Foam Core Board Speaker Enclosures?

[xrk971]

You will be fine, from the photos I can see that it looks like you sealed it well. The transitions between the different lengths look very good too. I see that the sawblades left some jaggedness on the edges of the channels but that won't matter as the glue seals it up. The X-acto does a good job in this area, albeit much more time consuming. I can't wait to see what you do next. I guess you need to drill holes where the speaker bolts will come through and also on the 4 corners?

For the speaker wire routing, I cut small holes (sealed with hot melt glue) along the channels and routed the wire straight down to where it exits at the midpoint of an edge - I have flying leads (12 ft) coming from the speakers rather than terminal lugs - cleaner this way for wall mount. I am using some leftover 4-conductor security alarm wiring which is good because it has a white sheath and is super low profile (I doubled up the 22 AWG wires which should be good for 2 amps or 24 watts with my 12 volt TA2020A+ amp, I think I rarely would use more than 5 W). For your drivers, you will of course need thicker real wires if you want to push 100 W into them.

For hanging the speaker, I used two screw-eye hooks on the back with stranded steel picture frame wire to hang it like a picture frame. This allows the speaker to slightly tilt down (for good imaging from a slightly above ear-level placement) when being hung and keeps the flat back off the wall. If mounted flat, I fear it would rattle when bass notes hit. I use some stick-on felt pads (feet) along the bottom edge of the speaker where it touches the wall. This way, you reduce rattle/buzzing from vibration-induced contact between the wall and the back of the speaker.

One other thing, stuffing: I used some old polyester stuffing from a pillow inside the main speaker cavity (pretty densely packed) to absorb the high frequencies and to smooth out the frequency peaks. I also put light stuffing into the first 4 or 6 inches of the entrance of the channels to absorb any back reflections and further reduce the high frequency output. You can of course play with this and adjust to taste. I don't think the original Cornu used any stuffing at all.

[Cal Weldon]

I will assemble it without any bolts, hangers or anything until I listen. Then I can decide how much love these babies see.

[Cal Weldon]

Changed my mind on the drivers. I think I will use the Fostex FF125WK that have received the full treatment by planet10. That way I don't have to figure how to fit a tweeter. They also have decent sensitivity.

http://www.madisoundspeakerstore.com...-5-full-range/

[xrk971]

Originally Posted by Cal Weldon

Changed my mind on the drivers. I think I will use the Fostex FF125WK that have received the full treatment by planet10. That way I don't have to figure how to fit a tweeter. They also have decent sensitivity.

The Madisound Speaker Store

Cal,
I agree with the waiting to listen before extra hardware, but it is imperative that these be hung on walls to do them justice for a first listen as the walls are integral to the design and serve as an extension of the horn mouth and make a big difference with the bass because of the floor+ceiling reinforcement. I was the same way and listened to them prior to wall mounting and it was good but not blow your mind good.

I was wondering what the frequency response was for your original drivers on the high end - you mean they are not "full range"? How did you select the Fostex FF125WK? It looks very nice and should work well - problem is now we have to wait to hear what it sounds like if you still have to order them . You should be OK with the piston area with regards to the channel entrance throat area at around 1.1 inch and 4.5 inch depth on channels.
Good luck with the rest of the build!
Regards,
xrk971

[Cal Weldon]

Originally Posted by xrk971

Cal,
but it is imperative that these be hung on walls

Yes, I have been aware of this cabinet for a long time. You are the first person that has led me down the path to building them because of the suggested materials. I will place them on stands against the wall.

I was wondering what the frequency response was for your original drivers on the high end - you mean they are not "full range"?

Correct, they are a mid woofer with a good top end. The VWR stands for very wide range. Unfortunately at my age I would need a tweeter and I wasn't sure how to incorporate it.

How did you select the Fostex FF125WK? It looks very nice and should work well - problem is now we have to wait to hear what it sounds like if you still have to order them

No waiting, I have lots of drivers. Have a look at link in my sig line, I am a speakerholic. This one went to the front of the line because you made it easy enough to build.

[xrk971]

I looked at your stuff in sig line. Oh my, you do have a problem... I feel for the Speaker Widow , or should I say, Speakerabler since you are the Speakerholic? I like the Pentagon, how does that sound? Must be great for parties.

Good thing is we don't have to wait to hear since you have drivers on hand.

[Cal Weldon]

Second spiral done.

I've been thinking of the rough edge on the foam. It was easy to deal with it with the hot glue but not so easy when add the fronts so I have an experiment I am trying. I am gluing the top edge with yellow glue then adding a thin strip of regular writing paper over that to act as a surface tensioner to hold the glue. Then I turn the whole thing over on a flat surface and weight it. I am hoping this will give me a flat surface to glue to. I am trying the same experiment with masking tape in place of paper. I realize this sets me back a day but what the heck, a week ago I wasn't going to be doing a build until the new year so...

[xrk971]

So you are building a glue fillet on paper, then gluing that to the front once the fillet dries? Sounds like it should work. Maybe hand cutting the channels with razor is the way to go? It takes about 30 minutes to make all the strips.

[Cal Weldon]

Ya, the two minutes it took to do it on the saw is going to be more like the same time it takes to cut them by hand when all is said and done.

I have hooked up the drivers OB style on the baffles to start them breaking in.

[xrk971]

Good luck with the build. Your second box looks good too. I bet the second one went a lot faster. How loud do you run the drivers for break in?