What's Left In Speaker Design To Reduce Distortion/Increase Detail Retrieval?

[tuga]

What part of controlled directivity seems like wider-directivity? You are letting your over-riding bias that single speaker testing cannot be best for two channel use interfere with the concepts involved.

If you look at the Mono vs Stereo preference ratings the narrow directivity Quad rates poorly when listened to in mono but identical to the others when in stereo.

 

[tuga]

Besides you absolutely need two speakers (one for each channel) to assess stereophonic effects and once you set up speakers close to side boundaries early reflections gain relevance and the amplitude of those reflections will depend on directivity.
Your blind faith on Toole's research is clouding your judgement.

 

[Thomas_A]

Avoid or mask? Isn't there a chance that adding a 3rd channel might create even more acoustic interference?

I get the impression that Toole's appreciation of 'envelopment' may streered his research (and interpretation of the data) in a particular direction.
To the best of my knowledge Toole's preference research seems to indicate that wider-directivity is preferred (namely for increased spaciousness).
The problem (with the research methodology and interpretation of the data) is that such preference is determined by plonking a single speaker in the middle of a wide room (and consequently away from boundaries) yet listeners will a) use (at least) a pair of speakers and b) each speaker will be close to one side of the listening room.

With respect to the comb filtering and HRTF errors in stereo, a center is better. Question remains if detail is improved as well. There should be papers around, or?

You are right about the geometric issues with mono vs stereo related to side wall. I know only of one system hat use center and side wall speakers to deal with these lateral reflections with ”correct delays and levels”. I hope to hear it one day. The only other means I know of in stereo is heavy toe-in such that the opposing speaker gives side wall reflections.

 

[Blumlein 88]

Besides you absolutely need two speakers (one for each channel) to assess stereophonic effects and once you set up speakers close to side boundaries early reflections gain relevance and the amplitude of those reflections will depend on directivity.
Your blind faith on Toole's research is clouding your judgement.

And yet Toole does not recommend wider directivity. A more controlled directivity will interact with side walls in stereo better. Even though the benefit of this directivity was found with single speaker testing. Sometimes people refuse to have their cake and eat it too as rare as those chances come along.

 

[Bjorn]

People tend to mix studies of preference with accuracy. These are not necessarily the same. The topic here touches an area of accuracy.

 

[tuga]

A more controlled directivity will interact with side walls in stereo better.

You're only taking frequency response at the listening spot into account but dismissing a) the negative impact of high-amplitude early reflections on imaging and b) the likelyhood of left and right early reflections not being symmetrical and/or treated in typical domestic conditions (even audiophile rooms).

 

[JRS]

I’m currently designing a speaker. It’ll be my first from scratch (I built new cabinets for drivers). I decided on a few arbitrary things to start: open baffle coaxial/full range and an enclosed sub. When I began modeling the drivers/enclosure it was pretty easy to get to +-3dB 30-20k even with cheap drivers with just 1st order crossovers. But with DSP, I don’t have to do a traditional crossover at all and even with those cheap drivers, I could get close to +-1 really easy. The trade off would be an equivalent sensitivity of 82dB/1 watt/1meter and any distortion the filters make.

Those are sim numbers so taken with a tablespoon of salt, but it did really point out to me some advantages of digital. To the point where I would never make passives. And that is without any of the other advantages of digital/active mentioned above.

Plus have an all star driver lineup of your choice. For instance, my latest creation = Acoustic Elegance 15" for bass/sub duties, 6.5" Audio Technology midbass/mids, and Aurum Cantus ribbons on top. I'm sure there are some directivity glitches here and there but it sounds absolutely awesome to me as all is off the walls and I'm the only listener 90% of the time--and all at a cost of about 2200. in drivers. I consider the cab construction is a labor of love, and use flat packs where I can. I use Listen Up (local chain audio salon) to recalibrate my ears every few years--so far things are holding up nicely against the best in the 5-10k range. Have all the advantages of active system and the opportunity to mix and match drivers that can't be done passively. Use case above the mids are only 88dB efficient, the woofers 94dB and the tweeters 98dB.

 

[Blumlein 88]

You're only taking frequency response at the listening spot into account but dismissing a) the negative impact of high-amplitude early reflections on imaging and b) the likelyhood of left and right early reflections not being symmetrical and/or treated in typical domestic conditions (even audiophile rooms).

You still seem to be arguing as if you don't know what the heck you are arguing against. Symmetrical controlled directivity. So you keep harping on reflections being problematic? That does not make any sense. A design guideline espousing controlled and limited directivity and the importance of off axis frequency response so what reflections there are don't color the sound badly seems exactly the prescription for good stereo speakers. That it also is the prescription for mono or multi-channel seems a nice convenience. You then claim I'm only taking FR at the LP into account (really, where have I implied such a thing), and as if the ideas of Toole don't address those. When in fact he has addressed that more than anyone. His use of a spin-o-rama is not something that pre-empts FR over everything except in the sense where testing has indicated exactly that.

 

[Kvalsvoll]

It's quite possible to have both great imaging/detail and spaciousness.

Indeed. And better directivity pattern can actually give a much more spacious and immersive sound, while also present more solid images. You get a much larger spatial contrast.

 

[Tangband]

You still seem to be arguing as if you don't know what the heck you are arguing against. Symmetrical controlled directivity. So you keep harping on reflections being problematic? That does not make any sense. A design guideline espousing controlled and limited directivity and the importance of off axis frequency response so what reflections there are don't color the sound badly seems exactly the prescription for good stereo speakers. That it also is the prescription for mono or multi-channel seems a nice convenience. You then claim I'm only taking FR at the LP into account (really, where have I implied such a thing), and as if the ideas of Toole don't address those. When in fact he has addressed that more than anyone. His use of a spin-o-rama is not something that pre-empts FR over everything except in the sense where testing has indicated exactly that.

As you know, a flat response is not always a holy grail - it depends on many things, for example how loud you play your music. With this in mind, a DIY loudspeaker with dsp peq and crossovers should always be optimized for a certain playback level.

You need a slightly different frequency response If your average music level are 70 dB , or 85 dB.

What is the Fletcher Munson Curve? Using Equal Loudness Curves in Mixing and Mastering

What are the Fletcher Munson curves, or equal-loudness contours, and how do they apply to audio mixing or mastering? This article will cover that all in detail.

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[Axo1989]

Toole used single speaker listening to assess listener (stereo) preference, which is clearly a mistake.

I think he (or they, perhaps it was later work by Olive) did a bit of both (but relied heavily on single speaker). But I agree that people read odd things into some of the comparison graphs. And that while mono listening is useful, the final analysis of a stereo setup requires both speakers, and good positioning vis-à-vis the room and the listener.

Edit: I agree with your other point that envelopment suits certain genres, and my awn preferences tend to go for narrower dispersion (and as we go up in frequency) with other types of music (those I listen to most).

 

[Thomas_A]

People tend to mix studies of preference with accuracy. These are not necessarily the same. The topic here touches an area of accuracy.

Accuracy to the recording or accuracy to what is heard in the studio? If it is accuracy to the recording, the stereo flaws creates a problem, and that especially when DR ratio is high. If it is accuracy to what is heard in the studio, we need to recreate the same DR ratio all other things equal. Possible but quite difficult.

 

[goat76]

Accuracy to the recording or accuracy to what is heard in the studio? If it is accuracy to the recording, the stereo flaws creates a problem, and that especially when DR ratio is high. If it is accuracy to what is heard in the studio, we need to recreate the same DR ratio all other things equal. Possible but quite difficult.

Can you explain to me what "the recording" is before it is heard and mixed in the studio?

 

[sarumbear]

Toole used single speaker listening to assess listener (stereo) preference, which is clearly a mistake.

He doesn’t use a single speaker to assess stereo rendering (duh!), he assesses for tonality.

 

[MattHooper]

Late to the party, sorry if this was already said but I believe the most important development for speaker design is increase of efficiency. Currently electromagnetic drivers are typically no more than about 5% efficient. In other words just 5% of the applied electrical energy is converted into sound, the rest is dissipated as heat from the voice coil.

A theoretical 100% efficient direct radiator driver would convert 1W of electrical energy into 1W of acoustical energy. This will produce 112dBSPL (at 1W, 1 metre, when radiating into half space). Typical hi-fi loudspeaker efficiency is around 90dB/W/m - only 0.62% efficiency! 99.38% of all applied power is wasted as heat.

When you are working with a transducer which is less than 1% efficient what quality do you expect? The so-called piston engine is 20-30% efficient, electric motors are 80% efficient. Yet, here we are stuck with less than 1%.

In my view, an efficiency increase of at least an order of magnitude is what a speaker designer should look to achieve.​

The argument for increased sensitivity seems at least intuitively compelling.

However, what nags at me is this: A certain "type" of audiophile has been arguing for higher sensitivity speakers for a long time, and for similar reasons. It started with a small Absolute Sound-type cadre when solid state had taken over. That is they would argue: People are now building really low sensitivity hard to drive impedance speakers, but they think it's ok because how watts are plentiful with solid state amplification. So, just throw more watts at the problem. However (enter dubious part), these new (at the time) high wattage amps don't sound very good. It's a lot of power, but not good sounding power (like name-the-favourite tube amp or whatever).

The knock on that view was that it was just wrong: the solid state amplification was perfectly fine. This "poorer quality high wattage" thing was a figment of those audiophile's imagination.

I think that rebuttal generally tracks the views of many on ASR. That the lower sensitivity speaker problem is mostly solved by supplying ample wattage, which can be done easily with current solid state, and hence higher sensitivity speakers don't have an advantage.

Your proposal seems to argue that, actually, not just in terms of wasted heat, but yes...SONICALLY...a higher sensitivity speaker will turn out to have an advantage. Is that right? If so I'm bumping on that because it seems of a piece with the old arguments made by tube-loving (or "first watt") loving audiophiles.

 

[sarumbear]

The argument for increased sensitivity seems at least intuitively compelling.

However, what nags at me is this: A certain "type" of audiophile has been arguing for higher sensitivity speakers for a long time, and for similar reasons. It started with a small Absolute Sound-type cadre when solid state had taken over. That is they would argue: People are now building really low sensitivity hard to drive impedance speakers, but they think it's ok because how watts are plentiful with solid state amplification. So, just throw more watts at the problem. However (enter dubious part), these new (at the time) high wattage amps don't sound very good. It's a lot of power, but not good sounding power (like name-the-favourite tube amp or whatever).

The knock on that view was that it was just wrong: the solid state amplification was perfectly fine. This "poorer quality high wattage" thing was a figment of those audiophile's imagination.

I think that rebuttal generally tracks the views of many on ASR. That the lower sensitivity speaker problem is mostly solved by supplying ample wattage, which can be done easily with current solid state, and hence higher sensitivity speakers don't have an advantage.

Your proposal seems to argue that, actually, not just in terms of wasted heat, but yes...SONICALLY...a higher sensitivity speaker will turn out to have an advantage. Is that right? If so I'm bumping on that because it seems of a piece with the old arguments made by tube-loving (or "first watt") loving audiophiles.

Notice that I said at least an order of magnitude increase in efficiency. There’s never been a speaker like that. Your comments are an order of magnitude smaller. I’m talking efficiency figures higher 110dB/W. That will still be in the range of 10% efficiency. 90% of what is fed will be dissipated as heath. That will allow the designer ten times larger space to manipulate the drivers to make them better. Reach the level of an electric motor efficiency and they will have 10,000 more space to work!

 

[Thomas_A]

Can you explain to me what "the recording" is before it is heard and mixed in the studio?

I mean the final record, i.e the digital music file.

 

[ryanosaur]

Notice that I said at least an order of magnitude increase in efficiency. There’s never been a speaker like that. Your comments are an order of magnitude smaller. I’m talking efficiency figures higher 110dB/W. That will still be in the range of 10% efficiency. 90% of what is fed will be dissipated as heath. That will allow the designer ten times larger space to manipulate the drivers to make them better. Reach the level of an electric motor efficiency and they will have 10,000 more space to work!

Are you looking beyond small signal performance in this recommendation and in what regard? Just curious your thought about what the goal is after making a Driver more efficient in terms of converting electrical energy into sound?

 

[sarumbear]

Are you looking beyond small signal performance in this recommendation and in what regard? Just curious your thought about what the goal is after making a Driver more efficient in terms of converting electrical energy into sound?

My comment is general. Transducers that have low conversion efficiency are not good in their job. The better the efficiency, the better their quality, which is measured by their transfer function quality. This is valid for a piston engine or thermometer or strain gauge.

 

[tuga]

He doesn’t use a single speaker to assess stereo rendering (duh!), he assesses for tonality.

That was a mistake, yes, to evaluate Spatial Quality of a single speaker.

"Because stereo imaging and soundstage issues were involved, listeners were interrogated on many aspects of spatial and directional interest.
To our great surprise, listeners had strong opinions about imaging when listening in mono.
Not only that, but they were very much more strongly opinionated about the relative sound quality merits of the loudspeakers in the mono tests than in the stereo tests."