Eminence Legend OB..strange question

[grantnsw]

Hi,
for 2 of these 4ohm per side SERIES connected (is this a dumbass Q?) for Open Baffle,

http://www.eminence.com/pdf/legend-ca154.pdf

(the Qts is too low maybe for OB?), and they will beam a lot? at first order 1500Hz. But they have a 97dB SPL.

Two by 4ohms in series yields effective new SPL? But, surely 2 of these MUST be good to cross very low to a 27TDFC or D3806.SS OB? It kinda makes sense to me, but...

be kind please! haha, I'm still trying to sort it all out. cheers Grant

[grantnsw]

I forgot to ask , is that Eminence driver plot believable?

It just looks too good too be true.

[grantnsw]

gainphile, moondog, ttan? anyone? it seemed like a good idea!

[tinitus]

Woofer looks ok
Using one 15" is difficult enough
Using two 15" makes it even worse, in terms of beaming and crossing to tweeter
One often used option is 2.5way, so that one woofer is crossed low around 300hz
Which makes even more sense with OB

But croosed at 1.5khz is hard enough for both 15" woofer and the tweeter
You need special xo
A simple "6db" is not likely to work, but who knows, it might do what you want, even if it doesnt satisfy others

3-4ohm is a problem though

Another option is the so called "fast" system, where you use a fullrange instead if tweeter
This allows a low xo point
It would work with two woofers in series, as you suggested
Crossed 200-500hz
You could still use a super tweeter, crossed 5-10khz

Dont let the choise of woofer determine whether to build OB or not
YOU have decide on hand whether YOU want OB or not
And you have to know the advantage and drawbacks

[Pano]

The mid Qt and highish Fs of the woofer means you won't get a lot of low bass. What you d get should be clean, tho. There are better choices.
Yes, the Eminence specs are usually quite accurate.

If running 2 woofers, a better choice is 2x8 ohm drivers for a total of 4 ohms. You'll gain 6dB for a given voltage and your low pass inductor will only need to be 1/2 the size.

[grantnsw]

Hi Tinitus,

Thank you VERY much from Grant in Australia.

We both had many great talks with Omni in Ohio USA previously.

I like the Eminence driver because of its response and SPL but as you say it could be difficult to implement in an OBaffle setup.

I really need to buy Mr J Krevosky's ABC dipole s'ware to see how it works with my new driver choices.

Many thanks for your info on full-range drivers to suit.
The one I am particularly interested in now is the TangBand W8-1808

http://www.tb-speaker.com/detail/1230_04/w8-1808.htm

To me, it seems that it would work so well with the Eminence Legend as above on OB. The response of both 'augers' well (ie fits well) with Martin King's (treatise or) study of OB considerations.

Cheers my friend Tinitus,
Its a pleasure to catch up with you again, and I hope you have built your new Stradivarius violin! Kindest regards, Grant

[tinitus]

Ahhh, hi Grant
I had forgot, thanks for reminding me
Nice to hear from you
Wonder what happened to our friend Omni
His last post was about him and friends doing good work on his speaker, and that he would report back with the result
Never heard from him since, or it has slipped my attention

nice post, thanks

btw
I agree with Panomaniac
Last time I looked closer at OB I also concluded that 2x Beta-8 might me a good choise
They seem to go relatively low for a pro 8" with 95db
I would still consider 2.5way tho
And might work with a Hivi planar
Since then there have been several good reports about the sound of Beta-8

Subs?
Beta-8 might be better suited for a box design, so sub may be welcome with OB

cheap and "easy living"

[gainphile]

Hi grant,

I have had quite a struggle with 15" crossing high (1kHz-1.5kHz). That was eminence Alpha and actively equalized too. I wanted to clone Physics CS2 but quit halfway.

The Legend would take more effort than Alphas I guess. The Fs is higher. I like the Qts of .5, that is critically damped.

[Moondog55]

Never built anything like a 2-way using 15inch bass, but when listening to may of the so called high end PA systems that use a 15 and a horn they have all sounded far too "Fat" in the vocals.
Could be just me tho.

As bass unit and crossing to a 10 or an efficient 8inch at 250/300 perhaps.

Haven't a clue really Grant/ sorry

[Pano]

That's cause most of them use a horn that won't go down low enough. So it's a stretch for the 15"

a 10 or 12" and mid size horn can work well (in PA)