Opinions on a Summer Project

[athos56]

I was thinking of building some speakers, always got the itch to build

Hears what I'm looking at:

1 Eminence delta pro-12a
2 Eminence alpha 6
1 Aurum Cantus G3Si Ribbon Tweeter

The Delta pro-12a on the response graph goes out to ~5k but the 3 ft^3 cab plans, and normalized amplitude response, that Eminence supplies shows the high end rolling off at 500. I was going to cross it at 500 with 2 eminence 6" mid's. The 6"ers have ~92 db-spl, so I was thinking I'd have 2 to keep up with the 12" and tweeters 99 db-spl. And then the Ribbon for the 5k to 20k+ range.

I would give the 6's there own internal space with the tweeter.

Any comments on how this would work? Just a "Sitting at my computer while bored plan so my feelings won't get hurt if it sucks. Thanks

[augerpro]

The Alpha 6 isn't that impressive. I would look at another brand for the mid, like Beyma, PAudio, or 18sound.

[athos56]

Looking at the B&C 6PEV13 6.5" MIDRANGE

Has the same sensitivity as the 12" and tweets so I would only need one... but its more then twice as much.

[athos56]

When you look at the response listed in the driver spec's and then the one in the enclosure recommendations; the spec's response goes out to ~5k while the Hi-fi cab recommendation sheet shows the response rolling off at 500hz. Why? Am I reading that right? Would there really be little midrange? Thanks

http://www.eminence.com/pdf/deltapro-12a.pdf
http://www.eminence.com/pdf/cab-deltapro-12a.pdf

[MJL21193]

Originally posted by athos56
When you look at the response listed in the driver spec's and then the one in the enclosure recommendations; the spec's response goes out to ~5k while the Hi-fi cab recommendation sheet shows the response rolling off at 500hz. Why? Am I reading that right? Would there really be little midrange? Thanks

http://www.eminence.com/pdf/deltapro-12a.pdf
http://www.eminence.com/pdf/cab-deltapro-12a.pdf

The second chart shows a 3dB drop at 1K, which is really exceptional for a 12". With that said, you'll want to cross below this. There is also mention of a 50Hz high pass to protect against over-excursion, therefore this driver gives nothin below 50 Hz. Not the most effective use of a 12" driver.
Might be an idea to look at one that has a higher Xmax, to reach down a bit further.

[Nordic]

500hz is not that low... roughly the frequncy at which you can shatter a glass, if I remember that Mythbusters episode correctly... was awesome to see the glass wobble like its made of water (glass is a liquid not a solid), on the slow motion shot...

[MJL21193]

Originally posted by Nordic
..to see the glass wobble like its made of water (glass is a liquid not a solid), on the slow motion shot...

Glass a liquid? In the imagnation of Salvador Dali maybe...

[carcass]

I think what Nordic ment was more in line with this:


http://www.acoustics.salford.ac.uk/f...wine1video.htm

or

http://www.acoustics.salford.ac.uk/f...wine3video.htm

great, isn't it?

greets

[MJL21193]

Clearly demonstrates oscillations in the glass due to excitation at it's resonant frequency. This is structural fatigue, not liquid disintegation.

[carcass]

well, of course MJL, but then again:

"What we observe as material bodies and forces are nothing but shapes and variations in the structure of space. Particles are just schaumkommen (appearances). The world is given to me only once, not one existing and one perceived. Subject and object are only one. The barrier between them cannot be said to have broken down as a result of recent experience in the physical sciences, for this barrier does not exist. (Erwin Schrodinger, on Quantum Theory)"