making my statement monitors open baffle.

[Coconutout]

I want to redo the enclosures for my statement monitors. I was thinking of going open baffle for the mid and the tweet. build a simple box for the woofer with the driver mounted at the very top, and suspend the rest of the drivers above of it with rubber bands and metal rods to make it into a decoupled open baffle; as they're done on diyaudio.com with praised results. this is a rough sketch of the idea.

Image not available

What I'd your input on is, how I can and should make the box. How narrow can I make it? how deep can it be from the back of the driver? should I make it bottom port? front? bass reflex? sorry, this is a lot of asking, I know. I'd appreciate it even if you just directed me to where I can research the answers. thanks.

[ThomasW]

If you want to make 'naked' driver systems (yeap all the rage on DIY Audio... :roll: ) you need to understand how drivers work in free air and what drivers are appropriate for that use....

To that end it should be obvious why a single little TB mid isn't a good candidate for use in a 'naked' system, since Curt's TL approach loads it not only to the baffle but also to the rearwall to increase it's output over the passband

Oh and don't forget you'll need to create an all new crossover for the new design.

[Coconutout]

well to be honest, my statments sounded much better to my inexperienced ears when I had it running without enclosures. the mids and the highs were much more spacious and uncolored which I now recognize to be the benefit of an open baffle design. I was simply wanting to get more taste of it while keeping the bass excursion healthy in a ported box. what aspects would i lose out by going renegade with Mr.Holtz's design? I'd imagine frequency balance and perhaps integration? but for that i'd gain greater dynamics, better room response and less coloration. frankly, I can only see the positives outweighing the neg. obviously I only have enough knowledge for imagining so please educate me further on this. thanks.

[Saurav]

I've tried naked-driver dipoles, and very-small-baffle dipoles. The crossover will probably get very complicated. Do you have measurement and crossover design capabilities? If not, the chances of ending up with anything approaching accurate response are slim. Of course, you may still find the end result very enjoyable.

I'm not sure why you think you'll gain dynamics and lower coloration. A driver which measures relatively flat on a baffle will have a rolled off bass response when run 'nude'. This will require EQ in the crossover to flatten it out again. Also, the driver will require more excursion to reach the same SPL levels, which will generally result in reduced dynamics, because the driver will run out of steam / go into higher distortion sooner.

[Jed]

If you want to make 'naked' driver systems (yeap all the rage on DIY Audio... :roll: ) you need to understand how drivers work in free air and what drivers are appropriate for that use....

To that end it should be obvious why a single little TB mid isn't a good candidate for use in a 'naked' system, since Curt's TL approach loads it not only to the baffle but also to the rearwall to increase it's output over the passband

Oh and don't forget you'll need to create an all new crossover for the new design.

+1... on all points.

I'll add that more than likely the TBW4 will have a rather large peak, if it is "naked," in the upper midrange and roll off drastically in the lower midrange and bass. It will therefore not sum correctly with the woofer with the stock crossover.

[Coconutout]

I assumed(i know.. that's wrong) that since sealed drivers have the least dynamic after the ported ones, open baffle would have the most because it would be free of any air suspension of sealed and resonate on all points instead of just two in a ported enclosure. a flashlight could seem brighter if you take the reflector off, especially in a smaller room, even if the light output is actually lower than it was beaming directionally, because the room is acting as a reflector of a sort. this was my logic behind an open baffle speaker seeming more dynamic sounding. lower coloration because of lack of reflection from the baffle and the transmission tunnel.

I can see how taking the tangband out of the tunnel would result in less 'body' to the midrange due to the lowered bass response but still, my perception was that the midrange actually had more substance and was thicker sounding when i ran the speakers without enclosures this summer when I was building them. the trade off was a less focused imaging. But people also say that pinpoint imaging is unrealistic in live music. Tell me, Sauray, did you find your experiments enjoyable? did you eventually go back to enclosure designs, and if so, why?

[Bear]

I assumed(i know.. that's wrong) that since sealed drivers have the least dynamic after the ported ones, open baffle would have the most because it would be free of any air suspension of sealed and resonate on all points instead of just two in a ported enclosure. a flashlight could seem brighter if you take the reflector off, especially in a smaller room, even if the light output is actually lower than it was beaming directionally, because the room is acting as a reflector of a sort. this was my logic behind an open baffle speaker seeming more dynamic sounding. lower coloration because of lack of reflection from the baffle and the transmission tunnel.

I can see how taking the tangband out of the tunnel would result in less 'body' to the midrange due to the lowered bass response but still, my perception was that the midrange actually had more substance and was thicker sounding when i ran the speakers without enclosures this summer when I was building them. the trade off was a less focused imaging. But people also say that pinpoint imaging is unrealistic in live music. Tell me, Sauray, did you find your experiments enjoyable? did you eventually go back to enclosure designs, and if so, why?

You are confusing science with extreme subjectivism. Your ears are not measurement instruments. They are biological devices that have a really unfortunate property of running through your brain where all sorts of cognitive and emotional processing takes place to arrive at "pleasing". If you want a noisemaker that "sounds good", then go for it. But don't confuse that with "better" from a reproduction standpoint since most people think "better" for a reproduction instrument as being more accurate to the original source material.

As always, he who pays the piper calls the tune, so if you want to go for a completely different design take, it's your time/money. However, it will be a completely different design, even if you take the existing Statements design as a starting point. If you want to bring science back into the design process, you will want measurement gear. You will also probably want design software and the ability to prototype different options without having to have a warehouse full of capacitors and inductors. Somewhere in there, you will realize the truth of the prior posts.

One final thought, drivers are designed with the idea of having an additional air spring to help their existing suspensions (spider and surround). Without that additional spring, your driver will have lower (perhaps radically so) power handling. Be careful you don't overdrive your speaker or else you will also need a warehouse full of spare parts.

[Saurav]

Tell me, Sauray, did you find your experiments enjoyable? did you eventually go back to enclosure designs, and if so, why?

I doubt I'll ever go back to box speakers, except maybe to play with horns again, and I'll probably try that on open baffles too. But it's been a long journey over several years to get to this point, where I feel like I'm just starting to get a handle on what it takes to make a dipole speaker sound OK.

FWIW, my early attempts were close to what you're describing. I put the midrange and tweeter on an open baffle, I cobbled up a crossover based on published measurements since I had no measuring equipment. Did I enjoy it? Of course I did, I'd built it Yes, it was open and spacious and pretty amazing. Was it good? Looking back from where I am now, definitely not. As I've learned more, my system has gotten better, and more enjoyable.

Like the others said, it's your time / money / ears. You will probably end up with something that you enjoy, because we humans are like that. You will probably not end up with something that's accurate or good on an objective scale. And over time, that will usually reveal itself. If you find yourself listening to a small subset of your music collection because the rest of the music sounds like cr@p, that's usually a good sign that something's wrong.

[AdelaaR]

You say you want an "open baffle" statement monitor, but you are mainly opening up the transmission line design of the midrange to be fully open.
You can't "open up" the neocd3.0's unless you take the driver apart.
You will definately need a complete crossover redesign.
I say: bad idea ... "sounds better" is not the same as "has more room reverb".

[---k---]

I know doing this will result in a speaker with a very funky frequency response. But, I've seen many many speakers reviewed by Stereophile that the reviewer loved even though they had a funky frequency response. Not saying either right or wrong, just different.

I agree with the posts above, but I think you should ignore them and build it. Seriously. What's the worse that can happen? You decide you don't like it and put the drivers back in the original enclosure. Oh the tragedy! The earth will not cry out over the wasted wood. No matter what, you'll learn something about how drivers respond and about your tastes.

Because I don't think the results will be good, I would suggest building a test box that can easily be modified. Maybe start with the naked like you are describing, then add a flat baffle, then add wings to the baffle. You should be able to hear how the system responds to each baffle change. Each change should be very audible.

Good luck.

[Bear]

What's the worse that can happen?

Tops on my list: start a fire.

However, I agree that the OP should pursue whatever will make him happy/keep him interested. The learning curve is pretty fun, and I haven't even really started designing my first speaker yet.

[ThomasW]

'Naked' will result in significantly less total output from the driver. So it won't be able to play as loud as the other drivers in the system, and won't play low enough to match up with the woofer.

Download a copy of "The Edge". Put in the driver diameter for the size of the baffle and see what happens to the output

http://www.tolvan.com/edge/

I haven't followed all the 'naked' threads on DIY-A; but IIRC StigEric sits so close to his speakers, (1.8m), he's virtually using the speakers as headphones.



Do you want to sit that close?

[Coconutout]

I tried listening to a mock up build just now. I flipped the enclosure upside down and mounted the tweeter and the midwoofer on top and blocked the tweeter hole on the baffle with tapes and foams. I can see now how this build would've been a bad idea- so glad that I came here for your advises first. the upper frequency of the tangband is way over-accentuated. It's downright un-listen-able just another one of my pipe dreams going bust. seriously though, this wasn't as bad as several years ago when I was swapping car drivers in my floorstanders as an upgrade just because they were better quality drivers xP. I thank you for your inputs, gentlemen. have a good one.

[---k---]

You're going to give up that easily??? :P

[CraigJ]

I haven't followed all the 'naked' threads on DIY-A; but IIRC StigEric sits so close to his speakers, (1.8m), he's virtually using the speakers as headphones.

Do you want to sit that close?

Thomas,

I immediately thought of you when I recently followed up on StigEric's RD75 build. Stig now sits 1.6m from the speakers. Very interesting and easy build.



Did the Statements ever get naked?

Cj