[Eldergod]

Anyone have any experience with a single Eminence Alpha 15 in an OB powered with a sub plate amp? Specifically looking at PE 100w vs 250w ones. Too little? Too much? Looking to pair one with some diy Betsy’s.

[Bumpy]

My question is so close to yours that I have posted it in your thread. Hope you dont mind. We may get combined answers that will help us both.

I have 3 way open baffles with 15" bass drivers, 8" midrangers and 4" tweeters. Playing just the mid and tweeter together, sounds perfect but lack much below 100Hz as expected.

The mid is an exceptional driver (SEAS Exotic W8) which I run full range without filters, and the bass driver is good but not great (Eminence Alpha). If asked to work at just very low frequencies it is perfectly acceptable, having a high Qts which is perfect for OBs.

Unfortunately the 'lower quality' 15" driver with passive low pass filter has a long 'tail' into the higher frequencies and this is muddying the sound of the midrange. My aim is to low pass the bass at 100Hz with a fairly steep slope and perhaps add a bit of amplification.

Throughout the process I am using REW to confirm what I am hearing.

So, does the following sound logical.

Divert the 'high level' signal from the bass driver into a plate amp with high level input. There I can adjust high pass, phase, slope and volume and from then back to the bass driver.

[Bumpy]

Eldergod. I did notice that the 100W PE plate amp has no facility to adjust slope.

[Bumpy]

Regarding power requirements.

Often in OB the base driver needs to be turned up considerably to counterbalance baffle cancellations. I guess its not abnormal to perhaps want to double its loudness.

"The smallest difference in level that most people easily perceive is 3dB. To achieve a 3dB rise in volume requires twice as much power from the amplifier.

But to double the apparent loudness is more like 10dB. To do this a 10 watt amp (say) needs to be replaced by an 80-100 watt amp.

[Eldergod]

Bumpy, sorry, I just saw your posts. Yeah, my concern was needing more power to match perceived output for sure. And I don’t think any of the PE plate amps have an adjustable slope. I think most are set at 12 or 18 dB slopes as default.

[Bumpy]

Bumpy, sorry, I just saw your posts. Yeah, my concern was needing more power to match perceived output for sure. And I don’t think any of the PE plate amps have an adjustable slope. I think most are set at 12 or 18 dB slopes as default.

Yes I fear you are right. Unless anyone knows better

[ooheadsoo]

I don't get all the math, but the bottom line is that because dipoles need an extra 6db of power per octave due to dipole cancellation/roll off, the typical bottleneck is the woofer's xmax, not amp watts.

http://www.linkwitzlab.com/models.htm#A1