Jims 3 way speaker build

[a4eaudio]

Will you build a base, use spikes, outrigger feet, etc.? If so, make sure to take that into account for your tweeter height.

I usually err on the side of the tweeters being on the high side rather than the low side (38" normal, 40" on the high side). My ears are higher than 36" in most of the listening spots in my house. I also figure I'm likely to stand up and walk around while still listening to music, but I'm never going to lie down and be lower than the tweeter.

[jimbones]

yes there will be footers so that is why I have them at 36. allow 3 inches for stuff and brings it up to ear level and still have another inch to 40

[DeZZar]

...at a listening distance of say 9ft.....even if the tweeter was 10 inches below your ear......that's still less than 5 degrees "off-axis". If your speakers measure and sound bad 5 degrees off axis....start again.

I'd have a hard time tolerating a speaker with a sweet spot so small that you had to have the tweeter within an inch of your ear height. So basically, don't sweat a few inches....

[jimbones]

...at a listening distance of say 9ft.....even if the tweeter was 10 inches below your ear......that's still less than 5 degrees "off-axis". If your speakers measure and sound bad 5 degrees off axis....start again.

I'd have a hard time tolerating a speaker with a sweet spot so small that you had to have the tweeter within an inch of your ear height. So basically, don't sweat a few inches....

I agree.

[jimbones]

Update: I am working on the details in the drawings and at the same time trying to locate a cabinet builder. Most dont like doing stuff like this so I may end up doing it myself. I have a question regarding the woofer mounting. I will be using a 1 inch thick Baltic Birch baffle. The frame of the woofer is thick. And the surround protrudes and will interfere with the grill cloth. I dont like removing too much material to recess the woofer. Is it OK to rear mount it with a round over on the front? Thanks as I finalize and get ready to building this bad boy.

[djg]

Add 1/2" or 3/4" layer to the baffle behind the woofer for reinforcement/adequate thickness with the deep rebate.

[silverD]

This is what Jeff B. did with the Continuums. The mid-woofer frame was recessed into the back of the baffle.

[DeZZar]

Is it OK to rear mount it with a round over on the front?

You'll just be dealing with an even further exaggerated z-offset between woofer/mid/tweeter.

[jimbones]

exactly why I asked lol no free lunch

[Steve Lee]

Waveguides on the tweeters, man . . . get creative and quit worrying . . .

[Chris Roemer]

It's not "good" (in general) to have the same distance from the center of a driver to the baffle edge(s). If your baffle is 14"w (for example), then the worst situation would be to ALSO have the tweeter center 7" down from the top of the cab. This is basically what your drawing currently shows. I'd suggest 5" for your design. This staggers the distance from the tweeter (diffraction) to the edges. 3-1/2" would (also) not be as good as the diffraction (distortion) would be shifted by one octave.

Look for the (free) Tolvan's "Edge" software to simulate these diffraction effects for yourself.

[DeZZar]

...or the diffraction module in VituixCAD if you already have it.

[jimbones]

I will change the tweeter location as suggested however that will bring the tweeter above my ideal 39 inch listening height. I allow room for footers under the speaker. My original design had the mid and tweet off center but I was told that it creates other problems and I was better centering them.

[jimbones]

Port location? Front back, how high off the floor? 4 in pipe is what I am using.

[djg]

How are you mounting the AC130F1? It has a complicated frame shape for rebating. The real reason the Continuum has it rear mounted. You want to overlap it to the Seas tweeter? If you rear mounted the woofer and mid, you'd have some visual harmony, but you're going to hide the beautiful drivers behind a grill? Just curious.

A big front port would look cool if you have the space. You could leave it uncovered by the grill.

[jimbones]

How are you mounting the AC130F1? It has a complicated frame shape for rebating. The real reason the Continuum has it rear mounted. You want to overlap it to the Seas tweeter? If you rear mounted the woofer and mid, you'd have some visual harmony, but you're going to hide the beautiful drivers behind a grill? Just curious.

A big front port would look cool if you have the space. You could leave it uncovered by the grill.

djg I am purposely not spending a lot of money on cosmetics of the cabinet. The design will be modular so I have an upgrade path in the future if I desire. Picture a Vandersteen if you will. It will have a nice wood top and plinth. I like the idea of mounting both the woofer and mid from rear. I could rout a roundover on the front. But the tweeter is front mounted. I assume that will cause phase issues between mid and tweet??

[djg]

IIRC, the late Jeff Bagby leaned the Kairos baffle back to help correct phasing. I'm not really qualified to advise you, but your cab sketch does show a leaned back TM module baffle?

Edit: Lots of work on dome tweeters mounted behind a small horn/waveguide if you're up to that approach.

[jimbones]

I dont mind a waveguide but Im not equipped to figure it out. I would like to just buy a waveguide that is designed for this tweeter. Otherwise front mount

[a4eaudio]

But the tweeter is front mounted. I assume that will cause phase issues between mid and tweet??

I think it is more accurate to say that may cause phase issues. The z-offset between the tweeter and mid can cause phase issues and two popular solutions are waveguides and angling the front baffle. But it isn't guaranteed to be an issue - I have a speaker with the midwoofer recessed 1/2" inch and the phase between tweeter and mid lie right on top of each other - even though it was due to just dumb luck on my part. Jeff Bagby's Continuums are another example and there are plenty of others.

1. You can affect the phase when designing the crossover. So as long as you are measuring the speakers on the baffle with the recessed driver you can account for it, you might just be making things a little more difficult. And you can always ask for advice on the forum when you get to the xo design stage.
2. There is some question about how audible (if at all) that offset difference is going to be at listening distance in a real room with reflections.

If it was me I'd rear mount (especially with those odd-shaped drivers and the grill issue) and figure things out from there. I'd recess the woofer on the back side so that it is not a full 1" round over, maybe 1/2" or 3/4" and round over or 45 degree chamfer.

[jimbones]

Thank you a4eaudio. Will do. I hope to start the cabinets in 2 weeks.I intend to do all frd measurements on the baffle as stated.

[jimbones]

So I made some minor adjustments to the front baffle. Also I will be making this from 18mm and 25mm Baltic Birch. The top and sides 18mm the front baffle and rear panel will be 25mm. I pick up the wood next week. Any thoughts for final modifications are appreciated. Thanks again for all your suggestions.

[DeZZar]

Not everyone will share this same view but personally, for a cabinet this size I would be using 25mm all round and I usually go 36mm for the baffle. Not sure what your bracing plan is but I also go for plenty of bracing.

If you are using Baltic birch for the aesthetics consider getting just a 12mm sheet with a sheet of 12mm MDF and layering them together for all the panels. (MDF on the inside obviously).

Should be a lot cheaper than 25mm slabs of birch ply.