What is special about horn loaded drivers?

[Defcon]

I didn't expect so many responses so fast so it'll take me a while to digest all this!

Is 'controlled dispersion' the same thing as 'constant directivity' ? I've read a few of Toole's papers (and his video talk which IMO is a must) and from what I understand from it as well as the Harman research I've read, what I understand is as follows -

- most listeners prefer speakers with good on axis and off axis response. Good off-axis means the bad effects of reflections are minimized
- First order reflections are not necessarily bad due to above for a well designed speaker and will in fact enhance the feeling of spaciousness. This may or may not be a good thing?

The CD speakers send out sound in a narrow beam towards listener, which some say needs extreme toe in, to prevent effects of the room distortion. And since most of these are coupled with a horn/waveguide, it also is much louder.

No my question is - is this considered 'cinema sound' or 'live band sound' simply because these are the speakers used in these venues (due to being loud) so we associate them, or is there anything special with regards to the sound itself? e.g dynamics.

The high efficiency means 'dynamics', i.e. speakers has much more headroom to handle sudden volume changes without distortion. But at home listening volumes, is a traditional speaker any less dynamic? Since its not being played close to its max volume.

 

[Dennis Murphy]

There are a lot of anecdotes flying around here about some experience with X speaker, but what we need to settle this is SCIENCIES! A blind comparison is in order. If all you golden ears can distinguish between a horn-loaded speaker and a non-horned speaker, both of which have a very good and similar response, that will settle this argument.

As for the Ring Cycle, Wagner would most definitely have been a horn guy!

I don't know what Wagner would have listened to, assuming he had any free time and wasn't fleeing creditors, which was how he spent most of his life. But I agree with the rest of your post. I really don't know quite what to make of the various schools of thought. I'm only sure of this much: 1) you don't need controlled dispersion to design an excellent sounding speaker, and you don't need CD to avoid flareups in the off-axis response. You just have to use the right drivers and the right crossover points. 2) Compression drivers with horns are very difficult to design, because most don't sound very good. I've worked with some very expensive samples with excellent reputations, and I could never pull of a design that Jim Salk was willing to use in a model intended mainly for dedicated music listening. However, there probably are successful designs out there. 3) high-quality coaxial designs, like KEF's, can sound excellent. They do have controlled CD because of the coincident mounting of the drivers, but I don't believe the overall dispersion is as limited as many CD designs with wave guides. Finally, and I'm only pretty sure of this, I think many advocates of CD overestimate the role that the delayed, reflected off-axis response plays in our perception of tonal balance. I'm not alone in that belief, and I've performed experiments with one of the measurement functions of Omnimic that show delayed reflections evening out and pretty much following the profile of the response closer to on-axis.

 

[Swerd]

No my question is - is this considered 'cinema sound' or 'live band sound' simply because these are the speakers used in these venues (due to being loud) so we associate them, or is there anything special with regards to the sound itself? e.g dynamics.

I'm not sure I understand what you're asking.

I've heard others say that movie theaters and auditoriums use high sensitivity speakers with horns, therefore they plan to use the same in their basement home theaters. It is wrong to believe that what works in a large auditorium will work the same in a much smaller room.

The high efficiency means 'dynamics', i.e. speakers has much more headroom to handle sudden volume changes without distortion. But at home listening volumes, is a traditional speaker any less dynamic? Since its not being played close to its max volume.

I've also heard people say that speakers with greater sensitivity sound better because the greater headroom handles sudden volume changes without distortion. But they usually ignore the fact that these pro-style speakers start with more audible flaws and distortion than a traditional speaker.

I don't believe this has been properly tested in a blind listening test. Compare two speakers where one has sensitivity of let's say 95 dB and the other has 88 dB. All other things, including the two speakers' overall dynamic range, are equal. If the listening volumes are identical, can people tell any difference? If the listening volumes are not identical, people will tend to notice the louder speaker because louder is interpreted as better. And it may be difficult to adjust those two different types of speakers to the same loudness.

I know what I expect the outcome to be, people will not be able to tell the difference. But I don't know of any such test of this.

 

[TLS Guy]

I have not heard the "Ring Cycle". I assume it has plenty of high frequency sound?

If that's the case, I will agree.

Here you go! Stay with it, it gets better and better.

 

[Defcon]

What I meant was that if you read the reviews of these types of speakers, a common theme is people say that its the 'cinema sound' they were looking for. That has to mean something more than just loudness, right?

 

[Swerd]

The Gedlee Abbey I once heard was at his (Dennis's) house. I had dropped by for a visit, and he played them just to see what my response was. It took me about 3 seconds to say it sounded like someone playing an instrument in a public bathroom with tile floors and walls.

Dennis

When I heard the Gedlee Abbey at your house, you heard the same highly noticeable horn sound that I heard, but you could find no feature in a frequency response curve that could be associated with that horn sound. Can you confirm this? Or am I mis-remembering things?

 

[Swerd]

What I meant was that if you read the reviews of these types of speakers, a common theme is people say that its the 'cinema sound' they were looking for. That has to mean something more than just loudness, right?

OK. When I hear people say they are looking for that 'cinema sound' they usually decide to get speakers like JTR, Danley, or JBL that use the same horn loaded compression drivers and big woofers.

I don't agree with that thinking for the reasons I said above. Perhaps, they had poor sounding speakers at home, and compared to them, the JTRs, etc. sounded much better. There is a lot more going on than just dynamic range and speaker headroom.

 

[Dennis Murphy]

Dennis

When I heard the Gedlee Abbey at your house, you heard the same highly noticeable horn sound that I heard, but you could find no feature in a frequency response curve that could be associated with that horn sound. Can you confirm this? Or am I mis-remembering things?

It actually measures pretty well. The highest frequencies are a little ragged, but nothing that would explain what we heard. I haven't taken any distortion measurements. Also, we only heard one in mono, so we don't know what advantages it might have in terms of imaging with a stereo pair.

 

[ski2xblack]

Finally, and I'm only pretty sure of this, I think many advocates of CD overestimate the role that the delayed, reflected off-axis response plays in our perception of tonal balance. I'm not alone in that belief, and I've performed experiments with one of the measurement functions of Omnimic that show delayed reflections evening out and pretty much following the profile of the response closer to on-axis.

Dennis, thanks for your comment, very informative.

I think this particular observation touches upon something that I'm not sure a solid consensus has actually developed. I recall in Toole's book he noted that listeners tended to fall into distinct groups, and some preferred a more direct sound and less involvement of local acoustics that wide dispersion speakers necessarily result in. Such folks may prefer a near-field arrangement, or speakers with more narrow (but still uniform/smooth) response, in order to get the "more source, less room" response they desire. ??

 

[Swerd]

I think this particular observation touches upon something that I'm not sure a solid consensus has actually developed. I recall in Toole's book he noted that listeners tended to fall into distinct groups, and some preferred a more direct sound and less involvement of local acoustics that wide dispersion speakers necessarily result in. Such folks may prefer a near-field arrangement, or speakers with more narrow (but still uniform/smooth) response, in order to get the "more source, less room" response they desire. ??

This captures the lack of any consensus on the subject. Those who favor more direct sound and those who favor more involvement of reflections both use citations from F.E. Toole as support for their views.

I think the proper scientific term for this division of opinion is "controversial". Leave it at that. It may be time time for the Fat Lady to sing.

TLS Guy – Speaking of Fat Ladies, thanks for the youtube video of Grande Dame in Pink. What is her name? She was enjoyable, even if I don't care for opera.

 

[Floyd Toole]

Hello everybody,
My ears were ringing so somebody has been talking about me . . . well, no, the ringing is tinnitus from too much loud sound over too many years, and I heard about this discussion from Gene DellaSala

Horns. They established themselves as the only practical way to deliver sound to large audiences. Back then 10 watts was a typical power amp. They were very directional - to hit the audience and nothing else, and they sounded dreadful. There really was no waveguide science to guide them and drivers were crummy.

They are still the way to deliver quantities of sound to thousands of people, but now the science has improved. Coverage can be calculated and designed into the horns, and arrays of horns, and with multi-kilowatts of amp power instant deafness can be delivered half way down the auditorium. They now can sound surprisingly good if they are given a chance.

What we hear in auditoriums and cinemas may start with a system with horns in it, but what we hear has been equalized, sometimes to the detriment of good sound. I wrote a paper about that for the Journal of the Audio Engineering Society last year. It is open source so anyone can download it. Go to www.aes.org, click on publications, click on open source and type in Toole. It is free except for the cost of the 30 pages you will print.

Please note the spinorama curves in Figure 20. That is the JBL Pro M2 - with a new style of horn and a new style of compression driver. The curves are superb, the sound is superb, the directivity is wide (120 x 100 deg) because it was designed for control rooms, home theaters, stereo listening rooms, etc. The directivity is very well behaved with the result that the (high resolution, no smoothing) home theater room curve shown at the bottom is without any EQ. The room curves of the same speaker in that room and in cinemas and screening rooms ranging from 24 to 516 seats shown in Figure 19 are also without "room EQ". Above the transition frequency they are very similar.

I lust after having three across the front of my HT, and the L & R in stereo are absolutely killer. In blind tests they are not distinguishable from cone and dome systems - until you turn up the volume. The "ring" would sound just fine. In stereo some music benefits from even wider dispersion - more early reflections in the listening room. That has to do with limitations of stereo itself and with certain styles of recordings. There is no single perfect solution with the industry in its present non-standardized state. For multichannel programs there is much more flexibility because ideally the ambiance is in the recording.

The point: a good speaker is a good speaker, horn or not. Most horns in the past had characteristic sounds - we believe we know why - we needed more science. And please, if you have a truly good loudspeaker, horn or not, don't equalize above the transition frequency. This too is spelled out in that paper.

You may think twice about sound in movies and cinemas after reading it . . . it is a mess.

Now, back to writing the next edition of my book.

Cheers,

Floyd

 

[AcuDefTechGuy]

If all you golden ears can distinguish between a horn-loaded speaker and a non-horned speaker, both of which have a very good and similar response, that will settle this argument.

Oh, hey, there are golden ears who can distinguish among amplifiers and bi-amp vs single-amp (with level matching).

So why not distinguish among all the different drivers?

I am definitely not a golden ear.

 

[AcuDefTechGuy]

What I meant was that if you read the reviews of these types of speakers, a common theme is people say that its the 'cinema sound' they were looking for. That has to mean something more than just loudness, right?

No, it means just loudness.

Not that it's impossible, but I have never heard any cinema sound (THX, Dolby ATMOS, DTS, SDDS, etc.) that sounded better than the best home theater systems I've heard.

So I don't want that "Cinema" sound; I want something that sounds better.

 

[Floyd Toole]

A state-of-the-art home theater is better than any cinema. But a good cinema can still be very good.

Part of the problem in both venues is the unpredictable quality of the soundtracks, which are mixed in x-curve calibrated dubbing stages (HF rolled off, bass insufficient). There is a fundamental incompatibility between cinema sound and the rest of the audio industry - read my paper!

Added to this is the unreliability of the cinema, dubbing stage, calibration process that follows an obsolete and flawed process. Lots of cinemas have been made to sound worse by the calibration process.

If movies don't sound great in your system, don't necessarily blame the system.

 

[Defcon]

No, it means just loudness.

Not that it's impossible, but I have never heard any cinema sound (THX, Dolby ATMOS, DTS, SDDS, etc.) that sounded better than the best home theater systems I've heard.

So I don't want that "Cinema" sound; I want something that sounds better.

But at what cost? The advantage of the 'pro audio' style speakers seems to be high efficiency which means they can be driven to insane volume levels by your normal AVR, no need for amps. I saw a youtube video of a JTR playing near 100dB with a $20 PE amp. And over on AVSforum there are literally hundreds of pages of people raving about how this style of speaker sounds better.

I honestly wanted to find out if this is a better option for HT use and am still not sure - why is audio so subjective when its all based on science? It seems there are contradictory positions on nearly every aspect even from the experts in the field.

 

[Defcon]

I wish I could have JBL M2 as my LCR, from all accounts its the be all end all of speaker design. But I can't.

Also one more point I'd like some clarity on - there's a lot of talk about how 2ch music is so different from HT and requires different guidelines/speaker choices etc. But I don't listen to music in pure direct mode anymore (this is where I should get ready to be called a heretic ), since the music matrixing modes like DPL II etc sound much nicer to me. And with multiple speakers, doesn't dispersion become less of an issue? What happens to soundstage and imaging? I doubt if there are even any proper DBTs conducted on this?

 

[highfigh]

The OP, Defcon, asked a question about horn loaded speakers. It may help to separate his question into two separate questions.

1. What about big loud high sensitivity speakers?
   and
2. What about speakers with limited dispersion, the so-called controlled dispersion speakers?

The answer to #1 is clear. These speakers sacrifice sound quality for quantity. They are good for large auditoriums, but not in homes.

The answer to #2 is, at best, controversial. I fail to understand why it would be better to deliberately limit dispersion.

It might be good to think about the reason directly projecting sound might have begun, which was for public address, not for music. Sure, the old Gramophones had a horn, but there was no electronic amplifier, so it had to be augmented acoustically. The first dynamic loudspeakers weren't very sensitive and they didn't even have a permanent magnet. Go back and look at the first speakers- nobody will accuse them of trying to achieve point source sound or wide bandwidth in a small package.

Since sound propagation follows the inverse square law, especially for a theoretical point source, if maximum use of the energy going to the speaker is to be used effectively, it must be directed to a specific area. Arguably, any sound going to places where the audience isn't located, is wasted. High power amplifiers were rare and expensive at the beginning of audio reproduction and they needed the most bang for the buck.

Fast forward to the modern age of audio and the debate over speaker design is as fragmented as ever. It's possible to build a great speaker, but almost impossible to reach consensus (very similar to Economics, in that regard). Some think the room/acoustics is as important as any other part of the system and some think it matters very little. It's possible to avoid some of the acoustical flaws by limiting SPL- the sound loses enough energy by the time 2nd and 3rd reflections would occur that they're no longer relevant. It's also possible to direct the sound toward the listener, but as some believe, that can't sound good. Others believe the exact opposite. Some believe that speakers should be point source radiators, but wouldn't that require the recording technique to enable that to happen? Pop and other recordings typically use close-micing techniques to capture as much signal as possible, in order (at least in the past) to mask the tape hiss or the sound of the room during the passages that were more moderate in SPL. Now, dynamics in pop music are a thing of the past, people still don't want to deal with the acoustics and speaker designs are all over the map.

Some rooms can't sound good for a wide range of musical genres played at anything more than a whisper while many can sound decent with proper speaker placement, selecting music that works in that room and placing furnishings in places that happen to diffuse or absorb some of the sound. The problem with this is the fact that placing speakers properly means they'll end up in the middle of the space where SWMBO wants the dining table, a sofa, chairs, etc.

 

[Floyd Toole]

Highflgh,

I'm sorry you seem to be so cynical. The situation is not so dire. If you can spare 75 minutes, watch my YouTube lecture:

Yes the debates about loudspeakers - and just about anything else - still exist, but most of the people debating have not taken the time to learn about what has been learned in the past decades. Some of the arguments are obsolete.

But that is human nature, opinions and beliefs prevail.

 

[highfigh]

That is totally contrary to my experience. I made recordings with monitors of my own design over a quarter century or so. I had my speakers in a huge variety of listening rooms, yet I could always trust the monitors and they sounded very similar were ever they were.

Reflections form any room are in general a very good thing, and the more the merrier.

My first level listening room has tons of reflections and a pronounced echoes. The room sounds absolutely wonderful and I enjoy listening in it immensely.

This is an area of audio, where there is far more bunk than fact. What I do know is that there are far too many lousy speakers around, and that is what really generates these discussions.

All I can tell you the better the speaker the less fussy it is about were it is placed.

I will say categorically a finicky speaker is a bad speaker.

I made your comment bold because it needs to be addressed in the context of the music type- YOU don't like, listen to or consider pop music of most styles to have any credibility and that's fine. Orchestral and choral music benefits from reverberation, but not distinct echo. That doesn't apply for the rest of the music that has been recorded, as much as you might not want to admit that it's actually music. You posted photos of the room with the tile floor- it works because of the music you listen to, but also because of the placement of the furniture. A bare room rarely sounds good for much of anything and even the design of a Gothic Cathedral accounted for people being there. The proportions and dimensions are very important to the sound of the space and music was written for the church, the churches weren't designed for the music. A concert hall isn't filled with folding wooden chairs, for a reason- the seats absorb roughly the same amount as a person, so it's less important from an acoustic standpoint whether the house is packed or empty.

I took some equipment to the ballroom I posted about and listened to a fairly wide range of styles/genres and as expected, it sounded OK for anything without sharp transients. When people were speaking, there was absolutely no localization, just sound that was like the Eveready Bunny. When the announcers on the radio station were speaking, I pressed the mute button and it took many seconds for the sound to be unnoticeable. I'll record it when I go back on Saturday. The constantly reflecting sound is annoying.

I know this thread is supposed to be concentrated on horn speakers and their benefits (or lack, thereof) but this leads me to what I believe to be an important question- if the room's acoustics aren't important, why do they spend so much money and effort on the acoustic treatments and sound control in concert halls?

 

[highfigh]

Highflgh,

I'm sorry you seem to be so cynical. The situation is not so dire. If you can spare 75 minutes, watch my YouTube lecture:

Yes the debates about loudspeakers - and just about anything else - still exist, but most of the people debating have not taken the time to learn about what has been learned in the past decades. Some of the arguments are obsolete.

But that is human nature, opinions and beliefs prevail.

I think I have seen that video but in light of the room I'm working with, I'll ask this- how would you deal with reverberation times that exceed 6 seconds? Wood lath & plaster ceiling, plaster on brick over poured concrete basement walls and terazzo floor. I can't imaging why anyone would enjoy listening to music or speech in this room. The home was built in 1917 and this room was called the Ballroom. The front and left wall have a small moulding around the perimeter, the walls in the rear have smaller framed areas and the right wall has a fireplace. Nobody has been able to find photos of the room when the original family was there, but the large area on the two walls make me think they may have hung tapestries or some kind of fabric wall hangings. The reverberation is very even, though. With a room full of people, it wouldn't be as bad.

I have photos, if you're interested in seeing them.