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-   -   DIY fullrange driver? (http://www.diyaudio.com/forums/full-range/28890-diy-fullrange-driver.html)

Nappylady 24th February 2004 07:31 PM

DIY fullrange driver?
 
Has anyone ever attempted this? I'm not an engineer, but it seems to me that not everything has been done in terms of making a truly full-range driver capable of large SPL figures without a subwoofer. :ashamed:

Here's my thinking: a 12" cone with a XBL2 motor (the one with two back-to-back voice coils to reduce inductance) (2" voice coil?) could provide high excursion and low inductance, so adding a whizzer cone would extend the usable frequency range up to maybe 12khz. :scratch2: At the same time, in a ported alignment, this driver could give output to probably 40hz or maybe even below. While this isn't quite reference range, it's enough for PA applications--no coincidence, this is my goal. :D To cover the frequencies above 12khz, a peizo horn could be attached to the back of the driver and horn-loaded through the pole piece and whizzer cone. I suspect this would be enough to reach all the way up to 20khz.

Since the woofer part would be an inductive load, and the peizo part capacitative, it's possible, I think, to design the thing so it wouldn't require a crossover; just hook both elements up to an amplifier. I like this idea a lot. :nod:

If it turns out that the bass isn't enough, we'll add a DIY parthenon to get enough extra thump. :smash:

What do the engineers in the room think? :2c: :spin:

sreten 24th February 2004 07:37 PM

For a fullrange driver the moving mass of the voice coil and
its former must be kept to a minimum for treble response.

So a long former with double coils is not really a starter.

:) sreten.

ronc 24th February 2004 07:46 PM

Sure, use a rear loaded low Qts HE driver. Now how much floor space have you got? A 40 Hz horn wall/floor loaded horn is BIG, if you can corner load its 1/2 the required mouth size but still going to be just slightly less sound path(length) due to the reduction in mouth size.
ron

AGGEMAM 24th February 2004 07:48 PM

These things characterise a driver able to produce low frequencies:

heavy diaphram
rigid suspension
long excursion

And these thing characterise a driver able to produce high frequencies:

light diaphram
loose suspension
short excursion

So you see it would be a impossible task to produce the perfect full-range speaker.

Lowther unit come close, but suffers the great disadvatage that they absolutely have to be hornloaded.

Nappylady 24th February 2004 07:50 PM

Ron, I think you misunderstood my reference to horns... the peizo element would be horn-loaded through the pole piece (so it would be a very unusual pole piece!) and the whizzer (since the whizzer is rather horn-shaped already) but the dynamic part--the woofer part--is not horn-loaded.

This probably isn't the optimal solution for making large amounts of sound in a small space, but AFAICT, it hasn't been tried yet in this combination.

AGGEMAM 24th February 2004 07:52 PM

Quote:

Originally posted by Nappylady
This probably isn't the optimal solution for making large amounts of sound in a small space, but AFAICT, it hasn't been tried yet in this combination.
Oh, this has been tried hundreds of times, no one to very good result though. Tannoy is probably the one that makes the best of such speakers. But even they aren't that good dispite their staggering price.

Nappylady 24th February 2004 09:21 PM

*jaw drops*

Has EVERYTHING been tried? Surely there must be some novel idea yet to be thought of!!! LET ME AT IT!!!

ronc 24th February 2004 09:33 PM

Small volume and low frequencies dont go hand in hand. Best is a 2 way, a seperate bass driver in a cab tuned for 40Hz then rolled off and a full ranger in a cab taking the hand off starting at < 200Hz and extending up. Lets face it, a wizzer cone in a FR is very near a mid and a tweeter. Kinda sorta like a co-axial without the added crossover. To me anyway a rear loaded horn with a single FR driver with a wizzer is more like a 3 way without electronic (<----NOTE!) crossovers. Even though there are designed in mechanical crossovers.
However its still my choice.
ron

PeteMcK 24th February 2004 09:40 PM

for sympathy,
 
try the Full Range driver forum

http://f18.parsimony.net/forum31999/


:-) cheers.,
Pete McK

critofur 24th February 2004 09:53 PM

Well, why try to make a full range driver that doesn't need a subwoofer when nobody has even made one that's anywhere NEAR being pefect to even cover the range above the subwoofer (to use WITH a subwoofer)???

Plenty of subwoofers do a fine job that it's not really needed to try to replace them by lowering the range of your main speakers. The range they cover is not nearly as critical as the range that covers human voice & instruments.

The human ear + brain is not nearly as discerning below the frequency range of the human voice. It makes sense to focus your efforts where the results have the most impact.


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