geoff wrote:
On 31/12/2017 11:06 PM, Adrian Tuddenham wrote:
geoff wrote:
[...]
I find it hard to imagine that professionals over several decades using
these headphones also hadn't noticed. Only JJ wouldn't be surprised.
Very often people under pressure to get a job done don't stop to
question the details of the tools thay are using. They may know that a
certain type of headphone has a good or bad reputation or they find for
themselves that one type sounds poor on cymbals but better on vocals,
for instance, but they don't have the time or inclination to make
laboratory-type measurements to find out exactly why it sounds like
that.
I thought the manufacturer's data sheet or some of the independent
reviews might shed some light on this dip, but I was soon disabused of
such a quaint notion. There doesn't appear to be any sort of meaningful
specification for the performance of these headphones and the reviews on
the Web are utter bo**ocks; it doesn't look as though anyone has ever
bothered to check their frequency response.
I find that concept to be utter ******** ;- ) There *will* be a reason.
I'm sure the manufacturers checked the prototypes when they were
developing that model, but they appeared to be keeping the results to
themselves. I can't imagine each unit was checked for response curve
during manufacture; even batch-sampling was probably only concerned with
cosmetic matters and major defects such as open-circuit coils.
None of the reviews mentioned frequency response measurements - indeed,
I got the impression that none of the reviewers would have known how to
make them, how to interpret them properly or, in some cases, what they
were.
[...]
I would be quite happy to do some simple frequency response tests if
someone is prepared to loan me suitable candidates. Perhaps more
elaborate dynamic testing would show up minor differences in the
performance of headphones that show apparently good static responses;
but when there are such gross errors in the basic properties, there
doesn't seem to be much point in going on to test for anything more
subtle.
Maybe pick up another pair of old K240s and compare ?
I can't justify buying them, but I will keep my eyes open in case I can
borrow a pair.
And another thought (though not necessarily specific to the particular
conundrum - what is the output load impedance specification of the sig gen ?
That is a very good point. The sig-gen was 600-ohms output and ran
through one of the distribution rack buffers which again delivered from
600 ohms. I seem to remember that I wondered about that at the time and
repeated the test with a completely different low impedance driver - but
although I have forgotten the details, I'm sure it made little
difference.
--
~ Adrian Tuddenham ~
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www.poppyrecords.co.uk