DC Noise problems! Ahhhh!

[Lord sonic]

Hi All,
Im on my second vox repeater, although relatively new to pedal builds, I have encountered the same problem with both. (Bear in mind this is the first pedal attempted with dc boss type adapter). I seem to be getting very noisy radio frequencies (increasing in pitch as I turn the rate knob), with my first build I put it down to poor soldering, even though it works fine with the battery, tried reflowing and rechecking to no avail. As this build was for me I was not that bothered as the unit didn't seem to suck to much juice anyway. This second version however is for a mate, and I would love to solve this problem. Have followed diagrams http://home.centurytel.net/flanneldrawers/mbb-wiring-diag.jpg  and it seems straight forward, I am testing it without putting it in the box, and no footswitch. But all grounds are connected, again noise free with battery, but noisy as hell with dc? Would a ferrite bead/choke help? Is it just this type of circuit? have re-soldered and rechecked, you guys really helped me solve my problem last time, would appreciate it again! Cheers Sonic

[Silver Blues]

I don't know much about that particular circuit, but:

1. does the circuit have built in filtering? (i.e. a large capacitor from supply to ground, or even a resistor inline plus a large capacitor)? This generally serves to remove almost all the noise from a circuit powered by DC. If not you can add it in.
2. Sometimes putting a choke or other type of ferrite filter around the power supply's wire (read: not inside the pedal!) can help cut RFI.
3. If you're using a switch-mode power supply (as opposed to a transformer), IME these things can inject a lot of noise depending on the circuit. For example, I have a Muff clone that hates switching wall bricks.

Hope that helps.

[Jon Rep]

I'd use Mark's Off Board Wiring.  To me the Earth's are not connected properly.  Try This.

http://tagboardeffects.blogspot.com.au/2012/02/offboard-wiring.html

[Lord sonic]

Iam using one of those brick type power supplies, which although cheap (ish) works fine with my other pedals which include overdrives, fuzzes, and terms. Not sure about filtering in this is the circuit:
http://tagboardeffects.blogspot.co.uk/2012/08/vox-repeat-percussion.html, also the diagram Im working from is from mark's page, although not his? Cheers

[Silver Blues]

Okay yeah, that thing's got a 100u worth of filtering, so that's not it. I'd follow the above suggestion (improper grounding's gotten me more than once), then if that doesn't work you know your brick/dirty power is the culprit.

[JaviCAP]

Hello,

Had the same problem with the Earthquaker Devices Hummingbird, that is a modded Vox Repeat: dead silent with battery, noisy as hell with a power supply.

Just had to put a 220R resistor  on the  +9V row and replace the 100uF filtering cap with a 220uf one.

Nos is dead silent too with  an external DC :)

BR

[Madferret]

Slightly off topic (but related), does anyone have any info on getting some of the crappier PSUs to have a little less noise? My understanding is that the cheapo (Dr Tone, Joyo etc) supplies use individual regulators and filtering for each socket but don't isolate them which is why Sonic seems to be having issues with some pedals but not others.  Does anyone know of any quick mods that can be done to help out?

Sonic, have you tried disconnecting all the other pedals from your supply? I've had to do this in the past to make sure the circuit isn't the problem, turns out my supply is just a steaming pile.

[Lord sonic]

Hi All,
thanks for the suggestions, not sure if I have this right Javi, but I put the resistor on the same row as power/+ and replaced the 100uf on the vero for a 220uf. Unfortunately, it didn't help, was just as noisy in fact. Think I am clutching at straws really. Madferret  I really don't think its the power supply, which is a soundlab brick, as it works fine (noiseless) with all my other various pedals, it must be a wiring mistake. As I say this is my first DC build. Would like to hear from anyone who has made this pedal successfully with noiseless dc, and possibly some pics? In the meantime gonna try a simple fuzz with dc, just to see if I can get it to work without noise, cheers People!