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Do high-efficiency speakers really have better 'dynamics'?

ctrl

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See my answer in the past:
Link
Please explain in detail how a software for sound analysis (e.g. why a dentist's drill is perceived as more unpleasant than a sinus tone with the same sound pressure, due to differences in e.g. roughness and sharpness) should explain the perceived increased dynamics of loudspeakers with high sensitivity (Update: or "micro details").


But if, for example, you put the O/96s and the speaker to be compared in any decent listening room (no hall with echoes or something like this), you will likely get the result that the O / 96s provide better micro-details there too.

Also in this case, the assumption that the directivity of the loudspeaker plays a decisive role could be true.

If we compare the O96 with the Revel F328Be, both speakers have a sensitivity of around 91dB.

O96:
My estimate of the DeVore's sensitivity was somewhat lower, at 91dB(B)/2.83V/m, though this is still usefully high.
Source: Stereophile

F328Be:
1631961676280.png

Source: https://www.audiosciencereview.com/...revel-f328be-speaker-review.17443/post-564848

Strange, why is the F328 not regularly mentioned here? Due to the wide sound dispersion, this speaker even radiates significantly more sound energy into the room than the O96 at the same voltage.

The three 8'' woofers of the F328 also have significantly less excursion than the one 10'' woofer of the O96 at the same sound pressure.

So, according to the facts, the F323Be is clearly the more "dynamic" speaker than the O96, but is never mentioned here in the thread.
The big difference between the two speakers is their directivity.

Regarding the micro-details, I would blame the ratio of direct sound to diffuse sound (as others already mentioned). The narrower the speaker's dispersion, the more direct sound reaches the listener and the better micro-details can be perceived.
An extreme case would be headphones (only "direct sound") where micro details can be heard very well.
 
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tuga

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Ken Tajalli

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DeVore has made a video about his take on the sensitivity issue. Does any of it make sense?

He keeps repeating a mistake:
It is not 88dB PER Watt PER meter.
It is 88dB for one watt at one meter.
The first statement means 98dB at 2 Watts! (double wattage, double loudness).
The second statement (correct one) means 91dB at 2 Watts.

The rest of his argument is somewhat valid . Specifying a speaker system's efficiency for 2.83V is not representative for a speaker system with vastly varying impedance, deviating from 8 Ohm.
Even a decent low output impedance amp. can run out of juice faster attempting to deliver 20V into a 2R load than an 8R one.
 

ctrl

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DeVore has made a video about his take on the sensitivity issue. Does any of it make sense?
Yep, you can look at it that way. Both speakers were measured with 2.83V@1m. That was 1W for the O96, 2W for the F328.
But both speakers have such a high sensitivity that amplifier power should not be a problem in terms of dynamics.

But according to the "old" definition, the O96 would still have "only" 91dB sensitivity and the F328Be almost 6dB less. It seems DeVore simply measured at 2W to achieve the 96dB sensitivity which were specified. Nevertheless, the speaker impedance is not constant anyway, so...

But regarding dynamics, cone surface area and excursion was mentioned here. In the bass range, the F328 has roughly 3x220cm², the O96 about 350cm².
Compared to the O96, the F328 has a lower excursion at the same sound pressure, so the cone velocity is also lower.

Now, one could interject and say that the F328 may have "better" dynamics in the bass range, but with the O96 the midrange is emitted by a 10'' driver and with the Revel by a tiny 5'' driver.

However, the 10'' paper cone of the O96 probably no longer oscillates piston-like well below 500Hz, but breaks up into modes, so that only parts of the cone surface contribute to the sound radiation.
Here, as an example, an 8'' full-range driver (Visaton BG20) at 570Hz and 2.2kHz:
570Hz bg20.gif 2200Hz bg20_2200Hz.gif
It is easy to see that only part of the cone surface area contributes to sound radiation to the front. Recognizable by the color code:
1631976019715.png
Whether this is helpful, to have a driver that no longer radiates piston-like very early on, for a realistic reproduction of micro details is up to everyone to decide.
 
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DrCWO

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My guess is completely different and I would like to try to explain that.

I recently exchanged my Passlabs XA30.5 for a Krell Evolution 2250e. Completely oversized for my horns in terms of power, but it reveals a lot more micro-details than the XA30.5. The difference that I blame for this is the significantly better signal-to-noise ratio (SINAD). My conclusion: microdetail has something to do with very small amplitudes. If an amplifier can resolve them and not drown them in its noise, then you can just hear them.

Loudspeakers are mechanical systems. Looking at these, there are two different coefficients of friction: Static-Friction and Kinetic/Sliding-Friction. Static-Friction always comes into play when something is not moving and it has to be made to move. The Kinetic/Sliding-Friction is usually lower and describes the friction that occurs when something is already moving. (https://en.wikipedia.org/wiki/Friction)

My hypothesis - and I say very clearly hypothesis - is, that the reproduction of micro-details depends on how low the Static-Friction of the membrane suspension is compared to its Kinetic/Sliding-Friction. Interestingly, most of the speakers I heard being able to deliver micro-details had paper cones and paper beadings and none made of rubber. Maybe the material acts different at very low levels...

Edit: found an interesting article about that here: https://www.klippel.de/fileadmin/kl...urement of Loudspeaker Suspension_Klippel.pdf
 
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tuga

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ETC is a property of the listening room and has nothing to do with micro-details. My guess is completely different and I would like to try to explain that.

I recently exchanged my Passlabs XA30.5 for a Krell Evolution 2250e. Completely oversized for my horns in terms of power, but it reveals a lot more micro-details than the XA30.5. The difference that I blame for this is the significantly better signal-to-noise ratio (SINAD). My conclusion: microdetail has something to do with very small amplitudes. If an amplifier can resolve them and not drown them in its noise, then you can just hear them.

Loudspeakers are mechanical systems. Looking at these, there are two different coefficients of friction: Static-Friction and Kinetic/Sliding-Friction. Static-Friction always comes into play when something is not moving and it has to be made to move. The Kinetic/Sliding-Friction is usually lower and describes the friction that occurs when something is already moving. (https://en.wikipedia.org/wiki/Friction)

My hypothesis - and I say very clearly hypothesis - is, that the reproduction of micro-details depends on how low the Static-Friction of the membrane suspension is compared to its Kinetic/Sliding-Friction. Interestingly, most of the speakers I heard being able to deliver micro-details had a paper cones and paper beadings and none made of rubber. Maybe the material acts different at very low levels...

I wonder if hysterisis, hardly ever mentioned apart from Dali and Klippel (here and here), can affect low-level detail transduction.
 

pogo

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Please explain in detail how a software for sound analysis (e.g. why a dentist's drill is perceived as more unpleasant than a sinus tone with the same sound pressure, due to differences in e.g. roughness and sharpness) should explain the perceived increased dynamics of loudspeakers with high sensitivity (Update: or "micro details").
I can't, but I believe that these objective measurable properties like sharpness, roughness, ... and especially impulsiveness can show a difference, which also contribute to micro details.
Interestingly, I recently had a second pair of my speakers optimised by a tuner, replacing the mid-bass drivers with 'faster' ones. Result: My room modes are no longer excited so strongly that I was even able to deactivate my DSP correction in the range of 50-100Hz and I can hear more 'micro details'!
 

MattHooper

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So did I Matt. After reading about high sensitivity speakers with low wattage valve amps I wanted to hear some so I went to listen to the Devore O/96's just yesterday. I tried listening to the same test tracks on my system just before I left (Revel F228Be/ARC VT100 MKll/Conrad Johnson ACT2/VPI Classic Series 3/RME ADI2 DAC fs) and left the session with the same feeling about the Devores as Matt. (They were paired with a Jadis 60wpc tube integrated.) There was a richness, a weight, to the sound as well as an ability to present every nuance, especially on vocals. I started by playing two tracks by Gregory Porter, God Bless this Child, (an acapella version from Be Good) and then Liquid Spirit (Claptone Remix), and while polar opposites the Devores presented each convincingly, seeming to display each tracks strengths equally well. (By the way if the remix of Liquid Spirit doesn't get you moving you're dead!)

I'm not at your guys level technically (I'm trying to learn) and don't have much experience with horns at all, but I really liked what I heard. I especially appreciated their sound at lower volumes. By the time I left I liked them enough that I'm already starting to rationalize how I might swing getting a pair. :eek:

And this is why I like exchanging personal impressions of how things sound.

Not everyone wants the same thing, but you can find some like-minded people who share an appreciation for similar characteristics in a sound system, who are "listening for what you are listening for, caring about what you care about" and so it can actually be fruitful to exchange notes like this.

Where I live we are inundated with live music - live bands of all sorts, from electric to folk to lots of jazz combos, are playing almost every day, on the streets, in the parks etc. Today I was in our nearby park and a jazz band was playing, standards like from Miles Davis etc. Drums, electric guitar, stand up bass, trombone, sax.

Like I usually do I closed my eyes to listen (and at different distances, and from various angles - in front of the band, the side, behind) and took in "what do these live instruments sound like?" As usual the first impression is "BIG." With lots of acoustic power. Everything sounds like the big, actual sized instruments they are. Even drum cymbals sound like the big discs they are when struck, with lots of richness, rather than the tiny, reductive little bursts of high frequency that stand in for cymbals in most hi fi systems. Sax and trombone were clear and dense, rich and rounded - not lazer-like image outlines, slightly diffuse in their image outlines, but full and dense, solid.

Drums had that dynamic aliveness you just don't get through hi-fi systems, snare sounded large and thick with a sense of "it's right there" texture.

Back to drum cymbals, I was struck reading Jonathan Valin's TAS review of MBL speakers, where he remarked: "Through the X’s, cymbals have something you rarely if ever hear with domes and membranes—a disc-like roundedness that makes them sound three-dimensional, just as they do in life."

I almost yelled out YES!!!

I'll never forget doing the rounds at a CES show, listening for any system that could sound close to real. None did. All sounded like cones and tweeters. Then I entered the MBL room, first time, a jazz piece was playing and the first thing that jumped out was the sound of cymbals.
They actually sounded, just as JV expressed. It was the first time I'd ever truly heard drum cymbals sound to me like real drum cymbals - big, thick, round, disc-like. My own MBL speakers, though smaller, did this as well.

These are the types of characteristics I seek in my own hi-fi experience, and what I push my own system toward as much as possible. I do it through choice of speakers, amplification, source, and playing with acoustics in my room (I can change around the liveness/deadness of any area in the room.

When I came home I cranked up my system, played similar music and closed my eyes and I'll be darned if it didn't have a lot of the qualities I'd just heard in the live music. Not true "live" sound of course, but enough of the character to allow me to slip in to an illusion of a performance.

BTW, the "texture" thing is one reason I sometimes prefer vinyl records (and my tube amps). It may be a bit of added distortion, but whatever it is, drum skins and snares on some vinyl can have more of that cut-through-the-air texture that I recognize and heard today from real drums.

I played some good drum recordings on digital first, but it was some of the drums on vinyl that had my brain click and say "now THAT has the gestalt of real drums!"

Anyway, some of us have found a similar "gestalt" coming from those Devore speakers. What some will immediately perceive as going off-neutral, another may perceive as reminding him a bit more of "live." For me, the combination of "texture" richness and the "heft" of sounds through those speakers do that.

I honestly don't know if the Devore sound would, for me, be cloying or tiring over time though, not having lived with a pair. I hope to try them out some day.
 
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MakeMineVinyl

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And this is why I like exchanging personal impressions of how things sound.

Not everyone wants the same thing, but you can find some like-minded people who share an appreciation for similar characteristics in a sound system, who are "listening for what you are listening for, caring about what you care about" and so it can actually be fruitful to exchange notes like this.

Where I live we are inundated with live music - live bands of all sorts, from electric to folk to lots of jazz combos, are playing almost every day, on the streets, in the parks etc. Today I was in our nearby park and a jazz band was playing, standards like from Miles Davis etc. Drums, electric guitar, stand up bass, trombone, sax.

Like I usually do I closed my eyes to listen (and at different distances, and from various angles - in front of the band, the side, behind) and took in "what do these live instruments sound like?" As usual the first impression is "BIG." With lots of acoustic power. Everything sounds like the big, actual sized instruments they are. Even drum cymbals sound like the big discs they are when struck, with lots of richness, rather than the tiny, reductive little bursts of high frequency that stand in for cymbals in most hi fi systems. Sax and trombone were clear and dense, rich and rounded - not lazer-like image outlines, slightly diffuse in their image outlines, but full and dense, solid.

Drums had that dynamic aliveness you just don't get through hi-fi systems, snare sounded large and thick with a sense of "it's right there" texture.

Back to drum cymbals, I was struck reading Jonathan Valin's TAS review of MBL speakers, where he remarked: "Through the X’s, cymbals have something you rarely if ever hear with domes and membranes—a disc-like roundedness that makes them sound three-dimensional, just as they do in life."

I almost yelled out YES!!!

I'll never forget doing the rounds at a CES show, listening for any system that could sound close to real. None did. All sounded like cones and tweeters. Then I entered the MBL room, first time, a jazz piece was playing and the first thing that jumped out was the sound of cymbals.
They actually sounded, just as JV expressed. It was the first time I'd ever truly heard drum cymbals sound to me like real drum cymbals - big, thick, round, disc-like. My own MBL speakers, though smaller, did this as well.

These are the types of characteristics I seek in my own hi-fi experience, and what I push my own system toward as much as possible. I do it through choice of speakers, amplification, source, and playing with acoustics in my room (I can change around the liveness/deadness of any area in the room.

When I came home I cranked up my system, played similar music and closed my eyes and I'll be darned if it didn't have a lot of the qualities I'd just heard in the live music. Not true "live" sound of course, but enough of the character to allow me to slip in to an illusion of a performance.

BTW, the "texture" thing is one reason I sometimes prefer vinyl records (and my tube amps). It may be a bit of added distortion, but whatever it is, drum skins and snares on some vinyl can have more of that cut-through-the-air texture that I recognize and heard today from real drums.

I played some good drum recordings on digital first, but it was some of the drums on vinyl that had my brain click and say "now THAT has the gestalt of real drums!"

Anyway, some of us have found a similar "gestalt" coming from those Devore speakers. What some will immediately perceive as going off-neutral, another may perceive as reminding him a bit more of "live." For me, the combination of "texture" richness and the "heft" of sounds through those speakers do that.

I honestly don't know if the Devore sound would, for me, be cloying or tiring over time though, not having lived with a pair. I hope to try them out some day.
Remember that in the majority of recordings, the sound of the instruments in the studio is sampled in a tiny sliver of space (the microphone diaphragm) yet the music we hear 'live' exists in all the space around us. How could these drastically different environments possibly sound the same?

When we listen to live instruments, we are hearing the off axis sound produced by all the instruments in addition to the direct sound as it interacts with the air around us. In a studio, the sound of the instrument is sampled only from a relatively tiny angle, and almost always at a short distance we would never listen to those instruments at. The sound of the instruments never has an opportunity to fully form in the foot or so from the microphone.

If we set our microphones at a more normal listening distance, the results sounds, well, 'distant' and un-natural. So recordings compromise, and that compromise usually isn't biased to the 'natural' sound of the instruments.

Its really a wonder that recordings sound as good as they do.
 

MattHooper

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Remember that in the majority of recordings, the sound of the instruments in the studio is sampled in a tiny sliver of space (the microphone diaphragm) yet the music we hear 'live' exists in all the space around us. How could these drastically different environments possibly sound the same?

When we listen to live instruments, we are hearing the off axis sound produced by all the instruments in addition to the direct sound as it interacts with the air around us. In a studio, the sound of the instrument is sampled only from a relatively tiny angle, and almost always at a short distance we would never listen to those instruments at. The sound of the instruments never has an opportunity to fully form in the foot or so from the microphone.

If we set our microphones at a more normal listening distance, the results sounds, well, 'distant' and un-natural. So recordings compromise, and that compromise usually isn't biased to the 'natural' sound of the instruments.

Its really a wonder that recordings sound as good as they do.

Good post!

Agreed. As someone who records lots of sound (and I've been in recorded bands) I know what you mean.

Actually, one of the cool things about listening to the live instruments in the open park is that it's effectively sort of "anechoic" - especially if you aren't too far away. That's what was so interesting as there was no immediate reflective room surfaces to boost the sound at all, and yet those instrumental images were so big and full even without room boost.

And so true about the distant recording effect. Lots of audiophile recordings to me sound listless when they eschew closer micing.

I love vivid instrumental timbre, so I like to be close to live sound sources, and I'm fine with close micing for recordings.

Ultimately, as you say, all things considered it's amazing how good recordings can often sound. It's all tricks and illusion, so I am happy doing my part at home to add tricks to make things sound more convincing to me.
 

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I wonder if hysterisis, hardly ever mentioned apart from Dali and Klippel (here and here), can affect low-level detail transduction.

Controversially, if you watch their motor design video, purifi think so.

Faraday rings (copper shorting rings) are used by the best motor design companies to reduce flux in the gap and hence distortion, but there may be more to it.

Troels gravesen has designed probably a thousand speakers now, many that measure very well, even advancing to the stage of designing and developing edge treatment for drivers that provably removes modal edge diffraction in most drivers showing in smoother on and off axis spl around 1khz.

He also feels there is some unexplainable advantage in 'jump factor' for high sensitivity speakers feeling the best speakers all seam to have this.

I would also like to ask Charlie sprinkle about this as the m2 uses exclusively neo magnets.

Years ago I read a detail analysis of the instantaneous temp of the coil in transients being way higher than you would expect.

I myself run a massive horn. It's tremendous at holding your attention. Prob all just subjective placebo, but either way, 20 years into trying to find an answer, I'm mostly at peace with my ignorance on the matter now.....mostly.

If you are interested in going down this rabbit hole, read the 'beyond the ariel' thread on DIY audio.....it will take you a couple of years to read, and you still won't get any answers!
 
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mocenigo

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You'll need, IME, more than 96 dB sensitivity @ 1 meter for the Decware amp with any reasonably dynamic source material in any reasonable sized room.

We're at about 104 dB per watt at 1 meter here, but (as I've mentioned elsewhere on this forum just recently :) ) the SE84B from Deckert won't cut it, fullrange. SE 2A3 (ca. 3.5 watts per channel) is fine in my room, which is fairly large (loft over a US-sized two-car garage).

EDIT: Dynamics? Yeah, we got dynamics. :cool:

DSC_0938 (3) by Mark Hardy, on Flickr

Cool! Can you tell me a bit more about the design? (components, loading... for that particular variant, I have seen various drivers attached to your horns, the bass unit as a coax with a multicellular horn and without it...)
 

Lbstyling

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That is where I am as well. I wish we could make progress on objective side, or prove that the subjective experience is wrong. We are in a bit of limbo here.

For me, I listened to low wattage tube amplifier driving horns at CES in a massive room which I cannot replicate with my Salon 2 speakers and massive amplification. This was the system and demo:


More recent experience has been no less than three JBL speakers that left me with that impression as well.

Generally Focal target higher sensitivity and also subjectively are closer to the 'drive' of horns imo (I own both and often play with crossing the horn to my focal bass drivers at 93db/1w)

Wonder if this follows your impression at all?

If you look 2 posts above at my comment on temp effects on driver coils, Erin has gathered measurements on various speakers on temp effects on coils generating compression over time, but not instantaneous 'softening' of peaks in lower sensitivity drivers and coils.
 
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Lbstyling

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Hi Amirm

I think there is a mechanism that could explain this conclusion / impression.
How relates top how we hear and the signal.


We are used to thinking about "level" like a VU-meter or a Sound Level Meter.


Both of these integrate the signal over some time period, with the VU meter in the days of analogue circuitry and recording tape the time integration made sense because if you went past 0dB, the level continued to increase but was only increasingly distorted. Going past 0 dB a little on peaks then was kinda ok because you can't hear even gross distortion on peaks if it is short enough.



That inability to hear "short" issues is also why you can't hear clipping if short enough.
In the old days there was a tool called an oscilloscope which would show the wave shape of a signal. This can easily reveal a problem like this.


In the early 2000's an amplifier company (QSC) went around to people in the sound business and carried an ABX switcher where you could compare amplifiers, your to theirs (which were typically lighter).
First you put in a sine wave to adjust the levels to be exactly the same and then you chose a couple tracks to listen to.

We listened on some speakers we sold and i was familiar with and my threshold stasis sounded VERY similar to the pro amps as in maybe a tiny tiny difference on a few places in only some music BUT as we turned it up a bit more there was a difference.
The Threshold still sounded essentially the same EXCEPT it sounded a bit less dynamic when going back and forth quickly with the switcher.



That seemed odd the Threshold VU indicators showed peaks of -20dB and at home I know they hit -12 occasionally on peaks.


I (eventually) grabbed an oscilloscope and looked at the amp output and I was stunned, with the tracks that were less dynamic, there was instantaneous clipping and I don't mean the terrible sound of sustained clipping, only being one or a few cycles long it was inaudible and all this did was remove some of the dynamic .


So lets say you had a speaker that had 85dB 1w1m sensitivity and you sat at 4 meters (-12dB from 1m).

Lets say you had a 50W traditional SS amplifier (in other words not class D with a magic power supply) that clips at 55 Watts. 55 Watts is +17dB over 1Watt.

So you have a maximum peak unclipped level at the chair of 85dB - 12dB (distance) and +17dB (peak of 55 Watts) or about 90 dB SPL.

If you were playing normal hifi type music say 20dB p/a at the maximum unclipped level, then with a sound level meter on slow would read about 70dB.
You can raise the measure SPL farther but the instantaneous peaks cannot exceed 70dB


This kind of underscores what the late Dick Heyser said "what we need for music is a clean 10W amplifier that can put of peaks of 1000W" (that is a p/a of 20dB).


So lets take a high efficiency horn speaker which might have a sensitivity of say 105 dB 1W1M And let say you had big triodes like those in the picture and lets pretend they are 10 Watt amplifiers. Tubes operated like that, especially if without -fb have to be run in a linear region and that means they also usually had output headroom they might be able to produce +3dB or more albeit distorted.


So the maximum peak SPL at the chair would be about 105dB 1w1m -12dB distance +13 dB peak over 1W = 106dB.

With 36 dB being about 4000 times more energy, that would be detectable even at a trade show.


The point is, unless you look with an oscilloscope you don't know if you have instantaneous clipping and if your feeling the dynamics are limited consider getting / borrowing an oscilloscope and looking at the amp output*. That point will show not only if the amp is clipping instantaneously but also anything else is in the signal path
*assuming you don't have a class d Bridged amp in which case read up on this.


The "other thing" that can create this impression is lets say you switch to a horn system that is say +10dB more sensitive than your previous speakers. With the same amplifier, you maximum unclipped level is now 10 dB greater.

If you had instantaneous clipping before, it may well be gone now and seem and actually be more dynamic as your amp is putting out 1/10 the average power to produce the same avg spl.
All this assumed there are no other non-linearity and while power compression is a longer term heat related thing, it is normally not an issue with these real short peak signals
Best Regards
Tom Danley

This may explain why 2 amps out of hundreds I have tried seam to have the 'horn slam' effect:

the old NAD 30w Amps (later tested to achieve 2000w+ before clipping!) And the early 30w Naim amps known to have very large capacitance banks and high peak before clipping (don't know the actual number though)
 

tuga

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Controversially, if you watch their motor design video, purifi think so.

Faraday rings (copper shorting rings) are used by the best motor design companies to reduce flux in the gap and hence distortion, but there may be more to it.

Troels gravesen has designed probably a thousand speakers now, many that measure very well, even advancing to the stage of designing and developing edge treatment for drivers that provably removes modal edge diffraction in most drivers showing in smoother on and off axis spl around 1khz.

He also feels there is some unexplainable advantage in 'jump factor' for high sensitivity speakers feeling the best speakers all seam to have this.

I would also like to ask Charlie sprinkle about this as the m2 uses exclusively neo magnets.

Years ago I read a detail analysis of the instantaneous temp of the coil in transients being way higher than you would expect.

I myself run a massive horn. It's tremendous at holding your attention. Prob all just subjective placebo, but either way, 20 years into trying to find an answer, I'm mostly at peace with my ignorance on the matter now.....mostly.

If you are interested in going down this rabbit hole, read the 'beyond the ariel' thread on DIY audio.....it will take you a couple of years to read, and you still won't get any answers!

I guess if you are aiming for constant narrow directivity then a massive 4+ way horn unavoidable.

I am also of the opinion that high-sensitivity and compression drivers produce a higher degree of "realism", what I think you mean by "jump factor".
 

mhardy6647

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Cool! Can you tell me a bit more about the design? (components, loading... for that particular variant, I have seen various drivers attached to your horns, the bass unit as a coax with a multicellular horn and without it...)
The configuration has altered over the past few years :) with the goal of improving HF dispersion (i.e., the "sweet spot" for listening to stereo).
Current configuration: The "woofers" are Altec 515B (on loan from a regional hifi luminary) -- which are, more or less,, equivalent to the bass drivers of the 604E Duplex (coax) drivers used previously. The treble horns are EMILAR EH-500 loaded with JBL 2441 2" drivers, and the "supertweeters" ("super" being relative when one is a sexagenarian ;) ) are B&C DE35s.
Crossovers are (gasp) all first order.
 

mocenigo

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The configuration has altered over the past few years :) with the goal of improving HF dispersion (i.e., the "sweet spot" for listening to stereo).
Current configuration: The "woofers" are Altec 515B (on loan from a regional hifi luminary) -- which are, more or less,, equivalent to the bass drivers of the 604E Duplex (coax) drivers used previously. The treble horns are EMILAR EH-500 loaded with JBL 2441 2" drivers, and the "supertweeters" ("super" being relative when one is a sexagenarian ;) ) are B&C DE35s.
Crossovers are (gasp) all first order.

Very nice stuff. I like it. I have a sweet spot for those components.
First order is fine if you are not stressing the drivers too much. And in home listening, you are definitely driving those drivers nowhere close to their max SPL.
 

hardisj

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Erin has gathered measurements on various speakers on temp effects on coils generating compression over time, but not instantaneous 'softening' of peaks in lower sensitivity drivers and coils.

Nah. I actually do both. In fact, if you look at my reviews made in the last few months you'll see the two tests (example copy/pasted below):



Dynamic Range (Instantaneous Compression Test)
The below graphic indicates just how much SPL is lost (compression) or gained (enhancement; usually due to distortion) when the speaker is played at higher output volumes instantly via a 2.7 second logarithmic sine sweep referenced to 76dB at 1 meter. The signals are played consecutively without any additional stimulus applied. Then normalized against the 76dB result.
The tests are conducted in this fashion:
  1. 76dB at 1 meter (baseline; black)
  2. 86dB at 1 meter (red)
  3. 96dB at 1 meter (blue)
  4. 102dB at 1 meter (purple)
The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components) instantaneously.
Kef%20R5_Compression.png



Long Term Compression Tests
The below graphics indicate how much SPL is lost or gained in the long-term as a speaker plays at the same output level for 2 minutes, in intervals. Each graphic represents a different SPL: 86dB and 96dB both at 1 meter.
The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components).
The tests are conducted in this fashion:
  1. “Cold” logarithmic sine sweep (no stimulus applied beforehand)
  2. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
  3. Interim logarithmic sine sweep (no stimulus applied beforehand) (Red in graphic)
  4. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
  5. Final logarithmic sine sweep (no stimulus applied beforehand) (Blue in graphic)
The red and blue lines represent changes in the output compared to the initial “cold” test.
Kef%20R5_Long_Term_86_Compression.png
Kef%20R5_Long_Term_96_Compression.png
 
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