Eminence Beta 12LT system

[planet10]

Re: Maria Update

Any plans yet?

Mail me. What i have is sufficient to build them, but not polished enuff to put up yet.

dave

 

[bigwill]

Ah, my thread back from the grave!

I never got to do this project because of lack of money, and a very good deal on some other widerangers which turned out to be not so good

 

[gpsmithii]

12lta

Ah, my thread back from the grave!

I never got to do this project because of lack of money, and a very good deal on some other widerangers which turned out to be not so good

Got mine today! I'm working on a Deathbox II sub ... then on to the "Chang" using the FE207Es .... then the 12LTAs for a summer time party speaker. I have a pair of these

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=290-442

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=290-442

from projects a few back ..... that I may use on the top.

 

[danielm]

Afterburner

Many yrs ago I messed around with the 12lta and found it to be typical of a stiff cone 12" with whizzer. At that time I had no knowledge of notch filters/zobels...

Now I am searching for a hi ef speaker to use with a SE or PP amp and The LTA can to mind.
During a search I discovered this thread, the Hammer Dynamics Super 12 and the afterburner files.
Excellent !

I've read the Super 12 is compared to the Quad ESL which, to me, had the best mids of anything I have ever heard. The Super 12 would clearly be the winner of SPL over the weak Quads which was my biggest complaint when I owned them.

Although, the stock 12lta is not the same driver that the Super 12 uses, I wonder how 'refined' it could be with a few mods.

Also, I noticed the old 12lta and the current lta have differing specs. Has anyone experienced the two versions side by side?

I figure roughly $250 for the pr of Afterburners using the FT17h.

Any suggestions for a 95+db/1w that would be around that budget? The Afterburner box may be a bit too big for WAF.

Cheers,
Daniel

 

[Godzilla]

>>> http://www.partsexpress.com/pe/psho...tNumber=290-442

I was considering this tweeter along with this Eminence for a smaller hi-eff system.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-516

any thoughts on this combo?

Godzilla

 

[GM]

Re: Afterburner

Any suggestions for a 95+db/1w that would be around that budget? The Afterburner box may be a bit too big for WAF.

HE = big box or no bass. Note that best bang/buck is to go vertical with 'BIB' pipe horn.

GM

 

[GM]

any thoughts on this combo?

Like any horn/point source combo, the horn's polar response dictates the size of the point source driver, so without any data about all I can say is that typically for a 1.5 kHz XO point a 12" is required. For use with a 10" then, a wider horn pattern is required, ergo either a closer listening distance or possibly more boundary damping will be required between the speaker/listening position and between the speakers themselves for good imaging, etc..

GM

 

[davidallancole]

Is there any MLTLs for this thing set up?

I see in Thorstens Afterburner project that he uses a short, squat box tuned to 40Hz. Its 75x48x30 cm which is close to golden ratio. If you wanted to get this up to ear height, would it be best to use a golden ratio box with a false bottom or stand? Or could one use a box with these dimensions: 4.47x18.9x57.9 inches? They have the same volume which is 80 liters or 2.83 cu ft but the later is shaped more like a MLTL. Thorsten said to use the 18.9 inches for proper wave launch and I chose 4.47 inches deep because thats how deep the speaker is, so it should be braced against the back wall.

Any thoughts?

 

[Godzilla]

>>> Like any horn/point source combo, the horn's polar response dictates the size of the point source driver, so without any data about all I can say is that typically for a 1.5 kHz XO point a 12" is required. For use with a 10" then, a wider horn pattern is required, ergo either a closer listening distance or possibly more boundary damping will be required between the speaker/listening position and between the speakers themselves for good imaging, etc..

Thanks for your input GM. Damn crossovers! I thought i was done with them a few years ago... coming back to haunt me again. I guess i have to choose to futz with them again or nix the idea altogether.

Godzilla

 

[GM]

You're welcome!

Nowadays many 'hornys' either just put a zobel on the woofer and use a digital XO/TD unit to dial them in or skip the zobel and use digital EQ to flatten the whole mess.

GM

 

[felixx]

Check this with an FT17H on top or a piezo coaxial mounted:
http://www.p-audio.co.uk/products/db_product_1_11_g-1250.htm


...and the stupid question:
What is the easy way to moddify fs on a such driver?

 

[GM]

Is there any MLTLs for this thing set up?

I've calculated a number of alignments including MLTLs for various folks based on different factory and measured specs over time.

Since the measured specs calc a larger cab I prefer to use them. Average of (2) units:

Fs 53.38
Re 7.3
Qms 5.17
Qes .66
Qts .59
Vas 92.19l
Sd 530.93
dB 95.33
Bl 11.96 T/M (10.5933/10.5189 calc'd)

Anyway, with these specs and your dims I get a ~37.66" i.d. from bottom driver position and a fairly under-damped, bass-shy alignment that will require quite a bit of stuffing to quell its ragged response, negating much of what little gain it has:

GM

 

[GM]

...and the stupid question:
What is the easy way to moddify fs on a such driver?

Add weight to the diaphragm. Note though that Qts goes up, so efficiency drops, box size increases. For example, lowering it to ~35 Hz raises Qts to ~0.4, eff. drops to ~91.9 dB/W/m.

GM

 

[davidallancole]

Thanks for the comments on the MLTL GM. How about this? 60Hx21.5Wx13.4D and tuned to ~40Hz.

 

[GM]

You're welcome!

Much better with the driver ~35.77" i.d. from the bottom:

GM

 

[davidallancole]

That does look better, but man is that one massive box. It looks like its riding around 97dB as well.

 

[GM]

Size is relative, at ~10 ft^3 it's only half the size of mine. Anyway, it takes big boxes to make efficient bass.

GM

 

[planet10]

Re: Maria Update

Any plans yet?

I've just put up the 0v9 something plans...

dave

 

[felixx]

Add weight to the diaphragm.

Because the suspensions is hard,strong?I'm thinking to replace or treat those to have a soft suspension to keep the spl.Do you think that will be a good idea?

 

[davidallancole]

So your boxes with the 12lta are 20 ft^3 GM? I am going to have to build a box out of cardboard to get a feeling for how big this really is.