[sdiy] Reverb picking up power supply hum

[Oren Leavitt]

Hi Scott and all,

I was about suggest a toroidal transformer, too - you beat me to it Harry!
I have nixed hum problems in the past by simply using toroidal power 
transformers in place of the old E/I frame type.
A 3 amp toroid for a Power One would be small enough to be easily 
oriented for best results, too.

A good toroid source (Maryland, USA):
http://www.toroid.com

I buy toroids from these guys and have been very satified.
They have toroids that would be perfect replacements in the typical 
Power One (or any) PSUs we use for SDIY.
Look under "Rectifier Transformers".

- Oren


HARRY BISSELL wrote:
> Its almost a sure bet that you have magnetic flux leaking from the
> power supply transformer and getting into the pickup coil in the
> reverb spring.  Move or re-orient the spring, get it farther away
> from the transformer, or shield the spring and/or the supply with
> ferrous metal (steel, better iron... or better still Mu-metal) Places
> like advanced magnetics sell mu-metal foil. Its REALLY REALLY good for this
> and has a really really high price tag to match the performance.
> 
> You might consider switching the power supply transformer to a toroidal
> type, which radiate a much smaller magnetic field.
> 
> H^) harry
> 
> 
> ----- Original Message -----
> From: Scott <Scott at scottwick.com>
> To: synth-diy at dropmix.xs4all.nl
> Sent: Fri, 24 Apr 2009 15:39:23 -0400 (EDT)
> Subject: [sdiy] Reverb picking up power supply hum
> 
> If I mount my power supply (power-one 3 amp) inside my synth cabinet, I pick up some hum in my reverb (tellun neural agonizer).  I've tried grounding the power supply frame to earth.. the reverb tanks to earth..  various grounding schemes using the synths neutral line, etc.  
> 
> Is there anything I can do?  There isn't a lot of room but I might be able to fit the p.s. inside a cage if that would help.
> 
> I know building a little case for my power supply and leaving it external would work, but that is definitely the last thing I will do.
> 
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