Midrange driver question.

a007udio · 18th January 2008, 04:24 AM

Hello.

I have buy B&C 8PE21 for my midrange driver in my new 4 way speakers. It would be used from around 300 Hz to 1,6kHz and the crossover will be active.
The question is, which tipe of box would be apropriate for this job?
reflex, closed or maybe even open baffle???

Thanks for help.

Regards.

a007udio · 18th January 2008, 04:16 PM

Fs 87.5 Hz
Re 5.6 Ohm
Qes 0.2
Qms 3.8
Qts 0.19
Vas 13 (0.46) dm3 (ft3)
Sd 220 (34.1) cm2 (in2)
Eta Zero 4.1 %
Xmax +/- 1 mm
Xvar +/- 4.5 mm
Mms 18 g
Bl 16.6 Txm
Le 0.5 mH

BHTX · 18th January 2008, 06:14 PM

It's a high efficiency mid with a very low Qts. A suitable sealed enclosure would be very small, which could have negative effects. I don't really see the point in going ported, unless you absolutely have to -to lower the highpass xover point (you already stated 300hz, so I'm assuming this won't be the case). But having a ported mid tends to cause more problems than it's worth imo. I say OB or possibly a horn of some sort (no experience with horns).

PeteMcK · 18th January 2008, 10:27 PM

Simm'd this in WINISD, for best response sealed box is 1 L ! and -3dB at ~300Hz; you'd have to get your xover spot on...
A more practical size is ~4 L, -3dB at 400Hz. Probably best to move your xover point higher.

In a ported box, 4L , 150Hz, -3db is ~150Hz. You could port the enclosure & close it if the port causes problems, but if you're going 4 way (why?), probably better to change xover point or use a driver that suits your chosen xover point

If it's High efficiency & sensitivity works with your other drivers, then OB might be best, you'd just have to get the baffle width right

a007udio · 19th January 2008, 08:49 AM

Yes i would like to use OB to but i have no expiriance with them.
How can i calculate the right width ?
I was thinking around 40 cm.

Can anyone help me with this?

Thanks.

BHTX · 19th January 2008, 11:11 AM

Could use Thorsten's xbaffle.xls spreadsheet to get somewhat of an idea. I have it, but don't remember where I got the download link, and I can't seem to find one anywhere. We could work out a way for me to send it to you if you want. Otherwise, maybe someone else will post a link and/or offer something else.

tinitus · 19th January 2008, 02:44 PM

Maybe apperiodic(closed with acoustic valve)...I wouldnt even think of BR fore a midrange

Thawach · 20th January 2008, 05:14 AM

Hi

Here is the link download

http://www.uploadtoday.com/download/...417c2e67d25560

a007udio · 20th January 2008, 11:20 AM

i cant download the file from your link.

Regards.

BHTX · 20th January 2008, 12:31 PM

PM me your email and I'll send you the spreadsheet.
..The forum will give an error message when attempting to post it, saying the file is too large.

18th January 2008, 04:24 AM	#1
a007udio diyAudio Member Join Date: Feb 2005 Location: earth	Midrange driver question. Hello. I have buy B&C 8PE21 for my midrange driver in my new 4 way speakers. It would be used from around 300 Hz to 1,6kHz and the crossover will be active. The question is, which tipe of box would be apropriate for this job? reflex, closed or maybe even open baffle??? Thanks for help. Regards.

18th January 2008, 10:27 PM	#4
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Sydney	Simm'd this in WINISD, for best response sealed box is 1 L ! and -3dB at ~300Hz; you'd have to get your xover spot on... A more practical size is ~4 L, -3dB at 400Hz. Probably best to move your xover point higher. In a ported box, 4L , 150Hz, -3db is ~150Hz. You could port the enclosure & close it if the port causes problems, but if you're going 4 way (why?), probably better to change xover point or use a driver that suits your chosen xover point If it's High efficiency & sensitivity works with your other drivers, then OB might be best, you'd just have to get the baffle width right __________________ ‘today… there lives alongside the twentieth century the tenth or thirteenth. A hundred million people use electricity and still believe in the magic power of signs and exorcisms” Trotsky

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18th January 2008, 04:16 PM	#2
a007udio diyAudio Member Join Date: Feb 2005 Location: earth	Fs 87.5 Hz Re 5.6 Ohm Qes 0.2 Qms 3.8 Qts 0.19 Vas 13 (0.46) dm3 (ft3) Sd 220 (34.1) cm2 (in2) Eta Zero 4.1 % Xmax +/- 1 mm Xvar +/- 4.5 mm Mms 18 g Bl 16.6 Txm Le 0.5 mH

18th January 2008, 06:14 PM	#3
BHTX diyAudio Member Join Date: Feb 2006	It's a high efficiency mid with a very low Qts. A suitable sealed enclosure would be very small, which could have negative effects. I don't really see the point in going ported, unless you absolutely have to -to lower the highpass xover point (you already stated 300hz, so I'm assuming this won't be the case). But having a ported mid tends to cause more problems than it's worth imo. I say OB or possibly a horn of some sort (no experience with horns).

19th January 2008, 08:49 AM	#5
a007udio diyAudio Member Join Date: Feb 2005 Location: earth	Yes i would like to use OB to but i have no expiriance with them. How can i calculate the right width ? I was thinking around 40 cm. Can anyone help me with this? Thanks.

19th January 2008, 11:11 AM	#6
BHTX diyAudio Member Join Date: Feb 2006	Could use Thorsten's xbaffle.xls spreadsheet to get somewhat of an idea. I have it, but don't remember where I got the download link, and I can't seem to find one anywhere. We could work out a way for me to send it to you if you want. Otherwise, maybe someone else will post a link and/or offer something else.

19th January 2008, 02:44 PM	#7
tinitus diyAudio Moderator Join Date: Nov 2005	Maybe apperiodic(closed with acoustic valve)...I wouldnt even think of BR fore a midrange

20th January 2008, 05:14 AM	#8
Thawach diyAudio Member Join Date: Dec 2007	Hi Here is the link download http://www.uploadtoday.com/download/...417c2e67d25560

20th January 2008, 11:20 AM	#9
a007udio diyAudio Member Join Date: Feb 2005 Location: earth	i cant download the file from your link. Regards.

20th January 2008, 12:31 PM	#10
BHTX diyAudio Member Join Date: Feb 2006	PM me your email and I'll send you the spreadsheet. ..The forum will give an error message when attempting to post it, saying the file is too large.

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