
-
-
My current home stereo is a patchwork of various pieces I got on
-flee markeds over the years. It is amazing what kind of equipment
-show up there. I've been wondering for a while if it was possible to
-measure how well this equipment is working together, and decided to
-see how far I could get using free software. After trawling the web I
-came across an article from DIY Audio and Video on
-Speaker
-Testing and Analysis describing how to test speakers, and it listing
-several software options, among them
-AUDio MEasurement
-System (AUDMES). It is the only free software system I could find
-focusing on measuring speakers and audio frequency response. In the
-process I also found an interesting article from NOVO on
-Understanding
-Speaker Specifications and Frequency Response and an article from
-ecoustics on
-Understanding
-Speaker Frequency Response, with a lot of information on what to
-look for and how to interpret the graphs. Armed with this knowledge,
-I set out to measure the state of my speakers.
-
-
The first hurdle was that AUDMES hadn't seen a commit for 10 years
-and did not build with current compilers and libraries. I got in
-touch with its author, who no longer was spending time on the program
-but gave me write access to the subversion repository on Sourceforge.
-The end result is that now the code build on Linux and is capable of
-saving and loading the collected frequency response data in CSV
-format. The application is quite nice and flexible, and I was able to
-select the input and output audio interfaces independently. This made
-it possible to use a USB mixer as the input source, while sending
-output via my laptop headphone connection. I lacked the hardware and
-cabling to figure out a different way to get independent cabling to
-speakers and microphone.
-
-
Using this setup I could see how a large range of high frequencies
-apparently were not making it out of my speakers. The picture show
-the frequency response measurement of one of the speakers. Note the
-frequency lines seem to be slightly misaligned, compared to the CSV
-output from the program. I can not hear several of these are high
-frequencies, according to measurement from
-Free Hearing Test
-Software, an freeware system to measure your hearing (still
-looking for a free software alternative), so I do not know if they are
-coming out out the speakers. I thus do not quite know how to figure
-out if the missing frequencies is a problem with the microphone, the
-amplifier or the speakers, but I managed to rule out the audio card in my
-PC by measuring my Bose noise canceling headset using its own
-microphone. This setup was able to see the high frequency tones, so
-the problem with my stereo had to be in the amplifier or speakers.
-
-
Anyway, to try to role out one factor I ended up picking up a new
-set of speakers at a flee marked, and these work a lot better than the
-old speakers, so I guess the microphone and amplifier is OK. If you
-need to measure your own speakers, check out AUDMES. If more people
-get involved, perhaps the project could become good enough to
-include in Debian? And if
-you know of some other free software to measure speakers and amplifier
-performance, please let me know. I am aware of the freeware option
-REW, but I want something
-that can be developed also when the vendor looses interest.
-
-
As usual, if you use Bitcoin and want to show your support of my
-activities, please send Bitcoin donations to my address
-15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.
-