Which 15" sub for a sealed enclosure?

[Inertia]

I have a well braced sealed enclosure that is 2.3ft3. What 15" sub would go good in this box? It would be powered by an O audio bash 500 watt plate amp. I would like to spend $250 or less on the sub....
Thanks for your time guys.

 

[annunaki]

That is not much air for a 15" driver.

You may want to look at 12" drivers for this volume available such as the 12W7 from JL Audio or a TC Sounds LMS equipped driver.

A 15" driver in an an enclosure this size will require significant EQ to properly shape the response. Your amp will also run out of steam well before it is needed to get much below 35hz from some of the woofers I have looked at so far as well if using EQ to lower response.

 

[johngalt47]

Actually, the Dayton RSS390HO-4 will work in that size box.

 

[bandphan]

Actually, the Dayton RSS390HO-4 will work in that size box.

As Rob pointed out heavy EQ and a Big amp would be needed just to get the ball rolling. That size enclosure sealed just cant sustain a 15" driver and be effective.

 

[highfigh]

As Rob pointed out heavy EQ and a Big amp would be needed just to get the ball rolling. That size enclosure sealed just cant sustain a 15" driver and be effective.

It might if the woofer is facing a wall or corner.

 

[annunaki]

The RSS390HO-4 may work but will require some eq to reduce the peak in response at 54hz. The 2.3ft^3 enclosure allows a natural f3 of 36hz which is suitable for music in many cases, however it has an overall Qtc of .953 which will result in a boomy or muddy sound if eq is not used to reduce the hump in response at 54hz.

If you do go this route, add -3db of cut at 54hz with a "q" factor of 1.0. This will result in a nice performing system overall with a net f3 of 31.8hz anechoic at 108db. If the EQ is not used this system will sound muddy. With 500 watts you will remain under rated xmax down to 8 hz. F10 is at 20.6hz.

To get any lower usable response (F10 is at 23.5hz natural, no eq applied to reduce the 54hz peak), again EQ will be required. The problem here is that any addition of EQ boost to lower response will cause the amplifier to clip and the driver to exceed xmax which will increase distortion or damage the driver.

 

[Inertia]

will this sub work good in my box? its a 12"
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-464

 

[highfigh]

The RSS390HO-4 may work but will require some eq to reduce the peak in response at 54hz. The 2.3ft^3 enclosure allows a natural f3 of 36hz which is suitable for music in many cases, however it has an overall Qtc of .953 which will result in a boomy or muddy sound if eq is not used to reduce the hump in response at 54hz.

If you do go this route, add -3db of cut at 54hz with a "q" factor of 1.0. This will result in a nice performing system overall with a net f3 of 31.8hz anechoic at 108db. If the EQ is not used this system will sound muddy. With 500 watts you will remain under rated xmax down to 8 hz. F10 is at 20.6hz.

To get any lower usable response (F10 is at 23.5hz natural, no eq applied to reduce the 54hz peak), again EQ will be required. The problem here is that any addition of EQ boost to lower response will cause the amplifier to clip and the driver to exceed xmax which will increase distortion or damage the driver.

The box could be well-stuffed to make it act like it's larger, too.

 

[TLS Guy]

will this sub work good in my box? its a 12"
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-464

That will give you an F3 of 44 Hz in your box. The volume of the driver is about 0.1 cu.ft so I have subtracted that from your box volume.

Name: RSS315HF-4 12"
Type: Standard one-way driver
Company: Dayton Loudspeaker Co.
No. of Drivers = 1
Fs = 23 Hz
Qms = 3
Vas = 84.95 liters
Cms = 0.114 mm/N
Mms = 421.7 g
Rms = 20.32 kg/s
Xmax = 14 mm
Xmech = 21 mm
P-Dia = 304 mm
Sd = 725.8 sq.cm
P-Vd = 1.016 liters
Qes = 0.52
Re = 3.3 ohms
Le = 0.95 mH
Z = 4 ohms
BL = 19.67 Tm
Pe = 400 watts
Qts = 0.44
no = 0.192 %
1-W SPL = 84.97 dB
2.83-V SPL = 89 dB
-----------------------------------------
Box Properties
Name:
Type: Closed Box
Shape: Prism, square
Vb = 2.2 cu.ft
Qtc = 0.553
QL = 19.16
F3 = 43.95 Hz
Fill = heavy

Now there is not much room for Eq. It really requires a boost of 12 db per octave starting at 50 Hz and a steep high pass filter at 25 Hz.

If you play it softly you will be fine.

You are up against the problem that a sealed sub can not be done of the cheap.

As I have pointed out before, a loudspeaker cone is a very ineffective acoustic coupler to a room especially at low frequencies. So to overcome that you need a costly driver with high xmax and high power handling, and then a mega amp with enough power to provide Eq from around F3.

A sealed sub always has to high an f3 to be an effective sub without Eq.

You can do it on the cheap, but you a limited to low spl. so an inexpensive driver is not damaged by the large cone excursions from the required Eq.

The only way of achieving high spl inexpensively in a reasonably sized enclosure is with a ported design. The bass quality is not to everyone's taste including mine.

For these reasons I don't use a sub as such, and use TLs which are not reasonably sized, but on the other hand I can make an integrated speaker. Sensitivity and efficiency is very satisfactory and total system Q is low giving a natural uncolored bass with low Fs and 12 db roll off per octave.

Its the old adage: - Do speakers have to be large? No but it really helps.

So any small speaker, or call it reasonably sized, reproducing the past octave will have significant trade offs.

 

[highfigh]

People who know about, and build, high performance car motors have a saying- "There's no replacement for displacement". It works for speakers, too. Bass frequencies can be transmitted in three ways- propagation directly through the air, conduction through materials like the floor/walls to the listener and radiation from the structure to the listener. Since conduction isn't the goal here and radiation isn't an easy way to reach an adequate outcome, propagation is the only way to do this cheaply. The problem here is that it's necessary to choose the driver first and make the box according to the drivers' characteristics in order to allow it to do what it will in order to achieve the desired response. Looking for a woofer to work in a box is reverse engineering and amounts to finding a needle in a haystack. It may happen and you may learn something along the path, but it's not an efficient way to do this.

 

[Inertia]

So I guess sealed isn't the way to go? I have the mid q kappa perfect sub build design right now. Should i make another kappa perfect enclosure? What sub would go good in the enclosure cuz the VQ kappa perfects are discontinued.

 

[bandphan]

Sealed can work but the driver, amp, and eq will make it less cost effective for low bass and spl. The velodyne 10" I've used in a small cubed enclosure sound awesome and plays low (without high spl) and for music plays flat and blends well. For the 1800 it cost in 2001, the performance compared to the dollar amount isn't there, though the WAF is.

 

[lsiberian]

So I guess sealed isn't the way to go? I have the mid q kappa perfect sub build design right now. Should i make another kappa perfect enclosure? What sub would go good in the enclosure cuz the VQ kappa perfects are discontinued.

If you want better 20-30hz performance you are a looking at a ported sub. However dual subs properly placed make a tremendous difference in overall system performance. All sealed subs are distortion limited by the box they are in. I think you'll find that dual subs would be a much bigger upgrade than a new driver.

 

[lsiberian]

Sealed can work but the driver, amp, and eq will make it less cost effective for low bass and spl. The velodyne 10" I've used in a small cubed enclosure sound awesome and plays low (without high spl) and for music plays flat and blends well. For the 1800 it cost in 2001, the performance compared to the dollar amount isn't there, though the WAF is.

There is a ported option that can be just as small as a sealed sub, but you'd need P-Rs for it. diycable.com has some kits with P-Rs if you want to downsize the boxes. I will probably get a couple of P-Rs some day to port my sub.

 

[Inertia]

I am not going to replace the kappa i am going to add another sub.

 

[annunaki]

The box could be well-stuffed to make it act like it's larger, too.

Not likely in this situation as the enclosure is almost 2.0ft^3 smaller than needed to achieve a .707 QTC

Stuffing only works to a small degree, not like the large variance that is needed here. Yes, it would help but no correct the inherent issue. The Poly fill solution for sealed drivers is like 120hz for LCDs, it is only a band aid for a real problem. In this case too little volume.

 

[annunaki]

So I guess sealed isn't the way to go? I have the mid q kappa perfect sub build design right now. Should i make another kappa perfect enclosure? What sub would go good in the enclosure cuz the VQ kappa perfects are discontinued.

The JL Audio 12W6v2 fits perfectly fine in the Kappa enclosure, and is a suitable if not more capable replacement.

 

[Inertia]

What size enclosure would be good for this TC sounds driver tuned to 20hz?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=293-650
Thanks for your time guys.

 

[TLS Guy]

What size enclosure would be good for this TC sounds driver tuned to 20hz?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=293-650
Thanks for your time guys.

This driver proves my previous point.

TC driver have high power handling great motor system with high xmax and are very insensitive and I suspect also inefficient.

Optimal box volume is just over 1 cu.ft. You need to add the driver volume and bracing, and heavily stuff.

F3 is 50 Hz. However with a huge amp this driver can be equalized. They have a very peaked response. Eq is mandatory for these drivers. Eq should begin around 65 Hz at 12 db per octave a steep high pass filter at 25 Hz is also mandatory.

It will be an expensive project. You will need a Behringer crossover/equalizer and a very powerful amp. This driver is only 86 db 2,83 Volts 1 meter at 100 Hz. At thirty Hz it will only be around 74 db! When it comes to small bass boxes there is absolutely no free lunch. Your box will be too big and Qts will be too low and cone excursion will be excessive. If you build it you had better make sure it is very well sealed.

No. of Drivers = 1
Fs = 24 Hz
Qms = 7.8
Vas = 91.2 liters
Cms = 0.167 mm/N
Mms = 263.4 g
Rms = 5.092 kg/s
Xmax = 22.9 mm
Xmech = 34.35 mm
P-Dia = 281 mm
Sd = 620.2 sq.cm
P-Vd = 1.42 liters
Qes = 0.42
Re = 3.66 ohms
Le = 3.2 mH
Z = 4 ohms
BL = 18.6 Tm
Pe = 500 watts
Qts = 0.39
no = 0.289 %
1-W SPL = 86.76 dB
2.83-V SPL = 86.6 dB
-----------------------------------------
Box Properties
Name:
Type: Closed Box
Shape: Prism, square
Vb = 1.082 cu.ft
Qtc = 0.615
QL = 19.62
F3 = 49.68 Hz
Fill = heavy

You could make a 4 cu. ft vented enclosure for this driver and get an F3 of 24 Hz. You would need to add vent volume driver, and brace volume. So it would end up being about 5 cu.ft.

Name: Epic 12
Type: Standard one-way driver
Company: TC Sounds
No. of Drivers = 1
Fs = 24 Hz
Qms = 7.8
Vas = 91.2 liters
Cms = 0.167 mm/N
Mms = 263.4 g
Rms = 5.092 kg/s
Xmax = 22.9 mm
Xmech = 34.35 mm
P-Dia = 281 mm
Sd = 620.2 sq.cm
P-Vd = 1.42 liters
Qes = 0.42
Re = 3.66 ohms
Le = 3.2 mH
Z = 4 ohms
BL = 18.6 Tm
Pe = 500 watts
Qts = 0.39
no = 0.289 %
1-W SPL = 86.76 dB
2.83-V SPL = 86.6 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 3.975 cu.ft
Fb = 20.3 Hz
QL = 6.355
F3 = 23.45 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = two flush
Hv = 2.5 in
Wv = 10 in
Lv = 38.15 in

Vent velocity is 18 m/sec

You won't need an equalizer and a much smaller amp as spec sensitivity will be maintained to around 30 Hz.

So the vented will need only 25% of the power of the sealed enclosure at 30 Hz.

The coloration of vented designs and PRs does not bother most as they have come to expect it. It really bothers me, and I just can't stomach the brute force and ignorance approach of sealed enclosures. So I'm prepared to put up with the size of speaker most would not. But I prefer to work with natures physical laws and not fight them.

 

[highfigh]

Not likely in this situation as the enclosure is almost 2.0ft^3 smaller than needed to achieve a .707 QTC

Stuffing only works to a small degree, not like the large variance that is needed here. Yes, it would help but no correct the inherent issue. The Poly fill solution for sealed drivers is like 120hz for LCDs, it is only a band aid for a real problem. In this case too little volume.

I never said poly fill. Long fiber wool used to be the recommended fill but it's probably not the best choice now- that was 30 years ago. Fiberglass helps, too- poly is just a nice, neat material for damping. I didn't crunch the numbers to see what the actual response or Q is and I really don't need training wheels here. I also posted that using an existing box is the backward way to go about this. It would be better to find a woofer that can use a smaller box and mod this one to fit than to hunt for a woofer that's a good match without any changes or stick with a box that ends up with a high Q.