Eminence Alpha 15" has bass in OB?

[Melo theory]

Don't worry about the published graph, its been known for quite some time that its wrong.
That driver is flat to 40 Hz.
I don't know why they don't fix it, seeing how popular the alpha is.....

 

[oon_the_kid]

I suspect that other people's measurements better reflect real life situation. My guess is that at 1watt. The speaker is clipping. See my previous post. After all at 1kHz it is almost 100db. Threhold of ear damage through long term exposure is 80db. So very likely most people would be listening and measuring it closer to 0.1watt or less. Without the speaker clipping, i reckon the graph would be flatter....

Oon

 

[renjiish]

The site below shows a better measurement.

Eminence Alpha 15A speaker. The Eminence Alpha 15A is a 15" 8 ohm speaker for all bass applications. Alpha-15A is a 200 watt RMS 15" woofer.

 

[CLS]

The published sensitivity and response curve are useless when you use it on OB, so, let's just drop it.

Suggestions:

Use (or borrow) some other boxed speakers (subs) to play some bass rich music in your place as loud as you need, measure the SPL in LF.

I remember there's a spreadsheet or S/W for calcuating OB's LF SPL somewhere. Plug the cone area and Xmax into that calcuator to see if it fullfill your requirement.

Alpha 15 has only 3.x mm Xmax, which is small. So I'm afraid it's not capable of doing loud and low at the same time on OB. Probably very limited SPL under 40Hz. Whether it's enough or not is up to you.

 

[DeonC]

Here is what the predicted response is according to Thorsten Loesch's excellent XLBaffle spreadsheet. The parameters and conditions is seen in the first pic.

In room response:

An externally hosted image should be here but it was not working when we last tested it.

In room power response:

An externally hosted image should be here but it was not working when we last tested it.

Deon

PS. Low-end power response is limited because I used X-Max and not X-Mech in the calculations.

 

[adason]

some interesting info about OB11 project of Troels Gravesen can be found here:
OBL11
He provides measurements directly on open baffle for Alpha 15A and DeltaLites, which he likes better on ob

 

[CLS]

....

PS. Low-end power response is limited because I used X-Max and not X-Mech in the calculations.

That'd be more practical because when it goes beyond Xmax, the distortion will be skyrocketing.

Louder, yes; better, no.