Re: looking for balanced power conditioner.

Dan Mills <dmills@xxxxxxxxxxxxxxxxxxxx> wrote:
Scott Dorsey wrote:

Probably not good, actually, since one of the big advantages of balanced
power is being able to deal with clapped-out guitar amps that have major
chassis leakage issues.

If you have 30mA leakage (EU RCDs trip at between 15mA and 30mA for the
common ones), then that amp will fail to meet the safety requirements of
the electricity at work act (.UK, others have something similar), and
would fail any portable appliance test (Effectively required for work
equipment), so why are you using it? Get it on the bench and get it sorted.

I am willing to bet that less than 30 mA leakage will result in audible
noise problems. But also, I have seen guitar amps with well over that
point turn up in the studio. You ask the musicians if you can fix it
and they get angry at the thought of anyone touching their amp and possibly
screwing up their signature sound.

People bring ALL KINDS of crappy gear into the studio, including synth
racks full of ground loops, leaky guitar amps, and cables spliced with
masking tape and the engineer is expected to deal with them. It's not
fun.

Finally, remember that a fault from the 'neutral' to the case of any bit
go gear has the potential to put 120V on it (rather more dangerous then
the 60V you get for the same fault in the states).
True, but still less hazardous than 240V.

But with a single sided supply, that fault will blow the fuse within 0.4
seconds (probably well within), and the earth connection will keep the
touch voltage under control. If the gear has not been modified to fuse
both legs (which then has the potential to make it dangerous on a single
sided supply), you cannot make that statement about it when used on a
balanced supply.

True.

It's a useful tool for a problem folks occasionally
encounter and it's worth keeping a little 200W balanced isolation box
around for when you encounter it. --scott

But you can get the same fix with a simple isolating transformer (with the
secondary treated as a separately derived supply), without the worries
about fusing.

There are some electrical code issues about that in the US, although I
agree that it's often a good idea.

I thought the OP was looking at a whole studio setup, which is what I have
major issues with.

Well, it doesn't fix anything more than any other isolation transformer does,
other than the chassis leakage issue. But if you're going to put an isolation
transformer in anyway, it's really no more added cost. Other than, as you
point out, having to use two-pole breakers.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
.