Box design suggestions?

[stochastic]

I've recently repaired some old woofers (nice quality sound from them) and I have a set of tweeters to match. Now I need to build a box for them (the old box was garbage). Here are the T/S parameters that I measured with REW (I'm mostly confident in my measurement capabilities):

TS Parameters file
Room EQ V5.01
Dated: 4-Apr-2013 5:59:58 PM
From measurement Apr 4 14:35:09

Zmin 3.95 ohm
fmin 180 Hz
f3 518 Hz
Le(f3) 0.978 mH
Motional impedance parameters
RES 29.47 ohm
LCES 30.811 mH
CMES 575.4 uF
RAMS 29470.222 mohm
Blocked impedance parameters
RDC 3.00 ohm
dR 0.61 ohm
Re 3.61 ohm
Leb 81.4 uH
Le 1.544 mH
Rss 1681.9 ohm
Ke 0.1592 S-H
Thiele-Small parameters
fs 37.6 Hz
Qms 2.906
Qes 0.491
Qts 0.420
Fts 89.6
Mms 30.89 g
Cms 0.579 mm/N
Rms 2.513 kg/s
Vas 86.39 litres
Bl 7.327 Tm
Eta 0.92 %
Lp (1W/1m) 91.78 dB
Dd 20.32 cm
Sd 324.3 cm^2
Added mass 8.40 g
Secondary measurement: Apr 4 14:19:39
Air temperature 20.0 C
Air pressure 1013.25 mB
Air density 1.2041 kg/m^3
Speed of sound 343.2 m/s

And here is the impedance curve (if that's needed)

I've always sort of wanted to build a rear-loaded horn enclosure. Although praise for open baffle systems have also piqued my interest. Got any suggestions?

 

[stochastic]

Nobody? Does anyone think this woofer would work in the Frugel Horn MkII?

 

[Jay1111]

No clue about using it in a horn. It looks like a sealed box of 60L will get you a Qtc of .75 and an F3 of 55hz.

 

[stochastic]

I'd rather get into some interesting box designs rather than simple sealed. Sealed would only be interesting to me if I could make this a nice desktop monitor but 60L is a bit big for a desktop.

 

[Jay1111]

Given the sealed box requirement, you're going to need about 100L for a ported box tuned in the 30hz range.

I dont deal with horns, sorry I cant help with that.

 

[stochastic]

Any thoughts on aperiodic? Would that help with the size issue?

 

[Jay1111]

Aperiodic would allow for a smaller sealed box, you're going to have to experiment and measure to figure out what works with that.

 

[GM]

Nobody? Does anyone think this woofer would work in the Frugel Horn MkII?

No, it requires a much bigger horn since it will be starting with a much larger filter chamber, throat.

GM

 

[stochastic]

No, it requires a much bigger horn since it will be starting with a much larger filter chamber, throat.

GM

Okay, would a rear-loaded horn in general be a good design choice?

 

[GM]

Sure, for a ‘50s era corner horn or prosound type scoop bin, though a 'BIB' pipe horn can work also depending on how much bass gain you want and/or how high you want to XO it.

Otherwise, some type of TL would be preferred with the mass loaded [vented] MLTL being the most common.

BTW, what is the brand/model?

GM

 

[stochastic]

Hmm, went through the calculations for a BIB and it looks like a folded BIB will be too tall to stand up in my basement suite with 7 foot ceilings. Is there a better rear-horn design that isn't quite as big? Should I fold it multiple times - might be worse performance and be a huge box as well? Really, with a box 18" wide and 25" deep already, folding it again, would be over 4 feet deep, makes me think it's a little unpractical for this speaker.

Open baffle instead? Any thoughts on what makes a good open baffle woofer?

Would aperiodic be my best bet for a small box?

What other options should I look into?

 

[GM]

Aperiodic would allow for a smaller sealed box, you're going to have to experiment and measure to figure out what works with that.

Hmm, a basic small, well stuffed, sealed alignment can't be made aperiodic since it can't damp down the driver's Fs impedance nearly enough, only a heavily stuffed [open or closed] TL or 'ideal' BLH can, which by today’s standards will range from relatively large to ridiculously so.

Of these, the max flat impedance [~aperiodic] open TL [driver at extreme top] is the best performance Vs bulk/build complexity compromise:

34.24” path-length, 196.1”^2 WxD uniformly stuffed along its length with however much stuffing density is required to damp its impedance peak flat, though most just damp them to ‘taste’, which is usually nowhere near aperiodic.

With a ~89.5 Hz base tuning, the trade-off of course is that once stuffed it will have a near I.B. [Vb = at least 10*Vas] response with only a minor amount of extra mid-bass extension, so without significant room gain it will have a progressively rolled off bass below ~70 Hz.

If a 69” path-length closed TL of the same net Vb is used, it will more closely match its I.B. response with a Qt approaching a transient perfect 0.5; a worthy goal for a ~matching impedance system, but not so much with today’s typically highly damped ones.

GM