Hi,
Please list parameters in order of their importance for a bandpass enclosure to cover 2 octaves. I believe the bandpass puts lots of strain on the driver so the cone should be pretty thick/sturdy. I know simple simulation in unibox can give out the frequency response but I want to know from parameters point of view what is more important and what is less.
Warm Regards,
WonderfulAudio
Please list parameters in order of their importance for a bandpass enclosure to cover 2 octaves. I believe the bandpass puts lots of strain on the driver so the cone should be pretty thick/sturdy. I know simple simulation in unibox can give out the frequency response but I want to know from parameters point of view what is more important and what is less.
Warm Regards,
WonderfulAudio
as far as I know the 4th order bandpass is not much critical on system Q if some ripple is accepted. Then the enclosure can have variation in volume.
Bose used pretty standard drivers even in eighth order bandpasses but here variations in driver parameters were critical.
Bandpass boxes can be easily damaged if driven hard because audibility of higher order distortion is lessened.
Bose used pretty standard drivers even in eighth order bandpasses but here variations in driver parameters were critical.
Bandpass boxes can be easily damaged if driven hard because audibility of higher order distortion is lessened.
here I had a random modification but end result sounded pretty well!
Also stiffened the cone with extra big dustcap added diy
Also stiffened the cone with extra big dustcap added diy
Depends on the order and how "correct" you want to be. If you consider the rear chamber, you want a suitable driver for that.
For 4th order the rear chamber is sealed, so you generally want woofers that do well in sealed enclosures.
Along similar lines, 6th order uses a ported rear enclosure, so typically uses a woofer that's more suited to ported boxes. Of course all of this is on a continuum, and how large a box you want, how you want to tune, etc. come into play.
From a more general standpoint, if you can find a woofer with much greater Xmech than Xmax, and/or one that is suspension limited (instead of the mechanical limit being the voice coil crashing into the back plate), those things can help as well. Bandpass boxes can mask some of the distortion you'd normally hear when a driver is being pushed too hard, so a more damage resistant driver can be a benefit. Or just use little power, a high pass/infrasonic filter, sealed rear chamber, etc., so you are less likely to get into excursion trouble.
If you are using large amounts of power, thermal considerations can also come into play, since some configurations may trap more heat than a standard box.
For 4th order the rear chamber is sealed, so you generally want woofers that do well in sealed enclosures.
Along similar lines, 6th order uses a ported rear enclosure, so typically uses a woofer that's more suited to ported boxes. Of course all of this is on a continuum, and how large a box you want, how you want to tune, etc. come into play.
From a more general standpoint, if you can find a woofer with much greater Xmech than Xmax, and/or one that is suspension limited (instead of the mechanical limit being the voice coil crashing into the back plate), those things can help as well. Bandpass boxes can mask some of the distortion you'd normally hear when a driver is being pushed too hard, so a more damage resistant driver can be a benefit. Or just use little power, a high pass/infrasonic filter, sealed rear chamber, etc., so you are less likely to get into excursion trouble.
If you are using large amounts of power, thermal considerations can also come into play, since some configurations may trap more heat than a standard box.
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Hi,
I was simulating many drivers in unibox and got a surprisingly small box for MCM 55-2421. Its too good to be true, I mean just 13 litres. If true, then what are the TS parameters which result in such a small box. Its unbelievable.
Datasheet here
Can somebody please explain?
Warm Regards,
WonderfulAudio
I was simulating many drivers in unibox and got a surprisingly small box for MCM 55-2421. Its too good to be true, I mean just 13 litres. If true, then what are the TS parameters which result in such a small box. Its unbelievable.
Datasheet here
Can somebody please explain?
Warm Regards,
WonderfulAudio
T/S max flat vented alignment:
Vented net volume (Vb) (L) = 20*Vas*Qts'^3.3
(Ft^3 = (Vb)/~28.31685)
Vented box tuning (Fb) (Hz) = 0.42*Fs*Qts'^-0.96
F3 (Hz) = Fs*0.28*Qts'^-1.4
(Qts'): (Qts) + any added series resistance (Rs)
Note that Qts' dominates with Vas second, so when both are low..........
Vented net volume (Vb) (L) = 20*Vas*Qts'^3.3
(Ft^3 = (Vb)/~28.31685)
Vented box tuning (Fb) (Hz) = 0.42*Fs*Qts'^-0.96
F3 (Hz) = Fs*0.28*Qts'^-1.4
(Qts'): (Qts) + any added series resistance (Rs)
Note that Qts' dominates with Vas second, so when both are low..........
Bandpass boxes are vented boxes where the stiffness (Vas) of the driver is modified by the sealed enclosure and the only output is from the port. The same thing that gives you a small box in a vented box gives you a small box in a bandpass box, namely low Qts and low Vas.
The new effective Vas for a bandpass drive is Vas+Vs/(Vas+Vs), where Vs is the sealed volume. The New effective Q is Qts*sqrt(Vas/Vs+1) that can give you the front volume from some curve fit if you want, or you can pick it based on response shape.. The tuning frequency is Fb=Fs*sqrt(Vas/Vs+1)
The vented volume alters your bandpass a bigger volume gives a narrower bandwidth and more gain and a smaller volume gives a wider bandwidth and less gain. The sealed volume generally alters the frequency of tuning (or the center frequency of the bandpass) and thus also changes the gain somewhat.