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Multi-Way Conventional loudspeakers with crossovers

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Old 17th June 2007, 04:02 AM   #1071
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Quote:
Originally posted by gedlee
One must close the loop with valid scientific subjective studies to show the level and significance of each and every claim. I do this in my own work as my publications will attest.
Hello,

What type of listening tests have you done to find the audibility of power compression between compression drivers and your direct radiator woofer system? At what levels? Do you find this significant? Why/not?

I ask because I have built quite a few 'hybrids' and all of them seem to fall flat on their face compared to mating the compression driver with a good bass horn. It doesn't really need to be loud to be significant. I have used JBL 2220, 2226, TAD 1601, 1603, EV 15L, 15B, Altec 912B, 416 and 515 as direct radiators crossed electronically to compression drivers in 300 Hz round tractrix horns almost anywhere between 600 and 1500 cycles. The direct radiator bass systems all seem to kill the dynamics compared to a bass horn.

I have not heard your speakers. Do you account for this in your design? How?

Thanks
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Old 17th June 2007, 08:31 AM   #1072
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Hi Scott,

You just wrote;-

>>So when someone comes to a quick conclusion about the sound of something, my first question isn't "can you prove that?" - but rather "whats your experience to make such a conclusion?". <<

I would think it fair to add that there are some who have heard differences in aspects of reproduction and made conclusions about the weaknesses they have heard (or read about in irrefutable reports), who then go on to wrongly apply that same conclusion to all circumstances relating to apparently similar (but not identical) applications, whether their conclusion is directly relevent for all alternative approaches or not.

Some designers take hundreds (thousands?) of hours to create and refine their optimum compromises, often basing new work on prior immeasurable findings which cannot be proved or disproved to have audible consequence until *after* each individual new construction has been fully examined.

Lynn has the hands-on (ears-on) experience to optimise these compromises, and thus I look forwards to reading the outcome of his on-going effort, even though it might not be optimum for me due to the proposed design having a poor signal to WAF-noise ratio!.


Cheers ........... Graham.
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Old 17th June 2007, 08:39 AM   #1073
Variac is offline Variac  United States
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I think things are back on track and if there even was any personal stuff, it is behind us. I also believe that Scottg's posts were intended to be helpful, as have been most of the other posts. I heartily agree that Mr. Geddes could make some useful speaker observations and Mr. Olsen has twice said that he is respects Mr. Geddes' opinion on the speaker issue, which is what we are supposed to be discussing here.

So.... let's drop any amplifier discussion for now, and any discussion of any possible personal issues, and get back to speakers. I'm as eager as the rest of you to keep learning from our amazingly knowledgable members here.

Variac
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Old 17th June 2007, 09:01 AM   #1074
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OK, deep breath, everyone. Visit this site to get turned on and inspired. Karna just showed it to me, and wow, a glimpse of the future! I want one of those - I'll take the personal UFO, too. Just gotta get better so I can enjoy it fully.

Just so we all hear it loud and clear: Earl has done things with horns I've never seen done before. LeCleac'h has done things with horns I've never seen done before. Alexander is taking ribbons in a new direction. Bud Purvine's EnABL is doing things for cones that have not been done before. ScottG, Magnetar, and lots of others in this forum have paid their dues with horns and are generously sharing what they've discovered over many years.

I believe in giving credit for breakthroughs to the people involved, and making their names known. This is personal for me: part of the reason I left Audionics was a decision by management to suppress credit for the work that Bob Sickler and I did. I later found this is common practice in the high-end industry, and the prime reason for the turnover of good, talented people. That's why the industry has such a long, sad record of two steps forward, and two steps back.

OK, my spiritual side is sticking out here, but I feel the Open Source model is essential if we're going to make any forward progress in audio. Mainstream high-end has been spiralling downward to irrelevance and extinction, controlled by the self-appointed gatekeepers of the Big Two review magazines, while genuine innovation is crowded out by slick marketing PR and a decadent boutique esthetic.

The DIY movement is only partly about doing it cheaper, for some of us, it's about breaking out of the CES exhibition -> paid-for-review -> dealership straightjacket. If you know any hifi dealers, they'll tell you they can't afford to sell anything other than magazine-endorsed products, end of story.

I began in hifi in 1973 by working as a commissioned salesman, one of the most degrading jobs I've ever had. I have some sympathy for these guys; it's a brutal business, combining the worst aspects of carrying high inventory costs with a fashion-driven product mix. They just don't have the freedom to take a chance on anything the magazines don't endorse - the buyers by now have become almost totally brainwashed by the inane reviews, and are just looking for "component of the year" at a discount. Very few audiophile buyers even know what a live acoustic concert sounds like; they buy idiotic "audiophile CDs" instead, complete with track-by-track listening instructions, telling them in the liner notes what sound effects to listen for.

Yes, this is a cry from the heart. You read that right. I'm not trying to prove anything here - I just want to get this big dumb beast to move forward again, and pull itself out of the swamp of indifference and decadence. My technique for the last fifteen years has been to tease the reader, draw them out a little bit, and get people to think about things a little differently. Sometimes I slyly put in a little spiritual tidbits, disguising them as I go. Some readers catch the little Easter eggs, while most miss them. That's OK, it's what I intended.

The most effective method has been to actually build the things, rather than write rants like this one. Before I started the Ariel, there was a weird prejudice that transmission-line speakers had to be inefficient. Wrong. Before I started the Amity, Aurora, and Karna, people thought that transformer-coupled amplifiers had high distortion. Wrong.

With this speaker, I want to move into the space between prosound and audiophilia. Not one, not the other. There are a few players there, but not many. The long recovery period from the accident - God, has it been since January 7th? - has been an opportunity to throw the project open to the diyAudio community, who have been nothing less than extremely gracious and hospitable to me.

I thank all of you.

This project is going to get built. By me, and I imagine, by some of the readers following this immense thread. I expect there are going to be many variations, some compact and leaning towards the Linkwitz direction, others going for ultimate dynamics and top-quality prosound horns, and others for new options we have with the RAAL ribbons commissioned for this project, and now available to the DIY community.

I thank all of you. This is your project too.
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Old 17th June 2007, 12:35 PM   #1075
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Lynn, nice commentary!

One thing though, about your Easter Eggs "while most miss them". I doubt you're looking to be engaged on some of your "isms". Besides, I'd be willing to bet that most readers of this thread have been fortunate to see your humor throughout. You are an amazing writer as well. But, don't think what you're saying is being missed.

Back to your project; the crossovers? How do you intend to cross the drivers over? I know that depends upon the final driver choices but you must have at least some framework your working towards? Or are you looking more toward the Bastini's as an exemplar? How are you going to compensate for the baffle losses?
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Old 17th June 2007, 12:59 PM   #1076
fiacono is offline fiacono  Australia
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Hi Tech,

The basic frame work has already been discussed, for example refer to post 940.

regards
Frank
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Old 17th June 2007, 05:39 PM   #1077
Teh is offline Teh  United States
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Thank you!
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Old 17th June 2007, 08:02 PM   #1078
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Quote:
Originally posted by Teh

Back to your project; the crossovers? How do you intend to cross the drivers over? I know that depends upon the final driver choices but you must have at least some framework your working towards? Or are you looking more toward the Bastini's as an exemplar? How are you going to compensate for the baffle losses?
Wait a moment while I do a writer-persona switch <click>, ah, all betta now.

Overall system topology:

1) Servo monopole bass, 60~80 Hz LPF. Rythmiks look like best candidates.

2) Midbass/Bass driver array. Independently powered and equalized for room and response ripples. EQ in the boost direction kept to an absolute minimum. Optional 60~80 Hz HPF, 200~300 Hz LPF. The simplest MB/B array is a single 21" driver; more complex variations are a group of three 12 or 15-inch drivers.

3) Widerange driver. This shares a high-quality amplifier with the tweeter; both use a passive crossover in the 1.2~2 kHz region. The passive WR/tweeter crossover has a design target of 10 degrees or better phase-match in the crossover region. A HPF in the 80~200 Hz region is optional - the degree of overlap with the MB/B array to be determined by measurement and audition.

4) Tweeter. Either an advanced-profile horn+CD with the best-possible impulse response and very low distortion in the 1~5 kHz region, a new-generation AMT from Beyma or Mundorf, or the new RAAL double-ribbon tweeter. Passive HPF in the 1.2~2 kHz region.

Although I'll probably use a Behringer or similar utility-grade digital crossover/EQ for the rough setup and measurement, I plan to use a passive crossover for the WR/Tweeter crossover in the finished system. The requirement for room EQ in the MB/B region implies that separate amplification and EQ (digital or otherwise) is desirable.
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Old 17th June 2007, 08:41 PM   #1079
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How many bands of overlaping parametric EQs do you think we need for each channel of the midbass/bass?

I have some vintage Rane parametric EQs with 3 bands for each channel. I think that should be enough. But maybe not and I need to start bidding on some Klark Teknik 5 band EQs.
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Old 17th June 2007, 09:16 PM   #1080
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The main design goal is a high-dynamic-range system that is dipole over most of the audio range. The biggest challenge will be system coherence, something designers of 3 to 4-way horn systems have to struggle with.

There is a reasonable chance the dipole-to-horn transition will be a little easier than it is with a conventional monopole-to-horn transition, which goes all the way from omnidirectional (in the bass) to the 90-degree conical radiation pattern of the horn.

The 15" + horn combination goes all the way back to the 1937 Bell Labs Iconic. The Iconic has a distinguished history, but we don't need to keep copying the format of a seventy-year-old design.

A dipole radiation pattern is similar to a pair of 90-degree conical patterns placed back-to-back. If we use a reverse-phase rear horn, well, the difference between the two becomes even smaller. We're no longer talking about the latest iteration of an Iconic any more.

Managing the radiation pattern of the Midbass/Bass array will need attention, although not as difficult as the WR/tweeter, since the MB/B array works at much lower frequencies - and in a range where the radiation pattern merges with the room characteristics. The things to watch for are the driver-to-driver phase angles and the radiation pattern in the 80 to 500 Hz region.

As mentioned earlier, the simplest - and most compact - way to realize the MB/B is a single 21" driver. The biggest drawback of the 21" is poor response above 200 Hz, since these are designed as subwoofers, not woofers, and certainly not midbass drivers. This implies a steeper slope for the LPF for the 21", making integration with the WR driver a bit more challenging, not to mention side issues of different driver colorations.

My esthetic favorite is the quad array of 12" drivers - one for WR, one for MB, and two for Bass. These can be mixed-n-matched for best integration driver-to-driver and well-behaved rolloffs at higher frequencies. If BudP's EnABL does the wonders for these that it does for the Lowther, that's going to make things easier all around.

As for the 20~80 Hz range, it's a choice between EQ'ed vs servo subwoofers. In this frequency range, where excursion distortion dominates, I think servo is the easy and obvious choice. Considering the depth of engineering that goes into the Rythmiks, the choice is even more obvious.
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