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Old 3rd April 2008, 05:56 PM   #3281
Anglo is offline Anglo  Canada
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Thanks rob. Very much appreciated!

I would love to respond to you in detail but it is thread farting Lynn's incredible thread. I don't see where Lynn has any concern in this thread regarding beaming.

I should begin a new thread regarding beaming from a 15" wideband.

Thanks
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Old 4th April 2008, 01:11 AM   #3282
CLS is offline CLS  Taiwan
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Quote:
Originally posted by Lynn Olson
....

So front-horn Lowthers still sound like direct-radiator Lowthers, only spatially bigger, louder and with more headroom - and the potential for additional horn coloration.
....

I think the horns not only make raw drivers <spatially bigger, louder and with more headroom>, but also alter the response shape, thus tonal balance. Especially on such wide range ones.

I've heard Lowther PM4 in Oris150 horn, it's much warmer and fuller in midrange to upper bass related to the driver itself. It's because the horn loads the midrange far better than high.

For people who are not sensitive to (or familiar with) phase and breakup problems, the change on tonal balance alone improves the overall presentation alot. Of couse this can be done with EQ, but do it accoustically has some other significant benefits.
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Old 4th April 2008, 01:34 AM   #3283
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I think we are all addressing different aspects of "beaming", and like the fabled Indian Wise Men describing the elephant, are using different words to describe the same thing.

The apparent size of the radiator, I submit, is directly audible as a sense of "bigness" - entirely apart from considerations like diffraction, re-reflection, diaphragm breakup, baffle size, etc. etc. In short, big drivers sound big, and horns with large mouth areas sound big as well. Little drivers, well, sound small. A Celestion SL600 is never going to sound "big" in the same way an Altec 515 or 340 Hz horn is going to sound big.

This isn't so much an aspect of image size, but more an aspect of "impact", or weight, when reproducing physically large instruments like a concert grand piano, a set of tympanis, a cello - or a Marshall stack! The real thing sounds big and has a sense of weight and scale to it, most notably when played softly. Loudspeakers with physically large emissive areas (granting that other aspects of the design are carried out successfully) can reproduce instruments like this more successfully than physically smaller loudspeaker with smaller emissive areas.

The real trick is getting physically large diaphragms to have the same kind of rapid time decay that is so easy with small diaphragms. Newell and Dr. Holland recommend time decays (in the midrange) be shorter than 800 microseconds, and I agree. This stretches horn/waveguide design to the outer limits of what can done today, but it can be done if care is taken to minimize diffraction in the whole system.

There's no free lunch here, and a large diaphragm off-axis will have degraded time response simply due to different arrival times from the left and right edges of the diaphragm - this happens with a perfect, non-energy-storing diaphragm, and is much worse with real-world diaphragms that go into modes on different parts of the emissive surface. With real diaphragms, in fact, the time response with quickest decay will probably be slightly off-axis, anywhere from 5 to 15 degrees.

I would submit that loudspeaker design is a trade-off between the desire to convey precision and spatial resolution (the domain of small radiators) and the desire to convey impact, scale, and power (the domain of large radiators). This is a separate matter from removing this or that coloration, source of distortion, control of polar pattern, etc. etc. Even after all those matters are brought under control, the speaker system will have an overall character - a sense of scale, presence, or physicality, and this has a direct relationship to the emissive area of the drivers (or the effective mouth area of the horn/waveguide).

P.S. ... JMMLC, you mentioned some favorite 2"-exit compression drivers. What about 1.4" or 1.5" exit compression drivers - where does the Altec 288 fit in this picture, compared to TAD, JBL, or collectibles like the Vitavox S2?
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Old 4th April 2008, 11:26 AM   #3284
Anglo is offline Anglo  Canada
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Hi,



>This isn't so much an aspect of image size, but more an aspect of "impact", or weight, when reproducing physically large instruments like a concert grand piano, a set of tympanis, a cello - or a Marshall stack! The real thing sounds big and has a sense of weight and scale to it, most notably when played softly. Loudspeakers with physically large emissive areas (granting that other aspects of the design are carried out successfully) can reproduce instruments like this more successfully than physically smaller loudspeaker with smaller emissive areas<

I have been talking about the "weight" factor that a 15" wideband driver gives to instruments for a few years now, for me it was a revelation compared to the "HIFI" trend of today. Hence probably why I enjoy Vintage drivers such as EV and Altec with the 515B. To me, I will live with the beaming, because it isn't that bothersome to me. I don't really walk around my room when I am listening. I know however that is I crossed my tweeter lower,towards the 1K area, and inturn cut the EV, that beaming would be much better. I would be halogen! I couldn't live with a ribbon tweeter to have better specs. Am I wrong, will I see the light one day---maybe!

How are you going to address the beaming issue Lynn? From what I have read you are basicaaly going to have a 15" driver, right?

Thanks,
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Old 4th April 2008, 11:40 AM   #3285
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Quote:
Originally posted by Lynn Olson
I think we are all addressing different aspects of "beaming", and like the fabled Indian Wise Men describing the elephant, are using different words to describe the same thing.

The apparent size of the radiator, I submit, is directly audible as a sense of "bigness" - entirely apart from considerations like diffraction, re-reflection, diaphragm breakup, baffle size, etc. etc. In short, big drivers sound big, and horns with large mouth areas sound big as well. Little drivers, well, sound small. A Celestion SL600 is never going to sound "big" in the same way an Altec 515 or 340 Hz horn is going to sound big.

This isn't so much an aspect of image size, but more an aspect of "impact", or weight, when reproducing physically large instruments like a concert grand piano, a set of tympanis, a cello - or a Marshall stack! The real thing sounds big and has a sense of weight and scale to it, most notably when played softly. Loudspeakers with physically large emissive areas (granting that other aspects of the design are carried out successfully) can reproduce instruments like this more successfully than physically smaller loudspeaker with smaller emissive areas.

The real trick is getting physically large diaphragms to have the same kind of rapid time decay that is so easy with small diaphragms. Newell and Dr. Holland recommend time decays (in the midrange) be shorter than 800 microseconds, and I agree. This stretches horn/waveguide design to the outer limits of what can done today, but it can be done if care is taken to minimize diffraction in the whole system.

There's no free lunch here, and a large diaphragm off-axis will have degraded time response simply due to different arrival times from the left and right edges of the diaphragm - this happens with a perfect, non-energy-storing diaphragm, and is much worse with real-world diaphragms that go into modes on different parts of the emissive surface. With real diaphragms, in fact, the time response with quickest decay will probably be slightly off-axis, anywhere from 5 to 15 degrees.

I would submit that loudspeaker design is a trade-off between the desire to convey precision and spatial resolution (the domain of small radiators) and the desire to convey impact, scale, and power (the domain of large radiators). This is a separate matter from removing this or that coloration, source of distortion, control of polar pattern, etc. etc. Even after all those matters are brought under control, the speaker system will have an overall character - a sense of scale, presence, or physicality, and this has a direct relationship to the emissive area of the drivers (or the effective mouth area of the horn/waveguide).

P.S. ... JMMLC, you mentioned some favorite 2"-exit compression drivers. What about 1.4" or 1.5" exit compression drivers - where does the Altec 288 fit in this picture, compared to TAD, JBL, or collectibles like the Vitavox S2?

Well, most 'big' narrow midrange horns (round horns) too me sound small unless you listen like 20 feet away. The smaller horns sound 'bigger' or more open and natural when you are closer then that. If you are referring to the response going lower that's true but up close it means (with the big round horns) you get the sensation of being pinned against the wall behind you. Different - mind blowing- but is this really exceptable for the long run?

Do you have your OB bass system up and running? If you do you should find this 'biggness' and weight or 'meat on the bones' with dense tonal texture is already present without unnatural beaming - in fact it should sound the opposite or what I keep describing as 'free' (for lack of a better word) What I mean by this is you shouldn't have to compromise much in beaming with the driver above the bass because you'll probably find the bass system or upper bass coupling system should be good to gorgeous to about around 800 to 1K. That is the range of the pure tonally density and power.

I'll sign out of this for a while bye
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Old 4th April 2008, 01:40 PM   #3286
Anglo is offline Anglo  Canada
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>If you do you should find this 'biggness' and weight or 'meat on the bones' with dense tonal texture is already present without unnatural beaming - in fact it should sound the opposite or what I keep describing as 'free' (for lack of a better word) What I mean by this is you shouldn't have to compromise much in beaming with the driver above the bass because you'll probably find the bass system or upper bass coupling system should be good to gorgeous to about around 800 to 1K. That is the range of the pure tonally density and power.<

So, now we are entering my thoughts on the "weight" factor or "tone density" of the 15" wideband driver. You feel that this weight issue comes from the lower mid range of the driver. I have been back and forth and around on this one, but when I cut my tweeter at 1 Khz, I hear the lack of presence and the signature of a ribbon. When I cut above 5Khz, the signauture is still there but much less and cover the area of resolutrion really well, which IMO the ribbon tweeter is a reference.

I haven't solved my beaming issue though, this is why I am curious to read Lynn's response on his taming or lack of taming of the beaming issue.
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Old 4th April 2008, 08:29 PM   #3287
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Anglo, I feel that the 'weight' and 'bigness' you're talking about is from easy volume displacement. Magnetar's 6x10 array will move a lot of air with little excursion, therefore lower distortion and will not sound strained beacuse of it. Similarly with your 15, at least compared to typical small 'phile drivers.

Quote:
Originally posted by Anglo
I haven't solved my beaming issue though
Try crossing to a good 10 or 8 in the midbass and then to your HF combination where the directivities match.
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Old 4th April 2008, 08:38 PM   #3288
badman is offline badman  United States
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Not to mention, bigger coils, more efficient drivers, better power handling. Less compression!
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Old 4th April 2008, 08:43 PM   #3289
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Quote:
Originally posted by badman
Not to mention, bigger coils, more efficient drivers, better power handling. Less compression!
Absolutely! Now if I can just get those 4 BMS 18's I want (soon, soon), I'll be a happy camper.
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Old 5th April 2008, 12:05 AM   #3290
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Quote:
Originally posted by Magnetar


Well, most 'big' narrow midrange horns (round horns) too me sound small unless you listen like 20 feet away. The smaller horns sound 'bigger' or more open and natural when you are closer then that. If you are referring to the response going lower that's true but up close it means (with the big round horns) you get the sensation of being pinned against the wall behind you. Different - mind blowing- but is this really exceptable for the long run?

Maybe it sounds a little a wishy-washy, but I'm agreement with all of the recent posts.

The horns I've heard around here (Denver area) were all AH-204's (or similar Tractrix horns) with 7" or 5" Lowthers. Spectacular, bigger-than-life sound, but extremely narrow sweet spot, no more than a few inches across, and not a whole lot of depth presentation. But that's a large throat size combined with the notorious Lowther whizzer, which can never work properly in any kind of horn - but does generate lots of High-Order-Modes, or multipath reflections.

Strictly speaking, if the big Lowther horns are to operate according to any kind of horn theory, the whizzer should be removed and the upper limit set to no more than 2~3 kHz, based on classical criteria of wavelength size in the throat and avoiding the first cone breakup. A Lowther-driven 204 is really an upper-bass/lower-mid horn, not a full-range device. Of course, once you remove the whizzer and limit the upper bandwidth to 2~3 kHz, that begs the question of using a Lowther at all, instead of a professional high-efficiency cone midrange like the Audax, 18Sound, JBL, or many others.

Anglo, the 12" Bastanis Apollo driver widerange driver I liked so much at the RMAF had a lot of beaming, and didn't sound good on-axis at all. It had to be rotated about 30 degrees off-axis to sound flat, and that's how Rob Bastanis demo'ed them, with the speaker facing straight forward, and the listener subtending about a 30-degree angle from the centerline of the listening triangle. If you listened to them on-axis, the upper-mids were way too hot, and tweeter integration was problematic. Off-axis, everything smoothed out pretty well, and tweeter integration improved.

The beaming didn't affect the depth presentation - which was very good, much better than most horns - but it did limit the listening area and restricted the lateral soundstage/ambient presentation. So no free lunch.

The real question is the presentation of the 340 vs 550 horns with a large-format compression driver, and how this choice affects the crossover with a pair of 12" drivers. Since this is looking a lot like one of those subjective calls, I may just order both sizes and see if Martin can ship them all in the same box. I'd rather the money goes to Martin than the shipping companies.

P.S. Less than 2 hours to the Season Four opener of Battlestar Galactica! Time to warm up the DVR and TV set!
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