Pork Barrel (Clock?) Noise

[Micpoc]

I've just completed a Pork Barrel build and, while it's chorusing fine, I'm getting a loud puttering sound which changes with the setting of the RATE pot. I've tried two different MN3007s in it, one of which came from a previous build that experienced no such problems, so I doubt it's the chip. I have this set up with a 15v Road Rage.  The Road Rage is located beneath the PB board, and the 15v/ground wires from the 15v are twisted. Right now, I'm running this off of a battery, as I discovered that my 9v wallwart puts out an unregulated 12+v and I don't want to screw up the ICL7660SCPAZ charge pump.

One odd thing - and I have to describe this as best I can as I'm unable to take photos - is that when I lightly touch the 9v pads at the top of the board, the puttering sound speeds up a bit from steady eighth note-type beats (da-da-da-da-da etc.) to a clipped triplet-like pattern (d-da (rest), d-da (rest), etc.).

I probably can't get back here until tomorrow afternoon, but any insight into this would be appreciated.

[juansolo]

Are your pots board mounted or on leads and go elsewhere?

My original build (currently being rebuilt) was the old board without the board mounted pots. Like a plank I got all the pots the wrong way around and it picked up a huge amount of clock noise. The fix wasn't so pretty, but it worked flawlessly. I wrapped each set of wires in foil tape then grounded them... Clicks went away.

If they're board mounted it ain't this



Hmmm, pretty!

[juansolo]

I suppose another thing to ask is where is your charge pump in relation to the clock on the board? Two clocks close together might be causing it...? Possibly.

[Micpoc]

I have the current, board-mounted pot version, and my Road Rage is underneath the main PCB, but the charge pump IC is jutting out from the lower edge.

[juansolo]

Pretty similar place to where I put it in the last one I built.



Dunno then I'm afraid. Not had any clock noise problems on the three I've made that wasn't down to my wiring, and yours looks fine.

[Micpoc]

Thank anyway, juansolo. 

Any ideas, anyone? At least where I should start to trace the problem from?

[spaceboss]

Major caveat: I know almost nothing about circuit design and little about his circuit, but here are a couple of ideas:

I do not know which chip is acting as the clock??? (3101???) but identify that chip and try replacing it. The TLO62 seems to have something to do with the depth of the modulation, so maybe look there too???

I had a bum transistor that was introducing a ton of noise, so --if-- there is a transistor driving/amplifying the clock signal I would look there. So far I've had a few out of spec 5088s and J201s from Tayda, so from now on, I'm socketing all of those bad boys.

Wish I could be more than mostly useless. Good luck getting up and running.
 
(I've gotten my PB working and have very very minor clock noise, that I hope will disappear upon boxing.)

[Scruffie]

Simple test, eliminate the charge pump, unplug the charge pump briefly and plug it straight in to 9V then you'll know, heterodyning (two clocks not playing nicely) is a possibility, especially with that location, may just be a case of tidying wiring up and adding some shielding to remove the noise.

Could also be the LFO bleeding in to the signal, sometimes useing a lower current drain opamp (TL022, LM358 & LM1458 are good candidates) can solve this issue, sometimes it might require a bit of its own filtering.

Oh and running the pedal in a chain could mean another effect is interfering with it.

I'm not sure on the Pork Barrels current draw, could be the ICL7660 isn't putting out the mA and is sagging... but I think it should be okay.

You have the board mounted pot board but did you use board mounted pots? Or at least a DIY version, excess wiring could be a problem.

[dbharris]

You could also try putting a buffer or buffered pedal in front of it to see if the noise stops.  This works with my BYOC ce-2 clone that has the LFO thump.

Good luck.

[Micpoc]

Awesome responses; thanks guys. 

I said "clock noise" in the title as I've read that it's a problem on some modulation effects, but I'm thinking that it probably is LFO bleed, as the speed of the thumping definitely changes with the Rate knob; don't know if that would happen with clock noise (?).

I AM using DIY board-mounted pots on this, BTW, and I'm not running any other pedal in a chain with it.

I'm going to take it out of the enclosure tomorrow and spread it out to make sure that it's not a wiring thing.  If that doesn't make any difference, I'll remove the Road Rage to see if that improves things. Hate desoldering power jacks - I always seem to end up deforming the crummy plastic they're made of - but it's a necessary evil sometimes.

[Micpoc]

Just disconnected the Road Rage. The thumping is still there, though it IS not as loud as before... nevertheless, still there and still annoying. I'm going to have to delve deeper into it this weekend. Bleh.

Is there a possibility that this is being caused by a component OTHER than an easily removable IC?

[shay1510]

I had the same ticking noise, with "rate" knob controlling the speed of ticking.
I've found out that when I move one of the pots (dont remember which) away from the input jack
The ticking stops.

Good luck.

[juansolo]

this is how I laid out my rehoused v2 pork barrel. See above for the mess that was by first attempt that had a lot of clock noise. This has none. I know it's not your prob, I just thought it was interesting how much difference the layout made to the noise of it.