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High Sensitivity Speakers

Helicopter

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Horns, including ones that don't have great crossover design or padding, are often used to reinforce live performances too, so a horn speaker may sound more like an actual live concert, even if it sounds less like actual instruments and voices than something with flatter frequency response. Of course dispersion can also be more like an actual live concert.
 

Sal1950

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I've been a horny guy for decades and decades.
Where's the issue? :p
 

Tim Link

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I'm sitting here listening to my 91" tall horn stacks and pondering the sound. I think the perception of dynamics even at low listening levels is largely caused by room interaction issues due to the directionality of the speaker. Sensitivity or efficiency may just be a surrogate for dispersion characteristics. Anybody know of a low efficiency speaker that's highly directional? Electrostatics! Except they have a back wave, but if they are far enough from the back wall they should still have a dynamic jump effect before reflections come in and reduce the buildup slope. This is the two streams concept. There needs to be enough time delay between the initial sound that reaches the listener from the speaker compared to the onset of reflections that cause sound level to continue to rise, but more slowly. Buildup of sound in the room always sounds "slow." Reverb never sounds dynamic, and if it comes on too soon it muddles up the perceived dynamics of the speaker.

That being said, I don't get the perception of superb dynamics from electrostatics or Magnepans I've heard - except some little desktop Maggies at close range. Those were pretty intense. So maybe a point source works differently than a line or plane source in how it loads up a room. Point sources have better fall off rates, so that's one possibility. My bass horns are stacked up as line sources and I have to admit they don't seem able to produce the punchy, slap you I the face and make you blink kind of bass I have heard from much smaller speakers I once had in a 6.0 surround configuration in the same room. Sitting relatively close to 6 little woofers that were surrounding me produced astoundingly tight and fast bass in that particular situation.

To evaluate the perceived dynamic speed of a system I think we need to consider how the speaker is interacting with the room and how much time we have between the sound immediately rising at the listening and the onset of the slower room buildup. That's my proposition. Immediate thoughts on how to test this - make a super wide dispersion horn system. Maybe add some sideways and backwards facing horns so it's an omni horn. If it sounds just as dynamic at low volume as the directional horn then my theory is weak. Another idea is to make a super low efficiency highly directional horn system. Mass load a compression driver and stuff the horn with foam, and add a load resister to make the amp work harder.

Right now I'm running a JBL2426h on a BL-409 plastic waveguide all the way down to 600Hz with a 1uF cap in series. That puts the 600Hz point 30dB or more down in sensitivity. There's also negative EQ added to extend the top end response. The driver is still super efficient because it's not drawing much current from the amp, but it is definitely not sensitive, as can be seen by the fact that I have the tweeters turned up 11 dB at the pre-amp compared to the woofers, and the woofers also have negative EQ added to them to extend their low frequency response. This doesn't rule out efficiency as a cause of dynamic sound but it does rule out sensitivity because if anything they sound more dynamic to me with their improved directional control and smoother response.
 

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Beershaun

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I'm sitting here listening to my 91" tall horn stacks and pondering the sound.
This is all I can see in my head right now. :p
1620705226818.png
 

Sal1950

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Tim Link

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I take it those wooden pillers were custom made for your room? Very attractive!
Thanks! Yes, my friend who was skilled at woodworking built the cedar grills, a well as the rest of the speakers. I assisted. They originally had a grill cloth which hid the fact from unknowing eyes that the large cabinets in the corners were actually speakers. At some point a plant watering accident soaked one of the grill cloths so I took it off to clean but kind of liked seeing the horns again so I left the cloth off. Now that I've got the plastic waveguide sticking out in front the grill cloth would need a hole cut in it. He made a mistake cutting the pillars too short so we added the transition pieces to the ends. I think it looks a lot better with those than it would have without them.
 

MakeMineVinyl

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Thanks! Yes, my woodworking master friend built those cedar grills for these speakers - which he also built. I assisted. They originally had a grill cloth which hid the fact from unknowing eyes that the large cabinets in the corners were actually speakers. At some point a plant watering accident soaked one of the grill cloths so I took it off to clean but kind of liked seeing the horns again so I left the cloth off. Now that I've got the plastic waveguide sticking out in front the grill cloth would need a hole cut in it.
Are you doing any time alignment between the drivers?
 

Tim Link

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Are you doing any time alignment between the drivers?
Yes, I'm using a modified Behringer crossover to do time alignment. I had hopes with the original coaxial tweeter configuration that with time and level alignment the waves would merge and eliminate diffraction. It didn't really work that way because the areas of the horn mouths didn't even come close to matching. I tried a lot of methods to deal with the diffraction and dispersion issues using absorption but the big waveguide simply works a lot better. At some point I'd like to re-do that mid horn assembly, maybe with one of these new Celestion compression drivers that can run all the way down to 300Hz.
 

Sal1950

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Yes, my friend who was skilled at woodworking built the cedar grills, a well as the rest of the speakers. I assisted.
You guys teamed up into a very talented workworking design pair. I'm extremely jealous of guys that can do that level of work, I have trouble driving a nail straight. LOL
 

Duke

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I'd like to hear those! Here's what I'm looking at :p
View attachment 129113

Very creative the way you get a HUGE round-over for the mouth of your woofer horns by disguising the lips as columns!

I think the perception of dynamics even at low listening levels is largely caused by room interaction issues due to the directionality of the speaker.

I think there is something to this, particularly in a small room where the first reflection path lengths tend to be short. The earliest reflections are the ones which are most likely to perceptually mask the direct sound, so the stronger the direct sound is relative to the early reflections (due to having a narrow radiation pattern for example), the higher the effective in-room "signal to noise" ratio, and therefore the better the dynamic contrast.

You might want to look at Wayne Parham's "Pi" loudspeakers/kits/designs, @S. Ghosh
https://www.pispeakers.com/contents.html
Full disclosure -- I have zero ears-on experience with any of them myself.

I have heard Wayne Parham's 7Pi and 3Pi speakers on multiple occasions at audio shows and in my opinion they are SUPERB. I say this as a competitor - I make conceptually similar designs (big prosound drivers, constant-directivity, pattern-matching in the crossover region). @S. Ghosh, you can build the enclosures yourself or have them built by a local woodworker, which saves many rubles on shipping costs.
 
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What is you opinion on Coherent Audio "15" (Frank employs modified 15” Radian Coaxial driver) loudspeakers, dear experts?:facepalm: With listed sensitivity around 100db they should be relatively easy to drive (not sure about their impedance curve).;)
 

mhardy6647

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Is DIY an option? Back in the day I built some Fostex FE207e transmission lines that sounded great. [email protected], so pretty efficient.
Pair of FE207E here, too -- in BR enclosures, though -- the 207E has a Qts (just barely) high enough to "get away with" BR. :)
These were built by a fellow on Audio Asylum and the Bottlehead fourm, a long, long time ago now. I was beguiled by (with?) them the first time I heard them, and he ulitmately passed them on to me at a very attractive price. The FE207E drivers don't have the tizzy aggressiveness of some of the Fostex "fullrange" drivers IMO and IME.

FE207E
by Mark Hardy, on Flickr
(we provided the cat)

FostexFE207online2
by Mark Hardy, on Flickr
(early days of =my hifi room here in NH -- before all the other [email protected] got moved into it from MA!) :rolleyes:
 

mhardy6647

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I would prefer not to go this route...

What is the name of your tiger? Looks like this one is a true audiophile...
I have my hopes for these Radian-based loudspeakers from Coherent Audio... Anybody has first-hand experience auditioning them, please?
That was Tim (the Timorous Tomcat). He had a good and long life, but passed away in August of 2019.
He and his life partner Zappa (who predeceased him in August 2018) were primary audio troubleshooting tools for the duration of their lives. Of course, they (particularly Zappa) were the cause of some audio troubles themselves -- e.g., pouncing on reel to reel tape as it was playing (Zappa) and occasional propensity to scratch on loudspeaker grilles (both). Generally good kittehs, though. :)

DSC_7921 (2)
by Mark Hardy, on Flickr
(a photo taken fairly late in their lives, showing their excellent form as they practiced for the US Olympic Precision Sleeping Team ;) )

Sorry for the digression!
 
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