"Larry Green" wrote in message
.. .
snip-----

The solution in this case was

to fit ferrite rings/loops at either end of his speaker leads and he
never heard me again.

If you are going to run long speaker leads it may pay you to invest in a
few ferrite rings/loops and save yourself a lot of headaches down the
road. They are readily available from the likes of Radio Shack at
reasonable prices.

--
Larry Green


That's a great tip, Larry. Would you mind detailing how these ferrite rings
are installed? In my case, consider that I'd have my wire running in EMT
for one set of speakers, and in PVC sch. 40 plastic in the other. Each
set terminates in a steel box, and the runs would be made of stranded 10
gage THHN wire, color coded to insure proper phasing. I'd like to make
sure we don't get any noise that isn't a part of the music!

Thanks---

Harold


Hi Harold,

Ferrite 'noise suppressors' can come in several forms such as beads,
rings, hinged 'rectangles' and cylinders. The fitting of each type is
different in each case.

Ferrite Beads
These are 'normally' very small (less than 1/4" dia.) and are slipped
onto a wire before it is attached to a piece of equipment. Usually used
internally on a device.

Ferrite Rings
These can come in a range of sizes up to several inches in dia. They can
also be 'salvaged' from the back of old speakers or TV tubes (be careful
of high voltages if messing with TV tubes even if they are switched off
and unplugged!) To fit a ring to speaker wire you simply pass the wire
around the ring several times by going through the middle and around the
outside. Six to eight turns are normally sufficient to block any stray
signals. Make sure the 'turns' are equally spaced around the ring.

Ferrite 'Rectangles'
These are the most common type found in Radio Shack and are two 'U'
shaped pieces of ferrite mounted in a hinged plastic holder with a clip
to keep the 'loop' closed. Undo the clip, open the 'loop' and wind
several turns of your speaker wire around one half of the 'loop' then
cross over and wind the wire around the other half. If you wind
clockwise on one side wind counter-clockwise on the other side. Close
the loop and re-clip when you are done.

Ferrite Cylinders
These can come as either solid or split (like the 'rectangles'). You
have more than likely seen this type many times and not realized what it
is. The 'bumps' on a computer monitor cable are ferrite cylinders to
prevent stray signals getting to the monitor. For solid cylinders you
simply pass the wire through the hole in the centre and hold them in
place with either electrical tape or a small cable tie at either end.
Split ones 'normally' come in a hinged plastic fitting. Undo the
fitting, slip the speaker wire into the 'slot' between the two halves
and close the fitting again. If the cylinder slides on the wire use
either electrical tape or a small cable tie at either end to stop it
slipping.

Whatever type you use they have to be fitted at each end of each set of
'long' wires in your system (the shorter wires are not 'normally'
affected) as close to the device in question as possible (i.e. where the
wires connect to the amp and speaker). A short length of wire (say up to
6") sticking out of the 'connection' end is OK if you don't have room to
fit all the ferrite rings/loops/cylinders close to the amp.

HTH

--
Larry Green