Getting a bit more oomph out of the Eminence Beta 8A...

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I've ordered some Eminence Beta 8 drivers for a small speaker project I'm working on at the moment, and I'm trying to come up with a design that gets a bit more bass out of them. What do you think of this?

HornResp data:
ID=28.00
Ang=4.0 x Pi
Eg=2.80
Rg=0.00
Fta=21.35
S1=390.00
S2=309.12
Par=35.20
F12=0.00
S2=309.12
S3=160.00
Par=64.90
F23=0.00
S3=160.00
S4=550.00
Par=12.00
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=210.00
Bl=9.70
Cms=3.71E-04
Rms=1.33
Mmd=14.41
Le=0.49
Re=5.99
OD=1
Vrc=0.00
Lrc=0.00
Ap1=0.00
Lpt=2.00
Vtc=0.00
Atc=661.30
Pmax=100
Xmax=5.0
Comment=Eminence Beta-8A TL2

Response looks good down to 60 Hz. Power handling in-band seems to be around 25W, which is a pretty good match for what I intend to drive them with. Cabinet is actually going to be vented out the bottom and will contain one internal fold, which should allow me to put the driver almost exactly where HornResp suggests I should get the flattest response.

Thoughts?
 

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Have you tried them in a bandpass horn?

You've looked at the group delay on this, and will be using some sort of time correction to delay your mids/highs.....right?

Perhaps I should have been clearer - I'm planning to use them as the bass-mid in a two-way system. I'm just trying to get a bit more low end out of them. The group delay rises to about 12ms at the low end in this alignment, but I suspect that really won't be an issue considering what it's going to be used for.
 
Perhaps I should have been clearer - I'm planning to use them as the bass-mid in a two-way system. I'm just trying to get a bit more low end out of them. The group delay rises to about 12ms at the low end in this alignment, but I suspect that really won't be an issue considering what it's going to be used for.

Where are you intending to cross these over, and what is the group delay at that frequency? That is the group delay to be concerned about.

Also, using a notch EQ on that 400hz peak is going to give you a pretty big phase/delay shift right in the low midrange, not good for vocal realisim.

Have you looked at using this in a ported horn?

What is driver for the highs? Some sort of full ranger, I presume?
 
Response looks good down to 60 Hz. Power handling in-band seems to be around 25W, which is a pretty good match for what I intend to drive them with. Cabinet is actually going to be vented out the bottom and will contain one internal fold, which should allow me to put the driver almost exactly where HornResp suggests I should get the flattest response.

Thoughts?
If the upper peak and dip is far enough away from the crossover point, it should do fine.

It will be fairly directional 150 Hz and higher, venting out the bottom would not be advisable unless the listeners are below the cabinet ;).

I'm using a Kappa 10 in a small ( 15" x 15" x 26.5") TH for a drum sub up to around 250 Hz where a pair of 5" come in, sounds pretty darn good, and gets loud.
 
Where are you intending to cross these over, and what is the group delay at that frequency? That is the group delay to be concerned about.

Also, using a notch EQ on that 400hz peak is going to give you a pretty big phase/delay shift right in the low midrange, not good for vocal realisim.

Have you looked at using this in a ported horn?

What is driver for the highs? Some sort of full ranger, I presume?


It's going to be crossed over quite high to a piezo tweeter (yes, I'm trying to be as cheap as possible). Ignore the HornResp predictions above 200 Hz or so - there's going to be a bit of damping in the first 1/3rd or so of the enclosure, so those FR wobblies around 400 Hz are going to be significantly smaller than predicted in the graph, if they're present at all. Venting it downwards should reduce their impact on the FR as well. 150 Hz is a bit outside of the peak response from the vent, so perhaps venting downwards may not cause any problems. In any case, I'll consider some other designs.
 
Ahh, I see now. This is basicly a rear horn / transmission line. Sure, looks like it could work. How does it compare to a bass-reflex design of similar volume?

The performance is basically similar. The advantage of the "TL" is that the inner panels will add some needed stiffness to the box.

There's another alignment I'm looking at - a 27 litre box vented @ 75 Hz. This will produce a 2dB bump around 90 Hz and better in-band power handling. The bump should disappear with a 80 Hz 12dB/octave high-pass filter, which will also reduce out of band excursion.
 
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