Open baffle: single piece baffle or mids/highs separated?

[madisonears]

I am building a 3 way open baffle system with mids/tweets OB but bass in a closed box. Should the baffle that holds the mids/tweets be separate from the baffle that holds the woofers? I see many designs that use a single piece for the entire baffle, even in hybrid systems like mine. I also see designs using two separate baffles. The geometry of my system makes it logical to break the baffle between the box and the OB. I want to use thin material for the OB so there is less restriction on the rear radiation of the mids, and the woofer baffle will be considerably thicker. The sides of the OB have a 3" radius, but the bass enclosure will have squared or beveled edges.

I think that separate baffles would help to isolate the mids/tweets from woofer vibration. Are there any other sonic artifacts that will be affected by putting a break between the two baffles? Should the gap be small, or large enough for the mids/tweets backwave to wrap around the bottom edge, between the top of the bass enclosure and the bottom of the OB? I plan to make the top of the bass enclosure slanted downward from front to rear, forming half of a "horn" at the back of the OB.

Peace,
Tom E

[AJINFLA]

Separate baffles might have a 1% effect on the sound of your loudspeaker system. What is your plan for the 99%?
Driver measurements mounted on cut baffles that simulated well, crossover design based on these measurements, etc, etc??
I'm sure that at some point, the size of the flag that you plant on the lunar landscape become quite relevant. But you kinda have to get there first

cheers,

AJ

[madisonears]

AJ,

Thanks for your reply, but I'm not sure what the purpose of it was, as it contributed nothing to my understanding and contained no useful information.

I don't know why the specific design of the entire system has any bearing on an answer to my question, but here are the details: buy one of every driver that Madisound offers, load them into the back of a van, then use the first three that fall out the back. I bought a 3 way crossover on eBay. It has three different electrolytic caps for flexibility, so I'll be doing a lot of testing! The woofer enclosure is the cardboard carton that my refrigerator shipped in, and the open baffle is a cutting board that I no longer use.

Now, if you'll excuse me, I'm a little late for my next flight to the moon.

I've been building speakers since 1970 (yikes!), so I understand quite a bit of the basics. I've made ported and sealed systems, transmission lines, and even folded corner horns. This is my first attempt at open baffle, however, so I still need advice from those willing to share it.

I have selected mids and tweets, built preliminary xovers, and right now, I'm testing baffle geometry. Planned shapes and materials to be positively exotic, but not without reason. I'll gladly post more details when I have something useful to contribute.

Peace,
Tom E

[Dennis H]

I think AJ's point is the 1-piece vs. 2-piece baffle doesn't make a heckuva lot of difference. Do whatever is easiest and fits with your other design goals.

[Undefinition]

The geometry of my system makes it logical to break the baffle between the box and the OB.

Then do that. Do what makes sense for the project. I've done OB+bass bin projects a few different ways. I honestly can't say that having the two as one piece or separate makes a sonic difference that I can perceive.

People have built my OB designs both ways, as well. For example...

From Left to Right (my original Aethers, the Aethers as done by a PE board member, the Sunflowers done by a PE board member, my original Sunflowers)

[dlneubec]

Hi Tom,

Welcome to the forum. I'm working on my first open baffle design as well, a 3-way, called the BaSSlines .

It sounds like your design is similar, since I have a ported bass bin with a 1.5" thick baffle and I'm using 1/2" Lexan (backed by hardwood around the drivers) for the Open baffle. I have the open baffle separated for several reasons. One is that I can remove it and it makes the speaker lighter and easier to move, transport, etc. Another is to allow a change of materials for the open baffle, change in baffle sizes, depths, etc. I also wanted to be able to play with different slopes on the baffle and try and achieve a decent time alignment of the drivers. The woofer baffle is sloped 8º, but I did not want to stuck with 8º on the open baffle slope, since that may not be optimum. It is looking like 4º is going to be optimum with my driver mounts and crossover design.

I figured that since my open baffle material would be thin and minimally supported, that separating it from the woofer baffle, could only help reduce potential panel vibrations in the thinner material resulting from the woofer. I plan to install some kind of gasket between the bottom of the open baffle and the woofer baffle, rather than have a space. Will the separate baffle offer a significant inprovement? I don't know, but I don't see any reason not to separate them and I wanted to do it for the other reasons mentioned. Why not go with what has some potential benefit, even if you can't quantify them. I'd say it would be a good idea to have as dead a bass bin as you can as well.

That was my line of thinking anyway.

Good Luck!

[---k---]

Two pieces sure would make them easier to move and transport.


Paul,
I must admit while I had your Sunflowers, I wondered about the attachment of the tweeter/mid to the bass bin. -For those of you who haven't seen them up close, Paul built the top separate from the bottom and uses two small angle brackets and 4 screws to attach the top to the bottom.- Some of us go so crazy with the double thick baffle or even thicker and then there are some crazies who attempt to use marble or whatever. It just seemed like the weak connection could allow vibration of the top.

It probably doesn't have a sonic effect, but it was much less than what I'm used to seeing from the crazies around here and elsewhere on the net. Every time I got done reading the forums, I was tempted to pull the top off and install a felt seal under it and then screw it down with 2x the brackets. Oh that and double up the thicknesses too!

[Paul W]

I've done it both ways, sometimes even separating the tweeter from midrange. I use felt feet on each module, but more to prevent rattles than anything else.

Another advantage of separate modules is the flexibility in experimenting or simply changing your mind about which drivers you want to use. The white guys shown here are just test baffles.

[---k---]

Wow.

[Undefinition]

I must admit while I had your Sunflowers, I wondered about the attachment of the tweeter/mid to the bass bin. -For those of you who haven't seen them up close, Paul built the top separate from the bottom and uses two small angle brackets and 4 screws to attach the top to the bottom.- Some of us go so crazy with the double thick baffle or even thicker and then there are some crazies who attempt to use marble or whatever. It just seemed like the weak connection could allow vibration of the top.

It probably doesn't have a sonic effect, but it was much less than what I'm used to seeing from the crazies around here and elsewhere on the net. Every time I got done reading the forums, I was tempted to pull the top off and install a felt seal under it and then screw it down with 2x the brackets. Oh that and double up the thicknesses too!

The felt and extra brackets are sitting on a shelf in my garage. I bought them with the full intention of using them. But once I mounted the top panel with the pair of brackets and a few screws, I tried knocking things around and testing for durability and was happy. Sonically, what difference could I hear? Suppose I could find out.

I suppose if anyone had an accelerometer they could bring it over and we could see if there was any added benefit to more isolated and/or secure attachment.

Some people put big spikes on their CD player. Some people fill their AV rack with sand and lead shot. Me, I really just want to make some music. When one worries too much about that last 1% of sonic perfection, I am reminded of my old drum teacher who, when people would go on and on about "which equipment was better," he'd reply, "Hey, don't let the instrument play you."

[---k---]

Agreed.

[dlneubec]

I've done it both ways, sometimes even separating the tweeter from midrange. I use felt feet on each module, but more to prevent rattles than anything else.

Another advantage of separate modules is the flexibility in experimenting or simply changing your mind about which drivers you want to use. The white guys shown here are just test baffles.

That looks like a pretty cool project you have going there, Paul! I like the pure white look. You should start a thread and tell us more about it.

A very good point about changing out the baffle for different driver setups, etc. That is a major reason I've done all of my designs in a modular fashion and also why I always make the baffles removable. It gives you a lot more flexibility in the future, without starting over. I also have been doing all my recent xovers with mechanical only connectors, so all crossover components can be easily changed or resused in the future. Who needs solder!

[dlneubec]

The felt and extra brackets are sitting on a shelf in my garage. I bought them with the full intention of using them. But once I mounted the top panel with the pair of brackets and a few screws, I tried knocking things around and testing for durability and was happy. Sonically, what difference could I hear? Suppose I could find out.

I suppose if anyone had an accelerometer they could bring it over and we could see if there was any added benefit to more isolated and/or secure attachment.

Some people put big spikes on their CD player. Some people fill their AV rack with sand and lead shot. Me, I really just want to make some music. When one worries too much about that last 1% of sonic perfection, I am reminded of my old drum teacher who, when people would go on and on about "which equipment was better," he'd reply, "Hey, don't let the instrument play you."

Yes, but still, if you add up enough 1% items, you can perhaps make an audible difference. If not, you can at least be satisfied that you did all you could to make the best speaker.

Of course, time and expereince begins to direct you to which 1% items are worth pursuing and which aren't! :yesnod:

[Paul W]

That looks like a pretty cool project you have going there, Paul! I like the pure white look. You should start a thread and tell us more about it.

No particular project, just learning different drivers. The white finish is semi-gloss latex...with throw-away trays and foam rollers it takes 10 minutes.

White test baffles are allowed in the house when I want to listen for a while. :W

[madisonears]

Excellent response, guys. Thanks to all. I'm getting the message that it probably doesn't make a big difference either way, and that's what I wanted to know. I will mount the OB panel separately because, if it doesn't detract from the sound, the other advantages make it worthwhile.

Guess I better start taking pictures as I make progress. Or revert! That happens sometimes, doesn't it, with DIY?

Peace,
Tom E

[Undefinition]

Of course, time and expereince begins to direct you to which 1% items are worth pursuing and which aren't! :yesnod:

Truer words were never said. And boy, how my "audio priorities" have changed over time!

[AJINFLA]

Hi Tom,

I guess I should apologize for not including "welcome to the forum" in my initial response. You may have missed the smiley at the end . My point has been well explained by the other responses. This part of your post

Are there any other sonic artifacts that will be affected by putting a break between the two baffles?

led me to believe that you were associating audible, rather than ease of construction, dis-assembly, etc. as your criterion for separating the baffles. My response was intended to highlight that there were a lot of other factors that will dominate the sound you attain. Perhaps I did not understand the importance you place on vibrations and their perceived impact ones system. A quick search has enlightened me :W System Strengths
I say you could go either way and still end up with the same great sound, as determined by all the other factors. Please do post any sims and such if you have. They are a lot of experienced eyes here to see them.

cheers,

AJ

[AJINFLA]

Btw, Paul, nice Insignia over the Excel :B
I've got to ask...whaddya think?

cheers,

AJ

[Paul W]

Well, the "I" drivers are back in the boxes...probably until they sell off my estate. :Z

[Undefinition]

The white finish is semi-gloss latex...with throw-away trays and foam rollers it takes 10 minutes.

White test baffles are allowed in the house when I want to listen for a while. :W

Excellent! I'm definitely filing that away in my mental notebook. I love latex paint; such a breeze to work with! I'm always looking for easy ways to hide MDF ugliness until I get bored and want to try a new driver combination (that's like 3 weeks for me :W )

[madisonears]

AJ,

Yes, I understand your response better now. I do believe that vibration, especially in loudspeaker baffles and cabinet walls, but also that transmitted to electronics, can be very detrimental to the clarity and smoothness of a system. So my initial concern is the transmission of vibration from woofers to mids/highs by way of an integral baffle. Of course, the OB upper panel, if separated from the bass baffle, must still be mounted to something, but I think there is a better chance of isolation by making them separate.

I have been experimenting with OB shapes and sizes and different driver orientations. My initial tests used some really crappy paneling that I liberated from someone's trash. The first baffles I made sounded awfully rough. The panels were vibrating like, well, vibrators, even with only two 4" midranges running full range and no woofers attached. That material is discarded, and now, even with just 1/2" plywood (still no woofers), the results are MUCH better, especially in the high frequencies. Sometimes a simple experiment will really clarify basic physical concepts. Vibration: bad. Anyone who claims you can mount drivers on cardboard or some other flimsy material to test baffle shapes is fooling themselves.

So you can make a single baffle for all drivers and take the high mass, crazy thick, monolithic approach to damping vibration. You might even use stiffeners or braces to reduce the moment on the end of that long, skinny slab where the tweeters are located. But then you've got a baffle that's inches thick, and the rear of the midrange radiates into a small cavity formed by the walls of its cutout. Of course, you round off or bevel the corners of the cavity, and now you've got a horn!

My approach is to make the OB portion separate and thinner, then damp and stiffen the panel itself. Now the opening at the back of the midrange will not be a horn, and everything should be pretty stable. I intend to use two thin layers (but different thicknesses) of PVC sheet, with a layer of damping material similar to Dynamat glued between them. The panel will be further stiffened by the "wings" attached to both long sides. The wings are also PVC, but not flat sheet. Rather, I have slit PVC pipe the long way, producing 60 degree sections that will be glued, on-edge, along the length of each side. Using 6" pipe, I now have a three-inch radius on the baffle edges to reduce diffraction, and a very strong stiffener that runs the full length of both sides of a damped baffle.

I'll take pictures.

Peace,
Tom E