Beyma 12G40 for a 3 way?

Ccdave · 22nd January 2012, 04:01 AM

I was wondering if the Beyma 12G40 low frequency woofer would be a good canidate for a 3 way home stereo tower cabinet? I have 2.65 cubic feet of volume with 2/ 3.5" ports. My amp is a Adcom GFA 555ii. My crossover has been designed for a 4 ohm woofer. Thanks

jerome69 · 22nd January 2012, 05:41 AM

The 12G40 is fine for the box but not the crossover. Redesign the crossover or choose an other woofer (B&C Speakers 12PH32 4ohms ?)

Ccdave · 22nd January 2012, 12:30 PM

They make a 4 ohm version of the 12G40.

a_tewinkel · 22nd January 2012, 12:33 PM

You'll have to design a new crossover in any case. A standard or previous one will simply not work.

Ccdave · 23rd January 2012, 12:52 AM

Why would a crossover designed for a 4 ohm woofer need to be re designed? How would one know what the current design is? Does every woofer that is 4 ohms require a redesigned crossover? I'm sooooooo confused

mdocod · 23rd January 2012, 01:01 AM

As I have learned here recently, unless the x-over is somewhat fine tuned for specific driver response and impedance characteristics of the drivers intended to be used, the results are not likely to be all that flat. It's *possible* for the speakers to turn out working reasonably well without a simulated design, it's however more probable that they turn out pretty far from flat.

Ccdave · 02:19 AM

Thanks for the explanation. Perhaps I should post the crossover values someone could give me a better idea?

Ccdave · 23rd January 2012, 04:02 AM

My crossover is as follows:

4 Ohm 12" Woofer Cerwin Vega
Resistor 5.0 ohms 10 watts
16 AWG Air core coil 2.2mH <0.5 ohms
Cap. 100wv 80/0uF <10%
Cap. 100wv 60/0uF <10%

4 Ohm 5.25" Midrange Scanspeak
16 AWG Air core coil 1.6 mH <0.5 ohms
16 AWG Air core coil 0.8 mH <0.5 ohms
Cap 100 mv 20/0uF <6%
Cap 100 mv 18/0uF <10%

6 ohm Tweeter 1" soft dome Scanspeak
16 AWG Air core coil 0.4 mH <0.5 ohms
Cap 100 mv 3.0/0uF <6%
Cap 100 mv 8.0/0uF < 6%

Crossover Frequincies 500Hz - 3kHz

jerome69 · 23rd January 2012, 04:41 AM

Here not need to redesign anything

Find a woofer with closed specifications

mdocod · 23rd January 2012, 06:29 AM

If you can get specific model numbers on the other drivers, then maybe we can pull some manufacture response and impedance charts and run a sim with the woofer you want to run and see if it will work.

Eric

22nd January 2012, 04:01 AM	#1
Ccdave diyAudio Member Join Date: Nov 2011	Beyma 12G40 for a 3 way? I was wondering if the Beyma 12G40 low frequency woofer would be a good canidate for a 3 way home stereo tower cabinet? I have 2.65 cubic feet of volume with 2/ 3.5" ports. My amp is a Adcom GFA 555ii. My crossover has been designed for a 4 ohm woofer. Thanks

23rd January 2012, 01:56 AM	#7
Ccdave diyAudio Member Join Date: Nov 2011	Thanks for the explanation. Perhaps I should post the crossover values someone could give me a better idea? Last edited by Ccdave; 23rd January 2012 at 02:19 AM.

23rd January 2012, 04:02 AM	#8
Ccdave diyAudio Member Join Date: Nov 2011	My current crossover set up My crossover is as follows: 4 Ohm 12" Woofer Cerwin Vega Resistor 5.0 ohms 10 watts 16 AWG Air core coil 2.2mH <0.5 ohms Cap. 100wv 80/0uF <10% Cap. 100wv 60/0uF <10% 4 Ohm 5.25" Midrange Scanspeak 16 AWG Air core coil 1.6 mH <0.5 ohms 16 AWG Air core coil 0.8 mH <0.5 ohms Cap 100 mv 20/0uF <6% Cap 100 mv 18/0uF <10% 6 ohm Tweeter 1" soft dome Scanspeak 16 AWG Air core coil 0.4 mH <0.5 ohms Cap 100 mv 3.0/0uF <6% Cap 100 mv 8.0/0uF < 6% Crossover Frequincies 500Hz - 3kHz

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22nd January 2012, 05:41 AM	#2
jerome69 diyAudio Member Join Date: Feb 2008 Location: Lyon	The 12G40 is fine for the box but not the crossover. Redesign the crossover or choose an other woofer (B&C Speakers 12PH32 4ohms ?)

22nd January 2012, 12:30 PM	#3
Ccdave diyAudio Member Join Date: Nov 2011	They make a 4 ohm version of the 12G40.

22nd January 2012, 12:33 PM	#4
a_tewinkel diyAudio Member Join Date: Feb 2008 Location: Enschede, Overijssel	You'll have to design a new crossover in any case. A standard or previous one will simply not work.

23rd January 2012, 12:52 AM	#5
Ccdave diyAudio Member Join Date: Nov 2011	Why would a crossover designed for a 4 ohm woofer need to be re designed? How would one know what the current design is? Does every woofer that is 4 ohms require a redesigned crossover? I'm sooooooo confused

23rd January 2012, 01:01 AM	#6
mdocod diyAudio Member Join Date: Dec 2011 Location: Black Forest, CO	As I have learned here recently, unless the x-over is somewhat fine tuned for specific driver response and impedance characteristics of the drivers intended to be used, the results are not likely to be all that flat. It's possible for the speakers to turn out working reasonably well without a simulated design, it's however more probable that they turn out pretty far from flat.

23rd January 2012, 04:41 AM	#9
jerome69 diyAudio Member Join Date: Feb 2008 Location: Lyon	Here not need to redesign anything Find a woofer with closed specifications

23rd January 2012, 06:29 AM	#10
mdocod diyAudio Member Join Date: Dec 2011 Location: Black Forest, CO	If you can get specific model numbers on the other drivers, then maybe we can pull some manufacture response and impedance charts and run a sim with the woofer you want to run and see if it will work. Eric

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