Large 3-ways design / build

[Brett]

John, are you still looking for mids? I thought you'd settled on some Vifa thingy?

I agree with Cal's comment many posts back that high output is going to be limited by most domes.

 

[MJL21193]

Possible candidates ...
can you source Eminence in the great white north?

I'm liking the Alpha 6A or 8A. I think it will be one or the other.
Yes, I can get Eminence here no problem. Thanks

Perhaps it is because most people have never worked with foam-core panels before, just ask them to jump on a pair of slalom skis or one of the new short surf boards, you can use this construction to do almost anything you want, from ultra stiff and springy, really dead to flexible and lively

Yes, lack of understanding seems to be the problem. This panel design is very stiff on it's own due to it's shape but the addition of the foam has really driven the strength up - it's hard for those with limited vision (you know who you are...) to grasp the concepts covered here.

John, are you still looking for mids? I thought you'd settled on some Vifa thingy?

I agree with Cal's comment many posts back that high output is going to be limited by most domes.

Always looking- nothing is written in stone except for the woofer which I already have. On that note...
In the interest of doing something a bit different, I have been thinking about maybe using a compression driver and creating an elliptical horn flare that would be integrated into the front baffle. Something like 90 degrees horizontal, 40 degrees vertical but like I said, elliptical not rectangular.
How does the B&C DE10 look? It is their lowest priced but I won't hold that against it. Remember, these are "hifi" speakers and not a part of Cal's block party Wall of Sound.

 

[infinia]

In the interest of doing something a bit different, I have been thinking about maybe using a compression driver and creating an elliptical horn flare that would be integrated into the front baffle. Something like 90 degrees horizontal, 40 degrees vertical but like I said, elliptical not rectangular.
How does the B&C DE10 look? It is their lowest priced but I won't hold that against it. Remember, these are "hifi" speakers and not a part of Cal's block party Wall of Sound.

Now you are going the right direction. If'n it were me I'd steal some ideas from the 18Sounds kit 8" 2 way with 80x60 horn but minus the baffle step. Using it more or less for the top end of a 3way. This horn has some discontinuity issues and is somewhat costly compared to some other cheaper CD horns ie JBL, Pyle and QSC variations ala Econowave designs.
I don't think you'll need too much BSC at all, re> indoors with all the woofers you have. Check the madisound website for Zaphs 12" 3 way kit for a discussion on BSC with a smaller kit than yours 3ways. EDIT> BTW I think you could do better than Zaphs 3way it has some real whoopt-de-doos in the on axis response as he briefly states, then ignores how bad they really are.

 

[FrankWW]

Those panels are cute! Very sharp execution of I-beam principle. Over kill, of course

 

[SaSi]

I think this is an exceptionally good idea regarding a lightweight and stiff panel. There is certainly a possibility of failure from "unfortunate" execution so the mock-up approach and experiments are a good practice.

I am wondering if you plan to employ bracing inside the enclosure. The curved panels will make cutting and fitting the braces more complex.

Another issue that I was thinking regarding panel construction is how to make them identically symetrical. i.e. the curvature at the inner and outer face being the same. This curvature has to do with the method of glueing the faces together and how you apply pressure to the panels. If they are not made identical then fitting the side panels together to form an enclosure might be a bitch.

 

[5th element]

Isn't foam cored aluminium what aeroplane wings are made of?

If it works for them it should work for you John Stiff, light and strong.

 

[Brett]

I'm liking the Alpha 6A or 8A. I think it will be one or the other.
Yes, I can get Eminence here no problem. Thanks

I think you can do much better than either of them.

Always looking- nothing is written in stone except for the woofer which I already have. On that note...

I have no idea on where you're thinking of xover points, or budget, so not quite sure what to suggest.

In the interest of doing something a bit different, I have been thinking about maybe using a compression driver and creating an elliptical horn flare that would be integrated into the front baffle. Something like 90 degrees horizontal, 40 degrees vertical but like I said, elliptical not rectangular.

You're going to have to engineer that yourself and it's going to need CNC most likely to get the shape correct. It will be interesting to see.

How does the B&C DE10 look? It is their lowest priced but I won't hold that against it.

Where do you plan on x-ing it? Lower than 2k, depending on flare loading looks like a no-no. DS250 is excellent but 2x the price. Lots of other good CD's out there too.

Remember, these are "hifi" speakers and not a part of Cal's block party Wall of Sound.

As are mine, but Cal's are still small. My sides/rears are about that big, and the mains larger.

 

[mondogenerator]

You have no faith my friend.

Curving the panel massively increases strength - the way these panels are designed and joined together leaves only one "weak" point: the vertical centre axis of the tallest panels may flex slightly. To help combat this I will use steel flat bar for the divider shown circled here:

View attachment 154639

Up the side panels and the bottom and top panels will have 1/4" x 1 1/2" flat bar and the back will have 1/4" x 1".

I like where youre going with the panels....foam would be tempting but i have heard what a drum like sound boat hulls make, however rigid they may be.

Had you considered fiulling cavity with polyester resin mixed with the hollow glass spheres that GRP fabs use to lighten some structures? I wouldve thought that would be mega stiff and light, though not as light as foam, and may well be miles better.

just an idea, otherwise, loving the concept.

 

[Cal Weldon]

I have been thinking about maybe using a compression driver and creating an elliptical horn flare that would be integrated into the front baffle.

 

[Cal Weldon]

Cal's block party Wall of Sound.

You called?

 

[jacco vermeulen]

what a drum like sound boat hulls make.

Eeh, high density polyurethane foam is used in fast aluminum boats to dampen engine and wave slamming vibrations.
(just wait till the screw propeller starts to cavitate)

 

[MJL21193]

Now you are going the right direction. If'n it were me I'd steal some ideas from the 18Sounds kit 8" 2 way with 80x60 horn but minus the baffle step.

Looks good, thanks for the suggestion.
Baffle step can be handled actively, as these speakers will be active. Crossover points yet to be determined - measuring response and adjusting on the fly with the DCX2496.

Those panels are cute! Very sharp execution of I-beam principle. Over kill, of course

I'm all about overkill! Thanks

I am wondering if you plan to employ bracing inside the enclosure. The curved panels will make cutting and fitting the braces more complex.

Another issue that I was thinking regarding panel construction is how to make them identically symmetrical.

The idea is to not use extra bracing, that these panels should be stiff enough on their own. Time will tell - I won't hesitate to use extra bracing but only if it is needed.
Fitting the panels together will be a challenge anyway. A slight difference in symmetry would make a difference if I were to miter the corners. Since I plan on coping the corners together, it shouldn't be a problem.

 

[MJL21193]

If it works for them it should work for you John Stiff, light and strong.

Thanks 5th,
You are obviously a learned man of discriminating taste and enlightenment!

I think you can do much better than either of them.I have no idea on where you're thinking of xover points, or budget, so not quite sure what to suggest.

This is always true but there are limits to every project. The 6A has the efficiency I want and the FR looks reasonable. I'm not one of those people that think that if it's good, it has to be expensive. As for budget, I don't really have one, just burn up cash as I go along but try to keep it within reason.
As mentioned above, I don't know what the crossover points are yet myself. Part of the fun will be "dialing" these in actively.

You're going to have to engineer that yourself and it's going to need CNC most likely to get the shape correct. It will be interesting to see.
Where do you plan on x-ing it? Lower than 2k, depending on flare loading looks like a no-no.

Moving to a compression driver is something I've been meaning to try and this is a good opportunity.
The horn flare will not be a problem to construct - I won't need a CNC (there were and are people that can fabricate accurately without them) and I'll try to go through the process with a few pics to show what I'm doing. I'm a bit pressed for time right now with a few different things happening but I may find time on the weekend to get started on the flare..
I don't want to cross the HF driver too low - 2-2.5k is where I want to be.

 

[MJL21193]

I like where youre going with the panels....foam would be tempting but i have heard what a drum like sound boat hulls make, however rigid they may be.

Had you considered fiulling cavity with polyester resin mixed with the hollow glass spheres that GRP fabs use to lighten some structures? I wouldve thought that would be mega stiff and light, though not as light as foam, and may well be miles better.

just an idea, otherwise, loving the concept.

Thanks,
I think that the foam will be as good a fill material as any, for the design objective (lightweight, extra stiff). It has some "give" which is probably better than a complete solid as far as sound is concerned. Would something like sand be better? - most likely but it would be very heavy and I want to be able to move these and not have to reinforce the floor to hold them up.
Not mentioned yet is the other advantage of this panel shape: no real parallel surfaces, both inside the enclosure and inside the panels.

You called?

THAT'S what I was talking about!

 

[5th element]

THAT'S what I was talking about!

THAT makes me somewhat nervous.

 

[MJL21193]

THAT makes me somewhat nervous.

What about his neighbours?

Foam should be at my door early next week. THEN the fun begins.
I have been thinking that I will make the baffle a bit more elaborate than pictured earlier. The body of these speakers will be veneered, with the back and the baffle painted. I'm looking to do a marble / granite effect in the paint - something a bit different.

 

[5th element]

What about his neighbours?

Cal's Neighbours relocate whenever he turns the sound on. Not by choice mind you, but their houses get physically pushed away by the wall of sound.

THEN the fun begins.

Don't you mean then the mess begins?

I'm looking to do a marble / granite effect in the paint - something a bit different.

I've always wondered about making loudspeakers out of polished marble, it'll be interested to see how this turns out looking. I'd be tempted to marble effect the entire cabinet.

Edit - that's if it's someone else is finishing the cabinets for me. If it's me I'll stick with MDF >.<

 

[MJL21193]

Don't you mean then the mess begins?



I've always wondered about making loudspeakers out of polished marble, it'll be interested to see how this turns out looking. I'd be tempted to marble effect the entire cabinet.

Edit - that's if it's someone else is finishing the cabinets for me. If it's me I'll stick with MDF >.<

Making a mess is fun too.

I like to experiment with finishes. I did a big table a few (hundred) years ago that was a dead ringer for marble, at least from a distance
For this I will try to be a bit more sophisticated in my approach and do some samples before I proceed. To get a more "real" granite effect, I have mica flakes to mix in. Black base, black candy with the mica and several coats of clear to give it depth.
More fun

 

[PKNJ]

Impressed....

I have to say I'm impressed with the thought put into the cabinet design. And you even thought out the construction in detail as well. I convinced it will work the way you think it will. Most of the naysayers seem to have fallen away. I voted "It'll Work" early.

The poll is closing soon. Remember folks, vote early, vote often!

 

[MJL21193]

Thanks again fellas!
It is strikingly like a basin A bit on the small side though.
Just about the right size for Holy Water...Amen.

It is taking forever for that casting to dry out. I may as well put my enthusiasm on hold for at least a day or two and let it dry.
Unfortunately, work in all it's glory calls tomorrow and I won't get anything "important" done. On a bright note, my foam may arrive and I get to look at that when I get home.

I've modified the front baffle some. The concept:



Somewhat more interesting looking I think.