Design my Own? Or do you know a design?

[Luke352]

Hey guys, I've posted on here a few times about building some design s but never really got there, other then the little Zaph Mini Monitors that are basically built.

Basically what I have sitting here is what are called Mpyre Audio 65m midwoofers, they are essentially a car audio version of the Adire Extremis 6.4/8 in actual fact I think they share alot more similarities with the CSS SDX7, as it looks like they share the same frame and they use a Carbon Fibre cone which is coated on the backside with some kind of resin but they don't have a phase plug like the SDX7.

Anyway here are all the specs and those of the Extremis and SDX7 for comparison.

Mpyre Audio 65M
Fs: 35 Hz
Qms: 2.8
Qes: 0.48
Qts: 0.41
Vas: 23 liters
Re: 3.50 Ohms
Le: .005 mH
BL: 6.13
Mms: 23 grams
Cms: 0.5 mm/N
Sd: 140 cm^2
XMAX: 13mm
XMECH: 15mm


CSS SDX7
FS 34Hz
Qms 2.2
Qes 0.41
Qts 0.35
Vas 23.77 L
Re 6.4 ohms
Le 0.75 mH
BL 8.45 TM
Mms 21.91 g
Sd 127.5 sq cm
Cms 1.03 mn/N
Xmax 11.1 mm
SPL 85 dB/1W/1m


Extremis 6.4
Fs: 37 Hz,
Qms: 3.3,
Qes: 0.36,
Qts: 0.31,
Vas: 27 liters,
Re: 3.5 Ohms,
Le: 0.11 mH;
BL: 6.7 N/A,
Sd: 140 cm^2,
Cms: 1 mm/N,
Mms: 19 grams,
Xmax 13mm on way.


Extremis 6.8:
Fs 30 Hz
Qms 2.54
Qes .383
Qts 0.332
Vas 33.2 liters
Re 7.02 ohms
Le 0.13 mH
BL 9 N/A
Sd 140 cm^2
Cms 1.2 mm/N
Mms 23.3 grams
Xmax 13mm one way
SPL 86db 1w/1m


So I was going to use these in my car but have instead gone for a 8" Morel for midbass. So I now have 2 pairs of these drivers here doing nothing and I thought why not use them in a nice Home Audio design using two per cabinet, which should provide me with an abundance of low end response for good integration to a sub and also for movies. I went searching for designs and couldn't find anything other then 2 way designs using single drivers per cabinet, which isn't really what I'm looking for. I want to build a nice floorstander. So does anyone know of any nice designs using twin Extremis or SDX7's in either a 2.5 or I think a 3 way would be best as I doubt the ability of these things to actually play much over 1.5k cleanly as the one thing I hate is a heavy sounding midrange. Or any designs that you think could be easily adapted for my drivers.

If not, do you have any suggestions on what to read up on before I attempt my own design, I have started reading through all the information and links provided in the forums wiki which is great.

Thanks

Luke

[PeteMcK]

This site has a method for combining different drivers in a BR box; I've tried it, works very well.: http://www.fortunecity.com/rivendell...d/dddllqd.html
As you say, the limiting factor will be how high those drivers can play, unless you get a good tweeter that can play low(SEAS 27BFCG?)

[Luke352]

But I'm not combining different drivers, I have 4 drivers of the Mpyre's which aren't really a low Q driver, the only reason I posted the specs of the Extremis and SDX7 was for people to see the similarities.

Thankyou though as I still read through that page and it was quite interesting.

Luke

[PeteMcK]

ah, Ok, Unibox gives me 50L tuned to 35 Hz or thereabouts for two Mpyres in series

[GM]

Greets!

FWIW, when I loaded these specs in WinISD PRO the CSS and Adire driver's T/S specs line up close when inputting the preferred Mms, Cms, etc., specs, but the Mypre isn't even in the ballpark in comparison, though of course without measuring all these we no idea what they really are:
http://www.hometheatershack.com/foru...-audio-65m.wdr

Anyway, don't know of any designs, but a bipole tower (aka MLTL) seems a good choice, then mate it to a suitable Fostex or similar big tweeter ~3" 'FR' driver with a 1st order XO and acoustically roll off the rear driver as required for a nice minimalist 2.5 way.

GM

edit: Hmm, just 'ran the numbers' for a 32 Hz EBS and the vents are too long, so a TQWT is a better choice.

[Luke352]

Interesting idea with the TQWT but I'm thinking i'll stick with a traditional vented chamber, until I get a chance to do some measurements to check the specs I think i'll go with 50L tuned to about 35hz which is what WINISD is telling me and what UNIbox is telling PeteMcK.

Now I've been looking at a few mids and tweeters, for tweeters I'm liking the Seas 27TDFC otherwise the 29TFFW and also the Vifa XT25 are looking good. Does anyone else have any other suggestions or reasons to take one of those listed over another.

Now mids I'm totally up in the air about, I can get Peerless 4" HDS mids and I know these are meant to be great but they don't seem as popular as there reputation seems. So I've been looking at drivers like the Vifa PL11MH09-08 and also the Seas MCA12RC and the MCA15RCY or even the CA15RLY, I've even considered drivers like the CSS CR/FR125 series.

I guess mids is where I'm having the biggest difficulty deciding as I'm not sure weather to go with a 4" or weather to try and keep up with the twin midwoofers am I going to need a 5" midrange. Also how large a frequency range I'm I going to need it to cover, I'm heavily involved in Car Audio and for that I follow the chain of thought that to try and get your midrange to go as high and low as practical 300hz -6/7khz for example, but is this really necessary or even recommended for a three way tower or can I play the midwoofers up higher and tweeter lower.

Thanks

Luke

[Luke352]

What do you guys think of using a pair of mid ranges? Something along the line of these > http://www.madisound.com/catalog/pro...oducts_id=1616 Most likely in a MTMWW arrangement.

[Luke352]

Ok, so I've decided I'll go with a TMWW design using the twin 65m's in a front vented 50L chamber tuned to 35hz, then i'll use a Seas MCA15RCY for midrange (most likely rear vented chamber) and the Seas 27TDFC for the tweeter.

My reasons for going with the larger 5" midrange was for better dynamics, plus I thought I should try and keep my sensitivity similar across all the drivers, since the tweeter is 90db the bass section will end up with a final sensitivity approaching 91db since each driver is 85db then +3 for two drivers and +3 again for the vented alignment. So I thought the smaller 4" Seas driver would struggle to keep up and matching them all through the xover would become quite difficult. So by going with the larger 5" unit I've kept sensitivity similar, allowing easier integration I thought.

Now before I go any further then basic enclosure outer shape etc... I'm looking to get some software to assist me with the design. Now I was thinking of getting the Dayton WT3 so that I can get actual true t/s parameters for all the drivers. But then I was looking at programs like BassBox Pro and Xover Pro and wondered weather I should look at these instead or can I do without those, are they really just nice to have items, whereas getting accurate t/s specs I imagine is alot more critical, especially when I consider by the time I get down to the finer details of xover design it's likely to be some time from now.

What do you think guys? Am I on the right path, or at least anywhere close to it?

[PeteMcK]

Luke, you're on the right track (although I'd go sealed for the mid unit).
Don't forget to take Baffle Step compensation into account in your sensitivity calculations, a few dB extra in the bass is a good thing...
For Software, ARTA is good:
ARTA http://www.fesb.hr/~mateljan/arta/download.htm
ARTA Jig - http://zobsky.blogspot.com/2008/01/s...t-jig-for.html

[Luke352]

Thankyou for bringing up Baffle step, I'll do some reading into as I didn't realise it had a big effect on bass, I was going to read into it later down the path when I was looking at xover design as I thought I made need to compensate for it through the xover.

My next question is i've done a little reading on driver spacing, and from what i can tell I'm really only concerned about my mid to tweeter distance. Do I need to look at my spacing from the centre of my tweeter and mid to the cabinet edges upper and sides. Should I look at keeping my tweeter centre further then the distance of the lowest xover point (wave length) I may consider.

Thanks again