First "REAL" loudspeaker project!!!!! please come and see :p - diyAudio
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Old 24th November 2004, 03:07 AM   #1
JinMTVT is offline JinMTVT  Canada
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Default First "REAL" loudspeaker project!!!!! please come and see :p

This is my first " almost completed now " real loudspeaker project.
I based it at 90% on info that i have gathered from this website, so i wish to thank you all for exchaging your ideas and knowledge on this forum !

This project makes use of 8 ( 4 per side ) hi-Vi AS2 drivers
HI-VI AS2 @ parts express

Click the image to open in full size.

The price was right, the looks were there, but most importantly,
the response graph was what i was looking for ...

Comments on this driver? maybe someone here has used it already ??

Neway, so the project is a dipole radiator OB line array, or whateever u wish to call it these days..

as it uses 4 drivers per side in an effort to gain higher sensitivity, and lower distortion from the drivers
( also i thought that 4 2" would still play good high hz, and have more volume to play down to the 300hz range .. )

I use pine wood to build this, this was also the second time in woodworking of my life, first timer was 2 months ago when i constructed a nice rack for my audio video gears ..

I added the aluminum insert as i thought it would match with the aluminum drivers, and i think it does it pretty well

here are pics of the assembled system ..
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Old 24th November 2004, 03:08 AM   #2
JinMTVT is offline JinMTVT  Canada
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here is another shot
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Old 24th November 2004, 03:15 AM   #3
JinMTVT is offline JinMTVT  Canada
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picture again ..




bon ...

this project is a Gift from me to my brother for his b-day + Xmas

Its intended use is in a small room, on desktop as computer/dvd/video games system .
It should be powered by an old 1970 Akai receiver ( 20W ? )

It had to be small enough to fit on his desk
it will be listened in near range ( 60-100cm )
and also at 2-3m range ( dvd/TV )

I didn't want to fiddle with crossover for this first project,
that is the main reason why i choosed wide range drivers ..

i will make him a small sub ( maybe 2 times 8" in a sealed box )
next spring ..
i ain't sure of the freq response of this system , but with a few calculations and decustions, i think it should start falling down at aprox 200hz pretty steeply combining the drivers F3 point and the OB effect ..

it should be pretty easy to make the crossover for the subs to match if it indeed starts falling down at ~200hz
( that's what i planned, but hey! i know nothing, just guessing here !!! ahhaha )


So what do you think ?
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Old 24th November 2004, 03:21 AM   #4
JinMTVT is offline JinMTVT  Canada
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Just plugged it in my Bryston 2B spare ..

I have to say that it doesn't play loud at all

i wonder if i made an error in wiring ..

my calcs put it up back to 8ohm impedance ..

here is how i connected the drivers :
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Old 24th November 2004, 04:32 AM   #5
Grahamt is offline Grahamt  Canada
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They look good. The way you wired them should put the impedance back to 8 ohms.
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Old 24th November 2004, 04:50 AM   #6
JinMTVT is offline JinMTVT  Canada
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ok so the wiring should be ok ..

but WHAT A BREAK IN!!!

OMFG!!

they went from not there at all ..
to super detailed in 2 hours of listening !!!!

It is the first time i can play the speakers to such a low volume that u don't even hear anything after 2 meters..but yet in nearfield they sound just as good as when the volume is up!

the bass is just not there though...as i thought it would
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Old 24th November 2004, 05:33 AM   #7
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Cool looking little drivers. Even though the array is so short you are still going to get some line array effect at least at some frequencies because the listening distance is so close. To verify
this, listen to them with your head level with them and stand up slowly. If as your ears pass the top of the line they get much more quiet, then you need to tilt them back so the center of the speaker line points to ear level.

Also, it looks like PE screwed up and posted the incorrect FR graph for those drivers. No way they are flat down to 100hz except when they are turned off. The specs say 500-15000hz which is much more realistic. That means no bass no matter what you do and you also don't need a baffle nearly that size.

All is not lost. You have room on the baffle for some small woofers and use those for tweeters.
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Old 24th November 2004, 12:17 PM   #8
Grahamt is offline Grahamt  Canada
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Quote:
ok so the wiring should be ok ..
Yep. Pull out the DVOM and measure the DC resistance to be sure if you want. Should be less than 8 ohms DC. Glad to hear they are sounding better.
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Old 24th November 2004, 02:09 PM   #9
dhenryp is offline dhenryp  United States
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Nice looking speakers. They are real step up from most first (or second or...) projects. I have always loved the look of those drivers. I think they are fine for near field use at a computer. You don't need to get very loud to have a nice experience. Your brother is lucky.

I think you probably have the wiring correct but I can understand why they wouldn't play very loud or low. The efficiency rating of the speakers (and all these small Hi-Vi speakers) are very low - in your case it is 78 db. This is about 10 db less than average drivers. The other limiting factor is the size of the cone which is probably not much more than 1.5 " effective diamter. The X-max of 1.5 mm is good for such a small driver but, combined with the cone area, can't move much air - which is critical for bass. Even the four drivers togther is problaly only equal to a single 3 or 4 inch driver with an Xmax of 1.5 mm. Open baffles are less efficient down low, because of cancellation effects from the back wave. Even with your wings you may still get some cancellation. I think the response graph is probably correct, but you could not expect to get much bass below4-500 hz given the cone size and XMax.
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Old 24th November 2004, 03:09 PM   #10
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Quote:
Originally posted by dhenryp
..... I think the response graph is probably correct, but you could not expect to get much bass below4-500 hz given the cone size and XMax.
I agree with the 4-500hz part, but the response graph needs to be the corrected. There's just no way a driver with an Fs of 153hz can be flat down to 100hz. Typically, those with an Fs of 100hz start rolling off at 200hz. Below Fs all drivers roll off steeply, I think at 12bd per octave.

I'd put the baffles even with the front edge of the monitor, to get them as close to you as possible. Tilt them up so your ears are in the center of the array plain and add 3 or 4 4" woofers plus a crossover at 500-600hz.
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