Honest opinion (peer review) about this 4Way before I build it

Status
Not open for further replies.
Especially since he has the drivers, crossover and amps on hand now. What would he use as a stand for the mid and tweet?

Top down's the approach I take on a multi-way speaker - get the mid/tweet right then work out the bass to mid XO, but since all the parts are ready to go, lets see it.

I'm looking forward to the build thread.
 
Has anyone ever built the ideal speaker
I doubt it
mine is certainly not
there are so many many details we could argue about, now and forever
tho, until its playing I have no idea what to expect of it
I suppose thats one exciting side of it

but I would be worried about a sagging woofer
 

Attachments

  • IMG_0601 (Large).JPG
    IMG_0601 (Large).JPG
    111.6 KB · Views: 157
  • IMG_0549 (Medium).JPG
    IMG_0549 (Medium).JPG
    59.9 KB · Views: 155
  • IMG_1160 (Large).JPG
    IMG_1160 (Large).JPG
    43.4 KB · Views: 154
  • IMG_1514 (Large).JPG
    IMG_1514 (Large).JPG
    74.7 KB · Views: 154
  • IMG_0566 (Large).JPG
    IMG_0566 (Large).JPG
    67.2 KB · Views: 156
I will share the building with you - It might be next year after Christmas; I just realized the parties starts this week-end.

About the sagging woofer... Yeah, I'll apply a DC offset 😀 I kid, I kid. How does the cheap HT subs do it ?

I'll read every reply carefully tonight. Might change a few things but maybe not the shape or most of the drivers.
 
The good news here is Yoshy has chosen drivers with performance that will stand the test of time, it is just up to his measurement and DSP programming skills to get filters that work. With the larger angle of your enclosures, I'd guess that you'll get a little less effective additional width than half the total enclosure width. Maybe start with the front surface plus 1/3 the additional width of the "chamfers."

Bob is the HiVi in the same league as the SEAS W15? I have heard the 16cm Mg cone and it was a really nice woofer. It lacked low end oomph (which is why it should be mated to a woofer like the W26) though.

Wonder if putting a cylinder in the middle of each enclosure will make it no longer behave as a 6 sided hexagon?

why not a pentagonal core?

If it is lightly stuffed with fiberglass you won't see any standing wave effects....Woofer sag might be an issue but you can also, like tires, rotate your woofers every season (top to bottom, etc.)

A bit of bracing and damping should resolve most renonace issues.

but I would be worried about a sagging woofer

Yes I would to the XXLS has a heavy cone and a single spider (guessing).

There is a classic two-box way of doing a 3-way to give small box dispersion and big box bass. It works very well and any other
arrangement IMO is very hard to justify, go for quality.

This design is mostly as a radical departure from the text book experiments I did. If I was to start again I'd put the 2 sub on the side of a box. It would probably be a triangular prism or something.

Yoshy if you have already got the drivers there is little you can do but forge ahead. The W15 will need help in the lower midbass from a larger woofer (the W22 would have been a better bet but you already have the HiVi).

I am still a little apprehensive about the 12" woofer being placed face down/up though.
 
What? Isnt a sphere near the best enlcosure shape for loudspeakers because it has no two parallel sides?

The cabinet shape issue is overblown. Unlike a listening room where you have problems getting enough depth of treatment, with an enclosure you can lightly fill the cabinet volume. This gets absorbtion in the center where velocity is high and pressure is low. This makes the stuffing very efficient.

As long as you use fiberglass rather than dacron or BAF (bonded acetate fiber) you won't have any problems with standing waves. These alternative materials are poor acoustic absorbers, in my experience.

The only cabinets I've had difficulty with are very long aspect ratio columns where I wanted a vented system with a low stuffing percentage. In that case an absorbtive barrier in the center of the cabinet (velocity maximum) did the trick. Non-vented cabinets should be lightly filled.

David S.
 
I view a sphere as having an infinite number of parallel sides.

It is one side with it's whole face visible from every spot on it's surface. In practical it's a regular lens or infinite number of lenses with the same focus distance and all focused in one point.

If you disregard the nuclear/fusion thing all other explanations apply to the behavior of an excited sphere. - http://www.glafreniere.com/sa_spherical.htm
 
A sphere could be strongly resonant, if you drove it from the center, and if you had no stuffing!

Sounds like we need a few extra dimensions of space to manage that in a practical way.

It is one side with it's whole face visible from every spot on it's surface. In practical it's a regular lens or infinite number of lenses with the same focus distance and all focused in one point.

If you disregard the nuclear/fusion thing all other explanations apply to the behavior of an excited sphere. - Spherical Standing Waves

That's cool, I am not sure how it applies, but it seems to me to support that a sphere is a bad idea for a speaker. Good for the baffle step, but the internal resonances will create some difficult nodes. I could be wrong though, so some one convince me otherwise.
 
As it is explained in the site I referred to, the amplitude in an excited sphere is always biggest at the center. So if there is absorbent material in the center it will be heated in the same way the stuffing in ordinary boxes is heated. That will transform the wave energy into heat energy and will solve the problem.
But sphere has another advantage - the amplitude of the waves is smallest at the perimeter, so the interference with the membrane would be less than any other enclosure even without stuffing.

As a matter of fact it would be less than the total internal area / speaker cutout area ratio as opposed to some rectangular enclosures which can get resonant "Q's" (if i may say it that way) near 1 🙂
 
The cabinet shape issue is overblown.

I agree. Damping a bracing should make this cabinet very useable.

As it is explained in the site I referred to, the amplitude in an excited sphere is always biggest at the center...As a matter of fact it would be less than the total internal area / speaker cutout area ratio as opposed to some rectangular enclosures which can get resonant "Q's" (if i may say it that way) near 1 🙂

I think we are digressing here. The cabinet size and shape are chosen and so are the drivers.

I think Yoshy was only doing a sanity check and in that respect the only apprehensions I had was the mounting of the woofers in a face/up down manner and that (though this argument is also mute since the drivers are chosen) maybe the SEAS W22 would have been a better fit than the HiVi 8a or that maybe a 3 way using a W18 might have been easier to build and tune.

Anyone see any other problem areas that cant be fixed easily?

I'd love to see Yoshy's final build.
 
Status
Not open for further replies.