Saturday, May 26, 2012

Power Supply for the Kinder AFB+ Pedal



The Kinder Anti-Feedback pedal has become an indispensable tool for many gigging harp players.  The only complaint I hear from those who use the pedal is that it does not have a provision for an external power supply, so we are stuck using batteries.  This is a pain for several reasons:  The pedal does not have a battery level indicator to warn you when it is time for a new set.  And when you do change the batteries you need to remove four small Phillips head screws and take the casing apart.  Not very convenient if the batteries go out in the middle of a set.

Furthermore, the pedal uses two 9 volt batteries instead of one.  My understanding is that the two sides of the AFB circuit  -- input and output -- must be absolutely isolated from each other for the anti-feedback properties to work right.  And I think that is the reason Kinder did not ship it with a power supply, or even include a plug for a power adapter.

David Brown posted a note on Harp-L about his solution for this, and I decided immediately I wanted to do it as well.  The key is that you need a power supply that delivers independent streams of isolated, filtered, regulated 9v DC power.  The Voodoo Lab Pedal Power 2 Plus is just the ticket.  That is what David used, and I decided to use it as well since two members of my band use the same power supply and swear by it.  It sells for $169.00.  I ordered it from American Musical Supply.

The Pedal Power 2 Plus comes with a variety of cables with different connections, including one with the battery snap connector.  You will need two.  You can order one from Voodoo Lab for $3.50.  (If you decide to build your own cables, REMEMBER:  The polarity must be reversed on the battery snap connectors.)



I used a 6-inch flat file to notch a small slot in the edge of the lower pedal housing right where the batteries are housed.  Then, snap the cable connectors to the battery connectors in the pedal and reassemble, routing the cables through the slot.  Plug the cables into the power supply, making sure they are delivering 9v.  Check the DIP switches on the bottom of the Voodoo Lab power supply.  They should be switched to NORMAL for the AFB pedal.

That’s it.  I don’t have a lot of hours on this rig yet but it seems to work perfectly so far.  The Pedal Power 2 Plus now drives all the devices on my board:  Line 6 Relay G30 digital wireless receiver, Kinder AFB+ pedal, MXR Carbon Copy delay pedal, and a BBE Sonic Stomp.  The first three are pretty standard gear, but quite a few people ask me about the BBE pedal.  I like it because it gives me slightly more cut without sound shrill or bright.  The effect is subtle.

And now the only device I use that relies on batteries is the transmitter for the wireless. If I replace the two AA batteries after every second gig I have no battery issues at all.  Nice!


ADDENDA:
- I used the battery snap cables because I wanted to be able to use the AFB+ with batteries if needed.  Just unsnap the cables and insert batteries.
- From an economics view:  9v batteries cost about $3.50 each, depending on where you buy them.  So, it's seven bucks to power the AFB pedal.  For the cost of the Voodoo Lab power supply you could re-battery the pedal 24 times.  If you get every hour of life out the batteries and they last, say, 25 hours of playing time per pair, then $169 could buy you 600 hours of playing time with batteries.  But, I am also saving on the 9v batteries for the other 3 devices on my board.  It makes economics sense to me, but I admit that it is a rather steep price for a power supply.
- Dan Hazen reports on Harp-L that he has done the same thing using two standard Dunlop power adapters.  

UPDATE:
As of December 2012 I've gigged this rig dozens of times and it has worked perfectly.

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