Author Topic: HUM/BUZZ when DC connected, why?  (Read 345 times)

Luca1997

HUM/BUZZ when DC connected, why?
« on: February 01, 2021, 03:31:35 PM »
Hello guys, that's my second build (same pedal as my first build actually, this one is for a friend ;D)
So, the pedal luckly sounds when in bypass and when turned on. The problem is:
Whitout power adaptor, zero noise in bypass mode. When DC plugged in, low buzz in bypass mode. When effect turned on, louder buzz.

My thoughts:
I don't think the problem is the power supply, because my first pedal works perfectly whit it.
I didn't try the pedal inside the box but, again, my first pedal sounded right when i tried it out of the box.
Maybe the filter cap is bad? (How can i test it? Sorry for the stupid question, but as you can see i'm a beginner  :icon_lol: )

What else can i check? Thanks!





Marcos - Munky

Re: HUM/BUZZ when DC connected, why?
« Reply #1 on: February 01, 2021, 03:57:42 PM »
I didn't try the pedal inside the box but, again, my first pedal sounded right when i tried it out of the box.
Well... I won't take any conclusions just based on this. Maybe you got lucky to not having so many electromagnectical fields around the first pedal when you tested it, and now got the bad luck to have those em fields.

I test my circuits outside the boxes on my pc desk. For some circuits, it's a matter to move it a bit to the side to get from pretty quiet to noisy due to interferences that cames from my pc. And for one specific build (okko dominator clone), removing the box lit was enough to get lots of noises.

Btw welcome to the forum!

iainpunk

Re: HUM/BUZZ when DC connected, why?
« Reply #2 on: February 01, 2021, 04:11:19 PM »
welcome to the forum,

could you post a more close up picture of the solder side of the PCB's, the one you posted is a bit shakey

i generally have a huge amount of noise on my work desk, especially when the o'scope is on as well.
the noiselessest place is on my bed (boxspring)

cheers, Iain
« Last Edit: February 01, 2021, 04:13:37 PM by iainpunk »
half man - half snail - 6 feet to scale - Snail man's - not frail - He's been - to jail - snail man is fuccing real
『snailpilled』

antonis

Re: HUM/BUZZ when DC connected, why?
« Reply #3 on: February 01, 2021, 04:22:58 PM »
I should also check for proper polarity of  C12 & C16..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Luca1997

Re: HUM/BUZZ when DC connected, why?
« Reply #4 on: February 01, 2021, 04:29:48 PM »
Here's the back of the pedal!
I've tested the pedal always on my bed because i can lay down all the cables (didn't know that the bed reduces buzz, nice to know!). Anyway, i'll test it tomorrow inside the box!
Can i post a link to youtube (private video) to show you the problem?






iainpunk

Re: HUM/BUZZ when DC connected, why?
« Reply #5 on: February 01, 2021, 05:15:53 PM »
Quote
Can i post a link to youtube (private video) to show you the problem?
yes, there is even a dedicated youtube button above the green smiley, but the text is gray, and the logo broken.

beds only reduce humm when its a box spring, since its a big metal cage, shorting out nearby radio signals. just like placing your radio on a metal park bench, you'll lose some signal. a box spring isn't grounded, but it does take out a part of the noise, my laptop has almost no wifi in the middle of my bed, but all bars on the corner.

cheers, Iain
half man - half snail - 6 feet to scale - Snail man's - not frail - He's been - to jail - snail man is fuccing real
『snailpilled』

Marcos - Munky

Re: HUM/BUZZ when DC connected, why?
« Reply #6 on: February 01, 2021, 06:53:32 PM »
Btw you can mount the pots directly to the board, if you get the ones with long lugs. Since you're using short lung pots, you can use a leftover lug that you cut from a resistor/cap/diode. Just be sure the back of the pot isn't touching the solder joings or else it'll short lots of stuff.

Luca1997

Re: HUM/BUZZ when DC connected, why?
« Reply #7 on: February 02, 2021, 02:43:32 PM »
Thanks for the advice Marcos! I didn't find long lugs pots.. but i'll definitely use some leftover lugs from resistors on my next build, since wire isn't that comfortable to cut and strip so short..  Anyway guys, i've soldered the battery snap and ZERO buzz when powered with 9v battery.. I think i'm gonna buy a lot of 'em 😂 thank you all again for your answers!

Marcos - Munky

Re: HUM/BUZZ when DC connected, why?
« Reply #8 on: February 02, 2021, 06:08:54 PM »
So your buzz may be related to the power supply itself... which may be related or not to the fact the circuit is outside an enclosure. I'd still test the circuit with the same power supply after box it.