[vilbig]

I am in the planning stages of either the Alpha 15 or Goldwood 18 designs. My question is regarding amplifier power. Should I get as close to the recommended power as I can or do these designs benefit from any additional horsepower?

Thanks

[mcgsxr]

I have not used either of those myself, though I have modeled them and considered them.

My experience with OB woofers is that it depends on how loud you listen - when a woofer is in a box, it has some measure of excursion protection from the suspension effect of how it is loaded in that box (sealed or ported).

On OB, there is no such protection.

I run a 500w amp on 2 OB 12 inch woofers, and have heard them bottom out, but only when being "exploratory" with upper end volume and bass intensive music.

I would aim for rated power myself.  Not much point in going higher - the Alpha's are pretty efficient too.

[vilbig]

Thanks for the info!

[JBspeakerman]

I have used both drivers.  In a H frame or plain OB both drivers reach Xmax at their respective FS with only 10 - 15 watts.  However, above FS both can handle 100 watts or more and both have large X-limit values.  IMHO, I consider a 100 watt sub amp as a balanced choice in a home HI-FI application with either of these OB drivers.

[vilbig]

Thanks, JB. I was trying to decide as to whether to use a separate subwoofer amp, or just use it full range with a passive xover as you do in your latest project.

[Tyson]

A steep high pass filter just above FS will go a long way toward protecting the woofer from being over driven.

[Poultrygeist]

I drive my two H-frame Alphas with two Dayton APA 150 amps in bridged dual mono. In this configuration they are rated at 150 watts a side. In my average sized room I can't go above 12:00 on their volume controls.

The Daytons ( aka Emotiva BPA-1 ) have built in crossover controls. You can download the BPA-1 manual on the Emotiva site.

[vilbig]

I drive my two H-frame Alphas with two Dayton APA 150 amps in bridged dual mono. In this configuration they are rated at 150 watts a side. In my average sized room I can't go above 12:00 on their volume controls.

The Daytons ( aka Emotiva BPA-1 ) have built in crossover controls. You can download the BPA-1 manual on the Emotiva site.

Thanks! - I will check them out.

[Davey]

A steep high pass filter just above FS will go a long way toward protecting the woofer from being over driven.

It will also introduce a large group delay that will probably be audible and detrimental.

The best way to limit excursion of open-baffle woofers is to select power amplifier(s) that can't easily overdrive the woofers and/or voltage limit higher-powered amplifiers at their inputs.

Cheers,

Dave.

[Poultrygeist]

As a less expensive option to the Dayton APA 150's I also use a 100 watt AV receiver to drive another pair of OB Alphas in another system. Each Alpha employs an 80hz low pass XO from PE. My CD player passes it's digital signal to the AV receiver while it's analog signal goes to a SET which drives the main full rangers.

Since so many folks have upgraded to HDMI receivers there are plenty of good used non-HDMI AV receivers available which have more than enough power to drive the Alphas. The Denon I use cost $35 at a garage sale. An advantage for me in using an AVR is having a remote to control the Alpha's volume.