Speaker sensitivity vs SQ

Mijostyn wrote:  "A speaker that can hit 110dB without compression is going to be more dynamic than a speaker that can only get to 100 dB even if it is less efficient."  

Agreed.  

Mijostyn again:  "Another issue is trying to run 15" woofers up to 700Hz then crossing to a horn."  

I understand your skepticsm.

Intuitively it sure seems wrong because it's almost never done in home audio. Actually, running a 15" woofer to 700 Hz is like running a 5" woofer to 2.1 kHz:  For the right kind of 15" woofer, it's a piece of cake.   (The 15" midwoofer I'm using is plus or minus 1 dB to about 1.7 kHz with no filtering, then it has a 3 dB peak at 2 kHz.  Its effective motor-strength-to-moving-mass ratio surpasses every small high-end midwoofer I know of, and falls in the ballpark of 5" cone midranges.)  

Some of the finest studio monitors in the world, the classic Augspurgers and the magnificent JBL M2, use the 15" woofer + horn format.  There are several brief YouTube videos about the M2 which are imo worth watching.

Mijostyn:  "Two very dissimilar drivers crossed right in the meat of the midrange."  

The big woofers and horn-loaded compression drivers are visually dissimilar, but ACOUSTICALLY they are far more similar than most cone midwoof/dome tweet combinations in the crossover region.  Let me explain:  

What we hear is a combination of the direct sound and the reverberant sound, the latter being dominated by the speaker's off-axis response.  Ideally the off-axis response tracks the on-axis response very closely.  However if there is a directivity mis-match in the crossover region, it is impossible for the on-axis response to match the off-axis response through the crossover region.    

A directivity mis-match in the crossover region is almost inevitable for a cone midwoof/dome tweet combination, because the cone's radiation pattern will be narrower than the smaller dome's radiation pattern.  There are two ways around this:  One is to widen the midwoofer's pattern by using (hopefully well-behaved) cone breakup, and the other is to use a horn or waveguide of some sort to deliberately narrow the tweeter's radiation pattern so that it matches the midwoofer's.  

The latter is what I do, only at a lower frequency than most midwoof/tweet combinations.  

Crossover frequencies are a juggling of tradeoffs. Briefly, for a combination of psychoacoustic and practical reasons, imo 700 Hz makes sense.  It arguably makes better psychoacoustic sense than just about any higher frequency does. 

So like I said I understand your skepticism, but I've put some thought into my (often unorthodox) design decisions.  

Duke

@erik_squires wrote: 

"Another area where attribution is difficult, the dynamic nature of high efficiency systems.  

"Is it that, or is it the controlled dispersion?  

"I'm not saying low compression speakers aren't good. I'm saying that some of what we may attribute to "fast" or high impact speakers is really just better room integration."  

I totally agree. 

I would not be surprised to learn that, in practice, room acoustics and radiation patterns usually play as big if not bigger role in real-world dynamic contrast as thermal compression.   

Duke

My point is that dynamics are a matter of volume. A speaker that can hit 110dB without compression is going to be more dynamic than a speaker that can only get to 100 dB even if it is less. efficient. Just a matter of power. Horns are very dynamic because they go very loud. They do it with less power because they tend to be very efficient. As far as sound quality goes, it's a toss up.

Thermal compression occurs with all voice coils. The less efficient the driver, in general there will also be greater thermal compression as the speaker is being asked to deal with more power. As the voice coil heats up (which it does on each individual bass note; yes, they can heat that fast) its ability to move the speaker cone is reduced. Result: lower efficiency speakers tend to have lower dynamic qualities as well and unless you move away from a voice coil M.O., you can't throw more power at it, more power makes it worse. IOW the louder you play, the more compressed it becomes.

Mahgister,
This will be my last reply to you because you continue to demonstrate no ability to understand or from where I am standing even attempt to understand. You just get your self all in a huff and go nay nay nay about stuff you are grossly and woefully lacking knowledge on. You embarrass yourself.

It is a fact verified by science that speech recognition is greatly improved with some early reflections... Which one and the timing with late reflections is an acoustical complex problem not to be solved by dogmatical ignorance...

https://nrc-publications.canada.ca/eng/view/accepted/?id=dd3c1e7a-8d8d-440e-bbcd-04c69ef20419

Clearly you don’t understand the discussion, but feel free to clog the thread with ramblings. Reproduction of sound/music, is NOT the same as creation of sound/music. Most music is mixed near field in setups that tend to have little in the way of early reflections. I am sorry that you cannot understand the difference between recording speech in an anechoic chamber and playing back speech recorded in a regular room and then played back on stereo speakers in an anechoic chamber. Have you never used headphones?

Floyd Toole specifically talks about using reflections to gain a sense of space. That is a taste thing. Gain space, loose imaging. You will note in my comment about imaging of stereo speakers in an anechoic chamber being laser focused. Want to guess why that is? Try to think more, and contradict me without adequate information less. You may learn something.

«I expect few people have actually heard stereo speakers in an anechoic chamber. Contrary to popular opinion, it is not bad at all, with pin point natural imaging.»

Complete non sense...
Read what musician think about that in this link:

https://www.violinist.com/discussion/archive/23998/

Again, you clearly do not understand, even though I repeated it, several times, that creation of sounds/music is much much different from reproducing it. I don’t know what else I can say except spend more time reading (listening) and understanding and less time reacting. You will be farther ahead.

The rest of your diatribe / attempted attack on what I wrote is just more of the same so wasting my time pointing out what you wrote that is wrong (probably all of it, I got bored reading it) would waste my time and clog the thread.

I will leave you with a little tidbit. Do you know what a lot of enterprising hobbyists do who can’t afford anechoic chambers, and need better measurements do when building speakers? .... They take them outside. Why? -- no reflections (again! except the ground as noted).

Have a nice life Mahgister.

p.s. "Sound in an anechoic chamber sound a bit like headphone, said Floyd Toole, the sound is in our head" ..... this is not remotely true. Not at all. I am not sure why Floyd Toole said it, and several, including me, who have heard stereo playback in an anechoic chamber called him on out on it.  Usually (almost always) people only have 1 speaker in an anechoic chamber, so it is quite possible he never actually heard stereo playback in an anechoic chamber even with all his experience and was talking off the cuff. I was doing contract research on some advanced signal processing and had multiple speakers in the chamber.  IF, and it is a big IF, you actually thought this through, in an anechoic chamber, with stereo speakers, all the social clues are there for angular position, depth, and some simulated height potentially from frequency shaping. None of that changes in an anechoic chamber. In fact, absent reflections, these items are all clearer.

alexberger330 posts




You don't have to have a highly efficient speaker to overcome dynamic compression in normal usage. As the article points out, there are methods of voice coil design, speaker design, material choices, etc. that can all mitigate these problems, hence probably why there are 100's if not 1000+ speaker designers, but very few professional driver manufacturers, and why top speaker companies design their own drivers.  It is also a reason why active speakers will be necessary for the absolute in sound recreation.