First (dual) subwoofer project, 12 inch, advice?

[basite]

Hi all!

Last week I was experimenting a little. I have a home theatre setup on my attic. I used a cheapish 8" subwoofer before, and while it did "sufficiently", it was not ideal...

On that same attic, had 2 advent speakers lying around. They were my dad's speakers. As the woofer surround had rotten, and internet wasn't around yet, he had replaced the woofer, the guy in the shop back then, gave him a 12" woofer. As I wasn't using the speakers (I bougth original advents), and they were just gathering dust, I just might try something with them...

I bypassed the crossover, and hooked up a stereo amp, and used the PC (source) as an equalizer.

the cabinets are the original "unmodified" (except for being molested with the bigger hole for the 12" woofer)

after some fiddling, I got to a result that was much much better than the original subwoofer there, much more punch, more articulated sound, not muddy,...

So, I'd like to make a new project out of them. As it would be my first actual subwoofer project, I could use some advise... I found the woofer's specifications somewhere on the net, at least, similar ones, it's the same series, but a newer model, so it seemed. The woofers aren't the best ones, and if this experiment is really worth it, I might change the drivers too later on, as budget allows better too...

At the moment now, the woofers are in the original advent cabinet, but I'd like to know how to be able to improve the cabinets, bracing, foam/padding inside, ...

I plan building 2 DIY class D amps, somewhere around 200 watts to drive them, when budget allows (poor student here )


I have always wanted to build speakers, or a subwoofer for a DIY project, and this might be a first & good opportunity to actually do so... I've built quite some turntables, cases and other "general diy", so I get around with all the materials needed

Any help and tips would be greatly appreciated...

Thanks in advance,

Regards,
Bert.

Sphynx SP-W12-BP

Woofer: 310 mm
Power Max: 250W
Impedance: 8 Ohm
Freq. Resp.: 30 Hz ... 4,5 Khz
Vas: 11,897 L
Cms: 723,705 µ M / N
Krm: 1, 709 µOhm
Erm: 0,840
Mms: 37,878g
Mmd: 30 gr
Kxm: 8,289 m H
Exm: 0,723
Revc: 7,8 Ohm
Fo: 30,398 Hz
Sd: 57,256 m M
Md: 30 gr
BL: 7,047 T
Qms: 3,617
Qes: 1,136
Qts: 0,865
No: 0,805 %
SPLo: 91,1 dB

[revboden]

Have you tried using WinISD pro. LinearTeam

It's very easy, use the help menu- getting started.

[bjorno]

Default First (dual) subwoofer project, 12 inch, advice?

..So, I'd like to make a new project out of them. As it would be my first actual subwoofer project, I could use some advise... I found the woofer's specifications somewhere on the net, at least, similar ones, it's the same series, but a newer model,..

Sphynx SP-W12-BP

Woofer: 310 mm
Power Max: 250W
Impedance: 8 Ohm
Freq. Resp.: 30 Hz ... 4,5 Khz
Vas: 11,897 L
Cms: 723,705 µ M / N
Krm: 1, 709 µOhm
Erm: 0,840
Mms: 37,878g
Mmd: 30 gr
Kxm: 8,289 m H
Exm: 0,723
Revc: 7,8 Ohm
Fo: 30,398 Hz
Sd: 57,256 m M
Md: 30 gr
BL: 7,047 T
Qms: 3,617
Qes: 1,136
Qts: 0,865
No: 0,805 %
SPLo: 91,1 dB

Hi Bert,

I guess you found the T/S here:

http://petoindominique.fr/php/mysql_...?marque=SPHYNX

and

http://petoindominique.fr/php/mysql_...ul.php?hp=2292

Take a good look again The Sd thus the Vas value are way off.

b

[basite]

Hi,

@Revboden: thanks, I have heard about winisd before. i'm using mac, so I have to run it through Wine, but it works fine. Will try with that

@Bjorno: Thanks for that site, great information there, however, I didn't find the T/S parameters there, I found a PDF catalog from sphynx (or so it seems, can hardly find anything about the brand), and copied the parameters from there...

given that the parameters on your given site are "more complete", I will use them too, and compare...

I hope to be able to use them, otherwise the project is a no-go for now...

thanks in advance

Keep them spinning,
Bert.

[basite]

UPDATE:

I tried WinISD, since the woofer was not in the database, I chose to add a new one, I filled in the parameters, using the values from the catalog I found (first), and indeed the Vas & Sd values were off (efficiency was also 15dB lower as a result in winisd), used the values on the site provided by Bjorno.

When I hit "save" it said "parameter error", adding that the consistency check of some parameter groups was wrong. This, while everything seemed logical. Almost all values were off

could this be a bug by running it on Mac? or is there something really wrong?

Thanks in advance,

keep them spinning,
Bert.

[bjorno]

..could this be a bug by running it on Mac? or is there something really wrong..

Don't blame your computer..The T/S given in the Sphynx catalog are corrupted.

b

[tb46]

Hi basite,

No need to give up on these drivers. Measure the Thiel/Small parameters yourself, e.g.:

Measuring Loudspeaker Driver Parameters

Then use the Hornresp parameter input functionality to "fine tune" the values.

It's easier than it sounds.

Regards,

[basite]

Hi Oliver, Thanks, I might just try that I think my multimeter has frequency test function, and all the other tools are here too...

something for the weekend...

Thanks for the link!

Keep them spinning,
Bert.

[basite]

Hi again!

it seemed the catalog was indeed wrong, but the values from the link that Bjorno gave, did match. It also seems WinIsd requires that you insert the values in a particular way too...

anyways, plotted a graph, and without EQ's, results are, well, not quite as I hoped . with a 100L box, I would have a -3 point at, 44hz... Not quite what i'd was hoping for...

I would need a very very very large box, for good results (with an infinite baffle, they would hit 20hz at -3, but I don't have space to do that).

this with all the parameters set as "standard". Vented enclosure doesn't make much difference, but the driver isn't really suited for vented enclosures...

However, this is not actually what I was hearing in the attic... any ideas? I'd say, maximum size of the cabinet would be 120Litres, with some EQ'ing I managed to get it pretty good though, but still...

anyone have ideas?
I also wonder, with the closed box design, would internal damping make it somehow better, and how can I simulate this in Winisd?

If all else fails, what would be a good driver for "not too much money", and that could work in a 80-90 litres box? Thanks in advance,

Keep them spinning,
Bert.

[tb46]

Hi basite,

The JBL GTO1214 is quite versatile, and not too expensive, e.g.: 2 JBL GTO1214D CAR AUDIO STEREO 12" 4-OHM GTO POWER SUBWOOFERS/SUB WOOFERS PAIR | eBay

Regards,