[Cy Suckerton II]

I really like Pete Millett's site. Here's an excerpt from a late
entry:




Software for the HP 8903 Audio Analyzer

Before the Audio Precision box became the de facto standard for audio
testing, there was the HP 8903...

The 8903 was available in three versions that I've seen: the 8903A,
8903B, and 8903E . The A and B versions include a low-distortion
oscillator (source), whereas the E version does not. The A or B
versions are certainly more useful for audio testing, and are required
to run the software I've written. The B version included a few
enhancements (like programmable generator source impedance), but for
the most part the A and B can be considered equals.

HP 8903A and 8903B analyzers are plentiful and relatively inexpensive
on the used market. I bought an 8903A freshly calibrated from a
rental company for about $900. A recent look on eBay showed 13 of
them, selling for buy-it-now prices of between $549 and $1699,
depending on condition, calibration, guarantee, etc. Compare this to
an Audio Precision boxes selling for $3000-$5000 in the used market,
and the old HP 8903 is a bargain.

OK, the HP 8903 does not do everything that an AP box does. The most
important thing it won't do for you, at least for me, is an FFT. But
since an FFT is a relative measurement - no precise absolute voltage
measurement is needed - a good sound card can perform at about the
same level as an AP box. I use an M-audio Audiophile 192 card and
Audiotester software to do FFTs, and the 8903 as the source. I get a
noise floor of around -140dB. The AP boxes at work have about the
same noise floor. And Audiotester is a lot easier to use than the
brain-damaged application that runs the AP box. Sorry, Audio
Precision...

But my biggest issue with the 8903 was that you cannot easily get
plots - swept measurements - from it. To measure frequency response,
I had to manually enter the frequency and write down the measurement
(or enter it into a spreadsheet) to get a graph. That is painful.

However, the 8903 can be fully operated remotely through the GPIB
port. For you youngsters, GPIB (also called HPIB) is a 8-bit parallel
bus interface designed back in the 1970's to connect computers
together with test equipment. It's a primitive interface by today's
standards, but it still works. It's all a simple matter of software.

I really do not like writing software.

Luckily there are shortcuts for the "C++ challenged" like me. I bough
a back-rev but brand new copy of a software program called VEE from
Agilent (actually Hewlett-Packard - it was really back-rev). VEE is a
sort of visual programming language that lets you design test programs
without really writing any code. It's still a pain and I curse at the
computer every time I use it, but at least it enabled me to make some
programs that are useful to generate plots from the 8903.

VEE programs can be compiled into an executable form that, when
coupled with a run-time package that is freely re-distributable (and
also downloadable form the Agilent web site). So, I can distribute my
programs, and you can run them for free!

Here are the four programs I have completed:

Frequency Response: FR_v2.vxe

As you might guess this plots frequency response.

The "Filters" radio buttons lets you select any of the 8903's built-in
measurements filters. Usually you don't want to use these if you're
measuring frequency response.

"Gen Level" sets the output voltage of the generator for the test.

[snip]


http://www.pmillett.com/hp_8903_software.htm

The 8903 is a microprocessor controlled box that was designed to
replace the HP 339 test set. It didn't and the 339 is still a high
dollar box. They are cheap enuff every true AUDIO phile could own one.