On Thu, 06 Jan 2005 20:27:55 +0000, Rob
wrote:

John Phillips wrote:
In article , Richard Wall wrote:

snip


BTW a set of ABX tests and results (including positive and negative)
are to be found at http://www.pcavtech.com/abx/abx_data.htm (down the
page, including a capacitor test).


That's quite interesting - some results I'd expect (speakers, tape
decks, encode-decode, cables) but some are pretty wild - a 450w ss amp
and a 50w valve amp sound the same for example.

If it's a *good* valve amp, this is quite reasonable. These tests are
of course conducted below the clipping point of the least powerful
amp, so the sheer power difference doesn't count. No one ever
suggested that you can't hear an amp clipping! :-)

I've had a quick look at a journal database and I can't see much on DBT
as a valid scientific method (I don't know about the journals on the abx
page - they don't look to be the peer reviewed kind). Its theoretical
basis seems psychological. Is there any methodological and empirical
analysis of this process?

Lots, both in psy journals and medical journals.

I've always thought it's not what people think, but why they think it,
is the most interesting thing. I'm not (quite!) enough of a pedant to
ponder on 'the same' results, but some qualitative analysis of
'different' would be interesting - does anyone know of DBTs that
includes this (not just audio)?

Try any medical journal. DBTs have been standard in drug trials for
many decades.

Linked to this is another thing I don't understand - do people know
what's going on in these experiments ('this is an abx test of cables'
for example).

Yes, people know what is being compared, they just don't know what is
actually connected at any given time. In an ABX trial, you can always
select A or B as known devices, only the identity of 'X' (A or B) is
unknown.
--

Stewart Pinkerton | Music is Art - Audio is Engineering