Re: setting up ABX tests at home

"Steve" <goldstarsteve@[EMAIL PROTECTED]
> wrote in message
news:focmm502k1l@[EMAIL PROTECTED]
> I want to set up an ABX test at home on different sources
> to see if I can hear a difference. I am doing this for my
> own education and fun - I don't want to start investing
> in SPL meters, switches gain equalizers of other boxes.

Please see www.pcabx.com .

> The sources are a Panasonic discman, an arcam CD player a
> squeezebox, and hopefully we will borrow a high end CD as
> well. I will obviously do it in pairs. I will have a
> helper switch manually. All units can be connected to my
> budget level integrated NAD 325 BEE and have a copy of
> the same media source.

One big problem  with real-time tests of various disc players is that in 
addition to matching volume, you also have to time-synch the two players. 
Otherwise, anybody with halfway working ears can figure out the identities

of the players in an ABX test by listening to the timing differences.

> My problem is how to neutralize differences in volume
> without investing in equipment I have no need for. I can
> think of four strategies

> 1) For each test start with volume at 0 and have testers
> ask for volume to be adjusted to level they like.
>
> 2) Have the helper randomly set volume each time

> 3) (Maybe) use a PC to measure volume - not sure how to
> do this but I do have a cheap microphone and audacity on
> the PC which should show me the volume level - I don't
> know how accurate this is.

PC' audio  interfaces can with appropriate software help make up a cheap, 
high resolution, wide-bandwidth, highly stable voltage measuring device,
but 
they have limited input voltage range and questionable calibration.

The good news is that when you do ABX, you're interested in the degree of 
matching, not the absolutely precise voltage. So the calibration issue is 
moot. That leaves you with the input voltage range problem. I've found
that 
a high quality 5 K ohm potentiometer can match up a PC sound card with a 
wide variety of audio devices.