Not so, loading a passive controller will reduce only the level, turn it up
a bit more, and it's the same. I agree that if the controller has a silly
value, say 1Kohm, and the output stage of the source is really poor and
can't drive 1K, then yes, unhappy results can occur, (I do not accept
"unpredicatable", as a knowledge of the output stage of the source will
allow you to predict what will happen into a low value load) but this was
not the case in the review. The Alner Hamblin passive controller has a 10k
pot, and the following power amp has an input impedance of 20K, so the
source should see a worse-case input impedance of 6.7K at maximum volume or
around 8-9K at normal volumes. If the source used (not stated in the review)
was of any sort of competence, it should drive this load correctly.

S.




"Trevor Wilson" wrote in message
...

"Serge Auckland" wrote in message
...
I don't know what the first one was, but more recently in HFN, almost
anything by David Allcock gets me going. It's almost as if he's
deliberately trying to live up to his name......

His latest, page 56 of the January 2006 HFN, when reviewing a passive
(note, passive) preamp (that, in itself, is a misnomer..its a switch and
a variable resistor....) he goes on about how "Stage depth was slightly
foreshortened" Give me a break, it's a resistor! how can it
"foreshorten" anything?

**Try it yourself. Load down the output of any given source by an
excessively low impedance load and unpredictable results ensue. Passive
controllers are often configured to present a low(ish) impedance load, so
that their source impedance is low enough for successive stages. The whole
issue can be easily and non-intrusively solved by the simple addition of a
buffer stage.


--
Trevor Wilson
www.rageaudio.com.au