analog delay Johnson EAD 2 humming when fed from wall-wart

[yeeshkul]

My fried has a problem with this Chinese analog delay Johnson EAD 2. When it runs on battery everything is all right. When he uses wall-wart there is a lot of hum (which is also changes in dependence on the MIX pot). Can there be a ground-loop through the common ground with his amp? The wall-wart apparently works fine wit the other stompboxes.

[Rodgre]

It could be that this delay is more sensitive to noise and ripple from the adapter than other pedals. There shouldn't be a ground loop issue if the adapter is ungrounded (no ground lug where it plugs into the AC line). If the adapter isn't putting out a clean, regulated DC voltage, like a lot of cheaper adapters suitable for non-audio power are, then that's the culprit.


Roger

[zombiwoof]

A non-regulated adapter is just what I was also thinking.  If you're friend doesn't have a good one to try, have him get a Dano like the one in this link:

http://www.musiciansfriend.com/product/Danelectro-DA1-Power-Supply?sku=151851

I assume that the Johnson pedal requires a common center negative adapter like this one, but he should make sure before purchasing it.  I've seen it for as low as $8 at other places, I've got one and it works great.
Also read the customer review on the link page, sounds like others had the same problem as your friend!

Al

[yeeshkul]

guys thanks!