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4 Pi Home Theater Build

18K views 83 replies 23 participants last post by  NWCgrad 
#1 ·
I am in the process of building three 4 Pi's for home theater, fully documented at http://audioroundtable.com/forum/ind...16208&start=0& .


Thought I would attach a few pictures here since this is the site that got me interested in waveguide-based speakers.


I was going to build either deluxe econowaves or Augerpro's No Quarter's, but in the end went with Wayne's design. I do have three of the QSC waveguides taking up space in my basement if anyone is interested.


_______________________________


I will be coating the enclosures this weekend with bondo followed by sanding (and repeating as required). The cabinets front and rear baffles (plus interior) will be primed (Zinsser BIN shellac-based) and painted as close to gun metal gray as I can get. The sides will be veneered with oak (glued with contact cement per the advice of Bill Epstein) and finished w/ stain. I assume sides/top/bottom do not need to be primed. I am not sure whether contact cement adheres well to primer??????


The entire enclosure will be given multiple thin coats of polyurethane - inside and out - for a humidity barrier.


Can anyone advise on paint?


I am thinking 100% acrylic latex enamel for durability. Will apply with the typical foam cigar paint roller. I read the technical sheet for the Zinsser primer (shellac-based) and could not tell if the topcoat should be water- or oil-based. The only advantage I can think of for water-based is that it allows the polyurethane coat to be water-based, which apparently cures faster than oil-based polyurethane. Since these will be crated up late June/early July for transport to the SE Asia drying time may be a factor.



Thanks for looking...




 
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#9 ·

Quote:
Originally Posted by tgaffner1 /forum/post/20515029


Also, what kind of Hors are those, and what are the dimensions on them?


Plase dont be shy, if you could give the the outside dimensions and mounting dimensions, you would be a HUGE help to me and my 4Pi project

They are the Eminence H290, the theoretical dimensions are 11.4" W x 6.5" H x 5.9" W. I say theoretical because they did not fit in the cutout I had in my baffle (see attached photos for my workaround).


When I go home this weekend I will get the tape measure and post the dimensions - including the thickness of the flange. I live weekdays in Newport, RI and weekends are spent with the family in Maryland - have been a military geographical bachelor for the past 20 months - so I can't do the measurements until Sat.


I have some bondoing to do this weekend!


 
#14 ·

Quote:
Originally Posted by NWCgrad /forum/post/20513075


_______________________________


I will be coating the enclosures this weekend with bondo followed by sanding (and repeating as required). The cabinets front and rear baffles (plus interior) will be primed (Zinsser BIN shellac-based) and painted as close to gun metal gray as I can get. The sides will be veneered with oak (glued with contact cement per the advice of Bill Epstein) and finished w/ stain. I assume sides/top/bottom do not need to be primed. I am not sure whether contact cement adheres well to primer??????


The entire enclosure will be given multiple thin coats of polyurethane - inside and out - for a humidity barrier.


Can anyone advise on paint?


I am thinking 100% acrylic latex enamel for durability. Will apply with the typical foam cigar paint roller. I read the technical sheet for the Zinsser primer (shellac-based) and could not tell if the topcoat should be water- or oil-based. The only advantage I can think of for water-based is that it allows the polyurethane coat to be water-based, which apparently cures faster than oil-based polyurethane. Since these will be crated up late June/early July for transport to the SE Asia drying time may be a factor.



Thanks for looking...

I'll try to answer all of your paint questions but it seems like there are a few of them so if I forget something just let me know.

First off what means of application do you have access to? If you can spray your finish with an HVLP set up then I would toss your above options out the window. If you will be rolling then I would personally go with oil for a number of reason. Now this is not to say this is a superior finish in all aspects but it presents a better solution to many problems you may encounter.

For packing: Standard cure time (NOT DRY TIME!! CURE TIME) for acrylics is 21-28 days. That means dependent on temperature, color, humidity, etc you may or may not be fully cured by time to pack and ship. Even then if you don't go with the correct option you still may exhibit some blocking (imprinting of an image/packaging etc on the coating that will not go away).

Secondly you will typically have less durability with acrylics versus alkyds (oils). Alkyds will withstand touching, scratching, wear & tear much better generally.

Third you will generally have a smoother finish using alkyds when rolled/brushed than acrylics. Given their long dry time and solvent content you should expect a more even finish (although there are some alkyds I wouldn't wish on anyone and some are even disguised as top of line products!).


Downfalls of alkyds: Slow DRY time (they actually never fully cure). They will lose their sheen much faster generally. They are more prone to fading with UV exposure (grey shouldn't be a big concern though like red, yellow, blue etc would be). Clean up with mineral spirits, high VOC content, stronger odor, ideal with china bristle brushes and others I'm sure I'm forgetting.


To conclude my vote would be Sherwin Williams Proclassic Alkyd (NOT the Acrylic-Alkyd blend) or Benjamin Moore Satin Impervo (again not the blend).
 
#16 ·
Quote:
Originally Posted by tgse3
First off what means of application do you have access to?
- I do not have access to an HVLP set up, so I will be rolling/brushing the finish.

Quote:
Originally Posted by tgse3
To conclude my vote would be Sherwin Williams Proclassic Alkyd (NOT the Acrylic-Alkyd blend) or Benjamin Moore Satin Impervo (again not the blend).
- Thanks for the advice, I will look into those items.


Based on information, it appears that I can use either water- or oil-based paint over the primer I have chosen. The short time-window from finish (at least two weeks away) and packing I think I will go with the water-based 100% acrylic paint - despite its inherent weaknesses compared to alkyd as pointed out by tgse3.


I will add the speakers to my air shipment, less time in transit should help to minimize the negative effects of humidity. The house in Cambodia will be air conditioned, making transit time the primary concern.


Thanks for the advice!
 
#18 ·

Quote:
Originally Posted by goonstopher /forum/post/20518849


how did you make the boxes?


I really want these but I can't do woodwork.


Are they prices per pair on the kit?

To save time I had the panels CNC'd by Dave ( http://techtalk.parts-express.com/sh...d.php?t=222369 ). I added an internal oak frame (1.5" x .75" x X") to add structural rigidity to the MDF as these speakers will endure multiple miltitary moves. Also, made front/back baffle 2x thick (inner layer of back panel has cutouts so is equal to 0.45" thick instead of 0.75" thick). To offset volume disruption from the original 4 Pi plan I increased the depth of the cabinet from 14.25" to 15.75".


The prices on the Wayne's website are per speaker, note the JBL and B&C drivers add significantly to the total cost.


I thought about just going with the vinyl peel and stick but will go with paint on front/back and oak veneer on the sides/top/bottom. Progress will be coming soon...

 
#20 ·

Quote:
Originally Posted by tgaffner1 /forum/post/20519126


Booo CNCin!!! Thats cheating, well not really. I imagine we all know how to cut. But, it definately takes the fun out of the project IMO....

I know, I am under a severe time crunch to get these done. I have already missed the window for the finish to be cured before my "sea" shipping date (big household good movement from MD to Phnom Penh is by sea) so they will have to go in the "air" shipment (obviously, the air shipment has a lot lower overall weight allowance than sea, I guess sometimes something has to give).


When I made my sealed Mal-X sub (using NEODan's 24" cutsheet) I bought all the tools to make the enclosure from sheets of birch. It was enjoyable and I prefer high quality plywood to MDF. here in Frederick, MD we have a great wood supplier ( http://hardwoodsincorporated.com/default.aspx ) that only sells A-1 grade - much better than what you can find at the big box stores.
 
#21 ·
Nice work so far.


For a limited LF extension application of handling 60hz and above, what's your opinion on making all three front LCR's sealed, with the HF element aligned with the LF driver?


Thank you
 
#22 ·
"how big is the cab? might be a bit big for my small ht room."


there is some design flexibility. since the 2226h is a easily modeled, you can do what you wish if you have some modeling skill or can have someone model it for you. the four pi was originally designed to be run without a sub. you have lots of flexibility there.
 
#23 ·
"Just curious, do you know why Wayne started carrying the B&C CD over the old JBL driver he used to offer?"


my guess is both price and sound quality. jbl cd's tend to be quite expensive. the b&c driver uses a different diaphragm material that many folks prefer.
 
#24 ·
"For a limited LF extension application of handling 60hz and above, what's your opinion on making all three front LCR's sealed, with the HF element aligned with the LF driver?"


dr. g employs the 15 tbx100 in a sealed cab, which is kind of a cousin to the four pi. for any q, the 2226h has pretty much an indentical, though more efficient, frequency response than the tbx100 (but requires a larger cab). for a 1.5 cubic foot cab, that gives q=0.707 and -3db point is just under 100hz. at 60hz, you would be down 9db. that is a little too much unless you want to put eq on it. then again, if you like to run your bass a little hot, crossing at 80hz with no eq should be good.
 
#26 ·

Quote:
Originally Posted by LTD02 /forum/post/20526608


"Just curious, do you know why Wayne started carrying the D&C CD over the old JBL driver he used to offer?"


my guess is both price and sound quality. jbl cd's tend to be quite expensive. the b&c driver uses a different diaphragm material that many folks prefer.

+1


There seems to be quite universal appeal to the DE250. Both the very reasonable price, and smooth response with adequate thermal/power capacity, make it quite attractive. Geddes thinks highly enough about it for it to be in the Summa.
 
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