"Sander deWaal" wrote in message
...
"Trevor Wilson" said:

**What Tannoy are suggesting is of limited benefit, since most of the
problem lies with the speaker cables themselves. And only under extreme
conditions. I have encountered the problem a few times, where the client
lived close (less than a few hundred Metres) to a local TV transmission
tower. The high power RF insinuates itself on the speaker cabling, then
enters the amplifier (through the outputs) and is then routed to the front
end of the amplifier via the negative feedback line. The only solutions
a

* To shield everything in the speaker circuit. This includes the cables,
the
crossover and the speakers themselves.
* To use an amplifier which has no global NFB or one which uses 'nested'
feedback.


Trevor,

Do you have any experience with class D amplifiers such as the Hypex
UcD modules wrt. RFI?

**Nope, but I have experienced other amps which use SMPS and measured the
problems they exhibit on AM radio reception.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" said:


Trevor,

Do you have any experience with class D amplifiers such as the Hypex
UcD modules wrt. RFI?

**Nope, but I have experienced other amps which use SMPS and measured the
problems they exhibit on AM radio reception.



Interesting.
I have a RAM audio pro-amplifier here, which also employs a switch
mode power supply.
It is supposed to put out 2 kW per channel in 4 ohms, and has switched
rails as well.
When the grounding is poor, there is audible noise coming out of the
speakers.....

I still haven't come around to measure what influence the PS has on
the amplifier part in terms of IM (it runs at about 200 kHz).

IMO, class D amps may suffer from the same phenomenon, when not
implemented correctly.
Hypex is pretty unsuspect in this regard, but the ICE-power B&O amps I
have heard may have some serious issues, if I am to believe my ears.

--

- Never argue with idiots, they drag you down their level and beat you with experience. -