Can someone guide me as to what Single driver ??

Duke, for an inexpensive driver, the Eminence Beta 12LTA offers pretty wide bandwidth and high sensitivity. Eminence has recently revamped their measuring techniques, so some of the spec's may be different than what is posted on PE's website. Lot of basic mods that can be done to improve performance without a lot of cost. Still want to check out the list of mods for the Hammer Dynamics that Darkmoebius listed above though, as maybe others have caught some things that i haven't.

Other than that, one can build a complex crossover with Zobel's to flatten the rising impedance, but i've never bothered. Running a pair of these nets you 99+ dB's @ 1 watt without ever dipping below 4 ohms anywhere in the band. Easy load, wide bandwidth and high efficiency for not that much money. Sean
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Still want to check out the list of mods for the Hammer Dynamics that Darkmoebius listed above though, as maybe others have caught some things that i haven't

Oh no, tell me it ain't so!

"Maybe" somebody thought of something you didn't?

A little full of ourselves don't you think?

Hi Sean,

Glad to hear you put these great Emminence drivers to good use. They are a true miracle value when properly used.

I should point out that there are some significant construction differences between the commercially available 12LTx driver and (the late)John Wyckoff's custom made Emminence Super-12.

To quote JW from the Super-12 mods page I linked above:

John Wyckoff's description of the Super 12 (compared to the Eminence Beta-12LT)

Cone composition: Beta-12LT is conventional Kraft type. Super 12 is slightly heavier (different mix of fibers).

Voice coil: Super 12 has smaller gauge wire with a Nomex former. (I dropped the Kapton former after the first ten samples.) Beta-12LT uses Kapton former which is not quite as neutral in the mids. Super 12 coil is slightly lighter bringing moving mass to about the same. Super 12 uses one shorted voice coil turn to reduce inductance and improve high frequency response.

Motor: Super 12 has a soft-iron polepiece to improve BL. Beta-12LT has low carbon steel. Super 12 has shorting ring at the base of the polepiece and is capped with an aluminum shorting ring (also called Faraday ring).

Spider and suspension: Super 12 spider is woven Kapton fiber and is slightly softer. The suspension on the Super 12 is doped to be slightly stiffer.

Glue: Super 12 uses a lower-mass, harder formulation, and less of it. Improves high frequency response.

As to how big a sonic difference that all makes, i have no idea. I've never heard the regular Beta 12LT.

Other than that, one can build a complex crossover with Zobel's to flatten the rising impedance, but i've never bothered.

The Super-12's use a very simple series 12uf cap + 7 ohm resister [url=]Zobel network[/url](x-over diagram) on the 12".

One of the big changes was switching from the stock Audax tweeter to the more sensitive horn Fostex FT-17.

>>A little full of ourselves don't you think?<<

Far better that than what you're full of.

Elvis: I've just been watching the audio detectives and learning from them, their discoveries and their mistakes.

Most everything that i've ever learned and / or shared here ( or in other audio forums ) is an accumulation of information that i learned from others that i've put together over the years. As such, i could have overlooked some mods as my detective skills are lacking. That is, i might have missed some other pertinent info that others have found to be both important and useful. I am not omnipotent and can't read / see / do / be everything everywhere at one time.

Obviously, I don't know anything that someone else hasn't already discovered ten times over. That's why i try to take the time to share what i do know, so that others can learn just as i did. While i might think that i've discovered something new, because it is "new" to my level of understanding, further research almost always confirms that many others have already been down that path many times over.

As such, i am proud of what i know. Having said that, i'll not take credit for something that i didn't do. NOTHING that i've ever shared here isn't already common knowledge to those that deeply care about such things.

Darkmoebius: I knew that the Hammer driver is a custom build , but i also knew that it was based on the stock Beta 12LTA. I didn't know the exact differences between the drivers though, so thanks for sharing that info. My brother was looking into these drivers for use with a low powered tube amp when i had to remind him that i've been using these for a couple of years now.

As far as the Zobel goes, i think that the resistor is a bit low in value, but i'm sure that it is better than nothing as far as "hi-fi" linearity goes. I'm using these for live sound reinforcement, where ANY form of increase in sensitivity is considered a good thing. Even if it is slightly less linear, there's always a rack full of effects and EQ to deal with problems like that : )

As you mentioned here, i'm also using a very sensitive horn tweeter. It is quite a bit hotter in output than the paralleled Beta's, but as mentioned, i'm crossing it quite high and there are always EQ's available. Having the higher output from the driver simply means less power draw from the amp. This not only reduces thermal strain on the amp, but also the driver itself. Sean
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