Why do horn loaded tweeters resolve more detail than conventional domes?

[shadyJ]

Don't really care what they use, their RP series is very accurate, has great imaging, and is very efficient. Their efficiency specs are much more accurate now as well. I have a pair of reference II speakers and their new lower model reference series, same size, same efficiency rating, but the newer model is about 3dB louder. I do believe their tech specs list it as a compression driver, not sure if it actually is or not. The specs on my R-15ms list a 1" driver, yet the throat of the horn only measures about 5/16", so obviously the driver is larger than the opening, which is typical of a compression driver.

Either way, klipsch has managed to work out most of the flaws that came with their old reference models, no harshness, much wider imaging across the entire frequency range etc. Its all about compromise I guess. For me, high SPL, hair trigger dynamics, and low distortion are my main priority. Obviously accuracy is important as well, but the new series is accurate.

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Sensitivity specs are a tricky thing to gauge, so you don't want to assume that the new model is actually more sensitive or efficient. The tests needed to determine that may be more precise than most people would guess. Not that Klipsch speakers are going to present a problem with sensitivity, but I still wouldn't trust their specs. For example, the RP-160M obviously is not going to be 96 dB at 1 meter for 2.83v as Klipsch claims in their specs, at least in an anechoic setting. I wouldn't be surprised if the newer RP speakers actually took a small hit in sensitivity due to the wider-angle horn. Still, they can stay clean at louder level than most people would ever listen to them. I would love to get my hands on one of the new RP speakers to see how they test, but I am more interested in their dispersion than their sensitivity.

 

[ski2xblack]

TLSguy is cracking me up tonight! Bringing facts to a feelings fight.

Yeah, I fail to see how a link to a replacement part, from an independent speaker repair shop that has no affiliation with Klipsch whatsoever, for an item that is different than any compression driver diaphragm Klipsch has ever used, somehow supports TLS' claim that Klipsch no longer uses compression drivers. The part he linked is a replacement diaphragm for, wait for it, compression drivers! A cursory check of their website indicates Klipsch still uses compression drivers as well.

It seems that TLS is the one bringing his feelings to the fact fight by engaging in such specious reasoning.

And nothing against Simply Speakers, they're nice folks.

 

[highfigh]

The ones I have have aluminum compression drivers, and they're new. Never seen a klipsch with soft dome tweeters.

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The older Heresy mid and tweeter diaphragms are doped cloth- haven't replaced one on a newer one, but the frequency response shown in the specs is broader than before, so I suspect they changed this to a different material or changed the test procedure. The original spec showed the upper limit as 16KHz and when I replaced a pair of diaphragms a few years ago, they sounded (and the RTA test showed) that they were hitting every bit of that range, and not more. Sounded OK for some music (limited frequency range), but for anything with content above the limit, they sounded the way they always do.

This is another one from Simply speakers and it looks the same as the OEM part which I can't show here because I finally tossed the old ones.

http://www.simplyspeakers.com/klipsch-replacement-speaker-diaphragm-k77-89486a.html?gdffi=34b62c7eac6d4867958a4d919b5d6929&gdfms=4496D16949254B3A8BD7D76EF7573B25&gclid=CjwKEAjwja_JBRD8idHpxaz0t3wSJAB4rXW5y1j9kg32CGgXUdsuJhgzVbnNMgQa625CH__0Sc4SvhoC26Xw_wcB

 

[highfigh]

Sensitivity specs are a tricky thing to gauge, so you don't want to assume that the new model is actually more sensitive or efficient. The tests needed to determine that may be more precise than most people would guess. Not that Klipsch speakers are going to present a problem with sensitivity, but I still wouldn't trust their specs. For example, the RP-160M obviously is not going to be 96 dB at 1 meter for 2.83v as Klipsch claims in their specs, at least in an anechoic setting. I wouldn't be surprised if the newer RP speakers actually took a small hit in sensitivity due to the wider-angle horn. Still, they can stay clean at louder level than most people would ever listen to them. I would love to get my hands on one of the new RP speakers to see how they test, but I am more interested in their dispersion than their sensitivity.

Why can't they hit 96dB? I have Vifa and Peerless tweeters that are rated in the 93-94dB range and since sensitivity is the result of the coil winding and magnetic flux, it's not hard to make a speaker produce more with a specific voltage. The hard part is making it sound good.

 

[highfigh]

umm..a Vifar tweeter I do believe would give a horn a run for its money...not the cheap knock off ones subjectively speaking.

But domes and horns aren't even designed for the same purpose- horns are supposed to cover a specific area and domes are made for wide, even dispersion. Horns are sensitive and Paul Klipsch wanted sensitivity. One of the quotes attributed to him is "Take my speakers and a good 5W amplifier- what more could anyone want?".

 

[highfigh]

Yeah, I fail to see how a link to a replacement part, from an independent speaker repair shop that has no affiliation with Klipsch whatsoever, for an item that is different than any compression driver diaphragm Klipsch has ever used, somehow supports TLS' claim that Klipsch no longer uses compression drivers. The part he linked is a replacement diaphragm for, wait for it, compression drivers! A cursory check of their website indicates Klipsch still uses compression drivers as well.

It seems that TLS is the one bringing his feelings to the fact fight by engaging in such specious reasoning.

And nothing against Simply Speakers, they're nice folks.

A horn on a dome tweeter isn't a compression driver, it's a tweeter with a horn. Compression drivers usually have a compression chamber, which increases the output through altering the acoustic 'connection' to the air, as mentioned in the explanation on the Klipsch site. The diaphragm material isn't important WRT the definition and the parts from Simply Speakers are made to be direct replacements for the OEM.

http://www.klipsch.com/blog/how-do-horn-loaded-speakers-work

 

[shadyJ]

Why can't they hit 96dB? I have Vifa and Peerless tweeters that are rated in the 93-94dB range and since sensitivity is the result of the coil winding and magnetic flux, it's not hard to make a speaker produce more with a specific voltage. The hard part is making it sound good.

There are more factors to sensitivity than coil windings and magnetic flux. There is the mass of the moving parts, the amount of air resistance is the acoustic impedance, there is resonant frequencies, electric, mechanical, and speaker wide. Cabinet design plays a part. Crossover design plays a part, and there is always loss in a passive crossover. There is electrical resistance of the coil, not to mention inductance of the motor. Stiffness of the suspension. Everything will affect sensitivity. And no way is that speaker even close to 96 dB for 2.83v at 1 meter anechoically, I guarantee you.

 

[TheWarrior]

Yeah, I fail to see how a link to a replacement part, from an independent speaker repair shop that has no affiliation with Klipsch whatsoever, for an item that is different than any compression driver diaphragm Klipsch has ever used, somehow supports TLS' claim that Klipsch no longer uses compression drivers. The part he linked is a replacement diaphragm for, wait for it, compression drivers! A cursory check of their website indicates Klipsch still uses compression drivers as well.

It seems that TLS is the one bringing his feelings to the fact fight by engaging in such specious reasoning.

And nothing against Simply Speakers, they're nice folks.

A cursory glance? The website even states 'titanium tweeter' under their top RP280 system. As already stated a dome tweeter with a horn is a far cry from a compression driver.

My comment about TLSGuy referenced a number of comments he had made that day. But I clearly chose the correct thread in which to thank him!

 

[TLS Guy]

I think it is time to define terms.

These are essential elements of horns: -

A vibrating diaphragm.

A high impedance expansion chamber.

A throat.

These elements greatly increase the acoustic impedance the driver sees.

After the throat there is non linear expansion. The may be exponential, parabolic, tractrix, and other geometric forms.

The essential object is to optimally match the diaphragm to the acoustic space, to greatly increase efficiency.

This is best seen in a bass horn.

This is the anatomy of a compression driver for mating to flared horn.

This shows the diaphragm, high impedance expansion chamber and throat.

A dome with flared guide in front of it does not fit the definition of a horn.

Now as I often point out, a vibrating cone couples less and less effectively to the air in a room the lower the frequency. That is why a sealed sub is in essence a dreadful idea.

The benefits if horn loading become greater the lower the frequency.

Now there is often loose talk, in that loudspeaker pipes are often referred to as horns, especially quarter wave pipes. This is just plain wrong.

The physics of pipes and horns are very different. For one thing the frequency radiated by a pipe is determined more then anything else by its length.

The low frequency radiated by a horn is largely determined by the dimensions of the mouth.

Musical instruments have examples of both. A French horn is a horn. A flute is a pipe.

Unfortunately woolly thinking abounds in the area of loudspeaker discussion, which is a severe problem. Instrument makers however, I'm certain are quite clear as to whether they are building a horn or a pipe. Loudspeaker designers should be as well. Unfortunately I'm pretty certain they often are not.

 

[yepimonfire]

Sensitivity specs are a tricky thing to gauge, so you don't want to assume that the new model is actually more sensitive or efficient. The tests needed to determine that may be more precise than most people would guess. Not that Klipsch speakers are going to present a problem with sensitivity, but I still wouldn't trust their specs. For example, the RP-160M obviously is not going to be 96 dB at 1 meter for 2.83v as Klipsch claims in their specs, at least in an anechoic setting. I wouldn't be surprised if the newer RP speakers actually took a small hit in sensitivity due to the wider-angle horn. Still, they can stay clean at louder level than most people would ever listen to them. I would love to get my hands on one of the new RP speakers to see how they test, but I am more interested in their dispersion than their sensitivity.

It is when compared to their old models. Klipsch does not derive their sensitivity ratings anechoicly, but in a reverberant field similar to an average room. Will klipsch speakers play much much louder than other conventional speakers with the same power? Yup. That's good enough for me.

Why can't they hit 96dB? I have Vifa and Peerless tweeters that are rated in the 93-94dB range and since sensitivity is the result of the coil winding and magnetic flux, it's not hard to make a speaker produce more with a specific voltage. The hard part is making it sound good.

While the horn assembly is likely extremely efficient, the woofer is not, which means it'd have to be attenuated.

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[yepimonfire]

Yeah, I fail to see how a link to a replacement part, from an independent speaker repair shop that has no affiliation with Klipsch whatsoever, for an item that is different than any compression driver diaphragm Klipsch has ever used, somehow supports TLS' claim that Klipsch no longer uses compression drivers. The part he linked is a replacement diaphragm for, wait for it, compression drivers! A cursory check of their website indicates Klipsch still uses compression drivers as well.

It seems that TLS is the one bringing his feelings to the fact fight by engaging in such specious reasoning.

And nothing against Simply Speakers, they're nice folks.

I'd take what TLS says as fact, the man knows more about speaker design than anyone on these forums.

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[highfigh]

It is when compared to their old models. Klipsch does not derive their sensitivity ratings anechoicly, but in a reverberant field similar to an average room. Will klipsch speakers play much much louder than other conventional speakers with the same power? Yup. That's good enough for me.

While the horn assembly is likely extremely efficient, the woofer is not, which means it'd have to be attenuated.

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If they don't use an anechoic chamber, that's exactly why the sensitivity tests higher- the room's reflections are part of the test results and that makes any comparison invalid because the room's effect isn't known unless they compared the in-room response with the anechoic response.

Sensitivity isn't usually an extremely important spec for residential use unless the room's dimensions/volume are so large that it makes insensitive speakers useless or the budget doesn't allow for enough power to achieve the desired SPL. In a small room, it's a useless spec.

 

[highfigh]

There are more factors to sensitivity than coil windings and magnetic flux. There is the mass of the moving parts, the amount of air resistance is the acoustic impedance, there is resonant frequencies, electric, mechanical, and speaker wide. Cabinet design plays a part. Crossover design plays a part, and there is always loss in a passive crossover. There is electrical resistance of the coil, not to mention inductance of the motor. Stiffness of the suspension. Everything will affect sensitivity. And no way is that speaker even close to 96 dB for 2.83v at 1 meter anechoically, I guarantee you.

I know that but when some of the arguments have been on the level of "But it goes to eleven", I didn't see much reason to go into that much detail.

 

[TLS Guy]

It is time to point out once again the sensitivity and efficiency are not the same thing, but to an extent related.

Efficiency of a loudspeaker is a measure of the percentage of electrical energy it can convert into sound energy. This is the total sound energy radiated by the driver.

Now sensitivity is the sound intensity radiated to a microphone placed at 1 meter on axis from the driver. This is measured and quoted as db 1 watt one meter, or 2.83 volts drive at 1 meter. For an 8 ohm driver the two methods will give the same number. A 4 ohm speaker will be 3 db higher on the 2.83 volt 1 meter, but it will have drawn twice the power from the amp. So the 4 and 8 ohm versions of the same driver, have the same efficiency.

Now if we take the same driver and put a wave guide in front of it, or what ever you want to call it, that restricts off axis radiation and directs more sound on the forward axis, the sensitivity will be higher. However the efficiency has not changed. The same energy will have been released into the room.

So actually the unit with the guide does not play louder, but can appear to. Psychological a speaker that especially restricts its off axis radiation does sound more forward and louder if you like. While the more broadly radiating driver appears to have a more pleasant depth of sonic field.

Now as Hi-Fi pointed at, it matters not if the sensitivity of the tweeter goes up if the mid/woofers do not. The tweeter has to be padded down to match the sensitivity of the mid/woofers.

There still is a problem though, as a speaker will not sound really correct unless the dispersion patterns of the drivers are similar. Good woofers and mids should have a high enough pass band not to break up in their pass band. In that pass band then those drivers will have excellent dispersion, and below the baffle step point will become true omnidirectional radiators, and require an increase in power drive below that point to keep the forward radiation constant. A cone driver driven in break up mode will increase its forward radiation and restrict lateral radiation. In other words it stats to beam.

So I think a lot of the perception of increased clarity from speakers like Klipsch actually comes from an imbalance of forward radiation between the drivers.

I always try and match the dispersion of drivers as closely as I can.

I think those that came from the previous generation, when the efficiency of horns was mandatory would horn load the front of the woofer cone when combining it with a horn compression driver.

 

[ski2xblack]

I'd take what TLS says as fact, the man knows more about speaker design than anyone on these forums.

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I respect TLS and the knowledge he brings to the forum, a lot, so color me disappointed in his use of that particular link to support his claim.

I also put a lot of credence into other experts who have studied this professionally, such as Floyd Toole, whose book covers directivity and reflected sound in a more academic manner than TLS' rather dogmatic brushing off of anything other than speakers that provide wide dispersion. Toole's research indicated that while many prefer wide dispersion speakers, there is a not insignificant portion of users that prefer less influence from local acoustics, and the solution for that group is pattern control via waveguides/horns. I think that that observation may directly address the OP's original question as well.

 

[highfigh]

I respect TLS and the knowledge he brings to the forum, a lot, so color me disappointed in his use of that particular link to support his claim.

I also put a lot of credence into other experts who have studied this professionally, such as Floyd Toole, whose book covers directivity and reflected sound in a more academic manner than TLS' rather dogmatic brushing off of anything other than speakers that provide wide dispersion. Toole's research indicated that while many prefer wide dispersion speakers, there is a not insignificant portion of users that prefer less influence from local acoustics, and the solution for that group is pattern control via waveguides/horns. I think that that observation may directly address the OP's original question as well.

The preference for narrower dispersion may come out of necessity- a live room is a bad place to be when the SPL is high and the sound reaches all of the surfaces before it begins to attenuate. If the SPL is controlled and the listening position receives the energy without later reflections, it can sound good, but when the reflections are almost as loud as the incident energy, don't expect good sound.

 

[TheWarrior]

This is the anatomy of a compression driver for mating to flared horn.

This shows the diaphragm, high impedance expansion chamber and throat.

A dome with flared guide in front of it does not fit the definition of a horn.

Now as I often point out, a vibrating cone couples less and less effectively to the air in a room the lower the frequency. That is why a sealed sub is in essence a dreadful idea.

The benefits if horn loading become greater the lower the frequency.

Now there is often loose talk, in that loudspeaker pipes are often referred to as horns, especially quarter wave pipes. This is just plain wrong.

The physics of pipes and horns are very different. For one thing the frequency radiated by a pipe is determined more then anything else by its length.

The low frequency radiated by a horn is largely determined by the dimensions of the mouth.

Musical instruments have examples of both. A French horn is a horn. A flute is a pipe.

Unfortunately woolly thinking abounds in the area of loudspeaker discussion, which is a severe problem. Instrument makers however, I'm certain are quite clear as to whether they are building a horn or a pipe. Loudspeaker designers should be as well. Unfortunately I'm pretty certain they often are not.

Quick question: is the diaphragm used in a compression normally a concave shape as the image suggests? Providing a narrow focused wave of sound that is then widened by the throat and expanded by the horn?

 

[TheWarrior]

I respect TLS and the knowledge he brings to the forum, a lot, so color me disappointed in his use of that particular link to support his claim.

I also put a lot of credence into other experts who have studied this professionally, such as Floyd Toole, whose book covers directivity and reflected sound in a more academic manner than TLS' rather dogmatic brushing off of anything other than speakers that provide wide dispersion. Toole's research indicated that while many prefer wide dispersion speakers, there is a not insignificant portion of users that prefer less influence from local acoustics, and the solution for that group is pattern control via waveguides/horns. I think that that observation may directly address the OP's original question as well.

This cracked me up simply because Floyd is a research scientist that prefers to fully explain his studies when explaining his view points i.e. The Measurement and Calibration of Sound Reproducing Systems which systematically takes down (over 30 pages IIRC) the basic premise of how auto setup programs (Audyssey, Onkyo, YPAO, early Dirac) function as incapable due to the lack of information provided to the software via omni mic.

TLS' only 'setback' in perceived authority is his cut through tactic to more quickly reach the conclusion, which can be seen as opinion, but of course he is more than capable of linking researched data to support his statements. He has certainly helped me as I am beginning to find my way with something that came from hobby, developed in to passion, and may now hold a future for me, somewhere in the ever expanding boundaries of sound reproduction.

P.S. Floyd has a new book coming later this year: Sound Reproduction II: Science Strikes Back.

Ok, thats totally not the title, but thought you'd appreciate the heads up to keep an open eye for its release!

 

[shadyJ]

Quick question: is the diaphragm used in a compression normally a concave shape as the image suggests? Providing a narrow focused wave of sound that is then widened by the throat and expanded by the horn?

some are ring shaped and also convex shaped like so:

 

[TheWarrior]

some are ring shaped and also convex shaped like so:

Huh.... a ring radiator with an enormous phase plug?