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timreeves 15th March 2011 10:21 PM

my almost full range speaker project
 
Hi folks,

just looking for some advice to help me narrow down my potential component list!

I'm looking to go for a 2 way speaker with a full range driver in a sealed enclosure with a large (up to 12") bass/sub-bass driver, again sealed and crossed no higher than 200hz and hopefully with as minimalistic passive XO as possible.

Why this arrangement i hear you ask...
First off, why both sealed? Quite simply because regardless of driver I've yet to hear a TL or ported speaker that I enjoy the sound of. ported to me always sounds a bit flabby and the sound stage gets screwy and tl's I find to sound weak and limp - like they're TOO transparent. sealed just sounds right to me.

Why the need for the bass driver? Because I like bass, yet dislike sub-woofers due to always being able to locate them (bass may not be locatable but distortion certainly is! as is the floor and objects directly around the sub shaking about) an F3 of 45hz I would be happy with and what I'm really after is that "punched in the chest" feeling when they're given a little bit of juice.

Why not a conventional 2 way design? Because I believe that the lower the XO point in a 2 way system the easier it is to get a sound that resembles what I crave. non-fatiguing, non locatable, balanced tonally. I am not after sparkle and precision either and will be pointing these rather off axis to lessen these qualities.

To summarise what I am after...
non fatiguing, precision bass, expansive soundstage, 2.5cft or less floorstanding speakers.

current potential drivers include
fullrange: markaudio alpair 7, alpair 10 or fountek FR135EX
bass: SB Acoustics SB29NRX75-6, Aurum Cantus AC-250MKII, Dayton DC300-8

If anyone can give any insight into any of these drivers or any thoughts on my project, that would be swell!

Thanks for your time

Tim

planet10 15th March 2011 11:28 PM

I am doing something similar, Alpair 7 & 4 SDX7 per side. I'd like to get the A7 into an aperiodic midRange TL, but the other constraints have them sealed so far. SDX7 in sealed box. Well capable of <40 Hz.

With the high XO, i'd use the smaller of the 2 Alpairs.

My only Fountek experience is th FR88ex, a good driver budget driver.

Lots of good midbasses, and once you limit them to <200 Hz, most of their big problems are out-of-band,

dave

freddi 16th March 2011 12:26 AM

how about a Trio12 on the bottom? -I've one in an old tapered pipe of ~4.6 cubic feet and it seems a good performer for the cost- not sure how it would do sealed (?) P10 - which Alpair would you suggest for me to play the big odaiko "reasonably loud"? - would it have to be in such a 2-way system?

Cal Weldon 16th March 2011 12:31 AM

Hmm...I wonder how the Trio 12 I have would match up with the Foster 10F3's as opposed to the Shadow (Dual Extremis 6.8) that are being used now. Geez I hate when you guys get me thinking like this. Mind you I can easily get 200 from the Extremis, how about the Trio 12 in a sealed cabinet.

Inquiring minds want to know. :)

sreten 16th March 2011 12:42 AM

Hi.

Look up baffle step and plan on getting a bass driver with whatever amount
you want higher sensitivity than your mid treble driver and cross them over
related to the baffle step frequency - I'd suggest FRD simulation tools.

Also see MJK's open baffle articles from the links below and the use of offset
electrical c/o points to compensate for baffle effects. Also note it going for
a simple (non offset) first order c/o a series arrangement might work better.

AIUI a 3" driver is around best for mid/treble with no tweeter, and I cannot
think of anything better on a budget than the FR88EX P10 has mentioned.
see : Zaph|Audio and Zaph|Audio

Note that with baffle step 85/86dB or so midrange is not too shabby, this
will need a bass driver IMO of at least 88/89dB sensitivity (for 3dB BSC).
(Nominally, if the bass drivers are near floor mounted that changes things.)

I'll repeat if going for a simple first order c/o, the series arrangement will
have numerous advantages over the parallel arrangement in terms of
driver impedance interaction, can be confirmed by simulation.

If you go for the FR88EX's I'd advise against chucking too much money
at the bass drivers, I'd say try and keep it as high value as possible.

rgds, sreten.

http://sites.google.com/site/undefinition/diy (see FAQs)
http://www.zaphaudio.com
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.rjbaudio.com/
http://speakerdesignworks.com/
http://www.htguide.com/forum/showthread.php4?t=28655
http://www.humblehomemadehifi.com
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm
http://www.quarter-wave.com/ (MJK)
http://www.frugal-horn.com/
http://www.linkwitzlab.com/
http://www.musicanddesign.com/

audiobomber 16th March 2011 01:06 AM

Quote:

Originally Posted by planet10 (Post 2505132)
I am doing something similar, Alpair 7 & 4 SDX7 per side. I'd like to get the A7 into an aperiodic midRange TL, but the other constraints have them sealed so far. SDX7 in sealed box. Well capable of <40 Hz.

I don't understand this. When I sim an SDX7 in WinISD I get an f3 about 74 Hz with Q of .71. Are you using EQ?

planet10 16th March 2011 01:18 AM

Quote:

Originally Posted by sreten (Post 2505202)

I'll repeat if going for a simple first order c/o, the series arrangement will
have numerous advantages over the parallel arrangement in terms of
driver impedance interaction

I found that to be the case with this FAST. Series made a big difference.

http://www.diyaudio.com/forums/attac...-mtm-front.jpg

http://www.diyaudio.com/forums/attac...-mtm-close.jpg

http://www.diyaudio.com/forums/marka...ml#post2356912
http://www.diyaudio.com/forums/marka...ml#post2337734

dave

Cal Weldon 16th March 2011 01:22 AM

Quote:

Originally Posted by Cal Weldon (Post 2505187)
Hmm...I wonder

Darn, i thought I deleted this post. Sorry for bringing my personal thoughts in here. Carry on, you guys are doing a great job. :)

planet10 16th March 2011 02:39 AM

Quote:

Originally Posted by audiobomber (Post 2505218)
I don't understand this. When I sim an SDX7 in WinISD I get an f3 about 74 Hz with Q of .71. Are you using EQ?

1st off f3 is not a very good evaluation of how deep a box will go (Toole). In a rrom, with room gain, f10 is much more meaningful. I usually aim for a bessel Q where F10 is about 35 Hz. The 40 Hz number is from a measure (in my room).

http://p10hifi.net/planet10/CSS/SDX7-sealed-pass1.pdf

dave

ultrakaz 16th March 2011 07:37 AM

I would suggest a 3" with a 10" or 12" woofer or 3" with (2x) 8" for a narrower profile. I think Fostex offers an iteration of the FE83 3" driver. Check out the possibility of using vintage woofers such as JBL 123a or Altec 404. Passive xover @200Hz probably requires a bigish coil and with low dcr so it might get costly; unless you biamp and use line level filters. If you cross a couple of octaves higher the crossover will cost less. Or you could simply use plate amps for the woofer section. This could actually sound very good.


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