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Discussion Starter · #1 ·
Hi everyone,

Have been reading and learning so I assume not a lot of you will know me but here is my first attempt on building a sub...

Finally coming to a point in the renovation of the house, that I can work on the corner with the gas, electricity and water meters.
This corner will accommodate a closet from floor to ceiling but needs to pivot open to read the meters.
This will be done by hinges on the left side and two wheels under the right side of the sub-woofer, which will function as a TV-stand and all other equipment.

The front face of this bottom part for the sub measures 114cm wide and ±60cm high.
so, with x height = 3.74 ft x ±1.97 ft
The net volume will be at least 400l / 14ft³
There is room for three 15" or two 18" woofers, how to choose? Are smaller ones better? etc.
(I also plan on building two smaller subs to put next to the sofa as side stands)
Although I didn't decide on the type of enclosure, I thought a bass-reflex would be best suited¿
I don't know enough about PPSL but it seems this would lower the frequency in case of a sealed sub¿

The ever lasting discussion about 'how low should it go' is always a problem with HT-subs.
Can I assume 16hz is needed or what do you think about it?

Room size is about 10m x 4.5m x 2.5m or 32.8ft x 14.8ft x 8.2ft

I prefer a bit of efficiency, since I have a couple of old amps that I'd like to use.
One is A-656 Pioneer, dynamic output at 4Ω 2x190W, damping factor 70
The other is from Velleman RMS 2x155W at 4Ω, damping >600
Are these or one of them fit for a HT-sub?
If there is no choice, I consider buying an amp.
What about filters? My receiver is a Cambridge Audio azur 540r.
This is not intended to be a reference sub, but how loud should it beat to give good HT experience?

Another thing I like is what I read some time ago on another forum about closing the BR-opening to go sealed in an instant for music.

Please consider I'm from Europe and have not the same options on the driver(s) as in the US, unless the shipping is reasonable.
I also can get 40mm multiplex ( a bit over 1.5") but that might be overkill and reduce the net volume unnecessary...

Anyway, I finally can design for real now, instead of running in circles, but I've learned a lot from forums.
 

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Discussion Starter · #3 ·
Thank you.

No, the dimensions are outside because I have yet to decide how thick the panels have to be.
The depth is actually 96cm / 3.15ft but I have to accommodate the wheels and the meters, so there will be strange corners in the sub at the back and underneath.
I could just make the depth a lot less for ease of construction, but then there would be lost space, useful to the sub.
The 400l / 14ft³ is a minimum estimation on what will be available to the driver(s), even taking in account for the large BR-port, if it would be a BR that is...

Thanks!
 

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Discussion Starter · #6 ·
The Velleman can be bridged to 600W into 8Ω, would that be usable?
If not, what specification do I want to see in an amp, to be suitable for HT-subs?

Drivers in Europe that I know of are; Monacor, Visaton, Pioneer, magnat, Seas, Eton, , JBL, Kenwood, Renkforce, Sinus Live, Infinity, Blaupunkt, Eminence, Mivoc, Focal.
Anyway, a lot more than I thought, might not be a big problem after-all.

I think Dayton is available too, in Germany at least (quick search). Price is a lot higher thou.
RSS390HF-4 is $320, without shipping :blink:
PE sells them for $172 :dontknow:

I'm willing to spend about $500 on drivers (or one driver if that cuts it)
Still, prices can be stretched somewhat, just a guideline as I don't want to just go buy the most expensive driver and go from there, then I can just buy the DTS-10 and be done with it.:hsd:

A tapped horn might fit in the space available too I guess. I'm not an expert on cabinet building but I'll do what it takes to get the job done...

Thanks for all the help!:T
 

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Here's a starting point.
Stereo Integrity is coming out with a 18" home theater driver, there is a pre oder happening now with a least a 90 wait for the drivers to arrive. The pre oder price is $165. I sent the owner an email to find out what shipping would be to you, just waiting on a reply.

Since you mentioned to 390HO, here is an estimated SPL graph comparing the the 2 drivers. Orange is the best the 390HO can do while green would be the SI 18D2 in 12 cu.ft tuned to 15 hz. Add the displacement of the slot port, bracing and the driver and it would be close to 14 cu.ft. total internal volume.

A 15 hz tuning is low enough you wouldn't need a hi-pass filter. The modeling is with a bit over 800 watts into a 4 ohm load. They also make a 18D4 driver for a 8 ohm load but I don't have the parameters for it.

Although the graph shows the 18D2 producing 113 db at 15 hz, it doesn't account for any room gain you may get depending on the size of he room.

Until I get a reply on shipping this driver to Belgium I'm assuming it will be within your $500 price range. The challenge now will be to see if there is any other options that will perform as good as the 18D2 for $500.

belgium.JPG
 

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Discussion Starter · #8 ·
Wow thanks! That looks very good.
I'll look up that driver to find out more and fire up WinISD with the T&S parameters.
Right now I have to go do a small job for a friend, I hope to have some time tomorrow.

Thanks for the time and effort Mike, that graph looks promising.
 

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Discussion Starter · #10 ·
Thanks, I'll have a look at that tonight (it's 6AM here)
I Didn't notice it right away but the driver I mentioned from Dayton was the 390HF version, sorry about that. I will put the specs in WinISD from the HO version too...

Is bass reflex the way to go then? I mean, there's so much going on around tapped horns I was starting to believe that it was THE way to go in HT?
Or is the space to restricted for what I want?
What about PPSL? Any benefit to that for HT?
 

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There are pros and cons top different types of subwoofers. Power wise tapped horns have their benefit which is efficiency compared to ported or sealed. They need to be big to go down low and they have to be a specific shape, usually long and narrow. Designing a tapped horn can be a challenge but for the people who have done so and got it right, the results are impressive.

PPSL is a beast of its own, the advantage being non-linear distortion cancellation. From what I read a 20 hz sub would be huge due to the design.
 

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Discussion Starter · #12 ·
So, best to leave the TH and PPSL alone for now...

I simulated three drivers:
Dayton RSS390HF
Dayton RSS460HO
and the 18" D2

The RSS390HF comes out very flat but less efficient.
SPL at 200W
Second pic is transfer function magnitude
I simulated the voice coil inductance and a second order high pass filter too.
 

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Discussion Starter · #14 ·
In WinISD I set all three entry's to 200W, 400liter volume and tuning at 16hz.
The transfer function magnitude looks different for all three drivers, but since the efficiency is different, they coincidently have similar results at the same input power.
I'm not sure how to explain it better. Shall I re-simulate and answer in detail? What would you like to know?
 

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Discussion Starter · #19 ·
Technical datasheet Monacor SPH-450TC
Impedance (Z) 2 x 4 Ohm
Free air resonance (fs) 20Hz
Max. frequency range f3–1,500Hz
Rec. crossover freq. (fmax.) 400Hz
Music power 2 x 500WMAX
Power rating (P) 2 x 350WRMS
SPL (1W/1m) 93dB
Suspension compl. (Cms) 0.22mm/N
Moving mass (Mms) 305g
Mech. resistance (Rms) 12.7kg/s
Mech. Q factor (Qms) 2.97
Electr. Q factor (Qes) 0.27
Total Q factor (Qts) 0.25
Equivalent volume (Vas) 480 l
RDC DC resistance (Re) 2 x 3.7 Ohm/1 x 7.4 Ohm
Voice coil induct. (Le) 2 x 1.1mH/1 x 4.6mH
Voice coil diameter 99.3mm
Voice coil former aluminium
Voice coil winding height 37.8mm
Air gap height 12mm
Linear excursion (X) ±12.9mm
Eff. cone area (Sd) 1,250cm²
Volume displacement (Vd) 1,612.5cm³
Force factor (BxL) 32.4Tm
Reference efficiency (No) 1.37%
Magnet diameter 220mm
Magnet weight 200oz
Mounting cutout ø 425mm
Mounting depth 220mm
Dimensions ø 460mm
Weight 17kg
 
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