Hello guys! A great conctructive discussion is about to go down.
(Lets not discuss drivers choice because my cost for them is lower an 25$ a pop..)
I need some input on how to add a second bass driver in 4 ohm (http://www.radio63.narod.ru/page/as/alphard/pict/LW80A4.pdf) to an existing 3-way design which already has a 8 ohm bass driver in place (https://mag-audio.com/image/catalog/Loudspeakers-8/M0821.pdf).
This is is because the original design uses a better sounding 8" 8 ohm PRO BASS driver (MAG 0821), but with a much higher FS of 60HZ, and I want to go lower and add a second driver with FS of 30HZ (ALPHARD/MACHETE/DEAF BOUNCE LW80-A4).
Additionally, I may want to keep the 6.2mH badass (only 0.19 OHM resistance) toroidal inductor cores I have had build for that original 3-way using only 1 8 ohm bass driver, the mag 0821.
I will also incorporate Troels Gravesens pre-amplifier HPF (-3db @ 60hz) for the bass section to make sure I dont tear out or burn the voice coils from abuse. (high-pass-filter)
Last question: I understand I can no longer use simple Zobel network for the bass, because it either wont work on the 4 ohm unit or cut the 8" units operation? If I can, please come forward with calculations.
Original design: (1st order passive 3-way)
tweeter (6" waveguided XT25TG30-04)
450hz -27db 57db
600hz -24db 65db
900hz -21db 74db
1200hz -18db 79db
1800hz -15db 84db
2400hz -12db 86db
3600hz -9db 88db
4800hz -6db 89db
7200hz -3db 90db impedance 4.0 C1 = 5.52uF
9600hz 0db 92.5db
14400hz 0db 91db
19200hz 0db 90db
midrange (BOWERS & WILKINS neo yellow kelvar Mclaren, Volvo 3.6")
ZOBEL: C = 2.13 uF - 6.55uf Rc = 11.88 Ohms
38 -24db 61db
56 -21db 65db
75 -18db 69db
112 -15db 73db
150 -12db 77db
225hz -9db 81db
300hz -6db 85db
450hz -3db 88db imp 9.3ohm C1 = 37.99 uF
600hz -0db 92db
900hz -0db 92db
1200hz -0db 92db
1800hz -3db 89db imp 9.7ohm L1 = 0.86 mH
2400hz -6db 86db
3600hz -9db 83db
4800hz -12db 80db
7200hz -15db 77db
9600hz -18db 74db
14400hz -21db 71db
19200hz -24db 69db
woofer (MAG 0821) ZMIN 8.5 OHM (@ 300hz) 92 DB ZOBEL: C = 11.52 uF Rc = 10.63 Ohms
38 -0db 75db
56 -0db 81db
75 -0db 85db imp 45.0 ohm
112 -0db 89db imp 18.0 ohm
150 -0b 91db imp 10.0 ohm
225hz -3db 89db imp 8.5 ohm L1 = 6.01 mH
300hz -6db 86db
450hz -9db 83db imp 8.5 rising fast
600hz -12db 80db
900hz -15db 76db
1200hz -18db 70db
1800hz -21db 70db imp 18ohm!! + breakup
2400hz -24db 68db
3600hz -27db 61db
This original system is about 91.5db sensitive.
Now I want to add a second bass driver, to extend the low end response, help out with baffle step loss, and will therefore enlarge the speakers cabinets to accomodate the driver:
LW80-A4 ZMIN 5.8 OHM (@ 300hz) 88 DB
38 -0db 76 45.0 OHM
56 -0db 81.5 20.0 OHM
75 -0db 84 9.0 OHM
112 -0db 86 7.0 OHM
150 -0bb 88 6.2 OHM
225hz -0db 88.5 5.8 OHM
300hz -0db 88.5 5.8 OHM
450hz -0db 89 6.2 OHM
600hz -0db 89.5 7.0 OHM
900hz -0db 90.0 7.6 OHM
1200hz -0db 90.0 8.6 OHM
1800hz -0db 87.0 9.6 OHM
2400hz -0db 86.5 10.6 OHM
3600hz -0db 86.0 11.6 OHM
https://geoffthegreygeek.com/calculator-speakers-in-parallel/
HERE IS THE TOTAL IMPEDANCE FOR THE BASS SECTION IF I ADD THE SECOND WOOFER: we see that the total impedance isn't too low, for 4 ohm amps. This solves at least 50% of the issues.
I guess the only real aspect of this idea, is that the 4 ohm unit bass driver will be rolling off (LPF) quicker than the 8 ohm unit, because its controlled by the same 6.2mH coil. Can you please verity this? If this is so, its just perfect, as the cheaper chinese 4 ohm unit wont go into as much voicing overlap with the better sounding Unit. But will my original 8 ohm PRO unit still be getting crossed @ 225hz?
If not, where will it be crossing itself? I can adjust the HPF on the midrange to get a match on the final system response.
Basically Im trying to figure out if my idea of controlling the LPF works.
What will happen with my tune of the MAG0821 (-3db@225hz, 8.5ohm min) if a add LW80-A4 (5.8 ohm min) in parrallel, all while keeping the 6.2mH inductor.
LW80-A4 IN PARALLEL TO MAG 0821 (approx sensitivity, exact resistance)
(59.4 watts to 4 ohm unit, 40.6 watts to 8 ohm units : power draw from 100w)
38 -0db 78.5db 22.0 OHM
56 -0db 84.0db 10.0 OHM
75 -0db 88.0db 7.5 OHM
112 -0db 91.0db 5.04 OHM
150 -0bb 93.0db 3.82 OHM
225hz -3db 91.0db 3.45 OHM L1 = 6.2 mH
300hz -6db 88.0db 3.45 OHM
450hz -9db 85.0db 3.67 OHM
600hz -12db 82.0db 3.98 OHM
900hz -15db 78.0db 4.65 OHM
1200hz -18db 74.0db 5.46 OHM
1800hz -21db 70.0db 6.58 OHM
2400hz -24db 68.5db 7.37 OHM
3600hz -27db 63.0db 8.36 OHM
Thanks for any revelant help, will be greatly appreciated.
(Lets not discuss drivers choice because my cost for them is lower an 25$ a pop..)
I need some input on how to add a second bass driver in 4 ohm (http://www.radio63.narod.ru/page/as/alphard/pict/LW80A4.pdf) to an existing 3-way design which already has a 8 ohm bass driver in place (https://mag-audio.com/image/catalog/Loudspeakers-8/M0821.pdf).
This is is because the original design uses a better sounding 8" 8 ohm PRO BASS driver (MAG 0821), but with a much higher FS of 60HZ, and I want to go lower and add a second driver with FS of 30HZ (ALPHARD/MACHETE/DEAF BOUNCE LW80-A4).
Additionally, I may want to keep the 6.2mH badass (only 0.19 OHM resistance) toroidal inductor cores I have had build for that original 3-way using only 1 8 ohm bass driver, the mag 0821.
I will also incorporate Troels Gravesens pre-amplifier HPF (-3db @ 60hz) for the bass section to make sure I dont tear out or burn the voice coils from abuse. (high-pass-filter)
Last question: I understand I can no longer use simple Zobel network for the bass, because it either wont work on the 4 ohm unit or cut the 8" units operation? If I can, please come forward with calculations.
Original design: (1st order passive 3-way)
tweeter (6" waveguided XT25TG30-04)
450hz -27db 57db
600hz -24db 65db
900hz -21db 74db
1200hz -18db 79db
1800hz -15db 84db
2400hz -12db 86db
3600hz -9db 88db
4800hz -6db 89db
7200hz -3db 90db impedance 4.0 C1 = 5.52uF
9600hz 0db 92.5db
14400hz 0db 91db
19200hz 0db 90db
midrange (BOWERS & WILKINS neo yellow kelvar Mclaren, Volvo 3.6")
ZOBEL: C = 2.13 uF - 6.55uf Rc = 11.88 Ohms
38 -24db 61db
56 -21db 65db
75 -18db 69db
112 -15db 73db
150 -12db 77db
225hz -9db 81db
300hz -6db 85db
450hz -3db 88db imp 9.3ohm C1 = 37.99 uF
600hz -0db 92db
900hz -0db 92db
1200hz -0db 92db
1800hz -3db 89db imp 9.7ohm L1 = 0.86 mH
2400hz -6db 86db
3600hz -9db 83db
4800hz -12db 80db
7200hz -15db 77db
9600hz -18db 74db
14400hz -21db 71db
19200hz -24db 69db
woofer (MAG 0821) ZMIN 8.5 OHM (@ 300hz) 92 DB ZOBEL: C = 11.52 uF Rc = 10.63 Ohms
38 -0db 75db
56 -0db 81db
75 -0db 85db imp 45.0 ohm
112 -0db 89db imp 18.0 ohm
150 -0b 91db imp 10.0 ohm
225hz -3db 89db imp 8.5 ohm L1 = 6.01 mH
300hz -6db 86db
450hz -9db 83db imp 8.5 rising fast
600hz -12db 80db
900hz -15db 76db
1200hz -18db 70db
1800hz -21db 70db imp 18ohm!! + breakup
2400hz -24db 68db
3600hz -27db 61db
This original system is about 91.5db sensitive.
Now I want to add a second bass driver, to extend the low end response, help out with baffle step loss, and will therefore enlarge the speakers cabinets to accomodate the driver:
LW80-A4 ZMIN 5.8 OHM (@ 300hz) 88 DB
38 -0db 76 45.0 OHM
56 -0db 81.5 20.0 OHM
75 -0db 84 9.0 OHM
112 -0db 86 7.0 OHM
150 -0bb 88 6.2 OHM
225hz -0db 88.5 5.8 OHM
300hz -0db 88.5 5.8 OHM
450hz -0db 89 6.2 OHM
600hz -0db 89.5 7.0 OHM
900hz -0db 90.0 7.6 OHM
1200hz -0db 90.0 8.6 OHM
1800hz -0db 87.0 9.6 OHM
2400hz -0db 86.5 10.6 OHM
3600hz -0db 86.0 11.6 OHM
https://geoffthegreygeek.com/calculator-speakers-in-parallel/
HERE IS THE TOTAL IMPEDANCE FOR THE BASS SECTION IF I ADD THE SECOND WOOFER: we see that the total impedance isn't too low, for 4 ohm amps. This solves at least 50% of the issues.
I guess the only real aspect of this idea, is that the 4 ohm unit bass driver will be rolling off (LPF) quicker than the 8 ohm unit, because its controlled by the same 6.2mH coil. Can you please verity this? If this is so, its just perfect, as the cheaper chinese 4 ohm unit wont go into as much voicing overlap with the better sounding Unit. But will my original 8 ohm PRO unit still be getting crossed @ 225hz?
If not, where will it be crossing itself? I can adjust the HPF on the midrange to get a match on the final system response.
Basically Im trying to figure out if my idea of controlling the LPF works.
What will happen with my tune of the MAG0821 (-3db@225hz, 8.5ohm min) if a add LW80-A4 (5.8 ohm min) in parrallel, all while keeping the 6.2mH inductor.
LW80-A4 IN PARALLEL TO MAG 0821 (approx sensitivity, exact resistance)
(59.4 watts to 4 ohm unit, 40.6 watts to 8 ohm units : power draw from 100w)
38 -0db 78.5db 22.0 OHM
56 -0db 84.0db 10.0 OHM
75 -0db 88.0db 7.5 OHM
112 -0db 91.0db 5.04 OHM
150 -0bb 93.0db 3.82 OHM
225hz -3db 91.0db 3.45 OHM L1 = 6.2 mH
300hz -6db 88.0db 3.45 OHM
450hz -9db 85.0db 3.67 OHM
600hz -12db 82.0db 3.98 OHM
900hz -15db 78.0db 4.65 OHM
1200hz -18db 74.0db 5.46 OHM
1800hz -21db 70.0db 6.58 OHM
2400hz -24db 68.5db 7.37 OHM
3600hz -27db 63.0db 8.36 OHM
Thanks for any revelant help, will be greatly appreciated.
Last edited:
Get a proper active EQ solution to boost the bass of the MO 821 and at the same time take into account the protection against over excursion.
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