Flabulanche dc noise

[toolguy]

Just got done my build. It sounds great but I get noise with a dc adapter.
I have tried another brand adapter but still getting noise.
9v battery power is clean.
Wanted to note I don't get any noise in my other pedals with either of my adapters.
I have tried moving the dc input plug/shielding the wires/a different wall outlet.
*I built it stock but did the "Put the 4n7 in C3, omit C4 and jumper R4" to get a bit more bottom end.
ic is a Texas lt1054cp

What can I look for to tweak?

[midwayfair]

A few questions: Is it a really high-pitched noise? Or some other pitch? Does it change with the tone control setting or the gain setting, or just with the volume? Does it change PITCH when you change any of the knobs? If you audio probe, can you identify where it's introduced? (I just need to make sure it's actual DC noise and not just noise related to something from the DC supply.)

[toolguy]

High pitched noise. All the time with no changes when turning tone, gain, or volume. Steady pitch.

[midwayfair]

High pitched noise. All the time with no changes when turning tone, gain, or volume. Steady pitch.

Wait, no change at all when turning the volume?

[toolguy]

No...it's strange.

[toolguy]

Zero noise on battery.

[jubal81]

Are you powering it with a One-Spot? I'm suspicious One-Spots and 1044/1054 don't play nice together.

[midwayfair]

If it's not changing at all when the volume changes, do you hear it in bypass as well?

This just got very weird, because the only stuff audio related that's physically close to the charge pump is the input jack, so even if it were bleeding into the audio from the charge pump, then turning down the volume ought to kill the sound. This means that somehow you have something at the output pad/wire of the effect picking up charge pump noise.

A few more questions: Did the noise exist before you boxed it? Try soldering a 100uF cap across the DC jack itself - does the noise CHANGE at all?

Are you powering it with a One-Spot? I'm suspicious One-Spots and 1044/1054 don't play nice together.

Mine makes no noise with a One Spot even though it's daisy chained with four more pedals, one of which is digital.

[jubal81]

I haven't gotten around to serious testing, but every 1044/1054 design squeals at least a little with my One Spot. Recently removed them all from my chain and it's been heavenly. Background noise is WAY down, too.

[madbean]

I actually don't have that problem with my One Spot.

I think audio probing is a good idea here. Find the origin of the noise as the signal goes through the circuit.

[toolguy]

*The noise will go away with volume knob set to zero...Sorry for any confusion. I did not test properly


Ibanez and a Radio Shack dc power. The Ibanez has a super loud low hz hum the Shack one is the high pitch. I 100uf capped the dc jack (about halved the High pitch but not the low). Then tried a 100 ohm resistor to the + lead. This took away the high pitch and helped a tad on the low pitch. So basically the cap and resistor worked on for the radio shack adapter....although I feel it has some background hiss now.
  Strange because my Ibanez unit has been with me since the early 90s and I have never had a problem with it. Again...pedal sounds great and everything seems to work well. Does anyone know if there is a vero build for building a "filter" with extra ports for dc power? I cant see spending that much for a pedal power (ie.Voodoo or t-rex) when I could probably build something.
  I do have a question on tweaking the tone knob (does not do much on my build) but I will start a different thread for that.

[jimilee]

Is it a multi adapter? I had one go bad on me, only hummed on a phaser project. Drove me nuts, turned out it started putting out about 12v dc.


Sent from my iPhone using Tapatalk

[midwayfair]

Chromosphere had a project to de-noise a DC adapter.

I really don't know much about the Ibanez adapter. I have a Boss adapter that's fine with almost all projects and I keep it around to have something industry standard. I would guess that the Ibanez either has some of its own filtering or the output impedance of the adapter is higher than the RS one (so it's using the in-pedal filtering better).

In any case, while I'm sure you could build a small dehummer type thing for the power supply, by the time you put it in a box, you're getting pretty close to the used price of something like a one-spot or another similar adapter made more recently. I hate to suggest "buy something" as the solution to a problem, but if you haven't done many charge pump designs, this could be a problem that appears later, too.

You might find that there is a problem with the 100R in line with the DC. Measure your voltage output after all the charge pump stuff -- it might be down around 14V or so, in which case you may need to rebias.

[madbean]

I'm with Jon on this one. If a limiting resistor doesn't eliminate it altogether then as different power supply might be the answer. The One Spot is cheap and has more than enough current to power several pedals. Plus, it's what I prototype everything on and I have not run into a situation yet where I found a noise problem being created solely by the One Spot (on individually tested circuits).

[jubal81]

OK, I think I've figured out my problem: The Triad 18V power supply from Origin Effects.


Having it plugged into the same outlet as a One-Spot where the One-Spot connects to a 1044/1054 circuit makes whine & noise.


Dangerous cocktail.