My Subwoofer

[harrisni]

Hi,

I'm starting my first subwoofer, after many weeks research and reviewing a number of designs I have decided on using the Peerless XXLS 830845 12" Subwoofer for in a sealed design.

The subwoofer will be powered by a Redgum Audio RGSW4 Subwoofer Amplifier Plate which is 600WRMS power output into 8 ohms / 900WRMS into 4 ohms with an Electronic Crossover adjustable from 20Hz to 200Hz.

http://www.redgumaudio.com/store/99.html

Going from the specifications on the DST website it recommends a seal box volume of 62L, I've come accross a number of other designs using a volume of 74L. Unfortantely I'm not very good with the winISD applications.

Most of the designs only seem to use about 300RMS of power, I thought it would be better to get a bigger amplifier just in case I decided to change the design in the future.

I know that ported applications are better for movies, but since its my first subwoofer a simple design is probally better.

What you guys think?

[MJL21193]

Hi,
Sealed may not give enough low bass to satisfy (though I am a big fan of sealed, I know it's limits). Any bass boost on the amp? This would help.
Better to have more than enough amp power than not enough (clipping kills).
Good luck.

[harrisni]

True, I am aware that Sealed has its limits.

The only other option was a 830500 12" XLS with a PR.

http://www.tymphany.com/papers/appxls12b.htm

[chops]

You know, you can save yourself tons of money on the amp alone if you go with this one from PE. Not to mention that it has a ton more features, including full parametric bass EQ!

http://www.partsexpress.com/pe/showd...number=300-808

[AndrewT]

Hi,
the amp spec shows it is safe driving 4r0 loads but the power has drooped considerably.
69.3Vac into 8r0 (+36.8dbV).
60Vac into 4r0 (+35.6dbV).
That shows a loss of 1.2dbV into the 4r0 load.
A good amp that can deliver current into a difficult load will lose <1dbV into it's lowest recommended load. A very good amp <0.7dbV and an excellent amp <=0.5dbV.

I recommend you stay with 8ohm speakers for this amplifier.
600W into 8ohm even if they are only 88db/W/m will produce a lot of bass.
High senstivity PA style drivers will not produce much low bass they are optimised for music and produce massive volume down to about 40 to 50Hz.
For low bass you are looking for 30Hz response and for sub-bass look at 20Hz response.

I know that ported applications are better for movies

that is the wrong conclusion.
low bass is useful for movies. Judging by what I hear I think movie sound tracks apply less equalisation to the bass information than music. the result is that there is good unadulterated content down there that enhances the whole experience if the speakers are capable.
Sealed can get down there if the somewhat complex design is properly carried out. Ported is probably easier and requires less Xmax if the tuning happens to suit the wanted low frequencies.

[harrisni]

How about this design:

http://www.solen.ca/domont/sxxls12/sxxls12.pdf

using a 830500 and a PR.

[harrisni]

Okay,

I think I have narrowed it down to:

1x 830500 XLS
1x 850548 PR
450W Redgum RSW3 Plate Amp

http://www.redgumaudio.com/Brochures/rgsw3.htm

Box Size 480mm x 480mm x 470mm

What you think?

[sfreak]

Hello Nick,

One thing I can say, is the Redgum amp... well is rather expensive. If you have the money and thats what your after, but there are better amps to be had for the money as far as I can see. Other than that, the Peerless sub & radiator are a good way to go.

Your box dimensions, I assume thats the outer dimensions, what thickness board and I assume MDF yeah?

[AndrewT]

Hi,
is a cube the best shape for a sub or bass speaker box?
Or at these low frequencies is shape irrelevant?

[harrisni]

sfreak: I was going to use MDF yes and probally 1inch thick?

Yeah the Redgum amplifiers are not cheap, but they are a plate amp and its all ready to go.

I was thinking of contacting Stones Studio to get an exact diagram for the box, costs about $100


AndrewT: Good question, not sure... Anyone?