In article , Serge Auckland
wrote:

"Jim Lesurf" wrote in message
...


Perhaps also worth recalling that around this time HFN organised a
detailed set of listening comparisons. The results of which showed
that the listeners couldn't tell one amp from another when all were
used with the same system gain and none were being taken outwith their
limits. The amps tested included the 405 IIRC.

Yes, but the operative bit here is "none taken outside their limits".
The original 405 could be so taken fairly readily due to the limited
current capability, and, as you pointed out, the severe IV limiting on
reactive loads. I don't know which test you are referring to, so don't
know what the load was. I recall a similar test being done using Yamaha
NS1000 monitors, you may remember we corresponded about that one a year
or two back.

A number of similar tests were done during the late 1970s and early 1980s
with broadly similar conclusions. The one I had in mind was published in
the June 1978 issue of HFN. I've not had a chance to carefully re-read it
this morning, but from a quick scan, they used a Quad II, 303, and 405. On
page 75 the article says, "Yamaha NS 1000 loudspeakers were used (although
this would not have been Acoustical's preference)" They used a scope to
check there was no clipping or limiting that might show up.

Maybe some subjective reviewers came to fancy the NS1000 because it tended
to be what they'd call "revealing". i.e. causing current limiting in some
amplifiers so they could hear a difference when they wound the wick up.
:-) Afraid I've forgotten what we said previously about the NS1000, though.

The Nov 1978 issue re-visited this kind of test, and later comparisons were
expanded to use different amps and speakers. Martin Colloms also in the Nov
1978 issue produced some measured results showing the changes in frequency
response for some examples of amp-cable-speaker combinations due to cable
impedance interactions with source and load.

Slainte,

Jim

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