MiniByzy (Mini Byzantium) Build Thread

[TN Allen]

Re: MiniByzy (Mini Byzantium) Build Thread

Non rectangular baffles will have different diffraction signatures, and can be beneficial. There's also the inherent advantage of curved panels to adding stiffness and strength compared to their flat counterparts. It's much more difficult to set a curved panel into resonance than a flat one.



The interior being a chamber composed of non-parallel sides, the chances for standing waves to form are reduced, but when properly damped with acoustic stuffing, standing waves shouldn't be a problem in rectangular enclosures either.

This shape was chosen purely for aesthetic reasons, based on the floor standing 3-way in my avatar. Ed did with this, what he wanted to do to the big ones, by adding the curved top/back.



The main reason for the waveguide, other than the really cool look it imparts, is simply to allow us to easily cross the tweeter at 1KHz to an 8" woofer. Preliminary models show that the filter will be down 20dB at 1KHz relative to the upper frequencies in LR4, which should allow it to keep up with the woofer and provide and even cleaner upper mid presentation.

Given the above, I assume panels that are complex curves would be somewhat more advantageous, though of course even more difficult to produce in wood, especially if the panels are to be veneered.

I don't want to sound facetious in the following, but I have been wondering about the visual/audio neurological connections that make things that look good, sound good as well. I suppose the way we see some shapes reinforces in some way, the way we hear the sound these shapes produce.

This is also interesting to me as a friend and I are working on some prototypes using old Epicure drivers. He wanted the inverse dome tweeters set back into the baffle so the two drivers would be as close as possible to the same plane. The hitch was that he also wants the drivers on the baffle plane, which was to be slanted. The cabinets are truncated pyramids in which 3 sides are slanted, the back face is square to the base. Both requirements are not possible so I cut a bowl shape in the baffle to produce a compromise we hope will produce the desired effect.

What interests me about your approach is that the waveguide is curved like a trumpet bell(?), rather than a bowl shape. I assume there is an acoustic advantage to the one over the other? I have photos of the baffle for the prototypes that show the inverse shape I cut with the Epicure tweeter in place. I'd be interested in your comments about this approach, however, I need to figure out how to reduce the file size so I can attach the photo file.

Thank you again for your response. tna

[Pete Schumacher]

Re: MiniByzy (Mini Byzantium) Build Thread

Given the above, I assume panels that are complex curves would be somewhat more advantageous, though of course even more difficult to produce in wood, especially if the panels are to be veneered.

Each side panel is a simple curve, a cylindrical section. Veneering is therefore fairly simple. Even the back curves in only one plane, though the radius of that curve is not constant, as it is with the side panels.

I don't want to sound facetious in the following, but I have been wondering about the visual/audio neurological connections that make things that look good, sound good as well. I suppose the way we see some shapes reinforces in some way, the way we hear the sound these shapes produce.

It is better to look good than to feel good my darling . . .



Of course a nice looking enclosure sounds better. That's just a fact. ;) :p

This is also interesting to me as a friend and I are working on some prototypes using old Epicure drivers. He wanted the inverse dome tweeters set back into the baffle so the two drivers would be as close as possible to the same plane. The hitch was that he also wants the drivers on the baffle plane, which was to be slanted. The cabinets are truncated pyramids in which 3 sides are slanted, the back face is square to the base. Both requirements are not possible so I cut a bowl shape in the baffle to produce a compromise we hope will produce the desired effect.

What interests me about your approach is that the waveguide is curved like a trumpet bell(?), rather than a bowl shape. I assume there is an acoustic advantage to the one over the other? I have photos of the baffle for the prototypes that show the inverse shape I cut with the Epicure tweeter in place. I'd be interested in your comments about this approach, however, I need to figure out how to reduce the file size so I can attach the photo file.

Thank you again for your response. tna

The reason for the trumpet shape is that it provides a uniform response change on the tweeter. A bowl shape will suffer from all kinds of issues due to the tendency of the bowl shape and the well defined edge to exacerbate diffraction.

Open the file in paintbrush, and then resize it using image stretch.

[TN Allen]

Re: MiniByzy (Mini Byzantium) Build Thread

Thanks for the response.

I'll work on reducing the photo file size. 19kb is small, the file is close to 1mb at present, but here is the CAD file for the prototype. This is not the bowl shape I finally made, the cone shape, was another thought, but the file shows the orientation of the tweeter baffle and woofer.

tna

[TN Allen]

Re: MiniByzy (Mini Byzantium) Build Thread

Here is the photo.

[Pete Schumacher]

Re: MiniByzy (Mini Byzantium) Build Thread

I'd suggest smoothing the transition of the edge of the depression with the baffle surface. That should help smooth the response. The section underneath the tweeter doesn't concern me as much as the sharper transition above and to the sides the tweeter.

[winslow]

Re: MiniByzy (Mini Byzantium) Build Thread

Coming from a car audio and auto body back ground, I would have skipped all of the putty coats unless you had rather large gouges. I would have shot the whole thing with a couple heavy coats of Slick Sand and then blocked it with 180. Then a 2k primer on top of that. Block with 320 and then 600, and finally scuffed the whole thing with gray scotch-brite.

And you can make flared ports in any ID you want. Cut a few disks in gradually larger sizes until you get the flare you want. Screw the disks to a piece of MDF as a base. Get a heat gun, heat the plastic tube and push the plastic tube down onto the positive mold you just made. Let it cool and you have your own custom flared ports in any ID and flare you want. You can use a program like Flare-It to calculate the effects of different flare radii.

[TN Allen]

Re: MiniByzy (Mini Byzantium) Build Thread

"I'd suggest smoothing the transition of the edge of the depression with the baffle surface. That should help smooth the response. The section underneath the tweeter doesn't concern me as much as the sharper transition above and to the sides the tweeter."

That's what we planned on doing, I left it for my partner in this to shape it. I haven't seen what he finally did, but should soon as he is assembling the drivers and cabinets today.

I see what you mean about the waveguide form your using, next time, I'll do something similar.

Thanks again for information. tna

[Pete Schumacher]

Re: MiniByzy (Mini Byzantium) Build Thread

Talk about pumped. I've been told they should be here Thursday. Here's a preview. Ed's taunting me!!!!

[winslow]

Re: MiniByzy (Mini Byzantium) Build Thread

They do look tight.

[Pete Schumacher]

Re: MiniByzy (Mini Byzantium) Build Thread

Well, they showed up this afternoon. The pictures don't do these justice. :eek:

Ed, these baffle fronts have the feel of polished glass. They're unreal. I stare at them for 5 minutes at a time, get some stuff done, and then come right back to stare at them some more. Now I know what you were talking about all those sessions on the phone. :D

I'm off to Ryan's tomorrow afternoon. Not sure what we'll tackle first, finishing up the baffle, getting measurements of the raw response, affixing feet, or veneering the enclosure. Regardless where we start, this is a project that has me at least as excited as I was when those Byzantium cabinets showed up, probably more. Can't wait to get these in listening position, in all their final glory.

I'm sure Ryan will take some excellent pics.

[Face]

Re: MiniByzy (Mini Byzantium) Build Thread

Is your camera broken? :D

[D, Rose]

Re: MiniByzy (Mini Byzantium) Build Thread

Um,... they look just like they did before I sent them, unless St. Louis makes cabs appear differently than they do in Detroit.;) I think Pete likes them!!!

[Pete Schumacher]

Re: MiniByzy (Mini Byzantium) Build Thread

Is your camera broken? :D

My camera is [email protected], and wouldn't improve on the picture above, believe me. That's exactly how they look right now, but you can't get an idea from a picture of how smooth they actually are when you put your hand on them.

The next pics of these will be of the baffle and enclosure finishes in their various stages of completion.

Debating whether to paint, powder coat, or vinyl wrap the baffles. I love the idea of powder coat, as they have some that cure at 350 in 10 minutes. We'll be doing a trial with a sealed MDF baffle before I submit the baffle Ed made for these enclosures.

[Eric.DeYoung]

Re: MiniByzy (Mini Byzantium) Build Thread

There is a place where I live in Grand Rapids that professionally powder coats MDF - they brought in a couple samples to work that instantly made me think "speakers!" Such a durable finish too. That's my vote!

Edit: The stuff that the guys brought in was similar to a traditional matte black textured powder coat on steel, but that website introduces a whole bunch of different options! Similar to this: http://www.powderbuythepound.com/BLA...E_TEXTURE.html

[greywarden]

Re: MiniByzy (Mini Byzantium) Build Thread

Can you get a smooth, glassy finish with powdercoat, though? Idk I've only ever seen some cheapo powdercoated wheel job that wouldn't cut it on a speaker.