Beyond the Ariel

[Variac]

To answer the more general question from our gracious moderator, the top driver is going to be about -3 dB at 200 Hz, and the function of the other drivers is to extend the bass down to meet a stereo subwoofer at 60 ~ 80 Hz. A combination of EQ, staggered lowpass filters, and asymmetric panel width is what covers the gap between the subwoofer and the wideband driver.

Am I the gracious mod?

Your paragraph in the quote sounds pretty close from my limited experience with my open baffle mid. Don't be surprised if things come out more in your favor than you expect- that's one of the open baffle charms..

I'm stunned by how many possibly useful ideas our ongoing yap-a-thon has produced. Yes it's time for Lynn to get his lab set up and start living down there! Too many exciting questions to be answered....

[johninCR]

Originally posted by Variac
Is the shelf above the bass drivers required? It seems to be a pretty long ways to the top of the baffle in that location. That's not enough?

I suspect that two 12" drivers will go down lower than 300 hz. Is this a conservative estimate? a calc? or is it about the integration of the bass module?

John in CR has a big advantage here, he has actually done this stuff so should be given careful consideration.

P.S. please don't show more than 4 drivers- it's just too scary!

Thanks Variac,

I learned a tremendous amount in the past year and a half. I was seeing how far I could take a single point source with an OB, so experimentation was the only way due to a distinct lack of info online.

Plugging in Eminence's Beta12CX into Linkwitz's DipoleSPLmax spreadsheet, with a "D" of only 20cm (~7.5"), a single 12 doesn't become excursion limited at 120db until 225hz. However, 120db at only 80hz (too high IMO) would require 4 15's of similar excursion (3.5mm xmax) AND a large "D" of 60cm (a 12" deep U baffle). Now you understand why designers "cheat" by boxing the bass.

Personally, I think 80hz is way too high, because I believe OB bass is a huge benefit in room. It's directionality results in greatly reduced reflections that is perceptively different. Linkwitz calculates this advantage to be +4.8db, making me question whether flat OB bass is even desireable. Whenever I dial in what should be close to flat, it sounds very bass heavy on music with strong LF content, and I back off the shelving EQ.

Note that the numbers I toss out there don't consider placement, or floor reinforcement. The floor cuts it back to 2 15's for 120db at 80hz, plus placement can be used to significant advantage. There's a catch 22 regarding placement. Mids love the breathing room, making the rear wave just ambiance, however, closer placement can reinforce bass, not as boundary reinforcement, but as extra delay for the net rear wave as it travels to the wall and reflects back to combine with the front radiation at the listening position. This is one of the effects that I hope to quantify as part of my measurement regime.

[Lynn Olson]

I might use this as my starting point, and see how much EQ this requires. I've heard the bass Gary Pimm gets from his cardioid/dipole W-boxes - down to 20 Hz with stunning resolution and tonality. This three-speaker setup ought to be able to meet the W-boxes or monopole subwoofers.

It is also simple enough to make a good test bed for the EnABL and Mamboni baffle and speaker-cone edge-termination systems. I'm thinking 18Sound, Radian, or Hemp Acoustics for the 12" wideband coax, possibly something as zany as the 12" Alnico Tone Tubby for the midbass, and a 15" high-Qts bass driver that is yet to be determined. (The new 15" Tone Tubby - who knows? Time to get better and start building!)

[Variac]

Now thats less scary but looks "right" somehow. Beautiful even.

I'm hoping that the coax works out, and the Hemp stuff is the most exciting, but there is another disadvantage to the coax because the "midbass" 12 will have a different response,-even if it is based on the same driver.

If the 12" and "midbass" 12 are exactly the same, then they should integrate better I'd think. But there is the possibility of different models canceling out each other's anomolies also... So either way there are possible pluses. Best to use the same brand though I'd think. At least the cones could then be similar stuff.

Considering the frequencies involved and the area needed, would an 18" be a better choice than the 15? A PA 18 is usually cheaper than two 15" but I don't see them used much. I guess the floor reflection will help here though...forgot about that..

[Lynn Olson]

Originally posted by Variac
Now thats less scary but looks "right" somehow.

I'm hoping that the coax works out, but there is another disadvantage to the coax because the "helper" 12" will have a different response,-even if it is based on the same driver.

If the mid 12" and "helper" 12 are exactly the same, then they should integrate better I'd think. So either way there are pluses.

Considering the frequencies involved and the area needed, would an 18" be a better choice than the 15? A PA 18 is usually cheaper than two 15" but I don't see them used much. Or is this 15" a high excursion sub type as Linkwitz uses?

I'm planning on the midbass and bass driver sharing a steeper 12 dB/octave crossover set to about 1 kHz to prevent mid colorations from sneaking in. The cascade of 6 dB/oct lowpasses for the midbass and bass will control the degree of overlap between the drivers, and allow response shaping without massive EQ from the power amps.

I suspect mildly dissimilar widerange and midbass drivers might be a good thing, actually - remember, all of these drivers are working in the piston band, with intrinsically flat response, so what we're hearing are IM distortion signatures and unusual things like "magnet sound".

As for the bass driver, either a 15 or 18 would work fine. This depends on sonics as far as I can tell. High Q is a must, of course, along with good efficiency to complement the 97 ~ 99 dB/metre drivers upstairs.

[mige0]

Hi

entertaining thread– and lots of input so far!

Thanks to all and special thanks to Lynn for bringing up here the very interesting point of cabinet coloration in an pinpointing and eloquent manner.

I am also on work to overcome this right now – though I am not through with reducing standing waves in closed boxes without the use of damping material. Its just an other attempt to make cabinet coloration "invisible". Every time I loose hope to finally manage to the point where I am confident with the results, I consider to make the step to dipole arrangement.


As for the changes in your route at the bottom end:

When you no longer consider a single low frequency speaker in order to compensate for the 6db roll off by doubling Sd every octave, it may come down to Sd and linear X against price per unit with a reasonable low resonance frequency. I found the Peerless sls 12"
http://www.tymphany.com/datasheet/printview.php?id=38
"http://www.tymphany.com/datasheet/printview.php?id=38"
to be a promising candidate in this respect.
When choosing 3 units, two of them could be placed close to ground one mounted at the side wing and the third one at the front in top of the other. The resulting shift in axis and directivity pattern at low frequencies might be welcome as it may give most certainly smother in-room response and extended flexibility for placing the OB in the room.


As for the changes in your route at the top end:

When looking for a high efficient tweeter instead of a coax driver, why not having a closer look at AMTs? These are not plagued by wear out like normal ribbons every time you over stress them a little bit.
Though not really at a bargain, the Mundorff's
http://www.mundorf.com/english/speak...ssis/index.htm
"http://www.mundorf.com/english/speakerschassis/index.htm"
might look interesting for example. They go up to 108dB, have good CSD, fairly flat FR and directivity may rather be a benefit than an issue for the intended application. Distortion is incredible low, which should fit nicely into a low coloration concept.
I doubt that the dipole feature of these devices can be used. Placing them closely to a potent midrange driver their diaphragm faces twice the pressure as normally, down to the cot off frequency of the mid unit. If possible though, you might want to break up the rear directivity pattern into a more chaotic behaviour. This should be an easy task at that frequencies. The small adjustable wings of BOSE (601?) loudspeakers come into mind immediately.
On the other hand, illuminating the room with rear tweeters might be not that demanding.
SONAB
http://www.carlssonplanet.com/oa14.php
" http://www.carlssonplanet.com/oa14.php"
also did this about three decades ago. In an appropriate environment this speakers created a smashing effect of "being there" at that time. SONAB
simply arranged several paper cone tweeters to fire in all directions at the top of the loudspeaker.
http://www.carlssonplanet.com/picture.php?p=365
" http://www.carlssonplanet.com/picture.php?p=365"

Greetings from the Alps,
Michael.


By the way , it is said that red wine is good for healing broken bones of elderly people - seriously!

[Lynn Olson]

Originally posted by mige0
Hi
When looking for a high efficient tweeter instead of a coax driver, why not having a closer look at AMTs? These are not plagued by wear out like normal ribbons every time you over stress them a little bit.
Though not really at a bargain, the Mundorff's
http://www.mundorf.com/english/speak...ssis/index.htm
"http://www.mundorf.com/english/speakerschassis/index.htm"
might look interesting for example. They go up to 108dB, have good CSD, fairly flat FR and directivity may rather be a benefit than an issue for the intended application. Distortion is incredible low, which should fit nicely into a low coloration concept.
I doubt that the dipole feature of these devices can be used. Placing them closely to a potent midrange driver their diaphragm faces twice the pressure as normally, down to the cot off frequency of the mid unit. If possible though, you might want to break up the rear directivity pattern into a more chaotic behaviour. This should be an easy task at that frequencies. The small adjustable wings of BOSE (601?) loudspeakers come into mind immediately.
On the other hand, illuminating the room with rear tweeters might be not that demanding.
SONAB
http://www.carlssonplanet.com/oa14.php
" http://www.carlssonplanet.com/oa14.php"
also did this about three decades ago. In an appropriate environment this speakers created a smashing effect of "being there" at that time. SONAB
simply arranged several paper cone tweeters to fire in all directions at the top of the loudspeaker.
http://www.carlssonplanet.com/picture.php?p=365
" http://www.carlssonplanet.com/picture.php?p=365"

Greetings from the Alps,
Michael.


By the way , it is said that red wine is good for healing broken bones of elderly people - seriously!

Thanks for the tip - maybe I should start drinking red wine - it would make the time go faster, if nothing else! One of these days I plan to return to Zurich, such a beautiful city, and such a friendly place.

The Mundorf 2530 certainly looks like a good complement to the 18Sound 12NDA520. So many choices! It's nice that we're not limited to the usual suspects from Scan-Speak, Vifa, Dynaudio, and Seas anymore.

I'm afraid to ask the prices from Mundorf, though - just how expensive are these new-generation AMT's? I've heard AMTs sound wonderful - the big problem with the US-made versions was variability, with no two alike, and some later-generation versions with serious FR problems. I imagine the Mundorf versions are very, very good - the specs are certainly better than anything I measured from the US versions. I couldn't find the prices anywhere, though - who distributes these products in the EU or the USA?

P.S. Very interesting article on clock jitter, by the way. This is much more audible than people realize, and part of the reason I'm not a huge fan of casually passing audio through a Behringer digital EQ - it's hard enough to build one good DAC in the system, much less a bunch of cheapo Chinese-made ones.

[planet10]

Originally posted by Lynn Olson
I might use this as my starting point,

The ladder structure at the back doesn't feel right, there must be a more elegant way of achieving the same ends.

dave

[mige0]

Hi

the Mundorf AMTs are available in europ from HIFISOUND
http://www.hifisound.de/oxid/oxid.ph...a1c48.83684768
"http://www.hifisound.de/oxid/oxid.php/sid/x/shp/oxbaseshop/cl/alist/cnid/469431430ea6a1c48.83684768"

or Lautsprechershop
http://www.lautsprechershop.de/hifi/.../baendchen.htm
"http://www.lautsprechershop.de/hifi/index.htm?/hifi/baendchen.htm"

also from Madisound
http://www.madisound.com/cgi-bin/ind....6232&pid=1962


As for the Behringer DCX: they have messed the unit in the analoge part by iferiour capacitors, inferiour layout and inferiour bypassing. Nothing that could not be fixed at low cost if you have time and skills. But there are lots of threads about it somewhere else.

Thanks for your comment on clock jitter! I fully agree.

Greetings
Michael


Yes, drinking red wine stimulates the production of an specific glue for the bones which is in deficency the older we get.

[slowmotion]

Sorry 'bout the long quotes, but I just thought this could be repeated....
I have to agree with panomaniac, to me some of the big hornsystems I've been lucky to hear here in Norway sound more like real music that anything else....

Originally posted by panomaniac


I think that I agree with you there. Because the most neutral, uncolored, realistic systems I have ever heard were horn based. Compared with the very best planars, e.g., Quad ESLs and Magnaplanars, the horns always sounded more like real music to me. All other direct radiating systems sound like speakers to me, as nice as they may be.

When I lived in Paris I was lucky enough to hear, use and live with a number of high end speaker technologies. At the time I also worked in the music business and lived with a cellist . My ears were full of live music every day, all day long. As great as some of the systems I heard were, none sounded more like real music to me than the horns. It was not a matter of nuance, the horns nailed it.

The very big horn systems that we put together at the Kiron Theatre demos (designed by J.Hiraga) were by far the best imaging of any system I've heard before or since. Absolutely no problem with mass choral or strings. In fact, that's where they really shone.

So when I was in the thick of live music every day, all day, the good horn systems were by far the most life-like, the most realistic to my ears. Lack of coloration and dynamic ease where where they stood out. No direct radiator was as good, tho many were still quite wonderful to listen to.

But maybe horn colorations just don't bother me. I certainly did not hear them in those systems. I do hear them in lesser horn systems, i.e., most P.A. systems. Is it a matter of taste, or do we actually hear differently?

Originally posted by Lynn Olson


There's nothing wrong with your hearing, there's nothing wrong with mine, and similarly for Linkwitz and Geddes. People really do hear differently, although the academic community sometimes says otherwise - again, it's very easy to make a study reach a pre-determined conclusion, especially if Philips or Sony are backing it.

My guess is that working with certain types of audio systems sensitizes us to certain faults, just as people who make color prints in a photo studio can see color differences that are invisible to most of us. I know I am very sensitive to stored energy, having battled against it in loudspeakers since 1975. I'm much less critical of IM distortion and high-level compression, an area where horns are dramatically superior to all other systems.

I find the horn coloration gross and immediately obvious, and not a pleasant euphonic one. But I am aware the dynamic compression and IM distortion congestion of direct-radiators (and electrostats) is completely unacceptable to horn enthusiasts. For them, horns are the only way to go.

Originally posted by panomaniac


I have come to believe that. Perhaps it's at the root of so many audio arguments. Some of it is condtioning, some of it innate.

But it's a subject that mertis a whole thread to itself. I'll start one later today.