"Arny Krueger" said:

Note also that most tube amps don't suffer from said effects because
of their inherent low pass filters,

OTOH, tubed amps are more prone to EMI problems due to unique tube-only
problems like grid rectification, Miller capacitance and their high input
impedances. I hard a lot more RFI problems during the days of tubes than I
do now.


Grid rectification: the voltage span of an average power amp input
tube is about 2 volts.
The voltage span of an average base-emitter junction is what...20 mV?

Miller capacitance: dependent on circuitry.
*Every* amplifying device with inverting output suffers from mr.
Miller.
Examples of said circuits would be CCC, CEC, CSC.

High input impedance: dependent on circuitry.
A tube amp with a 10 k resistor at the grid to ground won't be more
susceptible (sp?) to RFI than an average bipolar input.
Let alone FETs or MOSFETs.
What was the first transistor again in your FM-frontend, Arny? ;-)

Granted that most tube amps have higher value input resistors.


BTW, SS amplifiers are also inherently low pass filters.


In general, SS circuitry is capable of handling higher frequencies
than tube equipment, consider an average output transformer with a
corner freq. at 50 kHz or so.

Of course, a good practice is to add an anti-slewing filter at the
input of the amp (even with tubes this might be beneficial!), but some
designers select a corner frequency of 150 or 200 kHz.
Besides, that is mostly a simple RC 6 dB.oct filter, not steep enough
to supress real strong RF energy.


hence even if Shakti stones work
as described on their website, they won't do very much for tubed
systems IMO (from a technical POV that is!).

From a Sander technical view, that is. ;-)


Gratuitous personal insult ignored.

--
Sander de Waal
" SOA of a KT88? Sufficient. "