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Old 26th January 2003, 09:57 PM   #1
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Default Eminence Beta 12lta

I just got through building the bride of zen preamp and the zen 10 watt amplifier. On my bench I use JBL 4408A speakers for my testing. Im looking to build a more zen friendly speaker system and was looking at full range drivers when the Beta12LTA caught my attention. Does anyone have any experience with this particular drive or could you recommend something else that would break the bank ? Thanks for your input
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Old 26th January 2003, 11:57 PM   #2
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Old 29th January 2003, 07:02 PM   #3
Bull is offline Bull  United Kingdom
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The Eminence Beta 12 LT used to be rated 150w rms,now is rated 225 w rms,because Eminence have changed all the voice coils and even added some ribbon or hexagon windings of some of their voice coils. www.eminence-speaker.com

The Eminence Beta 12 LT is a good driver for mid bass,midrange and some lower treble.The Frequency responce is now 45 hz-10khz [fullrange], spl 1w at 1m 99 db.But in theory not 100 per cent fullrange,because 100 per cent fullrange would be 20hz-20khz for just a single speaker driver,which certainly does not excist yet.
Although the Eminence Beta 12 LT goes from 45hz-10khz,the lower bass and treble is not that good.It performs well in producing low midrange and midrange,especially vocals,so it makes an excellent midrange in a 3 way system.
I think if used with a subwoofer for lows,and a piezo tweeter for highs it could make an excellent 3 way system.

But if you play music without much sub bass,then you could leave out the subwoofer and use the Eminence Beta 12 LT fullrange with a CTS/Motorola piezo horn [twin driver piezo] KSN1177A 100w rms,3.5 khz-20khz, sens 1w at 1m 99db.
Which also matches the sensitivity of the fullrange driver exactly.
So you don't need a crossover because it's a piezo,and also you don't need a resistor for the piezo for hifi use,[only for pa use or high power use].
So wire the fullrange to the piezo.
And use them in a sealed or single ported enclosure.But ported enclosures are harder to build[you have to work out the enclosure volume and the port volume and they have to match the speaker cone dissplacement volume.]
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Old 31st January 2003, 12:55 PM   #4
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The Beta 12lt has specs that show it would work great in a TQWP. This could extend the bass lower then a BR.
Dave
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Old 9th December 2003, 10:12 AM   #5
MIKET is offline MIKET  United States
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Default BETA 12LT in a TQWT

I've been looking for this one for months, Finally found it.
http://home.pacbell.net/tullius/home5.html
Have 2 BETA 12LTA's under the Christmas tree from the wife.
December 26th, I warm up the table saw.
Will likely use the Fostex FT17H as a supertweeter:
http://www.madisound.com/ft17h.pdf
Here is the crossover link:
http://melhuish.org/audio/super12.html#crossover
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Old 9th December 2003, 01:31 PM   #6
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Konnichiwa,

Quote:
Originally posted by Bull
The Eminence Beta 12 LT used to be rated 150w rms,now is rated 225 w rms,because Eminence have changed all the voice coils and even added some ribbon or hexagon windings of some of their voice coils. www.eminence-speaker.com
Eminence made probably at least a dozend versions of the 12" Dual Cone since the 1980's and many before. I used to use earlier versions in Floor Wedge monitors, where they did fine when combined witha tweeter.

Quote:
Originally posted by Bull
use the Eminence Beta 12 LT fullrange with a CTS/Motorola piezo horn [twin driver piezo] KSN1177A 100w rms,3.5 khz-20khz, sens 1w at 1m 99db.
Which also matches the sensitivity of the fullrange driver exactly.
So you don't need a crossover because it's a piezo,and also you don't need a resistor for the piezo for hifi use,[only for pa use or high power use].
Sorry, but you MUST have an X-Over. The Piezo Tweeter covers a very substanial range from around 2KHz upwards. This means Beta 12LT and Piezo work together causing an average +6db SPL increase in the overlap range wher ethe 12LT already shows nearly +6db boost to start with and a very ragged frequency response.

The X-Over need not be overly complex though, a series capacitor and a parallel resistor would do fine, methinks an 12R parallel Resistor and a capacitor of 0u82 - 1u2 should do the trick. Also, either damp or remove (then place the Piezo Tweeter into it's own sealed volume) the plastic back chamber of the piezo tweeter, it causes severe colorations. Lacquering the 2" Papercones of the Piezo with Dammar or C37 is optional, as is damping the horn with Bluetack, rope-caulk etc.....

I also think a parallel RLC EQ circuit to cut the appx. 800Hz - 3KHz range by around 5-6db and a Zobel to offset the Impedance rise at high frequencies would be a very good idea, something like this:

Click the image to open in full size.

At a first glance it looks like L1 = 1mH, C1 = 8u2, R1 = 7R5 and for R2 I'd use 12R with C2 = 10uF

All values are quick guesses - I'd recommend experimenting with them a little bit.

Sayonara
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