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Are 18", 21" pro audio subwoofers better than 12", 15" hifi subwoofers?
Are 18", 21" pro audio subwoofers better than 12", 15" hifi subwoofers?
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Old 10th February 2019, 04:03 PM   #21
Vortex is offline Vortex  Hungary
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Quote:
Originally Posted by SpartanX58 View Post
Those have similar specs, which one is better in terms of linearity and distortion? At the first glance the LaVoce looks like a better driver since it has more force, higher compliance, better terminals and 1.5 mm of extra xmax.

B&C Speaker 18TBW100 - 18" Subwoofer
LaVoce SAF184.03 - 18" Subwoofer
I'm designing a stereo 3-way active system (for music) with 21" bass, 1 per side. After many-many datasheet checks I still find the RCF LF21X451 the best and nothing models better in WinISD, at least in PA league. It has a fairly "low" Fs of 28Hz and I tune it to exactly that frequency in a ~400-450 liter vented box.

It's rated RMS is 2000 Watts, sensitivity around 95dB (sitting in the box already). An awsome driver.

As amp I chose the Hypex UcD2k but looking at Powersoft too, right now. Still considering if I shall stay with the big Hypex or take the Powersoft route.

Btw I don't really like very deep bass so I'll employ a 24dB/oct filter at around 24Hz and below. In addition this relieves the 2 big boys and makes their sound more precise in the useful/needed region.


Btw lifting bass region via DSP or any other means (EQ, etc) for a sealed box might stress the woofer and it can run out of capable power easily. I'm not a big fan of it.

As somebody mentioned earlier, look for low Fs woofer types with somewhat less sensitivity, that won't harm transients (yet), especially not with a great Class-D amp with plenty of reserves. +3dB reserve should be in the driving amp for a best case scenario (or even more) which means for 1500W RMS you better have something that can deliver 2.5-3kW into 8 Ohms (!). At least on paper. I usually check the real impedance of the woofer and try to extrapolate (think about) how much my amp can deliver into those impedances in the used region.

The Hypex UcD2k can deliver
2500W into 4 Ohms
1600W into 8 Ohms
.. that's why I'm looking for something little bit stronger (for peak reserves).

Link to the RCF if you still want to stick to PA woofers: RCF LF21X451 - 21" Woofer
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Old 10th February 2019, 04:16 PM   #22
ErnieM is offline ErnieM  United States
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Like I mentioned earlier....consider high-power rackmount class D amps for this class of woofer. A 500w amp trying to push them to full excursion with eq in a small box can run into limits quick. The ultra low noise and distortion is of no benefit in the bass range. Raw power is.
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Old 10th February 2019, 04:24 PM   #23
Bfpca is offline Bfpca  Canada
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Are 18", 21" pro audio subwoofers better than 12", 15" hifi subwoofers?
There is a pro audio company Bag End that uses pro audio drivers to make subwoofers. Back in the early 2000s their 18” sub got good reviews in HIFI use. The natural response of their driver/sealed box is to roll off at 12db/oct at a high frequency. They apply a patented eq called “dual integrator eq” to get flat response to a very low frequency. To me it seems like a pole shifter type eq similar to the Linkwitz transform, only operating throughout the entire subwoofer bandwidth, which should give a more seamless response.
IME “for music” the amount of sound power that is in the sub 30hz range is not that great. To me it makes a certain amount of sense to have higher efficiency at 40-80 hz where there is more content in music. You will get this from a pro driver versus a heavy coned, low resonance, designed for hifi subwoofer driver.
I’m sure there are trade offs to be had with each approach. A lot of people complain about slow subwoofer response. IME a lot of this can be due to room modes, poor setup and integration of the sub with mains, hi Q alignments that cause resonant behaviour in the woofer and also heat buildup in the driver which causes changes in the alignment, particularly in vented systems.
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Old 10th February 2019, 04:55 PM   #24
SpartanX58 is offline SpartanX58  Brazil
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Quote:
Originally Posted by ErnieM View Post
Like I mentioned earlier....consider high-power rackmount class D amps for this class of woofer. A 500w amp trying to push them to full excursion with eq in a small box can run into limits quick. The ultra low noise and distortion is of no benefit in the bass range. Raw power is.
I won't use them in big rooms, nor do I want to achieve crazy high SPL, I just want something that can play subsonic tones without destroying itself and playing very distorted. I don't need more than 500 watts since that is all it takes to run those subwoofers out of excursion at those lower frequencies. Yes, they are rated for more and I can extract more SPL at higher frequencies, but this is not my intended use. I just want deep and clean sounding subwoofers for my living room, that can shake the house with movies special effects and that play a very controled and undistorted bass with music.
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Old 10th February 2019, 04:58 PM   #25
academia50 is offline academia50  Argentina
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Quote:
Originally Posted by SpartanX58 View Post
Are pro audio subwoofers better in terms of transient response and distortion than hifi subwoofers?
Quote:
Originally Posted by academia50 View Post
In my opinion, the speaker does not have any or very little influence.
No one has answered if the impulse response is an attribute of the speaker itself and that it can be significantly altered according to the type of box in which it is installed. We already know that the sealed ones win here.
Reading this article is not clear either, if it refers to a speaker "in the air" - as when we measure the resonance of it - or already located in its enclosure ...
It's not a typical T / S data, that's why I'm intrigued, can someone clarify this please?


Speaker impulse response explained – the basics – Audio Judgement
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Old 10th February 2019, 05:23 PM   #26
Vortex is offline Vortex  Hungary
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Woofers you should always design within box (except you're building something exotic without box)

T/S is a good baseline and it might give you a hint how something would behave if it behaves like stated in free air (or anechoic chamber) measurements, especially freq. and impedance curves, sometimes with off axis angles too, etc.

On the other hand, a woofer cannot be bought very much lower than its own resonance frequency. To some extent yes, but not very much.

Last but not least, a correction of declining SPLs towards low frequencies needs more and more energy from amp side and more and more motor/cone capability on woofer side. E.g. to correct a -3dB SPL point you have to drive that woofer with 2x more power with every 3dB step so for all those who try some kind of EQ/DSP on frequencies below Fs and box tuning, a juicy amp will be needed as long as the juicy woofer can follow the task.

And it's always better to have an oversized amp than a smaller one (compared to woofer maximum RMS).
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Old 10th February 2019, 05:30 PM   #27
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by kipman725 View Post
Why not the IPAL? B&C Speakers
That driver has a Qts of 0.14 - way too low to be all that practical, even for a vented box. Most woofers from B&C (especially models with neo motors) have rather low Qts.
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Old 10th February 2019, 05:42 PM   #28
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by Bfpca View Post
There is a pro audio company Bag End that uses pro audio drivers to make subwoofers. Back in the early 2000s their 18” sub got good reviews in HIFI use. The natural response of their driver/sealed box is to roll off at 12db/oct at a high frequency. They apply a patented eq called “dual integrator eq” to get flat response to a very low frequency. To me it seems like a pole shifter type eq similar to the Linkwitz transform, only operating throughout the entire subwoofer bandwidth, which should give a more seamless response.
IME “for music” the amount of sound power that is in the sub 30hz range is not that great. To me it makes a certain amount of sense to have higher efficiency at 40-80 hz where there is more content in music. You will get this from a pro driver versus a heavy coned, low resonance, designed for hifi subwoofer driver.
I’m sure there are trade offs to be had with each approach. A lot of people complain about slow subwoofer response. IME a lot of this can be due to room modes, poor setup and integration of the sub with mains, hi Q alignments that cause resonant behaviour in the woofer and also heat buildup in the driver which causes changes in the alignment, particularly in vented systems.
Wanted to flesh out your explanation of how the Bag End ELF Infrasub works, and what the dual integrator is for.

You start by putting a subwoofer in a closed box that is way too small for it in the traditional sense, e.g. Vb < Vas. What does that do to the response? In box the Qb will be around 1 or higher and Fs around 100Hz which is also where the impedance peak is located. With a higher Q value the impedance peak is relatively narrow. The rolloff in frequency response below 100Hz quickly becomes 12dB/octave.

An integrator is a circuit with gain that rises at 6dB/octave. Put two of these in series, and the gain has a 12dB/octave slope. You pair this with the falling 12dB/octave slope to flatten the response. The system is only used from the resonance frequency and below.

The idea is that below resonance the impedance falls back close to Re and flattens out. I think this was supposed to be easier to drive, especially at the lowest frequencies where the impedance is essentially resistive in nature. This is also where you need to apply the largest power boost: by 25Hz you are need 24dB or so. Bag End devised a limiter circuit that keeps the amount lift, and cone excursion, in check. But you will still need a very powerful amplifier for this to work properly, and I was not always so sure that a driver in a box with Vab<<Vas was a good idea from the distortion standpoint. But it did become a successful product.

It's a way to apply extra power to make a subwoofer in a small box possible. It is similar to but different than the Linkwitz Transform circuit.
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Last edited by CharlieLaub; 10th February 2019 at 06:05 PM.
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Old 10th February 2019, 05:49 PM   #29
poseidonsvoice is offline poseidonsvoice  United States
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Are 18&quot;, 21&quot; pro audio subwoofers better than 12&quot;, 15&quot; hifi subwoofers?
Quote:
Originally Posted by Vortex View Post
I'm designing a stereo 3-way active system (for music) with 21" bass, 1 per side. After many-many datasheet checks I still find the RCF LF21X451 the best and nothing models better in WinISD, at least in PA league. It has a fairly "low" Fs of 28Hz and I tune it to exactly that frequency in a ~400-450 liter vented box.

It's rated RMS is 2000 Watts, sensitivity around 95dB (sitting in the box already). An awsome driver.

As amp I chose the Hypex UcD2k but looking at Powersoft too, right now. Still considering if I shall stay with the big Hypex or take the Powersoft route.

Btw I don't really like very deep bass so I'll employ a 24dB/oct filter at around 24Hz and below. In addition this relieves the 2 big boys and makes their sound more precise in the useful/needed region.


Btw lifting bass region via DSP or any other means (EQ, etc) for a sealed box might stress the woofer and it can run out of capable power easily. I'm not a big fan of it.

As somebody mentioned earlier, look for low Fs woofer types with somewhat less sensitivity, that won't harm transients (yet), especially not with a great Class-D amp with plenty of reserves. +3dB reserve should be in the driving amp for a best case scenario (or even more) which means for 1500W RMS you better have something that can deliver 2.5-3kW into 8 Ohms (!). At least on paper. I usually check the real impedance of the woofer and try to extrapolate (think about) how much my amp can deliver into those impedances in the used region.

The Hypex UcD2k can deliver
2500W into 4 Ohms
1600W into 8 Ohms
.. that's why I'm looking for something little bit stronger (for peak reserves).

Link to the RCF if you still want to stick to PA woofers: RCF LF21X451 - 21" Woofer
Here is the driver I use from Funk, and yes it has low Fs, and is about 93dB efficiency:

UH21vU - HARBOTTLE

It's a super woofer for me and does extremely well in mid bass applications as well due to the underhung motor topology, and full pole sleeve shorting ring. Expensive? Yes, just pull out your CC.

Best,
Anand.
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Old 10th February 2019, 07:15 PM   #30
Vortex is offline Vortex  Hungary
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Interesting monsters. The website is lacking some information..
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