I have designed a 3 way + sub in a MTMWWSubSub speakers:
Tweeter: Dynaudio T330D: 2kHz (LR4) - 20kHz
Mid-woofers: Twin SS18W8531G00: 150Hz (LR4) - 2kHz (LR4)
Bass-woofers: Twin SS26W8861T00: 52Hz (BW2) - 150Hz (LR4)
Sub-woofers: Twin Peerless830500: 20Hz - 52Hz (XO slop to be decided)
The bass-woofers are in a sealed box with a F3=52Hz Q=0.68 with no electronic LP or HP. The lowest room mode is around 24Hz.
I think 0.68 is close enough to 0.707 so I could assume the roll-off response of the bass-woofers to be BW2. The question is how to cross the bass-woofers to the sealed subs?
(1) I initially planned for EQing the sub to be flat then LP at 52Hz with a BW2. Connected in reverse polarity, this would have a 3dB bump at 52Hz, which I could live with. But I am worried about 2 problems: (a) at 204Hz it is only 24dB down and at 406Hz only 36dB down. I don't want the subs to contribute to the sound above 200Hz. (b) I have just realised that because the bass-woofers are crossed at 150Hz with a LR4, there would be a substantial amount of phase shift around the area, so a BW2 with the sub would not work! Please let me know if this is a problem or not.
(2) Put an electronic BW2 HP at 52Hz for the bass-woofers to make it a LR4 HP. Use a LR4 LP for the sub. This would work but the group delay may be unacceptable! It was for this reason I initially choose the 3way+sub approach instead of 4way to avoid large group delay at low frequencies. This effectively converts it to a 4way.
Any solutions?
Many thanks
Bill
Tweeter: Dynaudio T330D: 2kHz (LR4) - 20kHz
Mid-woofers: Twin SS18W8531G00: 150Hz (LR4) - 2kHz (LR4)
Bass-woofers: Twin SS26W8861T00: 52Hz (BW2) - 150Hz (LR4)
Sub-woofers: Twin Peerless830500: 20Hz - 52Hz (XO slop to be decided)
The bass-woofers are in a sealed box with a F3=52Hz Q=0.68 with no electronic LP or HP. The lowest room mode is around 24Hz.
I think 0.68 is close enough to 0.707 so I could assume the roll-off response of the bass-woofers to be BW2. The question is how to cross the bass-woofers to the sealed subs?
(1) I initially planned for EQing the sub to be flat then LP at 52Hz with a BW2. Connected in reverse polarity, this would have a 3dB bump at 52Hz, which I could live with. But I am worried about 2 problems: (a) at 204Hz it is only 24dB down and at 406Hz only 36dB down. I don't want the subs to contribute to the sound above 200Hz. (b) I have just realised that because the bass-woofers are crossed at 150Hz with a LR4, there would be a substantial amount of phase shift around the area, so a BW2 with the sub would not work! Please let me know if this is a problem or not.
(2) Put an electronic BW2 HP at 52Hz for the bass-woofers to make it a LR4 HP. Use a LR4 LP for the sub. This would work but the group delay may be unacceptable! It was for this reason I initially choose the 3way+sub approach instead of 4way to avoid large group delay at low frequencies. This effectively converts it to a 4way.
Any solutions?
Many thanks
Bill
Put the SS26W8861T00 in an appropriately designed BR box & sell the unnecessary Peerless drivers?
Peter,
Thanks for your reply. Glad to have another forum member from Sydney.
I am rushing up to finish the speakers in a couple of weeks because the wife complained having loads of stuff all over the places and my friends will be coming over to stay with us over Easter. I tried using Speaker Workshop to measure the drivers, but after doing all the impedance measurements, the PC went south. I got a new motherboard for the PC but the new sound card did not have adequate resolution. I then used the M-Audio Transit and somehow burnt it. I then bought a Creative Sound soundcard but found it clips no matter what! just a bad quality soundcard. So I am temporarily giving it up and use simulations to complete the speakers.
By the way, do you have measurement equipment?
Regards,
Bill
Thanks for your reply. Glad to have another forum member from Sydney.
I am rushing up to finish the speakers in a couple of weeks because the wife complained having loads of stuff all over the places and my friends will be coming over to stay with us over Easter. I tried using Speaker Workshop to measure the drivers, but after doing all the impedance measurements, the PC went south. I got a new motherboard for the PC but the new sound card did not have adequate resolution. I then used the M-Audio Transit and somehow burnt it. I then bought a Creative Sound soundcard but found it clips no matter what! just a bad quality soundcard. So I am temporarily giving it up and use simulations to complete the speakers.
By the way, do you have measurement equipment?
Regards,
Bill
I use Synrta (free download) and a cheap electret mic (no calibration); This is useful for getting tweeter levels right & dealing with peaks, but not much use at the low end, too many room problems complicate the readings.
I must get off my **** some day and drag the gear outside and see how it goes there - but I'd rather be listening to music 🙂
I must get off my **** some day and drag the gear outside and see how it goes there - but I'd rather be listening to music 🙂
Yes. I am dreaming about having somebody to lent me the gears for a day to do some acoustic measurement.
I want to get accurate frequency response curves of the drivers from 200Hz above with a 5ms gate, and some near field measurements of the woofers.
I want to get accurate frequency response curves of the drivers from 200Hz above with a 5ms gate, and some near field measurements of the woofers.
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