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DIY Waveguide loudspeaker kit

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Earl, I've noticed you talking about needing an acousticly transparent screen in HT and having the center speaker behind it. Obviously for those of us that use LCD or plasma, this isn't an option. Although putting the TV up higher will undoubtedly want for a higher sound stage/source, I find it's easier to put all 3 front speakers at the same height and suspend the screen above the center speaker. Pretty sure that's how almost all movie theatres have been doing it for decades now. I realise that theatres don't TEND to have the absolute best sound, but it's my guess that it's because the loudspeakers used are not up to par, more than the sound field height...
 
All of the commercial theaters that I have been in have the front three speakers at the same height BEHIND the screen, never below it. This would be a seriuos problem with the sound image not being coincident with the visual image on a screen the size of a theater. In a home you might get away with this, but in my experience behind the screen is necessary.
 
Patrick Bateman said:
If anyone doubts that such a huge speaker can "image", here's something funny that happened this weekend.

I was watching this weeks episode of "Lost", and there's a scene with a lot of ambient information. Basically it's a scene where someone sneaks up on one of the characters from behind.

During the scene my girlfriend actually looked over her shoulder!

I asked her why she did that, and she said "I thought I heard someone in the room."

Crazy huh? I've never had speakers which imaged like this. (This is a two channel set up also. No rear speakers.)



I have heard similar things with the Nathans in my listening room.
 
Not what I meant; I certainly hope it does last as I hope everyone's enterpricse succeeds. Business usually comes in cycles; that you are doing well during a recession is in itself surprising. Your offerings are typically purchased with disposable income and currently that is not in abundance. Don't look for a nefarious meaning in my coment--there is not one.

Ray
 
some feedback on the kit assembly

I have glued up the kits and I would rather have had my kits without the pocket screw holes. I did try to use the screws in the assembly of the enclosures, but I didn't feel the screws were tight enough for the job. So I put the clamps on. I use titebond wood glue and like to have it very strongly clamped in multiple locations.

The holes for the pocket screws are pretty large holes to have to go back and fill. I used up almost a hole tube of wood filler just on these for a pair of speakers. Plus 2 of the screws started to push out through the face of the baffle.

It probably is a decent option for people without clamps though. I wonder if this was the cause of the latent separation at the seams that a couple of people posted about? Or they might have been using the never harden type glue?


Otherwords it was pretty easy to get them together so far. Glad the woodwork was part of the kit!

-Tony
 
Re: some feedback on the kit assembly

TRADERXFAN said:

The holes for the pocket screws are pretty large holes to have to go back and fill. I used up almost a hole tube of wood filler just on these for a pair of speakers. Plus 2 of the screws started to push out through the face of the baffle.
-Tony

Tony,

It's much easier to fill the pocket screw holes with 3/8" dowel and then use a Japanese flush cut saw. The end result won't take much sanding/filing to produce a smooth surface.

mike
 
Hey Tony

Wow, the screws should never come trough the front, you must be really tightening them.

I should have mention what I found to be a great choice for filling the holes. Get TAP Quik-Cast Polyurethane Casting Resin System from http://www.tapplastics.com Mix this up and pore it into the holes. 20 minutes its dry and it never shrinks. You can only do one side at a time however because it has to be level. So mix up and fill in small batches. Works great.

The seperations had occured on earlier kits that DID NOT use the screws. The kits with screws seem to be fine.
 
Re: Re: some feedback on the kit assembly

mike galusha said:


Tony,

It's much easier to fill the pocket screw holes with 3/8" dowel and then use a Japanese flush cut saw. The end result won't take much sanding/filing to produce a smooth surface.

mike

Mikes technique works fine too and may even be better because without a filler the polyurethane gets quite hard and sands at a different rate than the surrounding MDF. With a lot of micro-ballon filler it sands at the same rate. I use filler.
 
mike galusha said:
The screws in mine were too long as well and not over tightened. They didn't poke all the way through but did create bumps on the ones that were too long. Either that or the pocket holes were too deep.


Mike and Tony - At some point the screws for the sides were shortened by 1/4". Tony should have gotten the shorter ones, but Mike would likely have had the longer ones. (Unless you are using the longer ones for the sides, which should be used for the back.) But the screws were never intended to be very tight. They should basically just hold the enclosure togther for the glue. If you tighten them too much then things do start to bulg (been there, done that). Best is to just tighten them enough to hold the sides while the glue does its job.
 
Hey Dr. Geddes. I know you mostly abandoned your enclosure construction technique used in the Suma due to complexity and cost to produce, with MDF being the better value choice. I'm wondering if you have worked at all with casting foams, like hard polyurethane casting foams.

Because of what I am looking for with rear surrounds, I am thinking of possibly buying your kit minus the enclosure, and casting a hard foam enclosure to allow for a more rounded shape as well as lighter weight.

I also wondered if possible a front baffle for the Abbeys and Nathans made of something like that would allow larger edge radii than mdf.
 
pjpoes said:
Hey Dr. Geddes. I know you mostly abandoned your enclosure construction technique used in the Suma due to complexity and cost to produce, with MDF being the better value choice. I'm wondering if you have worked at all with casting foams, like hard polyurethane casting foams.

Because of what I am looking for with rear surrounds, I am thinking of possibly buying your kit minus the enclosure, and casting a hard foam enclosure to allow for a more rounded shape as well as lighter weight.

I also wondered if possible a front baffle for the Abbeys and Nathans made of something like that would allow larger edge radii than mdf.


The Summas and all the Ai products do use cast polyurethane foam. You can't use this foam as the visible surface because it isn't hard and smooth enough. So a skin is made in fiberglass and then the baffle and waveguide were cast in the foam. It works great, best that I have found, but it is outrageous in terms of tooling and labor. The Summa versus the Abbey is a classic example - a two to one cost differential is not insignificant.

I can still make Summas, but the cost differential is just not something that many are willing to put out.
 
mike galusha said:
The screws in mine were too long as well and not over tightened. They didn't poke all the way through but did create bumps on the ones that were too long. Either that or the pocket holes were too deep.


Yeah it didn't pierce through, just caused bumps.

Thanks for the advice but I don't have that saw, and not sure it would be worth buying one for this. I think the filler is fine just took more! I just used a tube of minwax. On my last project I used a larger canister type version, but the tube is much easier to apply and wasn't that bad for the holes. It was like injecting a pastry :D

Since the clamps were already bought and paid for it just would have been a better option for me. I am not sure if there is any real advantage to clamping it so well. But what I like to see is the glue line come out all along the seam so I can be sure I didn't miss a spot, and know its air tight. I wasn't getting that with the screws. There was a tiny bit of gap between the baffle and sides. After clamping it was very flush together.

-Tony
 
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