Lee wrote:

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Phil Allison wrote:


After asking the guy for more info about the speakers, as you asked what
there were, I now suspect the problem is his end* and he's getting it
back as it is.

But details anyway, since you asked.

If I feed it a 0.8v pp sinewave from my sig gen it doesn't clip at full
volume and doesn't go into protect.


** Are you using a dummy load ?

Please describe.

I was using a pair of 8 ohm 100W standard metal cased cermet WW
resistors on a big metal plate. One for each channel, obviously.


** Good, I need to know it was 8 ohms AND both channels were tested at once.



Where it's normally installed, it's paired with some very expensive
speakers


** And we are not allowed to know their identity either?

I have been told they are Kef R300, so not that expensive,


** $US1800 a pair is not cheap.


but I
wouldn't like to be buying them. I don't know if they are good speakers
or not.



** Very compact 3-way, bass reflex with impedance min of 3.2 ohms.

Low efficiency too so needs a decent amp.


He runs them bi-wired, apparently. Personally, I fail to see why running
two pairs of cables to the same speaker from a paralleled pair of output
posts on the *same channel* makes any difference. But I'm sure it must
or they wouldn't do it
I have asked the guy to double check the wiring for problems**.


** KEF makes a big deal of the bi-wiring idea in the handbook, there are extra terminals fitted and a link on/off switch.

Complete wank of course.


*assuming my sig gen is accurate, of course.

** Your scope should be accurate enough.

That a secret too?

The one I'm using for this is an old analogue Leader LS8050 50Mhz crt
scope. I do have a modern Rigol digital 'scope as well fwiw.


** Either will have good accuracy.



*Apparently, according to the guy, it's been "trigger happy" from new,
but it's been "more sensitive" after a recent speaker move.

** So I suspect the speaker wring, but he's plenty capable of sorting
that out.

I'm not interested in trying to deal with a potential design/build
issue. If he wants it modified he can find someone else to do that.


** The owner is likely playing the system to its MAX and the wimpy Marantz amp is protesting.



..... Phil