Linux apps useful for speaker/amplifier analsys

[Geek]

Checkout Japa and Jaaa.

Both of these programs are fair decent FFT displays, with Jaaa being more flexible, allowing markers, more configuration, a signal/noise generator, etc.

Works with ALSA, Jack and OSS (if you have a wrapper).

Cheers!

 

[DcibeL]

I am having trouble loading the website so I'll have to try it again later. I use Baudline myself and find it to be a very nice program. It works through OSS.

 

[anli]

Also, 'ams' has pink noise generator which may be useful (especially in use with japa - last one works as 'anti-pinknoise' filter, when 'Resp' is set to 'Prop'):

http://alsamodular.sourceforge.net/

Also, you can look at 'Room EQ Wizard':

http://homepage.ntlworld.com/john.mulcahy/roomeq/index.html

It is java app, but free and run under Linux.

Aha, now it is time to ask Has anybody thoughts how to measure an own speaker frequency respose (something like justMLS under win32, i.e. before first reflections come to microphone)?

 

[alinja]

I have also been looking for a MLS-based measurement app. Maybe one needs to be written.

So far I have measured responses with a frequency sweep (that has pauses to mark frequency points), and analyzed it in audacity with logarithmic amplitude scale. Spectrogram view gives some idea of distortion, but nothing accurate.

 

[anli]

QLoud

Probably, this app will be useful for somebody:

http://gaydenko.com/qloud/qloud-0.1.tar.bz2

It requires QT4 among others.

 

[anli]

... and QLoud screenshot:

http://gaydenko.com/qloud/shot01.png

 

[jcx]

http://scilabsoft.inria.fr/

MatLab workalike open source math software duplicates the functionality of most MatLab ToolBoxes - what real engineers use for system identification/signal processing - and has .wav i/o

for loudspeaker testing you should at least cruise Klippel's site to see what can be done

http://www.klippel.de/background/introduction.asp

 

[anli]

http://scilabsoft.inria.fr/

MatLab workalike open source math software duplicates the functionality of most MatLab ToolBoxes - what real engineers use for system identification/signal processing - and has .wav i/o

for loudspeaker testing you should at least cruise Klippel's site to see what can be done

http://www.klippel.de/background/introduction.asp

There are plenty science and/or plotting apps. There isn't one ready for use for DIY-measurements. This is the only reason I was forced to try write something useful myself.

Of cource, I mean Linux/open-source world.

As for "what can be done" - I know without Klippel, there are plenty things

 

[anli]

Because new versions appear, I have created tiny QLoud page:

http://gaydenko.com/qloud/

 

[anli]

Besides SPL plotting, Impulse Response power as function of time plotting is also available now:

http://gaydenko.com/qloud/screenshots/short02.png

Find last version here: http://gaydenko.com/qloud/

 

[anli]

Impulse Response power as function of time plotting is also available now:

http://gaydenko.com/qloud/screenshots/short02.png

Sorry, last shot link is http://gaydenko.com/qloud/screenshots/shot02.png

 

[anli]

QLoud is updated up to v.0.15

QLoud is updated up to v.0.15. Changes:

- a crash (hitting "Plot" with empty IR list) is fixed,
- pickers values are rounded now,
- multiple minor fixes and cleanup,
- now "Window, msec" is a time from IR peak to cutted reverberations, which is more intuitive, I think (earlier it was equal to applied window width itself).

Direct screenshot links:

- main window with few SPL plots: http://gaydenko.com/qloud/screenshots/shot01.png
- IR-power plot: http://gaydenko.com/qloud/screenshots/shot02.png

 

[anli]

Qwt v.5.0.0rc0 is released. As a result, QLoud doesn't depend on any CVS tree now.
v.0.16 is out - INSTALL is changed to be in accordance with Qwt development. Also, min. smoothing was reduced to 1/1024

If you already use the app, you can stay with v.0.15 (no bugs were found).
If you have rejected the app because of Qwt CVS-tree dependency - try it now

http://gaydenko.com/qloud/

 

[Geek]

Too bad it needs Qt4 and Jack

(I'd have to go to the unstable branch of Debian for those)

 

[anli]

Too bad it needs Qt4 and Jack

(I'd have to go to the unstable branch of Debian for those)

JACK-server is de-facto Linux standard audio interface. QT4 branch is more than one year(!) old.

 

[Geek]

JACK-server is de-facto Linux standard audio interface. QT4 branch is more than one year(!) old.

That just means it'll hit the stable branch in another four years

I did try Jack from source. Had some CPU gobbling issue I couldn't track down, so I went back to ALSA.

If there's a patch to simulate a Jack server, like ALSA has fo OSS, I haven't found it.

 

[anli]

...If there's a patch to simulate a Jack server, like ALSA has fo OSS, I haven't found it.

It is impossible. JACK server isn't a driver, it is a way applications communicate with each other.
If you are interested in linux audio, you can try these mailing lists:

The Linux Audio Developers' Mailing List <linux-audio-dev@music.columbia.edu>
A list for linux audio users <linux-audio-user@music.columbia.edu>

(I don't remember join-to-list points, just google)

 

[anli]

QLoud - distortions plotting is added!

QLoud is updated to v.0.17. Find it here:

http://gaydenko.com/qloud/

Harmonics (distortions) plotting is added. Direct screenshot link to harmonics plot:

http://gaydenko.com/qloud/screenshots/shot03.png

If you have a sound card with good DAC and ADC, you can plot harmonic
distortions for another audio equipment, say, for your power amplifier -
cited screenshot has also harmonics plot for loopbacked sound card.

 

[anli]

QLoud - Step Response plotting is added

QLoud is updated to v.0.18. Find it here:

http://gaydenko.com/qloud/

Changes:

- Step Response plotting is added, this is a direct screenshot link:

http://gaydenko.com/qloud/screenshots/shot04.png

These measurements are done for the same 2-way loudspeaker (see plots titles).
It is clear, a tweeter must be shifted lightly beyond from a listener.

 

[anli]

QLoud, v.0.19:

- bug fixed,
- plotting (smoothing) works much faster now.