[Phil Allison[_4_]]

Scott Dorsey wrote:

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Remember the *only" connector is a HP jack.

IME, such units do not have enough metal shielding to exclude buzz and hum
from fluoro and dimmed domestic lighting.



I have a little box that has 600:600 transformers in it and a shunt load
on the transformer secondary. The idea being that with a lower impedance
load, the keyboard noise is less severe. I have really only had to use it
with $10 Casio keyboards, gameboys, and the like, but it helps a bit for
the really cheap stuff.


** Grounding the common rail inside such contraptions often makes injected electrical noise from the environment worse.

When no such ground exists ( eg when the unit is on battery power ) signals tend to inject into all wiring equally, leaving little differential anywhere.

Same goes when coupled through a 1:1 transformer, with low capacitance to earth.




..... Phil