Low hz, budget subwoofer ??????

[bjorno]

FYI,
Summing up parts of this thread where the mentioned drivers are corner loaded and compared at x-max~/1 Hz.

Are the initial requirements still valid,like the focus on 18-35Hz?

b

 

[gadgeteer123]

ya my mains are ported, I believe that they are ported somewhere between 35-40hz because at those notes I can feel the air flow from my recliner 13 feet away. Also i'd like to add that these are sanyo avs 500 12" floor speakers, they have a built in circuit breaker, There is no wattage listed, but I have been using a 100rms per channel stereo on them and I can get the stereo to distort before the speakers ever do, I even tried that 400rms amp 200 per channel. And they took it pretty well. They bottomed out at 20hz, but i'd expect that since its below tuning. And as far as loudness I can feel the drum kicks in my chest from 13-14 feet away.

 

[tb46]

Hi gadgeteer123,

I'd go with two GTO1214 in 20"Dia.x24"H sonotubes (app. inside dimensions), a 4"Dia.x14-1/2"long duct will tune this to about 25Hz. That size box should work ported as well as sealed. Play around with the placement, and you can try stuffing the ports in your main speakers (and/or the new subs) to see if you like that combination. These don't have to be placed in the front, provided you have a low enough and steep enough high cut on the subwoofer amp. When used ported, the subwoofer should have a low cut to prevent the speaker from bottoming out (depends very much on the volume you use).

Just hard to beat the price/performance ratio.

Regards,

 

[GM]

Indeed, and squeezing them into a 62.5" long (assumes ~0.75" end caps) ~12" tube with the same vent should drop it down to ~20 Hz and maybe a little cheaper to boot.

GM

 

[hellonwheels]

Are you seriously both suggesting a single 4" diameter vent for a "true" subwoofer?

I think the best bang for the buck and effort and size would be the simplest tapped horn... Tapped Horn Experiments and I don't think you can beat the ebay jbl for price/excursion.

Here a 130L version with ~23hz corner... Should be dead simple to make.. and being that its got flat sides easier to place.


ID=28.00
Ang=2.0 x Pi
Eg=25.00
Rg=0.00
Fta=0.46
S1=180.00
S2=188.52
Par=14.50
F12=0.00
S2=188.52
S3=388.24
Par=340.00
F23=0.00
S3=388.24
S4=430.00
Par=71.10
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=511.00
Bl=16.72
Cms=1.56E-04
Rms=3.41
Mmd=200.00
Le=3.05
Re=3.76
TH=1
Vrc=0.00
Lrc=0.00
Ap1=40.00
Lpt=4.00
Vtc=0.00
Atc=0.00
Pmax=350
Xmax=14.0
Comment=NEW RECORD - simplest th jbl driver gto1214

 

[gadgeteer123]

SO what is wrong with the TRIO12 for this application? they both cost about the same. Also if I do get the jbl why not get the 15" instead of the 12" for the better low response. The highest note this sub will be hitting is 50hz tops maybe lower. But I wan't a good response down to 18hz.

 

[tb46]

Sealed, ported, tapped?

Hi hellonwheels,

Nice work with that tapped horn. Not that it matters, but Ap1 and Lpt should probably both =0.00.

To answer your question: Yes, I would go one step further, and stick "socks" in both the ports of the mains and the subs, and give that a try. I think gadgeteer123 looks for a low budget augmentation of an existing set of speakers, mainly for home theater usage. At about 14Hz a simple 80 Liter sealed box starts to outperform even your nice tapped horn. Add a little room gain (maybe some Linkwitz transform boost), who knows?

Hi gadgeteer123,

There is nothing wrong with the CSS Trio12 that I know of, but they don't sell them for less than $90.-- incl. shipping.

Here is what I found for the 15" version:

http://cgi.ebay.com/JBL-GTO1514D-15...Car_Subwoofers_Enclosures&hash=item4aa525c86a

http://cgi.ebay.com/2-JBL-GTO1514D-...Car_Subwoofers_Enclosures&hash=item588a4a5394

Regards,

 

[hellonwheels]

Hi hellonwheels,

Nice work with that tapped horn.

Thank you! You're obviously knowledgeable so I don't know why you dont agree with me 100 percent!

14hz at what spl and excursion limits? If you run the model I'm pretty sure I would not consider it usable after +room gain and -the equal loudness curve. The newly named "Skinny Thunder" box I modeled is 114db +or- 1db for 23-95hz and 110db @ 21Hz. That's modeled outside with a mere 150W, staying within excursion limits. And of course the distortion will be much lower than your sealed box over most freq. because of less excursion. I do not think you can do better than this without more drivers or more SD and more power with a vented or ported alignment.

I would like everyone to put an end to modeling ported subs without modeling port airspeed. Port compression and added distortion sucks. Theres a reason Meyer and even Peavey use huge ports on subs. Or the contrabass uses passive radiators.
Bass is simple, like all audio you want a linear system. Linear, just band limited.

 

[hellonwheels]

I did a spot check and 22hz would be 100db a full 10db below my TH alignment. You get 91db @ xmax @ 14hz with 80l sealed* which I do not consider useful output.

 

[GM]

SO what is wrong with the TRIO12 for this application? they both cost about the same. Also if I do get the jbl why not get the 15" instead of the 12" for the better low response. The highest note this sub will be hitting is 50hz tops maybe lower. But I wan't a good response down to 18hz.

Well, I said it wasn't suitable for down firing, but then I noticed today that my Excel SS got corrupted somewhere along the line, so re-ran the numbers and it's published specs puts it well within the limit, so is still an option. Sorry about that, 'spiff' happens sometimes..........

Bigger is better (BIB) if it has enough power handling, so it boils down to how big a budget and how big a cab size one can tolerate has.

Really, to go to 18 Hz at high SQ and at a high enough SPL to make it worthwhile means big drivers, cabs or multiple smaller ones as I previously noted along with enough power to allow them to 'be all they can be', but your $$$, size 'budget' rules out these options.

Also, there's the cost of the XO if you don't already have one plus it will need digital delay if you choose a TH alignment.

GM

 

[GM]

I would like everyone to put an end to modeling ported subs without modeling port airspeed.

I did calculate it and while not as low as I prefer (< 5% @ rated power) for a HIFI/HT app, it's not bad considering the rather restrictive limits set by the OP and as Oliver noted, he can always 'stick a sock in it' to damp it if need be, though I did recommended the MLTL variant as an acoustic solution to at least lower it a bit.

Bottom line, you're 'preaching to the choir' and I fought this 'battle' for many years before finally giving up since most folks who come here for help are more interested in cheap/small than high SQ no matter what they claim. Like it or not, we live in an 'Acoustimess'/WAF regulated environment and the way the world's economy is going it's probably only going to get worse, so folks like us are being forced back out to the 'deep fringe' of DIY audio where I started in the '50s.

GM

 

[hellonwheels]

Bottom line, you're 'preaching to the choir' and I fought this 'battle' for many years

Actually I did find a post by GPM (you!) that related my senitments exactly! A couple years back on techtalk bbs.