Tiny consumer sub puts my 10" sub to shame?

[hjf]

OK, what the hell? I have a 10" sub I made 10 years ago, according to mfg's specs (Brazilian sub "Selenium" brand, model 10SW2). The sub sheet said some things but I wrote an email and they told me to build a box, which curiously uses a 44cm long tube (!).

Box volume is about 50L or so.

The sub specs are as follows:

PARÂMETROS DE THIELE-SMALL
Fs 27.5 Hz
Re 3.52 Ohms
Qms 7.02 a
Qes 0.72 a
Qts 0.65 a
Vas 95.3 l
Ref Eff 0.32 %
Sd 0.03502 m2
Vd 155.84 cm3
Xmax 4.45 mm
Bl 7.0 T.m


Here are WinISD's plots

YELLOW is a Closed box I made for it
GREEN is my current Vented box
WHITE is just a random box. I chose 100L, just to see what happens.






Anyway, I was just listening to a tiny 6,5" sub (from a Philips HTS6600 system), and it was just... well, it made me realize my sub just plain sucks. That tiny 6,5 sub is LOUD, I can feel it on my chest several feet away. Placed in the same place, my sub just jumps a lot and it just... "sounds" but that's it. Sound is not great. I can hear it, yes. But I can't feel it. Also, I'm giving it way more power (up to 100W), still won't sound great.

What the hell is going on? Is my driver just that bad?

BTW, am I supposed to "hear" the bass if my ear is, say, 50cm away from the speaker? Because I don't. The only way to hear my sub is placing it on a corner and stand in the opposite corner of the room.

[chris661]

A couple of things. 6.5" drivers in home theatre boxes do not go low. They go loud, and put emphasis on the midbass range, where the bass can often be felt. Stick 40Hz through, output will be minimal. You might hear the cone flapping around, but the signal to the driver will often be filtered to stop frequencies that low getting to it.

Apply similar filtering to a 10" driver, it's easy enough to make it hit you in the chest.
It's all about playing to what a driver can do, and ensuring that it's not made to do anything it will struggle with. Cut off at, say, 50Hz high pass, maybe 2nd order. You'll be amazed at how loud it goes.

It takes suprisingly little power to get speaker cones moving in a reasonably sized cabinet. Much less than the 100w you could put through it.

Chris

PS - I assume the cabinets are properly sealed? Any leaks can cause substantial loss of SPL.

[hjf]

Well I was reading the specs on this thing, seems it does some DSP tricks as well. From the brochure:

DoubleBASS
DoubleBASS ensures you hear even the deepest bass tones from compact-sized subwoofers. It captures low frequencies and recreates them in the audible range of the subwoofer - delivering sound with more boom and panache, and ensuring you a full, uncompromised listening

The cabinets are properly sealed, yes. I have a bigger box, I'll try using the 10" in that one. It's about 125L. WinISD shows that the 10" sub, in a 125L box, tuned to 30Hz (just an arbitrary frequency I chose), will give me +5dB at 40Hz and the lowest is about 28Hz.

What frequency should I aim for? I want to build a sub for reinforcing my TV's built-in speakers and double it as a TV stand, so box volume is not an issue. I will be using it for the occasional movie (I only have time to watch movies on weekends), but I do want it to hear some bass while playing video games and music. I don't want to disturb the neighbors either - this is a city house. There's a 30cm brick wall between me and my neighbor.

[OscarS]

IMO, that driver is not optimized for ported enclosure. The very high Qes/Qts indicates a very weak motor. EBP (=fs/qes) should be closer to 100 to be generally suitable for ported box use. Yours EBP is 38. Hardly suitable for even a sealed box unless you use a huge enclosure; otherwise your Qtc will be through the roof and you'll gets lots of overshoot due to low damping.

Ditch your 10". Find a better woofer. Start over and ask questions before you make your final decision.

[djk]

-3dB at 35hz, 92.7dB/2V(1W at 4R)/1M in this box:

Driver Properties
Name: 10SW2
Type: Standard one-way driver
Company: Selenium Loudspeakers
No. of Drivers = 1
Fs = 27.5 Hz
Qms = 7.02
Vas = 95.3 liters
Cms = 0.547 mm/N
Mms = 61.22 g
Rms = 1.507 kg/s
Xmax = 4.45 mm
Xmech = 6.675 mm
P-Dia = 211.2 mm
Sd = 350.2 sq.cm
P-Vd = 0.156 liters
Qes = 0.72
Re = 3.52 ohms
Le = 0.76 mH
Z = 4 ohms
BL = 7 Tm
Pe = 120 watts
Qts = 0.65
no = 0.27 %
1-W SPL = 87 dB
2.83-V SPL = 90.03 dB
-----------------------------------------
Box Properties
Name:
Type: Bandpass Single-Tuned Box
Shape: Prism, Bandpass
with two chambers
Chamber 1 - lower-freq.
Vb = 1.3 cu.ft
Fb = 52.1 Hz
QL = 5.851
F3 = 35.87 Hz
Fill = minimal
Chamber 2 - upper-freq.
Vb = 2.403 cu.ft
Fb = 52 Hz
QL = 6.718
F3 = 75.85 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = one flush
Dv = 4.046 in
Lv = 1.5 in

[hjf]

Originally Posted by OscarS

Ditch your 10". Find a better woofer. Start over and ask questions before you make your final decision.

I've been looking around... no good woofers here. I got this one 10 years ago and it was the best I got.

No one is into Hi-Fi DIY here (Argentina), it's either car audio or pro audio. Maybe a very specialized store carries a woofer like that, but it will probably cost WAY too much. Ordering from somewhere else is out of the question... shipping would be over $100 for anything, and while I love to make things myself, I think this would be another huge disappointment.

For reference, some prices:

Pioneer TSW-308 12" Sub: $110
Or a JBL GT512 or....well any kind of badass-looking sub with badass-sounding names (or funny ones like the brazilian BICHO PAPÃO ones - means bogeyman).

Add about $50 for wood, more for finishing, a powerful enough amp (I'm not sure if a 60W gainclone will work).

Then I searched for a powered sub. Excluding 5.1 systems I found this:

Polk Audio
PSW-10 $350
PSW-110 $375
DSW Pro 400 $510

(See what I said about prices? I think these sell for $100 in the US)

I love DIY, I love building things, I love saying "I made this X thing"... but I think this time it would be wiser to just get a ready-made sub and be done with it.

[hjf]

Originally Posted by djk

-3dB at 35hz, 92.7dB/2V(1W at 4R)/1M in this box:

Box Properties
Name:
Type: Bandpass Single-Tuned Box
Shape: Prism, Bandpass
with two chambers
Chamber 1 - lower-freq.
Vb = 1.3 cu.ft
Fb = 52.1 Hz
QL = 5.851
F3 = 35.87 Hz
Fill = minimal
Chamber 2 - upper-freq.
Vb = 2.403 cu.ft
Fb = 52 Hz
QL = 6.718
F3 = 75.85 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = one flush
Dv = 4.046 in
Lv = 1.5 in

Thanks. I simulated this in WinISD:



Is this correct? Blue shows your box (if I got it right?), Purple is something i got fiddling around with different values.

Is that for real? +11dB at 67Hz and +10dB at 44Hz. I have a ~125L box around. I guess I could make it into a 6th bandpass just to test. But those numbers are too good to be true (or my understanding of what the graph means is all wrong).

[djk]

You have the port in the wrong chamber.

This driver is perfect for a BP4, it is not suited for a BP6.

At 40hz my BP4 has about 9dB more output than the driver does in a sealed box. It should handle about 100W on real program material, for a maximum output around 112.7dB in 2Pi, or over 120dB in a corner.

"but I think this time it would be wiser to just get a ready-made sub and be done with it. "

Why, isn't 120dB enough?

Your driver in my design placed in the corner with your idea of a 60W gainclone should be able to hit 120dB.

[djk]

A general note about BP4 drivers.

High Q is fine.

For maximum output, figure out what sealed box size gives a Qtc=1.1, and what the Fb is.

Use that box size for the sealed side of the BP4, try different box sizes on the vented side (all tuned to Fb).

This allows the use of cheap drivers and gives maximum output, and has a reasonable sized port.

[chris661]

Right, figured what the clever DSP does.

By recreating harmonics of a fundamental frequency, then cutting out the fundamental, the subwoofer doesn't have to move very much (ie, to recreate 30Hz, it'd play 60Hz, 90Hz, 120Hz etc), and yet the human brain fills in the fundamental. It sounds like it goes low, but it really doesn't. Hence the "recreates sound in the audible range of the subwoofer". Apply similar to a 10", and it'd go staggeringly loud, too.

Chris