Natural Science Forum / Physics / Acoustics / February 2008

Praxis has a dedicated USB interface that acts like a dongle - without it
you can use the program in demo mode, which still does quite a lot.  The
interface includes a mic amp but it isn't a sound "card", you still need one
and they recommend M-Audio Transit.  You do need a good sound card but
Praxis seems to take very firm control of the Windows mixer.

It does chirp and MLS and other test signals, and has fairly comprehensive
processing capabilities. (In fact it looks as if you could create your own
chirp and use that.  I have an idea to do one that spends longer on the low
frequencies to optimise the dynamic range for RT measurements.)

I commented on the human interface in my previous post.   The oddest
feature is that every separate aspect of the program is a separate window on
the desktop.  Typically a normal operation will have 5 or 6 windows open,
and they can be difficult to keep track of.  The other down side that I have
so far come across is that the plotted results do not look very
professional.  But I needed fairly urgently a system to do laptop based time
and frequency response and Praxis does it.  The alternative would probably
have been WinMLS but I didn't like their pricing model - to do the things I
need would have needed pretty well their top price.

I don't want to make too many comments on Praxis yet as I am still learning
to use it.  So far I can say, it does work!  I have crashed it once by
trying to post process at the same time as it was acquiring data, but I
haven't been able to do it again despite trying.

I would be interested in keeping in touch with any other Praxis users.   At
the moment there isn't a user forum although the author has said he will
organise one if there is interest.