It's possible to lower the crossover quite a bit when you put a dome on a waveguide.
Think about it this way:
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In a conventional speaker, the sound begins to wrap around the baffle around 1400Hz or so. (this assumes a baffle that's 25cm wide.)
When the sound starts to wrap around the baffle, the tweeter is radiating into 360 degrees. So the sensitivity drops like a rock.
Now if you stick it on a waveguide, you're only radiating into a fraction of that. For instance, if you put a dome tweeter on a 90x90 waveguide it's radiating into a space that's 25% as large as if it was mounted on a flat baffle.
That reduction in the radiation angle, that's how you get the big sensitivity increase from horn loading. There's nothing complex here; it's the same amount of energy radiated into a space that's very small. It's the reduction in the beamwidth that yields the increase in sensitivity.
Nowadays, most domes on waveguides look like this. Very small. The soft dome is 'loaded' to a very small extent.
But there's very little stopping you from loading it with a much larger waveguide. And the use of a larger, deeper waveguide allows you to control directivity down to a lower frequency, while also loading the driver down to a lower frequency.
Even a 3/4" dome can get down to 2000Hz, even 1500Hz on a fairly large waveguide.
will you get a huge efficiency increase for say 15 driver??
I was expecting the user would remove the existing waveguide and use/create a much larger waveguide.
-the benefit is that rising response that works to keep average sensitivity up, rather than the typical LARGE drop in pressure as freq.s raise for most dome tweeters in waveguides.
Horns and waveguides increase sensitivity because they constrain the radiation into a narrower beamwidth.
An externally hosted image should be here but it was not working when we last tested it.
For instance if you put a tweeter on a waveguide that's 15" wide, the waveguide constrain the radiation of the tweeter down to 900Hz. (speed of sound / 15" = 900Hz)
Now if you wanted to achieve the same result at 225Hz, you'd need a waveguide that's 60" in diameter. (speed of sound / 60" = 225Hz)
So, theoretically, it WOULD be possible to get a huge efficiency increase for a 15" driver. But nobody goes that route because the size becomes insane. And once the horn/waveguide is no longer effective, you're limited by the xmax of the driver.
IE, you could put a 15" woofer on a horn with a mouth that's larger than a Volkswagen, and the waveguide/horn will still lose directivity control on the low end... And when it does that, it won't be able to generate any more output than a plain ol' sealed box. For instance, a Volkswagen Golf is 14' long. If you put a 15" woofer on a horn that's 14' in diameter, the horn will still lose directivity control at 80Hz. At 40Hz the horn will be capable of the same output as a sealed box!
That's why horn subs are fairly uncommon.
By the way, this post is a dramatic simplification. The horn loading is a product of box volume and horn length, the directivity is based on the diameter of the mouth. There's a bunch of variables at play and the best way to visualize all this is to model it in Hornresp.
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Higher sensitivity above their low frequency cutoff and directivity control. The latter is particularly important; IMHO waveguides are the 'gold standard' for directivity control. While sensitivity isn't of great importance IMHO, maximum output IS important and raising the sensitivity of a device will generally allow you to generate more output.
Directivity control in a small room is just as important as it is in a large room, albeit perhaps for different reasons. In a small room we want to avoid detrimental very early wall reflections and so high directivity is desirable. In a large room we want to direct the sound to the audience so that it is not wasted in the rest of the space. Both are trying to avoid the walls, but perhaps for different reasons.
Thanks, I understand this completely, but no matter the directivity there is no getting away from your environment, its best IMO just to deal with speakers/rooms together, now when i go to the opera I don't hear a directed sound, like horn/waveguided speakers direct sound, so i still really don't see any benefit, with the sever differences in eff from bass to treble how in the hell can you get it to play all together coherently ?
I know music is very subjective but if you so worried about the room why don't you just use hi quality headphones then and be done with it??
That can't be a serious question. Headphones do not in any way sound like loudspeakers.
How much very early lateral reflections one wants really depends on the style of music they listen to. You mentioned opera so I would guess that you value spaciousness over image. Very early reflections will increase spaciousness, but degrade image. I prefer rock solid images as usually appear on studio work. The two venues are vastly different and lend themselves to different approaches.
How much very early lateral reflections one wants really depends on the style of music they listen to. You mentioned opera so I would guess that you value spaciousness over image. Very early reflections will increase spaciousness, but degrade image. I prefer rock solid images as usually appear on studio work. The two venues are vastly different and lend themselves to different approaches.
Thanks again, your conformation is why I have NOT found horn speakers to sound like when you goto the met or opera or college band etc.
The only reason why I asked because It would be nice to use a much higher eff speaker...... and would be use and build better lower power amplifiers, so again for someone like me who listens in a home environment and to good recordings that are not manipulated in a studio there is zero advantages IMO
for studio work headphones would/should be your choice for manipulation
I don't think that mastering is ever done over headphones. I would never use headphones when loudspeakers are available.
I don't think it likely that you have ever heard a good wave-guide. They don't sound like horns, they sound like a good dome tweeter, but with 20 dB more headroom, and better directivity control - to me that is an advantage in any setting.
I don't think it likely that you have ever heard a good wave-guide. They don't sound like horns, they sound like a good dome tweeter, but with 20 dB more headroom, and better directivity control - to me that is an advantage in any setting.
I think directivity control is important when you're listening in a room with walls
Then again, have been thinking about a VERY directive loudspeaker for my backyard, so I can listen to tunes without bugging the neighbors...
Yes Sir you are probably correct, I have never heard what you say proper wave guided speaker, I have heard several hornload speakers and they all have the POINTED sound there is nothing pointed in when listening to an acoustic live event period end of story etc. etc.
BTW my large fulton speakers have 5 tweeters with 25db more headroom
so i can understand what you mean.
where can i hear such a speaker? I am now residing in Surprise AZ area
and ...and you still have not answered my question Sir on how do you match up a woofer for the last octive and half to such a hi eff speaker??
To heck with the neighbors - play on!!
I wish! My HOA would fine me if I left a gum wrapper on the sidewalk. I live in the land of million dollar "starter homes" where your nearest neighbor is six feet away. I can literally hear my neighbor turn on their upstairs faucet, not exaggerating at all. (I live in San Diego.)
I was totally happy with the Summas, I literally had to sell them because I'd need a three million dollar home to do them justice. And I'm not being ostentatious here, $600K won't even buy you a dirt lot.
-you know, I've thought more about this.
I have heard reasonably eff. loudspeakers (not just the tweeter), with the same amplifier clipping problem.
So I'm going to have to make another caveat:
It doesn't just require that the rest of the loudspeaker is substantively more efficient, but rather that ALL of the loudspeaker*s* INCLUDING THE SUBWOOFERS connected to the amplifier are substantively more efficient.
-of course the condition here is your typical HT Receiver with multi-channel internal amp driving all of those loudspeakers AND your subwoofers.
My guess is that the power supply isn't adequate for those output amplifiers at their full rated output spec..
-so really: it's a lowest common denominator situation, and the RESULT really doesn't have anything to do with how efficient the tweeter in your loudspeakers is.
So NO, it doesn't really support your (Earl) argument in the use-cases I was trying to describe.
I always get into flame wars over this, surprised I haven't been banned over at diyma for beating this drum, but I just don't see how efficiency is all that important. I think *displacement* is important because displacement dictates how low a driver can play.
Also, I think that the tweeter is generally the weakest link in a system. Because it must be small in order to play high in frequency, and due to it's small size, it's displacement is limited.
It's similar to the engine in a car, your output is determined by bore and stroke. But in a tweeter your "bore" is limited.
Due to all that, waveguides start to look really compelling. If you understand that output is limited by displacement, then it stands to reason that if you radiate the output of that driver into a beam that 25% as large as a conventional loudspeaker, the sensitivity of the system rises dramatically.
Of course there's a limit to this; I'm not saying that I want to use a tweeter with an efficiency of 70dB. But I might take a tweeter with an efficiency of 90dB over a tweeter with an efficiency of 95dB if the former has a displacement of half a milliliter while the latter has a displacement of half that. It's the same reason I'd use a subwoofer with an efficiency of 85dB and a displacement of half a liter over a sub with an efficiency of 90dB and a displacement of one quarter liter.
These decisions happen a lot in the design of a high output loudspeaker I think. Because the obvious solution is a high efficiency driver. But high efficiency drivers tend to have limited displacement, because the very things that raise their efficiency limit their displacement. IE, you're not going to see a lot of high efficiency drivers with big heavy surrounds and deep motors with lots of xmax. Those things add weight, which lowers efficiency.
Also, I think that the tweeter is generally the weakest link in a system. Because it must be small in order to play high in frequency, and due to it's small size, it's displacement is limited.
It's similar to the engine in a car, your output is determined by bore and stroke. But in a tweeter your "bore" is limited.
Due to all that, waveguides start to look really compelling. If you understand that output is limited by displacement, then it stands to reason that if you radiate the output of that driver into a beam that 25% as large as a conventional loudspeaker, the sensitivity of the system rises dramatically.
Of course there's a limit to this; I'm not saying that I want to use a tweeter with an efficiency of 70dB. But I might take a tweeter with an efficiency of 90dB over a tweeter with an efficiency of 95dB if the former has a displacement of half a milliliter while the latter has a displacement of half that. It's the same reason I'd use a subwoofer with an efficiency of 85dB and a displacement of half a liter over a sub with an efficiency of 90dB and a displacement of one quarter liter.
These decisions happen a lot in the design of a high output loudspeaker I think. Because the obvious solution is a high efficiency driver. But high efficiency drivers tend to have limited displacement, because the very things that raise their efficiency limit their displacement. IE, you're not going to see a lot of high efficiency drivers with big heavy surrounds and deep motors with lots of xmax. Those things add weight, which lowers efficiency.
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I am always happy to answer questions, but I need to be sure of what is being asked, and in this case I am not. IF you are asking how I do the crossover then that's a very valid question but one that might get very technical, and certainly off topic. Designing a high efficiency two-way is nothing like the usual speaker designs around here. Most of the usual "rules-of-thumb" don't apply.
-you know, I've thought more about this.
I have heard reasonably eff. loudspeakers (not just the tweeter), with the same amplifier clipping problem.
So I'm going to have to make another caveat:
It doesn't just require that the rest of the loudspeaker is substantively more efficient, but rather that ALL of the loudspeaker*s* INCLUDING THE SUBWOOFERS connected to the amplifier are substantively more efficient.
-of course the condition here is your typical HT Receiver with multi-channel internal amp driving all of those loudspeakers AND your subwoofers.
My guess is that the power supply isn't adequate for those output amplifiers at their full rated output spec..
-so really: it's a lowest common denominator situation, and the RESULT really doesn't have anything to do with how efficient the tweeter in your loudspeakers is.
So NO, it doesn't really support your (Earl) argument in the use-cases I was trying to describe.
I guess that I am not following your argument. Clipping amps are a sure way to bad sound no matter what speakers one is using. But the more efficient the speakers are, the less likely the amp is to clip. This seems so obvious that I don't believe this is what you meant.
I once spent weeks trying to find out why my speakers sounded harsh on a particular song that I liked. Turns out (after substantial investigation) that the recording itself was clipped and removing the clipping made the problem go away. (This is not always possible, I should note.) Clipping can occur in many places.
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My nephew lives in SD, so I know the price situation. Fortunately the salaries are high and his wife's parents are Chinese billionaires. So they just bought them a 1,000,000$ home as a wedding gift! AT some point I may visit and I'll look you up.