Looking for a few 12" subs as I have a McIntosh Mc 2500 (did 735w from 10-100000 hz into % .001 THD @ 8 ohms both channels driven) that I would be using to drive them. I'm not concerned with the ohmic load as the amp is capable of 1 ohm if need be. I'd like for them to be in a sealed box and I'm happy to build it myself. I'd be using them for everything below 75- 80 Hz and would love if they would do 15-20 Hz on the low end. I'm not too concerned with total SPL, but 100 DB @ 20 Hz is a goal. Any recommendations?
@The G.O.A.T.145 What filtering and/or bass management are you going to be able to apply to the subwoofers? Do you plan on including a DSP unit in the signal chain to enable high-pass filtering, low-pass filtering, and parametric EQ to be applied to the subwoofer? If so, it would be helpful to know which one.
Also, do you have any constraints on the maximum enclosure volume that you can accommodate for each subwoofer? Admittedly 12-inch subwoofers can be relatively compact, especially for sealed designs, but there can be a big difference between a 60-litre enclosure and a 120-litre enclosure.
Can we assume that the target 100dB at 20Hz is the summed result from 2x 12-inch subwoofers?
Also, do you have any constraints on the maximum enclosure volume that you can accommodate for each subwoofer? Admittedly 12-inch subwoofers can be relatively compact, especially for sealed designs, but there can be a big difference between a 60-litre enclosure and a 120-litre enclosure.
Can we assume that the target 100dB at 20Hz is the summed result from 2x 12-inch subwoofers?
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I'd recommend larger drivers.
Drivers generally reach ~10% distortion at Xmax, and above Xmax distortion rises well above that with little more excursion.
Without accounting for room gain or loss, 2 sealed 12" would need to have 17mm excursion to reach 100dB at one meter at 15Hz.
That much clean excursion is unusual (and expensive) for 12" woofers, and would require more than 500 watts in reasonable size (not family refrigerator size) enclosures.
Using 15", only 11mm would be required, easily found, and easily within the 500 watt range.
Art
Here are a couple 15" that would work as well as a 12" that may do it, all on sale.
https://stereointegrity.com/product/sql-12-series-2/
https://stereointegrity.com/product/sql-15-series-2/
https://www.parts-express.com/Dayto...vz-0Ehf9ILvvJg-yWtitbIzW0yd1wdrhoC_DYQAvD_BwE
https://stereointegrity.com/product/sql-12-series-2/
https://stereointegrity.com/product/sql-15-series-2/
https://www.parts-express.com/Dayto...vz-0Ehf9ILvvJg-yWtitbIzW0yd1wdrhoC_DYQAvD_BwE
I've done a feasibility study of the Dayton Audio RSS390HF-4 15" Reference Series HF Subwoofer 4 ohm that was one of the drivers suggested by @mordikai. The closed-box enclosure volume that I used was 80 litres, so it is relatively large.
The results of the simulation are shown below. It includes a 4th-order Linkwitz–Riley low-pass filter set to 83Hz to produce an acoustic roll-off that is −6dB at 80Hz relative to the passband. The response has an f3=17.8Hz, and f6=16.1Hz. The parametric EQ that is applied to achieve this response is quite extreme, consisting of 12dB of boost at 19Hz with a Q of 2.0.
The results of the simulation are shown below. It includes a 4th-order Linkwitz–Riley low-pass filter set to 83Hz to produce an acoustic roll-off that is −6dB at 80Hz relative to the passband. The response has an f3=17.8Hz, and f6=16.1Hz. The parametric EQ that is applied to achieve this response is quite extreme, consisting of 12dB of boost at 19Hz with a Q of 2.0.
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Another option for the Dayton Audio RSS390HF-4 15" Reference Series HF Subwoofer 4 ohm is to increase the enclosure volume of the closed box to 180 litres and to add a 2800µF capacitor in series with the woofer. Using a PEQ of +3.5dB at 15Hz with Q=2.0 produced the following response. The response has an f3=15.0Hz, and f6=13.5Hz, and we almost get to 100dB at 20Hz without exceeding the Xmax=14mm (albeit with a bit of distortion, as was pointed out by @weltersys). The power requirements are quite modest, peaking at about 75W.
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I have a behringer CX2310 at the moment and all i want the subs to do is 60HZ and lower. My mains do 50hz and above.
I would prefer not to as the rest of my gear is analog.
I can make whatever work as i will build to suit.
100 @ 20 would be Ideal
The Behringer XC2310 uses 4th-order Linkwitz–Riley low-pass filters for the subwoofer. Their rapid roll-off should help you to integrate the output with your main speakers.
Going back to a 12-inch subwoofer concept, I've done a simulation for the Dayton Audio RSS315HF-4 driver in a 16-litre closed-box enclosure. The results are shown below. The subwoofer's f3=20Hz, and f6=16.1Hz. The driver is being driven at well below its Xmax capacity, thus distortion should be minimised. Of course, 2 of these subwoofers would be needed to produce 100dB at 20Hz for this power level. At these low frequencies, we can expect room gain to help boost the low-frequency output a bit.
I used a power input of 90W re 4ohms. Because the subwoofer is being used where its response is dropping away at 12dB/octave, the 4th-order L–R LP filter was set to 37Hz to achieve a point at around 50Hz relative to the peak output in the subwoofer's passband.
Note that when the cut-off frequency of the LP filter is increased, then the low-frequency −3dB cut-off point of the subwoofer will also increase. As this occurs, the subwoofer will produce a little bit more peak output. This complex behaviour is related to all the interactions of the various frequency response curves.
Going back to a 12-inch subwoofer concept, I've done a simulation for the Dayton Audio RSS315HF-4 driver in a 16-litre closed-box enclosure. The results are shown below. The subwoofer's f3=20Hz, and f6=16.1Hz. The driver is being driven at well below its Xmax capacity, thus distortion should be minimised. Of course, 2 of these subwoofers would be needed to produce 100dB at 20Hz for this power level. At these low frequencies, we can expect room gain to help boost the low-frequency output a bit.
I used a power input of 90W re 4ohms. Because the subwoofer is being used where its response is dropping away at 12dB/octave, the 4th-order L–R LP filter was set to 37Hz to achieve a point at around 50Hz relative to the peak output in the subwoofer's passband.
Note that when the cut-off frequency of the LP filter is increased, then the low-frequency −3dB cut-off point of the subwoofer will also increase. As this occurs, the subwoofer will produce a little bit more peak output. This complex behaviour is related to all the interactions of the various frequency response curves.
Oops! That should have been a 60-litre enclosure in Post #8, not a 16-litre enclosure. Sorry about that! 😳
Did you use DSP to tame the sealed enclosure? Sealed boxes need heavy eq
The simulation of a closed-box enclosure that I described in Post #8 does not seem to need heavy EQ to produce a quite useful 20-Hz −3dB cut-off frequency. Of course, the term "heavy EQ" could be ascribed to the use of a 4th-order Linkwitz–Riley low-pass filter, which interacts with the driver's natural response to obtain the useful subwoofer response function.
Below is a simulation of the Dayton Audio RSS315HF-4 in a 50-litre closed-box enclosure. Here a large amount of EQ has been applied, which enables a −3dB point of 17.3Hz to be obtained. There is 10dB of EQ applied at 18.8Hz with a of Q=2.00 to achieve that. The maximum SPL is only about 98dB when Xmax is reached. This is still useful for two such subwoofers to be used in a stereo configuration.
F3 with no boost in my room is around 33hz. For music I don't find any eq needed; I have usable output in to the high 20's.