wrote:
Hi bear (and others),

let me first tell you a bit about the kind of experiments I would like
to perform: speech signals which are _distorted_ in various ways are
supposed to be evaluated in subjective tests. The signals are presented
diotically via headphones. Since the above mentioned
amplifier/headphone combination was used in similar tests carried out
in the past, I would like to be consistent and use the same set. But
unfortunately the amplifier is no longer available.

No longer available?

Have you tried any dealers in Japan?
Used dealers in Japan??

Ebay in Japan? etc....

The idea was to buy the same headphone and a different amplifier -
different in the sense that those STAX amplifiers available on the
market do not have this diffuse field equalization. I found this
(little useful) link for the _traditional_ amplifier:

http://www.simplystax.co.uk/heritage...tml?prod_id=79

Also, the question is whether diffuse field equalization does actually
make sense for experiments with diotically presented stimuli...

Only you can know that.

Nevertheless, I had the chance to listen to the diffuse field
equalization and - it makes a clear difference at least in my
perception (less direct, more spatial than without equalization).

So, how should I reasonably solve the _problem_ :-)? What would you
suggest?

Find the same system, IF any correlation between earlier tests and the
new tests is required - and certainly IF there is a spatial component to
the "test" signals.

Alternately, I suppose you'd have to repeat certain earlier tests to
show a baseline result that corresponded as a "control"??

In lieu of the original unit, there was/is a company in the USA I think
called HEAD (??) that made headphone amps with a similar sort of circuit
built in - and also available alone as a module. Iirc, the way it worked
is that it cross fed signal that was equalized and delayed (perhaps with
respect to frequency from one channel to the other...

But, what do I know? ;_)

_-_-bear

Thanks again