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Discussion Starter #61
:) Maybe this year.

Have part time studies I have to finish first about 6weeks left then I have more time but we are also having or second child this summer so time may be limited. But I really want to continue building subwoofers :)
 

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Discussion Starter #64 (Edited)

I must confess that I´m a bit confused I was under the impression that my design was push pull but with the both drivers folded and the very large opening would not act as an port for tuning. But you are the second one recognizing it as an isobaric.

My inspiration came from here.
http://www.faktiskt.se/modules.php?name=Forums&file=viewtopic&t=50138&postdays=0&postorder=asc&list=full
Ino Audio infraZ-12 design with Peerless SLS 830669


After more research I´m now certain that the design is correct and called folded baffel or almost Linkwitz W-frame also sketched one with pushpull in M-frame like this build.

http://www.faktiskt.se/modules.php?name=Forums&file=viewtopic&t=53812&postdays=0&postorder=asc&start=0

http://www.bd-design.nl/contents/media/ultimate_subwoofer.jpg


Interesting reading and resources to bookmark
http://www.hifizine.com/2012/12/subwoofer-origami/

http://www.linkwitzlab.com/woofer.htm

http://jazzman-esl-page.blogspot.se/2011/01/ripole-subs-are-underway.html

And regarding port resonance
http://www.studyphysics.ca/newnotes/20/unit03_mechanicalwaves/chp141516_waves/lesson51.htm

Easiest design would be if I put the drivers inline with the cabinet and layed it down on the side that would put the opening at the middle of the front so my design is just my taste in looks and the diagonal positioning made it possible to make it shorter when standing up.
Drivers like the SLS12 wouldn´t have the same problem with space since it has much smaller motor. I thought about if there would be negative effects when a driver plays upwards any thoughts about that?
 

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Discussion Starter #66
Bob what is Xmech with the SDX12 driver?

I don´t think there is a common standard for defining Xmax which would make Xmech more accurate to compare different drivers.
 

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Discussion Starter #67 (Edited)
Really pleased with my two SDX12 subs they play loud and dig very deep. Friends have visited and they think they sound great too very defined sound. Even at high excursion they play without any audible distortion.
Redone the livingroom and now have the gear at the short sided wall instead of the long side problems with 48Hz was replaced with 33Hz but now I have a minidsp balanced 2x4, umik-1 and REW.
Did six measurements with each sub and did this first with all ports open then with one port sealed. Total of 24 measurments and did EQing in REW and transferred to minidsp.

Details in the bottom field the measurment with the higher SPL is both subs with EQ all ports open and it´s not MAX SPL. Sweetspot aprox. at 4meters tuning around 22Hz.
At this measurment linear repsons down to 15Hz in room at 102dB if this is correct and using this calculator ----> http://www.sengpielaudio.com/calculator-distance.htm gives [email protected]

Same as above but with two ports open a little bit lower tuning around 18Hz in this EQ I left more port gain if you think about the bump under 20Hz.


When all EQ was done the highpass was set to 15hz BW24 and the limiter in my inuke 6000DSP set to 994w.
Read this forum thread when I determined how the inuke limiter works
http://www.hometheatershack.com/forums/subwoofer-amps-high-pass-filters/66351-how-set-peak-limiter-values-behringer-6000dsp.html

Have played them very loud and some music with Infected Mushroom triggers the limiter a little bit but excursion looks safe :)
Measurments above have no highpass.
Falling respons at higher frequency I believe is the Marantz 7005 preamp spooking or the absence of the front speakers as I only disconnected them temporary for measuring.
 

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Discussion Starter #68
Have done some more measurments with our new furniture in place.

The response in this picture is with EQ to take care of my 33Hz problem.

This time I did 10 measurements for each subwoofer in sealed mode the lower output yellow line then I replaced the front plate and measured them vented and now you see the port gain approx. 5.5dB gain at this SPL level. Port compression will be apparent at higher levels but I´m satisfied with the result. I would recommend a slot port it would probably be more effective.

 

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Discussion Starter #70 (Edited)
Thanks! I´m very impressed with the performance and how very articulate they perform.
A big wake up call was when I visited XTZ at their main location in Sweden to compare my M&K 150THX vs the new Cinema series. I was not so interested in the W12.16 subwoofers in the demo room since I have owned them and a lot of XTZ products. All of them well worth the money but when we were finished listening to the monitors we switched on the subwoofers and what a huge disappointment compared to what I´m now used to.

Still these cabinets are one of the few first builds I have done so especially the bracing is lacking a lot of useful design they could have been done much better and passive radiators may also be a much easier way to go with this driver. Even though I would like to try slotport my vented design works very well but hard to fit.

The last builds we did with TC sounds and Dayton Ultimax have a very good bracing.
 
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