All Builds Are Noisy?

Ok, you got your soldering iron and nothing is going to hold you back, but you have no clue where to start or what to build. There were others before you with the same questions... read them first.

All Builds Are Noisy?

Postby sixseveneight » 10 Feb 2014, 18:05

I've done quite a bit of searching and haven't been able to find anything that solves my problem. Hopefully this post isn't redundant.

I just quit smoking and so I decided to start building pedals so I'd have something better to do than pacing around the house and cursing the day I was born. I have a pretty solid understanding of electronics, but I'm sort of stuck.

The problem I'm having is, even when I filter my input power, there's so much noise that I wouldn't consider any of my builds so far to be successful. Whether I power them with a transformer or batteries, the problem is the same. What strikes me as really odd is that I'm getting what sounds like 60Hz hum even when I use a battery. Does anybody have any ideas on what might be causing this hum, or what I can do to locate it? I'm prototyping everything on a breadboard. I'm thinking it's probably bad grounding or something really simple that I'm overlooking, but I don't know for sure.

I'm mostly just building different types of simple single transistor (3904) distortion circuits while I brush up on my transistor theory and learn about audio electronics. I just haven't been able to figure out this issue, which seems like it shouldn't be all that complicated. Any help would be awesome. Thanks!
User avatar
sixseveneight
 
Posts: 4
Joined: 06 Feb 2014, 23:44
Location: Western Colorado
Has thanked: 1 time
Have thanks: 0 time

Re: All Builds Are Noisy?

Postby induction » 10 Feb 2014, 20:25

What other gear are you using? (Guitar, amp, pickups, etc.) Do you get similar noise when you play loudly with just guitar and amp?

Maybe post some pictures of one of your troubled breadboarded circuits.
induction
Resistor Ronker
 
Posts: 273
Joined: 07 Feb 2012, 21:47
Has thanked: 61 times
Have thanks: 132 times

Re: All Builds Are Noisy?

Postby Nocentelli » 10 Feb 2014, 21:22

A breadboarded circuit will be slightly more prone to noise than a boxed pedal, since there is no RF shielding: However, it shouldn't be drastically worse. I use an old enclosure with a switch as a "breakout box" - it has a power jack, in and out jacks, and supplies +9 volts, ground, send and return to my breadboard, and sits right alongside the breadboard with only short unshielded cable runs between the switchbox and the circuit input and output. It then sits in the middle of my regular pedalchain so I can try new circuits out alongside my regular pedals. It is rarely any noisier than my pedals, but does very occasionally pick up radio when testing high gain fuzz circuits from 40+ years ago and this is usually cured by the RF shielding of an enclosure, or failing that a small resistor in series with the guitar input. 60 hz hum when using a battery seems to me to suggest mains hum from another source spilling into high-ish gain circuits.

Induction is right - Post some pictures of your test rig and people can have a look over to spot any potential problems: Long unshielded audio cable runs, especially in the vicinity of anything that geneates hum (TV, fluoro tubes, PC, frifge etc) and a flaky ground connection between circuit and guitar and amp ground are common culprits.
Last edited by Nocentelli on 10 Feb 2014, 21:27, edited 1 time in total.
mmolteratx wrote:absolutely zero commercial use allowed. If I find anyone selling these, I'll fly to your house and kick you in the nads. And you may or may not find yourself in trouble.
User avatar
Nocentelli
Tube Twister
 
Posts: 2071
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 842 times
Have thanks: 830 times

Re: All Builds Are Noisy?

Postby Lucifer » 10 Feb 2014, 21:23

Breadboards do not provide a protective metal shield around your circuit, so there is more chance of picking up extraneous noise during the breadboarding stage.

I find that my circuits pick up noise from my inspection lamp (one of those circular fluorescent things with a lens in the middle), and they also pick up loads of shash from my soldering station.

So, it's a good idea to turn off these things when testing your circuits, and any other nearby equipment that might be radiating noise.

The guitar itself can also pick up all sorts of interference from nearby equipment, so try moving it around to see if the noise level drops.

Lastly, I would consider the gain of your circuits. Any unwanted signal (eg, from the above sources) that gets into the input will be amplified by the gain of your circuit at that particular frequency.

If all else fails, try a cigar :twisted:
”Sex is great - but you can’t beat the real thing !” - The Wanker’s Handbook
User avatar
Lucifer
Cap Cooler
 
Posts: 671
Joined: 06 Apr 2011, 13:59
Location: Dorset, UK
Has thanked: 104 times
Have thanks: 95 times

Re: All Builds Are Noisy?

Postby sixseveneight » 18 Feb 2014, 00:08

Sorry for the delay everyone. I'm a broadcast engineer in real life and four of my transmitters went down all at the same time. Had to switch over to focusing on that for a while.

So anyway, I'm running a Gibson SG with P-90's through the breadboarded pedal and then to a Deluxe Reverb. It's never near as noisy as it is when I try to use my own circuits.

I haven't tried the breakout box suggested by Nocentelli, but it sounds like a good idea. I will make one. Thanks for the tip! I get the hum regardless of where the pedal is. The closest communications sites are about five miles away, but pointed away from me. I don't have any problems with interference on any other devices, so I think I can rule out rf as a source of noise.

I'm using Beavis Audio's Trotsky Overdrive for this test. Every circuit I've tried so far has done the same thing, including this one. They work, but there's also a terrible hum. I've attached the schematic. In my breadboarded circuit (also attached) I omitted SW1 and the 22nF cap. I also didn't have the right pots, so I used two 10k log pots. The 2.2MΩ resistor was replaced by two 1MΩ's and a 180k in series. I replaced the two 34A's with 4001's because I'm still waiting on more parts to arrive. Blue rails are ground. Please let me know if anything doesn't make sense! I'm sort of wondering if my "rig" might be causing a problem. I superglued two 1/4" jacks and a DC input to the frame of the breadboard. Maybe these things should be mounted to a separate board?
You do not have the required permissions to view the files attached to this post.
User avatar
sixseveneight
 
Posts: 4
Joined: 06 Feb 2014, 23:44
Location: Western Colorado
Has thanked: 1 time
Have thanks: 0 time

Re: All Builds Are Noisy?

Postby merlinb » 20 Feb 2014, 13:05

sixseveneight wrote: Every circuit I've tried so far has done the same thing, including this one. They work, but there's also a terrible hum.


Then you're probably making a common mistake. Like wiring the jack sockts back to front by accident, so the shield ends up being the hot conductor. Or forgetting to connect the ground altogether! :roll:
merlinb
Solder Soldier
 
Posts: 175
Joined: 18 Nov 2010, 18:39
Has thanked: 0 time
Have thanks: 160 times

Re: All Builds Are Noisy?

Postby Nocentelli » 20 Feb 2014, 13:14

merlinb wrote:the ground


Can you highlight where the input output and power ground are on your rig?
mmolteratx wrote:absolutely zero commercial use allowed. If I find anyone selling these, I'll fly to your house and kick you in the nads. And you may or may not find yourself in trouble.
User avatar
Nocentelli
Tube Twister
 
Posts: 2071
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 842 times
Have thanks: 830 times

Re: All Builds Are Noisy?

Postby sixseveneight » 20 Feb 2014, 22:57

Nocentelli wrote:
merlinb wrote:the ground


Can you highlight where the input output and power ground are on your rig?


The grounds are all on the blue rails, which are tied together.

merlinb wrote:
sixseveneight wrote: Every circuit I've tried so far has done the same thing, including this one. They work, but there's also a terrible hum.


Then you're probably making a common mistake. Like wiring the jack sockts back to front by accident, so the shield ends up being the hot conductor. Or forgetting to connect the ground altogether! :roll:


I'm sure I've got the jacks right, but the ground I'm not so sure about.
User avatar
sixseveneight
 
Posts: 4
Joined: 06 Feb 2014, 23:44
Location: Western Colorado
Has thanked: 1 time
Have thanks: 0 time

Re: All Builds Are Noisy?

Postby induction » 21 Feb 2014, 00:00

Does the hum change in level when you move the guitar around? Is there an orientation where the hum mostly disappears?

Alternately: have you verified that all of your ground points are connected with a DMM? (Perhaps there's a discontinuity in the breadboard.)

For this message the author induction has received thanks:
sixseveneight (21 Feb 2014, 17:21)
induction
Resistor Ronker
 
Posts: 273
Joined: 07 Feb 2012, 21:47
Has thanked: 61 times
Have thanks: 132 times

Re: All Builds Are Noisy?

Postby sixseveneight » 21 Feb 2014, 17:21

induction wrote:Does the hum change in level when you move the guitar around? Is there an orientation where the hum mostly disappears?

Alternately: have you verified that all of your ground points are connected with a DMM? (Perhaps there's a discontinuity in the breadboard.)


Good call! My breadboard is pretty old, and I never even thought to check it. That's what it was. I found it, moved all of the grounds to a good rail and the hum was gone! Thanks!
User avatar
sixseveneight
 
Posts: 4
Joined: 06 Feb 2014, 23:44
Location: Western Colorado
Has thanked: 1 time
Have thanks: 0 time


Return to Absolute Beginners

Who is online

Users browsing this forum: No registered users and 2 guests