In article , harrogate2
wrote:
I must admit that I have never subscribed to the 'golden ear' brigade.
However I have used a Quad 33 as a pre-amp, later replaced with a
Cambridge C70 (A1 without the power amps) and now a NAD 3120 as a
pre-amp only.

I have to say that after getting used to the Quad, when I replaced it
with the Cambridge the sound was totally different - much more solid -
perhaps what some would describe as warmer - and with a noticable loss
of higher frequencies. The Quad by comparison would be described as
polite and laid back with a distinct lack of dynamics. Comparing their
outputs on a network analyser shows them to have a similar frequency and
phase response - certainly nothing that would account for the audio
difference.

The change to the NAD was more subtle but still noticable. Certainly the
top end was more detailed (cymbals and triangles show things up
remarkably well) and the bass was noticably deeper but not so 'in your
face' (I like classical organ music.) Again however the frequency
response and phase responses were almost identical to the other two.

Anyone any polite suggestions as to cause? Even my wife and children
(then teenagers) noticed the difference without asking or prompting.

My recollection is that the 33 does not have a very flat response even with
the controls set as near flat as possible compared with more modern units.
FWIW my experience is that even quite small changes in overall response can
be audible.

I'd be interested to know how you measured the response in terms of the
circumstances of use. Afraid I don't know much about the other amps you
mention, but wonder about things like the levels of hum/ripple, output
impedances, etc.

Slainte,

Jim

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