Evidence-based Speaker Designs

[Frank Dernie]

I get the impression that there has been a lot of solid development invested in BT speakers and sound bars.

Me too.
Reading about the R&D that went into the Apple Homepod speaker is most impressive.
I won't be using one though since it seems it only works streaming, which I don't do much and I have Qobuz not iTunes for streaming.

 

[Frank Dernie]

one because they have an autistic child

I am Aspergers but don't believe the bollox about vaccines causing autism, there isn't any credible evidence.
In fact my sense of humour was rather tickled by a meme I saw where one person said "a lot of scientists have autism" to which the reply was "in that case one could say autism causes vaccines"

 

[Blumlein 88]

I am Aspergers but don't believe the bollox about vaccines causing autism, there isn't any credible evidence.
In fact my sense of humour was rather tickled by a meme I saw where one person said "a lot of scientists have autism" to which the reply was "in that case one could say autism causes vaccines"

I understand that. But I'll cut some slack for people facing an aspect like an autistic child. They desperately look for answers, and if they latch onto it being vaccines I can forgive them their mistake. Such reactions are only human. I'll have no forgiveness for those who peddle this garbage thinking and seek to profit or gain power via it.

 

[Frank Dernie]

High end audio is the entertainment business.

My view has always been that it is a fashion business. What is considered the thing varies from country to country (depending on the marketing IMHO) and the prices of used kit is far more in line with fashion than entertainment.
When I went to work in France the most heavily marketed US brand of amplifier here was Krell with Levinson not really mentioned much or damned with faint praise.
In France the opposite was true. All about the contacts/marketing of the appropriate importer.

 

[Blumlein 88]

The "Lego" approach is being used by Nord. There are now single board Hypex and Icepower amplifiers. That means power supply and a stereo amp on one board. Just put it in a box. The only drawback is low input sensitivity where 2.35V is needed to reach 200 watts. Anyone know of a good cheap preamp?

Just use a recording interface. Most of those put out a few volts. You'll have a nice DAC, headphone amp and monitor output in one box. Plus you can do some recording if you wish.

 

[Blumlein 88]

You're right, it would really be difficult for Amir to make tests of amplifiers for the reasons you've mentioned and speakers are even more complicated logistic wyse. However, what is average Joe's problem is the obsession with DACs and belief that changing DAC would improve SQ.

It is one of those cliche situations. The guy looking for his keys by the lamp post. Not because he lost them there, but because being in the dark you can only see to look over by the light.

 

[JJB70]

Me too.
Reading about the R&D that went into the Apple Homepod speaker is most impressive.
I won't be using one though since it seems it only works streaming, which I don't do much and I have Qobuz not iTunes for streaming.

Indeed. Audio equipment has changed and evolved. I think many are too dismissive of wireless speakers and sound bars. The traditional stereo system is increasingly a niche product and I think even the high end will increasingly move towards wireless digital speakers. Even Beats headphones, they are still too bass heavy for me but under Apple ownership they have addressed some basic issues and now seem to be be well engineered products if you like their sound (and many clearly do like it).

 

[GGroch]

I seems like the main criteria on this list is the dispersion pattern of the speaker, or more precisely constant directivity. While I do agree that the dispersion pattern is important, I don't think the psychoacoustic evidence so far suggests that it's the most important factor when it comes to perceived fidelity.......But at the moment, I don't think there's enough evidence to point out constant directivity designs as inherently more "evidence-based" than others. ".

This is what confuses me on this thread. The terms directivity/dispersion are not used until actual evaluation begins in paragraph 3.

Choosing "rationally-defensible approaches at constant directivity" as the primary determinant of what constitutes evidence based speaker design seems highly subjective. Its importance would depend on the circumstances. As mentioned earlier, a lot of science goes into the development of many speakers, from the Apple Homepod, to many soundbars, to almost any Bose product.

Is prioritizing constant directivity inherently more science based than prioritizing dynamic range, minimizing the audible effects of cabinet resonance, or even creating a sense of envelopment from a 2.1 system?

 

[Ron Texas]

Just use a recording interface. Most of those put out a few volts. You'll have a nice DAC, headphone amp and monitor output in one box. Plus you can do some recording if you wish.

Is this what you had in mind?

https://focusrite.com/usb-audio-interface/scarlett/scarlett-2i2

Do these things apply gain to the USB playback? It even has balanced out.

Any other products in mind?

 

[Ron Texas]

Anyone care to supply a list of domesticated active speakers at reasonable prices. A lot of the pro stuff just isn't housebroken, unless you like the industrial look. Kii and the 8c are more than I would ever spend, even after a windfall. The main one which comes to mind is the LS50w. A sub out feature, which the Kef has, would be nice.

 

[JJB70]

I have Kef X300 speakers in my home office. I paid about £250 for them (new, clearance), I like them.

 

[Blumlein 88]

Is this what you had in mind?

https://focusrite.com/usb-audio-interface/scarlett/scarlett-2i2

Do these things apply gain to the USB playback? It even has balanced out.

Any other products in mind?

This or something similar yes. That particular one has an output of 2.45 volts at max (0 db FS). If you go up in price just a little you'll usually see more output. The Scarlett 6i6 for instance has 3.1 volt max output.

https://focusrite.com/usb-audio-interface/scarlett/scarlett-6i6

The Clarett is a better quality of DAC and ADC from Focusrite. This one puts out 6.15 volts. Its a bit more expensive at around $400. There is also a version for Thunderbolt instead of USB if that matters.

https://focusrite.com/usb-c-audio-interface/clarett-usb/clarett-2pre-usb

You can get similar performance from other brands in this type of product.

http://motu.com/products/proaudio/ultralite-mk4/specs.html This one for around $600 has 7.75 volt output, some good specs and is controllable with smartphone or tablets. An increasingly common and useful feature.

The big drawback to these is no remote control which the MOTU solves more or less.

 

[Ron Texas]

This or something similar yes. That particular one has an output of 2.45 volts at max (0 db FS). If you go up in price just a little you'll usually see more output. The Scarlett 6i6 for instance has 3.1 volt max output.

If I go this route, 2.35V will drive the typical 200W @ 8 ohms Hypex amp. However, I am more likely to look at active speakers. Unfortunately, a lot of them are on the ugly side. The JBL's have better cosmetics than most.

 

[Floyd Toole]

Yes, that was David Smith's interpretation, not mine - and he explicitly says in the rest of the quote (that I didn't include) that he thinks dr. @Floyd Toole moved towards emphasizing room curves later on, in spite of the findings from his early NRC studies.

But I do think dr. Toole has beeen indicating here on the forum that room curves are not the most important thing in itself - that they rather are a function of a well-performing speaker? Which would roughly mean that "a well-performing speaker a decent room curve makes", but that "retro-fitting a decent room curve doesn't a well-performing speaker make". Better to let the Dr. explain it himself!

What I do think one can see from both dr. Toole's research and other studies, is that a wide directivity is often preferred by many listeners - as it increases envelopment etc, and this is often perceived as more important than razor sharp stereo imaging. I tend to agree with @Cosmik that the directivity pattern of the loudspeaker is the one area in sound reproduction where there's no "right" answer as to what fidelity would entail.

Hello again. I've been otherwise engaged for a while and am catching up. You are right that the strongest evidence linked to perceived sound quality in a room is a comprehensive set of anechoic data. Room curves are only loosely connected, except at low frequencies where they are the only reliable data. When we see a family of on- and off-axis anechoic curves, all smooth and indicating either constant DI or gradually rising DI we have learned (a) that there are no audible resonances and (b) that the spectral balance of direct and reflected sounds will have something in common. Which is more important? I vote for the absence of resonances, because timbral colorations of that kind are easily heard and corrupt all program material independent of the listening space. Neutral loudspeakers tend to "disappear" behind the double-blind screen, allowing the spatial cues in recordings to be heard.

The matching of direct and reflected spectral balances is less well defined. In Figure 7.12 in my current book describes an elaborate test done around 1985. I show that the least preferred loudspeaker had arguably the most constant DI, but was more directional than the higher rated speakers with quite uneven off axis radiation, but more of it. Listeners seemed to have voted for more "space" and seemed to be able to rationalize the low-Q directional variations. BTW the spatial perceptions cannot be "envelopment" in the classic sense because that is correlated with much delayed (e.g. 100 ms) sounds, as in concert halls. This is why multichannel reproduction has huge advantages. What is it then, that causes the preference for some reflected sounds? My personal theory is that it has to do with the fundamental limitation of two-channel stereo, in which some of the sound almost inevitably emerges from the L or R loudspeakers - hard panned by console controls or by mic techniques. When this happens close miked solo instruments or groups of orchestra instruments emerge from a point in space. I have found this to be highly annoying in some recordings as it is plainly unrealistic. Spraying the sound around adjacent walls softens the mono L&R images. It also softens the amplitude panned images between the loudspeakers which some people disparage and others find appealing. The musical genre is likely a factor. But the basic issue is that conventional stereo cannot deliver the goods and we look for ways to improve it.

Is constant directivity, including omnidirectIonality, better than the slightly increasing DI of conventional forward-firing cones and domes? Having heard both over many years I have no preference. If there are no audible resonances the difference devolves to the localized sense of space and delocalization I just described. Neither is more "correct" in stereo reproduction. In multichannel systems it simply does not matter - with more real sound sources direct sounds dominate. Forward firing designs occupy less room volume and are likely to be preferred.

My current preference for multichannel upmixing is based on its superior performance and its adjustability for different programs. Such a system also permits playback of multichannel music recordings, music videos (some of which are excellent) and movies. If your circumstances permit it, I highly recommend it.

Here is a link to a description of my present system:
https://www.dropbox.com/s/gg5wnct6010gvuq/3-Part Toole Home Theater 2018.pdf?dl=0

 

[Krunok]

It is one of those cliche situations. The guy looking for his keys by the lamp post. Not because he lost them there, but because being in the dark you can only see to look over by the light.

So true. But then, isn't the word "cliche" in fact very related to the word "average" in terms of behaviour?

 

[RayDunzl]

The only drawback is low input sensitivity where 2.35V is needed to reach 200 watts.

Well...

It leaves a little headroom in the amp (1.4dB) if driving with 2V.

2.35V /2.0V =1.175

Or is it only 0.7dB?

Either way, not much.

You plan to run it wide open?

(assuming you have 2V, of course)

 

[Ron Texas]

@RayDunzl, I don't know. My thinking right now is either keep the D30/LS50/Dynamo 1000W/XLS 1502 combo or look for active speakers, either with or without a built in DAC. The problem is most of them are not decor friendly.

 

[oivavoi]

Thank you so much for a very thorough and enlightening answer, dr. @Floyd Toole ! I am seriously thinking about going the mch route.

 

[Soniclife]

Couldn't agree more, and feel like you're one of the few people in the audiophile world saying this.

IME the sound quality of some of the better BT speakers in 2019 is light years ahead of then more-expensive "mini systems" and boomboxes of 20 years past.

I would love to see some measurements of old crap hifi, I think they might be shockingly bad. It's hard to work out what would be representative of old kit, to make it worth testing.

 

[Blumlein 88]

If I go this route, 2.35V will drive the typical 200W @ 8 ohms Hypex amp. However, I am more likely to look at active speakers. Unfortunately, a lot of them are on the ugly side. The JBL's have better cosmetics than most.

Some actives will have inputs labeled -10 dbv for consumer and +4 dbu for pro. The consumer setting required about 3.1 volts for Max out. The pro setting required about 12 volts for Max out. Of course there are exceptions. Something with 3 or 4 volts out is unlikely to be a problem.