need help for isob. sub

Hi all diy addicted!

I wish build a subwoofer for my system - I'm using two horn-loaded fullrange - just to fill the region below 70 hz at moderate volume. My goal is a fast, audiophile bass, no ht boomboom.

Now, I wish stay on the cheap side, and wish use two woofer I have from an old project (tnt primaluce speakers - using hertz hs200 for bass)

I'll post the specs:

hs200 sub driver: D:168 mm
xmax: 8.5
Re: 2.5
Fs: 29.4
Le: 0.98
Vas: 33.2
Spl: 90 db

Now, the sub will be powered by a klipsch sub module rated at 150 w rms... so the max spl is not a problem. I'll hear my music not so loud, and prefer to achieve best quality bass. (with horns sub pairing is delicate, isn't?). I've read a multitude of threads, used various programs but.... I'm still a newbie, and dam'n, especially a POOR newbie and the fear is to trash my money...

How can I achieve a decent result using this components?
I could realize an isobaric configuration in a sealed box, with only one of the speaker facing out of the box: maybe this could give me a small box and a tight, musical bass. But no extension in the bottom side..? BassPC and winisd don't help me (maybe I'm not able to use them)

Ok, You can see I'm lost in a lot of newbie's considerations.

Your advices are extremely welcome... THANKS


2002-08-15 6:21 pm
My personal opinion is that a pair of 8" drivers will not be enough to fill in for sub duty, especially if you're using horns. Horns generally have very low distortion and therefore you need something with a simillarly low distortion to match.

Using direct radiator stuff I'd look at commercial servo driven stuff from Paradigm or Velodyne, or go for a pair of 18" pro drivers per side and lose the very low (sub ~20hz) stuff.

Another option is some horn subs but they're huge. Maybe the tapped horn thread could hold some inspiration.

Just some thoughts,

Thanks Rob! Your thoughs are surely right and if I could buy this kind of stuff i'd be certainly happy. (my girl a little less, with two 18' ufos in the living room..;) )

But my target is achieve the best compromise using only the drivers I have, or simply live without a sub (and without sound below 60-70 hz..). I have spent all my audio budget for the horns and I'm considering a momentary solution expecting the day I become rich! :D

Naturally not the state-of-the-art, nothing hi-end. Only a little more punch with massive attack without blurring too much all the fabolous work the horns can do...

So, even I could resume a little bottom-end, maybe to 35-40, i'll be happy anyway.

The challenge is finding the best compromise (saving quality and low distorsion the more we can) using non-optimal drivers...I know.

As I know, 20hz flat in my room is a dream.
But maybe 30-35 hz at -3db is reasonably possible?

I'm still searching a ray of light.... :D

Thanks again and... please continue to post thoughs and advices (feed my noobs dreams! )
Great, add resistance is a choiche I've not considered.

Now, i need your opinions upon
1)the loading type (closed Vs vented),
2)Cabinet internal volume to get a good speed (low distorsion and low q I think)
3)and compound vs paired drivers both facing outside

Thanks for your patient help. Your knowledge is gold.
:D great, I love sismic emotion too,

but I'm concerned if I could achieve a good, tight bass for horn loaded fullrange pairing... If (partially) possible, I'm seeking for the best configuration with this goal in my mind.
No matters how deep and how terrific can be, only the best quality possible!

Shown is for one driver, for two drivers isobaric, halve box volume.



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Well, closed will be tighter and roll off more smoothly, but you won't get much stock (though its a tiny enclosure), and if you add even just 2ohms, the sealed volume is out of hand and at 3ohms it nearly doubles that, so I'm guessing you'll need to go ported just to get a reasonable size box. A 20.6 l box tuned to about 27.5Hz is what WinISD is showing me will work nice. Should get you pretty flat to around 30Hz with room lift and whatnot giving you fairly useful output to 23-25 (this is all assuming isobarik loading). If you tune it to 32Hz, you'll lose a few Hz on the bottom end, but it'll flatten the response out to nearly ruler between 30 and 185. Designed this way you'll have a 4th order rolloff at the bottom and a nice first order on top so it should be pretty easy to integrate and keep from distortion due to infrasonics.

Just 2 drivers facing forward, the enclosure volume actually goes up 4x and it gets you similar flat response about 2dB down from the isobaric with a few Hz at the bottom and the top end reaching up to about 350Hz before rolling off.

I would vote for the isobarik load tuned to 32Hz, but that's just me looking at sims in WinISD. I've never actually used an isobarik, so I have no idea what they actually sound like.


I will go for the isobaric configuration, and I'm beginning to learn how to use winisd.

I could use a volume of 28l tuned to 25hz (flat to 30 hz, -3db at 24hz), vent D 60mm L 43,2cm
or V 19l tuned at 28hz (flat to 40, -3db at 28 hz) with a vent of D 60mm
and a lenght of 50 cm............ (too much!)

I've noticed a strange think: the reflex vent that winisd indicate to tune the box to 28-30 hz is VERY long or VERY thin: both solutions are problematic, I think: too thin will produce airflow noise, too long tube will resonate and/or be problematic storing it in the box.


Any ideas?
No martini no party!

I've seen your link, and think it could be nice but my few bucks are a no-no for buying new drivers. For me, diy is money saving too... so, if I can re-utilize the drivers I own..

Thanks for the advice anyway.

This diy community is a great resource to learn and have fun even without searching hi-end absolute performances... (but often i read the supermegaiperquality sound researcher and dream listening this kind of beauties..)

Ps: sorry for my poor english. It sucks, but maybe can be understood. ;)

As you may have noticed going reflexed isobaric with said drivers
you end up with silly sized ports, you would have to use PR's.

Basically the drivers are not really suitable for isobaric reflexed.
(could work as a 20 to 25L double pair sealed in push
push or the same in 33 to 35 L tuned to 25 / 26 Hz)