[thomasjefferson]

Okay, just to summarize this strategy for the 4-way OB:

The subwoofer crosses to woofers somewhere below 60 Hz.  Woofers cross to mids somewhere above ~150 Hz.  Mids cross to tweeters somewhere above 1500 Hz. 

There are still a million possible ways this could end up!  The next issue to debate would be baffle size.  See Rudolf's commentary about the tradeoffs between more and less baffle.  I've been experimenting with tapered baffle shapes to reduce the size toward the top.  Reducing the baffle (particularly at the midrange) seems to move the sound quality in the right direction.  The effect is also somewhat like the B&W 800 series speakers, which is the "nude" equivalent for a monopole design.  It's basically the reverse of a waveguide, minimizing the cabinet's acoustic shaping of the sound waves.

This can be a challenge aesthetically--it's easier to make a rectangle look subtle and not draw attention (and easier to build).  Then again, a more sculptural shape can be interesting. 

[Danny Richie]

I've been experimenting with tapered baffle shapes to reduce the size toward the top.  Reducing the baffle (particularly at the midrange) seems to move the sound quality in the right direction.

I agree. My testing has shown the exact same thing.

[thomasjefferson]

So long as Danny and I are agreeing on things, here's another thing.  While I have not heard his actual servo OB woofer setup, I do have roughly similar capability and will vouch for how this sounds.  Good, that is, and in surprising ways, really different from a box.  For an Orion owner you already know about that, but there's room to up-size the bass section. 

If you are happy with the character of OB bass including the mild or "dry" bottom octave, then the system can remain 3-way and be fully OB.  One example would be Danny's dual-12" setup.  Another example would be a dual-15" flat baffle (using Acoustic Elegance woofers), which would have a usable range to at least 300 Hz.

Of course there is the tendency for people to first really like the OB bass sound, then start to want more, and begin an arms race.  Using a closed box (or better, an infinite baffle) for the lowest octave (and change) is commonly accepted as a good solution. My current setup is a 4-way using an OB subwoofer (and 3-way OB mains) and that's not quite a recommended solution.  Better to either reconfigure this as 3-way or use a closed box for the deepest bass.

[Danny Richie]

I've done both OB bass with separate sealed sub and all OB bass only (full range) and can really give you some comparisons, but then I'd be talking about stuff that I sell. I'd have to put that comparison in my circle. I'll write something up later tonight if I can. 

[Nyal Mellor]

Yep, the (of course approximate) modeling shows one AE Dipole 12 in a rectangular baffle is sufficient to produce 110dB SPL with a 70Hz XO frequency.

Onto the midrange. Preliminary model shows good XOs to midrange would be 150-200Hz.

[Nyal Mellor]

Maybe a SEAS Nextel 5" for the mid; matches the AE aesthetically and can also do around 110SPL with a 200Hz XO to the AE Dipole 12. I would need to go bigger with the SEAS if I drop the XO to 150Hz...

And then something for the top. Not sure what yet.

[Nyal Mellor]

Yes, the Beyma AMT xo at around 1.5kHz.

Thinking so far:
- AE Dipole 12" running 70-200
- Seas Nextel 5" running 200-1500
- Beyma AMT running 1500+

XO'd to multiple monopole subs at 70Hz. OB drivers mounted to a flat panel baffle, maybe a triangular magician's hat...

[thomasjefferson]

Nyal, you will not get enough output from a single 5" driver as low as 200 Hz.  If you're trying to estimate SPL using x-max, that's not realistic when it would take kilowatts to reach x-max at 200 Hz.  I haven't tried to simulate that but it's just a general rule, you can't move much air with a driver that size.   However, it doesn't necessarily change the concept if you're working with a DEQX, when you can figure this out experimentally.  So long as the woofer is free from cavity resonance (no deep cabinet shape) it can just cross higher to the mid, like 300-350 Hz.

Note that the AE woofers are almost the same price for the 15" as for 12", and the larger ones have a more open basket, higher sensitivity and of course more displacement.  Even when adding a sub it would be advantageous to get the 15", if you can make room for it.

I agree that the silver phase plugs would look good together!  That counts for something.

[Danny Richie]

Nyal, you will not get enough output from a single 5" driver as low as 200 Hz.

I have to once again agree with Mr. Jefferson. I have tried it. That mid is real pricey for what it is, but should be a good sounding mid.

That Beyma really looks interesting. I have not tried it. Just keep in mind that it's tall height will limit vertical dispersion so you will need to stay seated in line with it to listen to it. Stand up and all of the highs will fall out of it.

If you go with an uncontrolled woofer for the bottom end (not servo contoled) then that AE woofer is a good choice. If you limit it to 70Hz and up then one might be just enough.

Late last night I was able to post something in my circle about open baffle verses sealed bass response. I hope it proves to be useful insight. 

[HT cOz]

What about the Beyma used with multiple CSS WR125ST?  How many of the CSS drivers would be needed to get the output to match?

[HT cOz]

What about the Beyma used with multiple CSS WR125ST?  How many of the CSS drivers would be needed to get the output to match?

A few interesting links

http://www.ziogiorgio.com/viewnews.php?id=17368

http://www.diyaudio.com/forums/multi-way/142015-my-open-baffle-dipole-beyma-tpl-150-a.html

[Danny Richie]

What about the Beyma used with multiple CSS WR125ST?  How many of the CSS drivers would be needed to get the output to match?

The problem of using mulitples in series parallel to get the output level up is that your acoustic centers get far apart.

[HT cOz]

The problem of using mulitples in series parallel to get the output level up is that your acoustic centers get far apart.

What about a pair servo mids driven by something like the ClassD Amps with the servo control added to that amp?

or Visaton B200? 

[Nyal Mellor]

I have to once again agree with Mr. Jefferson. I have tried it. That mid is real pricey for what it is, but should be a good sounding mid.

That Beyma really looks interesting. I have not tried it. Just keep in mind that it's tall height will limit vertical dispersion so you will need to stay seated in line with it to listen to it. Stand up and all of the highs will fall out of it.

If you go with an uncontrolled woofer for the bottom end (not servo contoled) then that AE woofer is a good choice. If you limit it to 70Hz and up then one might be just enough.

Late last night I was able to post something in my circle about open baffle verses sealed bass response. I hope it proves to be useful insight.

I admit that I have not tried servo controlled OB but I am not convinced that for low bass reproduction ob is the way to go based on my experience with the Orion.

[lowtech]

Sure, and it's easy to do, and it's [the Orion] a great sounding speaker, but look at the limitations.

You have a mid playing down to its physical limits in that arrangement and at 85db sensitivity it has limited output capability, and very limited dynamics.

This is complete misinformation based on a misunderstanding of the design.  The mid range driver in the Orion is nowhere near being stressed.  In fact, the mid will play louder than either the tweeter or woofer... so please get your facts straight before bashing a product that you do not understand.   

[PDR]

I too was not convinced that the OB servo subs were "All That". When I purchased
my V-1 I was expecting a good bass response, thinking that the "hype" was probably
more than what I was was going to recieve in product. When I first set them up I was stunned.
I couldnt believe the response I was getting, It really has to be heard.
I posted at the start of this thread that you should see if there is someone in your
area that has these to audition, I'll say it again.
Then you can make your own mind up, until then its just heresay and opinion.
If you do get the chance.......let us know what you think 

[HT cOz]

A few interesting links

http://www.ziogiorgio.com/viewnews.php?id=17368

http://www.diyaudio.com/forums/multi-way/142015-my-open-baffle-dipole-beyma-tpl-150-a.html

I read the enite Eric Steg thread at Diy Audio last night and have created a gallery showing his progression of design.

Here is where he finished his project.

[Updated "whats playing now" list:

Drivers (each side)
4x Beyma 21SW1600nd in H-baffle 16-170 Hz
4x Seas W22EX001 170-500 Hz
2x Seas W15CH001 500-1800 Hz
Mundorf AMT 2340 without frontplate 1800 Hz ->

Subwoofer H-baffle outer dimensions are 60x60x112 cm

Amplifiers of my own production, based on ICEpower standard modules:
Tweeter: 60W / 8 ohm
Midranges: 120W / 4 ohm
Woofers: 2x 120 W / 4 ohm (one amp drives two 8" woofers each)
Subwoofers: 4x 1200W / 4 ohm (one amp drives two 21" woofers each)


XO:
Computer software: Console, PLParEQ
Computer audio interface: RME Fireface 800
DAC: Digital Audio Denmark AX24 (8-channels)]

Some of the things that strike me and have been talked about here in this thread is that to get the output he has used many drivers and has massive amounts of OB Subs. 

I can't help but wonder if he could solve the OB bass puzzle by using servo driven OB subs.  It shows what it takes without them.

I am really amazed by Eric's project.











































































Enjoy
Robert

[Danny Richie]

This is complete misinformation based on a misunderstanding of the design.  The mid range driver in the Orion is nowhere near being stressed.  In fact, the mid will play louder than either the tweeter or woofer... so please get your facts straight before bashing a product that you do not understand.   

The context of the discussion involved the original posters idea of using a single mid-range driver with relatively low sensitivity. It will limit SPL levels and dynamics. I used an example that he can relate to as he already owns that speaker, but is now looking to upgrade.

You are absolutely correct though, the whole speaker has limited SPL capabilities and dynamics, and not just the mid.

[HT cOz]

The context of the discussion involved the original posters idea of using a single mid-range driver with relatively low sensitivity. It will limit SPL levels and dynamics. I used an example that he can relate to as he already owns that speaker, but is now looking to upgrade.

You are absolutely correct though, the whole speaker has limited SPL capabilities and dynamics, and not just the mid.

In Eric Steg's design the single 8" didn't play high enough to reach the tweeter and the 5" didn't play low enough to reach the subs.  That is why he landed at using both 5" and 8" drivers.

Danny do you think that by using 2x5" and 4x8" drivers he was adding bandwidth and output to get the sensitivy up?  Somewhere in that thread I remember reading he was still padding down the 99db tweeter by ~7-8db.

What would it take in the midrange to run without padding down a tweeter like that?

I hope we keep this thread on the right track, at some point everyone has to understand nothing is static and everything can be improved, including the Orion...  We all stand on the shoulders of giants!

Kind Regards,
Robert

[lowtech]

You are absolutely correct though, the whole speaker [the Orion] has limited SPL capabilities and dynamics, and not just the mid.

This is yet another unfounded comment based on your misunderstanding of the design.  I'm not sure why you are continuing to bash the speaker given that you have stated to understand the concepts and goals of it.