Subwoofer with Coral Beta 8?

[pengboon]

Anyone has any experience in adding a subwoofer to further extend the lower range of the Coral Beta 8 in BR box? Interested to hear your experiences and opinions.

cheers!

[pengboon]

I am considering the Rythmik Audio sealed 12" kit. Will this match well? And suggestions as to which configuration to choose?

thanks!

[bigwill]

If it was me, I would take out the Coral 8 (carefully) and put then on open baffles with a high Q 15" woofer or two per side crossed over at about 300Hz.

[pengboon]

Hi Bigwill,

You mean l mount the corals on OB on top of the sub, Kinda like watt/puppy style? So it's more of a bass driver, any suggestions on which driver/design to pursue, i'm a complete newbie as I've lived with only my corals doing full range duty.

FYI, my living room is not very big, just 11' back to front and 14 ' left to right, but left opens up to dining room. I don't need earth shaking bass, just to augment my corals in the deeper end.

thanks for the ideas!

[bigwill]

What I meant was, have two big baffles, and on each, have a Coral and one or two 15" PA woofers such as the eminence beta 15. The bass will be very tight and musical. The woofers will be open baffle too.

Here are the upsides:

Very easy to build
Cheap big PA woofers are easy to come by, AND they're efficient
The bass will be very nice sounding.
The Coral may benefit from having no enclosure and sound a lot more open.


Here are the downsides:
They will be pretty big
They won't go particularly deep, but I think the quality of the bass in this setup is worth this drawback.

[paulspencer]

I'm not familiar with the driver you mention but I'm familar with the Rythmik sub kit (I have it). You can cross the Rythmik at 100 Hz and no higher. That point is the limit of the servo feedback mechanism.

I believe the Rythmik kit is easier to integrate than most subs for a number of reasons:

1 - different options with the preamp/filters
2 - very low distortion
3 - articulate with a high crossover point - this is a musical sub, not one of those monsters that won't behave above 40 Hz

An important decision is whether you want a sub or a woofer. A woofer will happily cross up higher, like 200 or 300 Hz. Which approach will best fits depends on where you want to cross. If you are happy with 80 - 100 Hz then I'd go a sub but keep in mind that most subs won't cross well that high.

If you do go with a sub, then I think you can't do better than Rythmik. If one isn't enough, then go more than one.

[pengboon]

Thanks for your inputs, appreciate it!

It is a full range driver whose specs are supposedly 37Hz - 20kHz. So I think I should be crossing the sub at under 100Hz.

BTW, is it better to use the high level (speakers?) or line level (RCA?) inputs? I would prefer to run my speakers full range and cross the sub using the built in crossover.

[paulspencer]

Crossing higher will improve the performance of your Coral driver. 80 Hz is a good place to cross although you have to consider localisation and placement issues. A simple solution is often seal your main speaker which often gets an F3 @ 80 Hz and a predictable 2nd order rolloff which is easily matched with the sub controls.

If you go with a 4th order crossover, you can then use built-in highpass on the mains at 80 Hz (use line level and use line level outputs to go from plate amp to power amp input for the mains). The result is a symmetrical 4th order crossover at 80 Hz

The sub has a 4th order low pass @ 80 Hz
The mains have an effective 4th order highpass at 80 Hz (2nd order acoustic and 2nd order electrical summed to 4th order)

For this reason consider line level, as you are then going active and improving the performance of your mains.

[pengboon]

I understand what you're saying, sounds interesting!

But according to the manual, the high-pass line out is at 100Hz (-3db) Will this still work well?

[paulspencer]

... unless you request 80 Hz (I believe you can ask for the frequency you want there).