A sealed sub vs one designed for ib or oversized box, the qts dictates that.
How big of a difference can be in sound quality?
How big of a difference can be in sound quality?
An infinite baffle or oversized box limits placement options.
Since the room plays such a large role in "sound quality", placement can make a big difference.
You would have to measure the difference to quantify how "big" it is.
Since the room plays such a large role in "sound quality", placement can make a big difference.
You would have to measure the difference to quantify how "big" it is.
A sealed subwoofer radiates as a monopole at low frequencies, i.e., equally in all directions. That's irrespective whether or not it is in an oversized box or not. On the other hand, an infinite baffle subwoofer would nominally need to be mounted in one of the room boundaries, so as to meet the "infinite" requirement of its infinite baffle mounting. Placing a sealed subwoofer closer and closer to a room boundary would tend to make it behave like a subwoofer in an infinite baffle, due to the way the monopole radiation pattern is modified by the boundary.
My question is strictly abou sealed vs sealed big. A woofer with high qts needs to have the box more than double than his VAS a woofer with normal qts designed for ported and sealed needs to have a box as the vas or under, in my experience box es lower then vas make the bass sound congested and not good. I wonder if ib or large box is worth it. So far i am getting only random responses
It isn't clear what you mean by a "congested" bass sound. Some elaboration would be worthwhile. Maybe even provide us with the driver Vas, Fs, Qts, Vb, and Qtc for the low-frequency alignments in question. Some concrete data would be very helpful.
All other things being equal, it just boils down to the frequency response of the subwoofer and its −3dB low-frequency cut-off point. The combination of Vas and Qts can be adjusted through an appropriate choice of box volume, Vb, to attain a value of Qtc for the chosen low-frequency alignment. The driver's Fs will determine the resonance frequency of the driver in the sealed enclosure, Fc, which in turn allows the attenuation or peakiness of the SPL at Fc to be determined.
All other things being equal, it just boils down to the frequency response of the subwoofer and its −3dB low-frequency cut-off point. The combination of Vas and Qts can be adjusted through an appropriate choice of box volume, Vb, to attain a value of Qtc for the chosen low-frequency alignment. The driver's Fs will determine the resonance frequency of the driver in the sealed enclosure, Fc, which in turn allows the attenuation or peakiness of the SPL at Fc to be determined.
Here's a hopefully non-random response:
As you decrease the size of a sealed box, the internal air-spring compliance decreases. ie, smaller box = harder for the driver to compress the air. This reduces efficiency at LF**.
** NB - There will be some efficiency gain around the system resonance. I'm talking about what happens below that.
Of course, you can EQ the difference. So long as the driver has enough thermal power handling, the maximum SPL is mechanically-limited by the driver's excursion. ie, for an 18" driver to produce 120dB at 40Hz, the cone needs to move 21.3mm each way. You could put it in a tiny cabinet and throw lots of power at it, and that will get the same SPL as using a very large box and relatively little power.
The audible difference will be this: distortion.
When current is passed through a voice coil, it distorts the surrounding magnetic field. More current = more harmonic distortion.
Some sources of distortion (suspension etc) are unavoidable, but increasing the size of a sealed box will increase efficiency at LF, which will reduce the power requirements. In turn, this reduces the distortion contribution from the motor.
Now, some motors are better than others and will handle large currents more comfortably. Others will really suffer. I once tried to use an Eminence Beta 12 in a 40L sealed box for a subwoofer, and it was terrible. The frequency response was nice and flat, and it was well within Xmax. The culprit was that the motor itself (in the case of that driver, a very basic ferrite one) was adding lots of distortion because of all the EQ I'd applied.
Chris
As you decrease the size of a sealed box, the internal air-spring compliance decreases. ie, smaller box = harder for the driver to compress the air. This reduces efficiency at LF**.
** NB - There will be some efficiency gain around the system resonance. I'm talking about what happens below that.
Of course, you can EQ the difference. So long as the driver has enough thermal power handling, the maximum SPL is mechanically-limited by the driver's excursion. ie, for an 18" driver to produce 120dB at 40Hz, the cone needs to move 21.3mm each way. You could put it in a tiny cabinet and throw lots of power at it, and that will get the same SPL as using a very large box and relatively little power.
The audible difference will be this: distortion.
When current is passed through a voice coil, it distorts the surrounding magnetic field. More current = more harmonic distortion.
Some sources of distortion (suspension etc) are unavoidable, but increasing the size of a sealed box will increase efficiency at LF, which will reduce the power requirements. In turn, this reduces the distortion contribution from the motor.
Now, some motors are better than others and will handle large currents more comfortably. Others will really suffer. I once tried to use an Eminence Beta 12 in a 40L sealed box for a subwoofer, and it was terrible. The frequency response was nice and flat, and it was well within Xmax. The culprit was that the motor itself (in the case of that driver, a very basic ferrite one) was adding lots of distortion because of all the EQ I'd applied.
Chris
Yeah, distortion. I believe that ib or large sealed will sound better, the reason being better efficiency(from the same coils as ordinary subwoofers that can handle tons of wats) and no back pressure (thats why the efficiency)
The coil can move a lot with little power and no "restrictions" . Now i am wondering it is still worth it 😂
The coil can move a lot with little power and no "restrictions" . Now i am wondering it is still worth it 😂