Hello to all of You,
Some time ago I decided to built myself a good speaker set for my
computer.
I have already built two Visaton CT Center 81's
(http://www.visaton.com/en/bauvorschlaege/computer/856/index.html),
they
sound great but need a subwoofer which is the next I will build (this one
http://www.visaton.com/en/bauvorschlaege/subwoofer/564/index.html),
together
with 3 more of these little speakers (their looks are even better then
their
sound, though one might think otherwise when looking at the one on the
site - I also did not use the grid).
I also wanted to build my own "5.2" amplifier (two separate amps for the
speakers in the subwoofer, that's what I meant with the .2 and the ""'s)
based on not-too-expensive integrated amplifiers but now I managed to lay
my
hands on a Technics 5.1 home cinema receiver for much less money than the
diy option would cost (the sub output is passive so I will have to build
an
amplifier for that, but that's no problem).
However, now I have another problem. The receiver wants surround speakers
of
at least 6 ohms where the CT Center 81 is only 4. In the past there was a
CT
Center 80, the difference was in the filter that was less sophisticated
but
also had an impedance of 6 ohms. I could of course use that design to
built
into my speakers but I think it would not improve sound quality (it won't
be
just for fun that Visaton changed the design).
Unfortunately I have not much knowledge about the math behind filters. I
was
hoping to find someone in this group able and of course willing to have a
look at the schematics and the technical data I have put at the bottom of
my
post and see of he/she would know how I might change the values of some
components in my current filters.
Many thanks in advance!
Yours sincerely,
Rene
The filter of my speakers is:
http://www.visaton.com/bilder/weichen/gross/ct_center81_w.gif.
The old
version can be seen on
http://www.visaton.com/bilder/weichen/gross/ct_center80_w.gif
but as I
said,
I would rather use the first one.
Data from the SC5 tweeter are here:
Nominal power handling with high pass 60 Watt (12 dB/Okt.; 6000 Hz)
Peak power handling with high pass 100 Watt (12 dB/Okt.; 6000 Hz)
Nominal impedance 8 Ohm
Frequency response (-10 dB) 1500 - 22000 Hz
Mean sound pressure level 90 dB (1W/1m)
Resonance frequency fs 2500 Hz
Magnetic induction 0,7 Tesla
Magnetic flux 33 µWeber
Voice coil diameter 1,3 cm
Height of winding 0,18 cm
Cutout diameter 4,8 cm
Net weight 0,098 kg
D.C. resistance Rdc 6,2 Ohm
Inductance of the voice coil L 0,08 mH
And here are the data of the F8SC "woofer":
Nominal power handling 20 Watt
Peak power handling 30 Watt
Nominal impedance 8 Ohm
Frequency response (-10 dB) 80 - 15000 Hz
Mean sound pressure level 82 dB (1W/1m)
Maximum cone displacement 5 mm
Resonance frequency fs 103 Hz
Magnetic induction 0,8 Tesla
Magnetic flux 150 µWeber
Height of front pole-plate 3 mm
Voice coil diameter 2 cm
Height of winding 0,45 cm
Cutout diameter 7,6 cm
Net weight 0,25 kg
D.C. resistance Rdc 7,7 Ohm
Mechanical Q factor Qms 3,03
Electrical Q factor Qes 1,52
Total Q factor Qts 1,01
Equivalent volume Vas 1,4 l
Effective piston area Sd 30 cm2
Dynamically moved mass Mms 2,2 g
Force factor Bxl 2,69 T · m
Inductance of the voice coil L 0,35 mH
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