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PostPosted: April 25th, 2017, 11:12 am 
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Roscoe,

Thanks for the offer. The Qt is a bit lower than ideal (shooting for around 0.5), but could prototype using these and substitute the Eminence Kilomax-Pro or Beyma driver later. A higher Qt should help me alot to avoid any equalization, but since I have enough amps, I should just think about the possibility of going active anyway.

I am fairly sure that the slot follows the 1/3 cone area that Nelson Pass talks about in his paper. In reading various posts on DIYAudio, it appears there is some benefit is a slightly higher area (0.4), but that should be easy to play around with. The Pass design uses a 15 inch driver (Eminence Definimax 15LF). The Beyma 18 inch driver is actually cheaper with the same Qt (0.5) and a lower Fs.

David


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PostPosted: April 27th, 2017, 2:31 pm 
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What's the qts of your current woofers?

Roscoe


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PostPosted: April 27th, 2017, 3:14 pm 
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Really low, around 0.22. Not much point in using them.

I actually am going to knock together a quick open back cabinet using 4 MCM 55-2981 10" drivers in a PPSLOB array. The drivers are cheap @$28 apiece, have the parameters in the ball park I am looking for (Qt-0.54 and Fs=42 Hz, Eff=93db/1W-m at 1kHz, and around 96dB at 100 Hz) and I can keep my existing upper baffle intact on top of them. I can use MDF from Home Depot and paint for now, and dress up later if I like them. If not, I have a guitar player friend who would really get off on a stacked array of 8 -10 inch drivers for cheap.

I started pricing the wood I would want to use (baltic birch ply) for the one I talked about earlier, and it was getting a bit higher of a cost than I wanted to do at this time. Also wanted to stay with 15" if I did it due to integration with the 8" widerange at 200 hz. This is Plan B for something pretty.

My draft plans are attached


Attachments:
File comment: Datasheet for MCM 55-2981 driver
55-2981.pdf [41.84 KiB]
Downloaded 212 times
SLOB Enclosure Model (1).pdf [60.07 KiB]
Downloaded 244 times
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PostPosted: April 28th, 2017, 9:46 am 
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Attachment:
SLOB Enclosure MK 2.pdf [77.58 KiB]
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Did some more thinking about the depth of the enclosure in the version posted, and wanted shorten the depth to avoid any boxyness (even though the back is open). Added foldout wings on piano hinges to the design to compensate for the reduced depth. So this is the concept I will build. The overall baffle size unfolded 30" high by 46" wide, and the cabinet depth should increase the apparent width and height. With it folded up, it is the same footprint as my current bass cabinets

Probably will run to Home Depot after work today and pickup some materials to get started. It has been a long time since a speaker project.


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PostPosted: April 28th, 2017, 10:43 am 
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Here's a few that look like good prospects:
https://www.parts-express.com/prv-audio ... --294-2749
https://www.parts-express.com/dayton-au ... m--295-042
https://www.parts-express.com/peavey-18 ... --294-3112
https://www.parts-express.com/peavey-18 ... r--294-300
https://www.parts-express.com/bc-15hpl7 ... r--294-682
https://www.parts-express.com/bc-18ps10 ... --294-6003
https://www.parts-express.com/eminence- ... w--290-696
https://www.parts-express.com/selenium- ... r--264-387
https://www.parts-express.com/prv-audio ... --294-2753
https://www.parts-express.com/eminence- ... r--290-434

The last one looks especially good.. I have four of them in the garage, but they all need to be re-coned. Ought to be about $100/each less than buying new... I quit looking when the prices got above $250/each...

Roscoe


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PostPosted: May 1st, 2017, 5:05 am 
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Roscoe,

That was some quick work over the weekend! :clap: Look forward to your impression. I cut out most of the panels for my project, and I get the 8-10" woofers today. It will probably take me a bit more time due to other things I have going on, but hope to get this finished over the next couple of weekends.

The oak plywood at my local Home Depot was waterstained (the whole pallet), so ended up getting the birch ply, which in this case actually had a pretty decent and void free poplar core. Not much more expensive than MDF and a hell of alot easier to work with. Have the iron-on birch edging to finish the cut sides that will be exposed, except for the side wings which will double thick and have maple 1x2 wrapped around them. Maybe I should check on availability of 1-1/2 iron-on edge veneer before I make my final cuts, it would save on the effort.

Looking forward to your report.

David


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PostPosted: May 1st, 2017, 1:33 pm 
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A couple more drivers that might be good candidates:

https://www.parts-express.com/dayton-au ... m--295-475
https://www.parts-express.com/dayton-au ... l--295-518

I hope to have them both up and running this evening....

Roscoe


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PostPosted: June 24th, 2017, 7:26 am 
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David McGown wrote:
Roscoe,

That was some quick work over the weekend! :clap: Look forward to your impression. I cut out most of the panels for my project, and I get the 8-10" woofers today. It will probably take me a bit more time due to other things I have going on, but hope to get this finished over the next couple of weekend.

David


Any progress? :confusion-confused:

Roscoe


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