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DJ7UA > DSP 02.11.96 23:54l 71 Lines 2645 Bytes #-10475 (0) @ WW
BID : 02B609DB0IZ
Read: DH9MAG LX2GT DF3EH DJ2TK DL1EEC DK5RAS GUEST
Subj: SPEAKER ANALYSIS BY DSP????
Path: DB0AAB<DB0PV<DB0WGS<DB0RGB<DB0ABH<DB0SRS<DB0SIF<DB0AIS<DB0IZ
Sent: 961102/2024z @:DB0IZ.#NRW.DEU.EU [JO31NE, Op: DL6EE] $:02B609DB0IZ
de DJ7UA @ DB0IZ.#NRW.DEU.EU (Mario)
to DSP @ WW
hello, dsp-users!
i'm looking for a possibility to analyse homebrewed speakers for
hifi applications.
the target is to record the frequency response (realtime online)
and the group delay or the waterfall diagramm (TEF) indicating the pulse
response.
the idea is to use the dsp-kit DSK TMS320C26 (normally used as cw filter)
or a soundcard.
so far, i tested the programms CEVAL/RESP.ASM and the DSK_AA26.ASM.
it's all not what i'm really looking for.
CEVAL is quite nice, but gives some odd results and program-errors
under real tests at speakers. unfortunately the frequency range is
not sufficient (not low/high enough).
but the basic idea of sending test-pulses through the test target
is the right way as a principle, i think.
no online-analysis is supported.
DSK_AA26 is a fragmental application, not powerfull enough to be used
for determining the system response.
the frequency is stepped through rather roughly and it gives only an
overview on the amplitude frequency response.
so, do u know a more powerfull solution using the dsk?
concerning the SOUNDCARD, i tested COOL-EDIT for WIN95.
that is quite amazing, what u can do with it.
interesting is to produce pink or white random noise for testing the frequency
response. but i couldn't start an online sampling and fft analysing.
they don't offer a group delay analysis neither.
in the internet i found some software for the soundblaster programming,
but all the the stuff was worthless for my target.
there are some software peoducts for speaker analysis now offered, but
at a rather high price and i'm afraid that the performance will be poor.
do u have experience with a soundcard solution for that purpose?
finally, i will tell u how i have checked my equipment until today:
i start a test-cd with pink noise in loop mode.
with an small electret mike i take the probe in the playback room
(my living room). i feed it into an analog-input card made by advanced
analogic and produce a DFT, done on the card via a build-in DSP.
then i send the dft-figures to the pc and desplay it as an on line analyser.
that works quite well for determining the frequency response,
but says nothing about pulse response.
for reason of high soundpressure level i'm actually using hornloaded mid-
and highrange speakers and a 15 inch wooofer, but i'm afraid the horns
are causing some group delay that affects the pulse response.
so before redesigning the speakers i would like to improve my
test equipment - espacially using the DSK or a SOUNDCARD as a state of the art
solution.
can u give a hint?
thanks in advance,
mario
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