noise.

I have not done the 100uF(C26) and diode swap yet, but to the point that I'm going to consider it. I don't want to give up on this build since the flanging I can hear sounds exactly like I want.

[Scruffie]

Are your power supplies switching? Try a transformer based one or a 9V battery to rule out supply noise.

[Bucksears]

Thanks Scruffie

I'm using a BBE SupaCharger that has isolated outputs, plus I tried an Ibanez AC109; both had the same results.

I've got the PC-mount pots incoming and will be working this out in a new case.
I'll report back after that.

Thanks again,
Buck

[jvg13]

Shld be no issue using 550, using them in mine & they're fine.  You shld look up the datasheet.  The 549 & 550 are siblings, prob cut from same wafer I think.  Like bc107/108/109 group. 550 has slightly higher specs in some characteristics than 549.

[Bucksears]

Bumping this one as an update.

I used PC-mount pots and did the 100uF (C26) and 1N5817 (D4 and D5) mods; this cleaned the noise up considerably.
I'm still getting a WEE bit of a static-like tick and can hear the analog 'swoosh' a bit, but it's not nearly as bad as it once was.

Quick question: the output and input pads on the PCB are opposite from each other in that they HAVE to cross when connecting to the footswich (or at least the leads when running from switch-to-input/output jacks). So does it matter (noise-wise) at what point they cross? Anybody cured all noise using shielded wire?
Also, for those of you who use this circuit with a 3PDT footswitch, are you doing the 'grounded input' config, or regular (with the LED on the 3rd legs)?

Thanks,

[Scruffie]

Bumping this one as an update.

I used PC-mount pots and did the 100uF (C26) and 1N5817 (D4 and D5) mods; this cleaned the noise up considerably.
I'm still getting a WEE bit of a static-like tick and can hear the analog 'swoosh' a bit, but it's not nearly as bad as it once was.

Quick question: the output and input pads on the PCB are opposite from each other in that they HAVE to cross when connecting to the footswich (or at least the leads when running from switch-to-input/output jacks). So does it matter (noise-wise) at what point they cross? Anybody cured all noise using shielded wire?
Also, for those of you who use this circuit with a 3PDT footswitch, are you doing the 'grounded input' config, or regular (with the LED on the 3rd legs)?

Thanks,

No reason not to use input grounding and also... change your switch lugs so the wiring doesn't have to cross, problem solved.

[Bucksears]

Bumping this one with an update.
It's a little difficult to change the switch lugs WITHOUT crossing them somewhere; either between the board and the switch, or between the switch and the in/out jacks.
I've tried two different MN3007's and it didn't make much difference. In the end, I used shielded wire going to/from the board to the footswitch.
That cut out most (but not all) of the clock noise. I might try shielding the footswitch/in-out jack wiring as well.

[Droogie]

Are you running at 9 volts or 12? Mine likes 12 volts (no noise) more than 9 (some noise). Just an observation.

[Bucksears]

12V
Are certain op-amps potentially noisier (4558 vs TL072)?
If the diodes near the charge pump were an area that has had a fix, could the wiring to the DC jack need to be shielded too?
Just trying to think of possible noise breaches; seems like several users have had some issues getting 100% noise-free.