Power supply causing interference to audio???

[Julian G]

Ok so I recently re-configured my pedalboard and am getting a lot interference, like some hiss and whooshing for want of a better description, boosting the treble on the Spectradrive preamp increases the noise level. Have checked all the cables and all seems ok with the cables. I'm using the Mooer Macro Power S8 which has been working fine and needed the 15v option that it has to run my Eden Californiwah.

I have just been reading regarding Volts and mA. The Spectradrive requires 9v and 250mA or more but the interference seems louder when I have it in the 9v/400mA than in the 9v/200mA. Does this make sense? Could potentially what I'm hearing because maybe I'm not powering the pedals with the right v/mA configuration? I know little about electrics and only configured my first pedalboard this year so this is all still relatively new territory for me, so appreciate any input you may have. Thanks.

Incidentally along with the Spectradrive and Calforniwah I'm running the Ampeg Optocomp and Liquifier, EHX Enigma Q Balls, Mooer Tender Octave and Behringer TU300 tuner.

 

[Sunset Shalom]

Often times it's a specific pedal causing most of the noise so it helps to go through and test them, an easy way is to start in the middle instead of testing them one by one. Just plug right into the middle pedal instead of the first and if there's noise then it's one of the pedals after and if there's no noise it's one of the unplugged ones.

Some pedals get weird when sharing supplies so it can be worth leaving some plugged in to individual wall wart style supplies. Also a good way to test for power supply noise is by getting a 9v battery and cable to convert it to fit with pedals power jacks, that way you can just plug the battery in to pedals to see if that helps with the noise which it often does.

I got a cheap power conditioner awhile back after assuming they were unnecessary for years, but it did end up making a considerable difference especially with certain pedals even though they're all using isolated supplies. I still get some noise from certain sources but it helped reduce a good bit of noise from dirty power as the wiring here is pretty old and not the cleanest. They make EM testers but sadly they cost about as much as a decent conditioner (100$~) Still want to get one eventually as it seems very useful being able to plug it in and test outlets for interference.

Also MA generally isn't a big deal as long as the pedals are getting enough. Under powering certain digital gear can cause issues I've heard but for most analog pedals it won't matter much and they usually don't need much anyways. With preamps providing extra MA can sometimes improve the sound but mainly if they weren't getting enough or were designed to be able to take extra current. And thankfully you can't overpower a pedal with MA like you can with voltage.

 

[frankzap]

It could be that this power supply uses DC/DC switching converters. I can't see specified in their specifications but this is likely. These may be filtered differently on each power output and that is why you have a different level of wooshness.

Switching converters use hi-freq pulse modulation which is not easy to filter or eliminate because it may be induced in the power cables and transferred to the audio circuits. If you will use linear regulated power sources instead, you will not have to deal with hiss noises.

Drives pick up this hi-freq hiss easily because they have very high gain stages and that noise gets amplified quickly.

Is important to power the pedals with proper voltage. It is not important from which power output you drive the power from, as long as you have enough current (measurable in mAh) available from that output. If the Spectradrive requires 9v and needs to draw 250mAh you need a higher current source output, like the one ensuring 400mAh. If you would use the 200mAh output that might enter Undervoltage protection mode if it has such a thing and stop working. If it doesn't, the voltage will drop while the current is drawn high and the device will not perform correctly. De device will be all right but the power source internals could overheat and break.

 

[Julian G]

Thanks for the response guys, will have a closer look at everything and see what i can do