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francorovereto 9th December 2007 03:17 PM

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

francorovereto 9th December 2007 04:15 PM

ps: the woofers are 8 inch units

RobWells 9th December 2007 08:54 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,


francorovereto 9th December 2007 10:54 PM

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! )

Kensai 10th December 2007 04:20 PM


Add some resistance inline with the drivers (low if you run them parallel, high if you run them series maybe 2-6ohms), and that will flatten out their response a bit and, as WinISD Pro tells me, get get you an F3 down to the very low 30s and maybe even into the high 20s.


francorovereto 10th December 2007 08:46 PM

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.

Rigs64 13th December 2007 12:03 PM

I use two 6.5 inch Peerless woofers in a two chamber box with both chambers ported and get room rattling results while watching movies.The woofers are mounted face to face and wired out of phase.This design was made with ProBox 5.0.

francorovereto 13th December 2007 03:04 PM

: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!

sreten 13th December 2007 04:24 PM

2 Attachment(s)

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


Rigs64 14th December 2007 02:38 AM

I use the double woofer isobaric sub with a pair of two way quarter wave tapered pipe front speakers.This combination yeilds some very tight bass.

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