How NOT to set up speakers and room treatment ( Goldensound)

[Axo1989]

There's a huge disparity between house sizes in 'young' countries vs. old European homes.
The following floor plans are of a typical layout for a 2 & 1/2 bed, 2-storey house here in Oxford (good luck finding one for less than £600k).
I hope it helps people understand that we have different requirements both in terms of speaker beamwidth as well treatment.

Looks like from the time when you received visitors front-of-house but maintained a separate private living room. What period?

 

[tuga]

You just flunked the test of whether you had read Dr. Toole's book and teaching.

Dr. Toole/Olive's research showed that for broad resonances, minimum audible resonance is that is audible in bass frequencies is 0.5 dB. With that knowledge, you then look at the minimum impedance of the speaker in low frequencies. For any broad minima, you then compute what the resistance of the wire would be to cause that 0.5 dB drop and hence cause an audible difference. This is covered in page 425 of Dr. Toole's book (original revision):

View attachment 290149

So either you have not read Dr. Toole's book, or if you have, did what I said: didn't pay attention to what you were reading.

I hope you don't mind me posting a rebutal quote taken from one of the BBC Research Department research reports by H. D. Harwood:

A/B testing
(...) Now the alarming fact is that A /B testing may under certain circumstances give rise to completely wrong results when comparing the sound quality of two loudspeakers.
If pink noise is used as a convenient source, and a deep narrow crevasse (dip) produced in it, it has been shown that the effect will be almost inaudible.
If this is listened to for, say, half a minute as if programme were being used to judge a loudspeaker, and then the crevasse (dip) is switched out so that a uniform spectrum is produced, the ear will hear a strong colouration at the frequency of the crevasse (dip).
It seems that there are two mechanisms at work; the conscious one ignores the crevasse (dip) but the subconscious one detects it clearly.
When the uniform condition is suddenly heard the subconscious mechanism comes forward and points out that there is now a considerable amount more sound energy at the frequency of the crevasse (dip), and as that condition had been accepted as satisfactory the only conclusion to be reached is that there is now an excess in this region and that the sound must now be highly coloured.
Transferring this to loudspeakers it is implied that if one with a crevasse (dip) is first listened to then it will probably appear that one with a uniform response is coloured. (...)

 

[tuga]

Looks like from the time when you received visitors front-of-house but maintained a separate private living room. What period?

I think that the style is Edwardian, slighly over a hundred years old perhaps.
But new homes are even smaller; the joys of a profit-driven economy.

 

[tuga]

I have taken the following from a BBC Research Department report on a reflection-free style studio desgn titled "CONTROLLED IMAGE DESIGN: The management of stereophonic image quality".

3. EARLY EFFECTS

In the time immediately following its emission from a small source, a sound wave will propagate as if it were in an open space. Each radial vector from the point of emission can be treated somewhat like a light-ray. An entire branch of acoustics has been developed to study such ray-like propagation. At its simplest, each elemental ray may be followed through its interactions with surfaces and objects as they are encountered. Some of these methods follow these hypothetical rays until they vanish into insignificance.

In reality, the accuracy of representation of the interactions becomes inadequate for such extended multiplication and the system becomes more or less chaotic. However, the representation may be sufficiently realistic to be useful for the short term response and for a few interactions. (Some ray-tracing implementations approximate the later behaviour by assuming non-geometric behaviour for higher reflection orders.)

Many workers have studied the human hearing response in the time domain. The ‘early’ sound can be subdivided into three different time-intervals*. In the time period up to about 5 ms, there is no directional discrimination between the sound travelling along the direct path from source to listener and any reflected sound, provided that their relative levels are reasonable. This ‘precedence (Haas) effect’ dictates that the apparent direction of the sound is that of the first arrival.

After this first time interval and up to about 50 – 80 milliseconds after the arrival of the direct path from source to listener, the human auditory process can perceive and interpret a detailed pattern of reflection arrival times. Parameters such as apparent source direction and distance are derived from the sound signal. In the region between 5 and about 10 – 20 ms, reflections are capable of causing confusion about the apparent direction of a sound source.

After about 80 ms, at most, the sound energy is integrated. Reflection events are either not perceived individually or appear as discrete echoes, depending on their level relative to the remainder of the sound.

The human perception mechanism is capable of carrying out all of these processes on a continuous pattern of arrivals — it does not need isolated sound events.

For the acoustic designer of sound control rooms, these properties mean that some control of the pattern of reflections reaching the listener is desirable.


4. THE CONTROL OF EARLY REFLECTIONS

The control of early reflections and the effects on stereophonic imaging applies only to those rooms in which sound is reproduced by two or more loudspeakers. These include sound control rooms, post-processing areas and listening rooms. (In studios, early reflection control is important, to avoid anomalous acoustic effects, but this is usually a matter of artistic judgement by the programme makers and is part of the production control process.)

The extent to which control of the early reflected energy is necessary is not immediately obvious. Much has been written on the audibility of relatively early ‘echoes’, essentially beginning with Haas in 1951. Most of this is applicable to large performance spaces. Practically all prior work on simulations relates to the audibility of single echoes. In contrast, the problem of the effects on stereophony of a multiplicity of early reflections in a ‘real’ room is less well reported*. This is inevitable because of the large number of dimensions involved in such investigations: the time and direction of arrival, relative amplitude and frequency response are all important parameters. When multiplied by even a small number of reflections, the investigation problem becomes intractable.

It is quite clear that the threshold of audibility of a single early reflection, which some results suggest may be at a level of about −30 dB (or even −40 dB) relative to the direct sound, is not the appropriate limiting criterion for the satisfactory perception of stereophony in real rooms. Indeed, there is some evidence that the stereophonic illusion is less convincing (or doesn’t work at all) in an anechoic room. The levels of early reflections in conventional sound control rooms, treated with acoustic absorption only, are in the range −5 dB to −12 dB for the first 20 ms. Stereophonic listening has been carried out reasonably satisfactorily for many years in such rooms.

For the purposes of this work, a consensus of the available information suggested that a target of −20 dB and 20 ms would be appropriate for the assessment of stereophony. That is, at the listening position, no reflection greater than −20 dB relative to the direct sound would occur in the first 20 ms.

This was not supposed to be a precisely justifiable and objectively supportable criterion. Rather, it represented a goal which would be realistically achievable in reasonable sizes of room. It encompassed much of the available objective information about the disturbance of stereophonic images. It was a convenient, simple rectangle in time and sound level. What is meant acoustically by ‘the listening position’ is discussed below.

In other applications, time windows of up to 80–100 ms are used to calculate some quality criteria, but these are not related directly to the perception of multi-channel stereophony as commonly implemented in small rooms. Indeed, it is well-known that the common form of two-channel stereophony, using a pair of spaced sound sources, does not work very well if the spacing of the sources is larger than about 4 – 5 m.

Most of the published work suggests that the audibility of early reflections diminishes rapidly for levels below about −20 dB, even for isolated reflections.

To control the early sound energy, those surfaces located in positions capable of creating early reflections at the listening position must be designed to avoid causing such reflections.

One anticipated problem arose from the knowledge that the stereophonic illusion did not work so well in an anechoic environment unless the listener was very close to the centre-line between the loudspeakers. If the principle of the control of early reflected energy was to be usable, some investigation of the sensitivity to changes in the listening position was needed. One of the main purposes of the construction of a prototype room was to investigate the severity of this potential disadvantage.

http://downloads.bbc.co.uk/rd/pubs/reports/1995-04.pdf

 

[restorer-john]

The following floor plans are of a typical layout for a 2 & 1/2 bed, 2-storey house here in Oxford

That's pretty much the same floorplan of the 2 storey house my mother grew up in in Burton-on-Trent in the 1940s, built in the 20s or 30s I'd guess. I think they are pretty bog standard aren't they?

The only difference is two or three chimneys and several fireplaces are missing these days. And a hallway is missing. Do you really have to walk through all those front rooms to get to the kitchen?

 

[tuga]

Amray's 2D raytracing simulator is an interesting tool to understand sound reflections.

Amray - The Raytracing Sketchpad

Sketch your room shape and play around with speaker and listener positions. See in real time how you could splay walls to get rid of unwanted reflections. Or find out where all first andsecond reflections come from.

amcoustics.com

 

[tuga]

That's pretty much the same floorplan of the 2 storey house my mother grew up in in Burton-on-Trent in the 1940s, built in the 20s or 30s I'd guess. I think they are pretty bog standard aren't they?

The only difference is two or three chimneys and several fireplaces are missing these days. And a hallway is missing. Do you really have to walk through all those front rooms to get to the kitchen?

They're pretty standard all over, yes. This one is actually on the big side for Oxford.

In regard to your second questions, Brits are very conservative and some developpers still request that we add fake chimney breasts in the sitting room and to put fake plastic chimneys on the roof...

 

[restorer-john]

In regard to your second questions, Brits are very conservative and some developpers still request that we add fake chimney breasts in the sitting room and to put fake plastic chimneys on the roof...

OMG. That's crazy. So fake plastic chimneys?

 

[DanielT]

Again, it's a question of taste and also music style preference. I much much prefer it as dry as possible as I think it represents the mix "as it's supposed to sound". But again; I also put an effort in getting my HiFi system as close to my IEM. -Because I like it that way.

I get the thought of listening to classic music in a lively room but I can't get my head around that rock or electronic music would sound especially good in the same environment.

The amount of bass is just that amount used in that example. Here is where personal EQ comes in handy.

Edit: And I really don't get the stubbornness from either "side" on an issue that is, IMO, clearly a question of taste, flinging each and every "biblical evidence" at each other. -It's not pretty.
The premise from the start was the (young!?) dude on YouTube who tries to advice on room treatment and acoustics without the prerequisites to do so with too much credibility. But he tried. Mind you there is far worse advice out there. -Multiple videos from GR Research and PS Audio comes to mind..

Sure, like and taste. In that video example, with less bass and added EQ, I would prefer treated rooms with that music.

At full mix untreated room if you listen at high volume the bass sounds terrible. Better bass then with the treated room but for my taste a bit too much bass even then. When listening at a higher volume, that is.

It could also be that my headphones maybe boosts the bass too much (I suspect this is the case). Nothing I've researched because I only use them (Soundcore by Anker Life Q30 headphones) when I'm lying on the couch and casually surfing YouTube and similar sites. Plus listening to internet radio (music and talk podcasts).

 

[Sokel]

They're pretty standard all over, yes. This one is actually on the big side for Oxford.

In regard to your second questions, Brits are very conservative and some developpers still request that we add fake chimney breasts in the sitting room and to put fake plastic chimneys on the roof...

I once saw a big statue of an elephant on the roof of a big property in Namibia and thought it was extreme but these chimneys easily outperforms it

 

[tuga]

OMG. That's crazy. So fake plastic chimneys?

The public and the planners don't want new land to be developped, but if it has to happen then it better look like it's been there for the past half century...

 

[tuga]

I once saw a big statue of an elephant on the roof of a big property in Namibia and thought it was extreme but these chimneys easily outperforms it

Here we have this on the roof of a home where an artist used to live (the sea is some 80 miles out):

 

[Sokel]

Here we have this on the roof of a home where an artist used to live (the sea is some 80 miles out):

I would prefer that over the fake chimney,at least that is near Tom Robbins's monolith analogy,makes you think,imagine,makes a story!

 

[Axo1989]

Amray's 2D raytracing simulator is an interesting tool to understand sound reflections.

Amray - The Raytracing Sketchpad

Sketch your room shape and play around with speaker and listener positions. See in real time how you could splay walls to get rid of unwanted reflections. Or find out where all first andsecond reflections come from.

amcoustics.com

Yes, it's great. I posted some images upthread (from a while back in my downstairs room, being renovated now). What I didn't do was use a detailed background image like this one, must do that next time.

 

[thewas]

Maybe because of the translator we do not understand each other well.
I know the information and some gurus comment that correcting above 500hz is harmful because the off-axis response cannot be corrected,
it may even be farther from the ideal, even if the correction is on the anechoic response of the box.

The Edifier of that test has though a simple waveguide and not a too bad directivity so when equalised doesn't look too bad:

My comment was not only in that direction, but in that blind test shows that a box with a mediocre design according to Harman group standards
according to Harman group standards, which is cheap, of simple construction,
with a lousy front end from a diffraction point of view, whose score without EQ was very low,
after equalization it was only 2 tenths below the theoretically excellent Neumann HK80 in the "Sound Rating" graph,
with a spinorama bordering on the ideal.

That its score with EQ is so high is result of its decent directivity and thus not in contradiction to the Harman research.

 

[TheZebraKilledDarwin]

I get the thought of listening to classic music in a lively room

Have you ever heard a good classical discrete multichannel recording, in a good sounding dry room, with 7 good sounding and correctly installed identical speakers?
The Austrian state television every year is broadcasting the concert of the Wiener Philharmoniker. It is broadcast in discrete 5.1 and the sound engineers of that event have a good reputation worldwide. They seem to know what they are doing.

I don't know where this claim of additional room reverb for classical recordings comes from, but it seems not to come from people who have heard classical surround recordings in professionally sounding, quite dry rooms. I wonder if anyone making such a claim, has ever heard a good classical stereo recording on a professional setup.

The depth and envelopment of good classical 2.0 recordings is amazing.
A perfectly set up 7.1 system with identical speakers and an upmixer not adding any kind of ambience (Auro) or coloration (DTS, Auro), like the standard Dolby upmixer in Atmos capable receivers, will "only" spread the antiphase side channel information perfectly into the 4 surrounds without changing the stereo image, but only enhancing the perceived depth.

To me the recording engineers and mixers of these old 2.0 recordings, who did not have 7.1 upmixers available to emphasize and hear potential problems more clearly, but only had the proven mid-side-technique and their stereo monitors available - in their DRY rooms - were geniuses.

Imagine making a classical stereo recording 40 years ago, that is upmixed on par with the best discrete surround recordings...

Once you have heard that, you have gathered the empirical knowledge that all the spatial information obviously can be contained in great stereo mixes and no additional reverbation is needed for "envelopment" or "depth" for classical music.

 

[amirm]

Why that (Toole's preference) is suddenly better or right is beyond comprehension... Your admiration for the man and his work is clouding your judgement.

Suddenly? Didn't you not read me repeatedly saying how much personal research I performed before accepting Dr. Toole's compelling view? And what is the alternative? Listening to Joe random online? Or reading and understanding this paper:

LOUDSPEAKERS AND ROOMS FOR STEREOPHONIC SOUND REPRODUCTION
FLOYD E. TOOLE National Research Council of Canada, Ottawa, Ont., KIA OR6,Canada

For which Dr. Toole received a Silver Medal from Audio Engineering Society? This paper was published back in 1990 or 23 years ago. In there, you see graphs like this:

Making a safe bet that you don't know how to read this graph, let me interpret it for you. It says that in the common domestic rooms where delays are below 10 milliseconds for a lateral reflections (10 foot longer path length), to hear what you think is bad, i.e. distinct reflections, the reflection needs to actually be louder than the direct signal! I have marked the 0 dB line indicating this (and the dashed/solid lines based on Haas and Meyer/Schodder research). This is obviously is not going to happen in any room unless it is the shape of a circle or something. So whatever you gut tells you here is wrong.

At the other extreme, the threshold of hearing if there is a reflection at all, is -15 dB or so. In other words, it doesn't take much for the side reflection to become inaudible.

In the middle we have image shift or spreading of the sound away from the speaker -- the very thing many listeners like.

Notice how the graph is composition of research by others plus that of Dr. Toole's team. And all of it is before Dr. Toole arrived at Harman.

So lets see: we listen to you or a man who has dedicated his 50+ year career to this topic. Thinking...thinking... I think I will go with Dr. Toole and all the other researchers instead of what you have to say.

 

[tuga]

The depth and envelopment of good classical 2.0 recordings is amazing.

I am happy with 2-channel, and the recordings don't have to be BIS or Channel Classics level, lesser ones work fine too (musically they're just as engaging). I don't need or enjoy the effects of early side-reflections, nor do I need extra channels although I am sure that multi-channel recordings over as many channels are going to produce a more enveloping and realistic illusion. Upmixing, no thanks.

 

[tuga]

Suddenly? Didn't you not read me repeatedly saying how much personal research I performed before accepting Dr. Toole's compelling view? And what is the alternative? Listening to Joe random online? Or reading and understanding this paper:

LOUDSPEAKERS AND ROOMS FOR STEREOPHONIC SOUND REPRODUCTION
FLOYD E. TOOLE National Research Council of Canada, Ottawa, Ont., KIA OR6,Canada

For which Dr. Toole received a Silver Medal from Audio Engineering Society? This paper was published back in 1990 or 23 years ago. In there, you see graphs like this:

View attachment 290184

Making a safe bet that you don't know how to read this graph, let me interpret it for you. It says that in the common domestic rooms where delays are below 10 milliseconds for a lateral reflections (10 foot longer path length), to hear what you think is bad, i.e. distinct reflections, the reflection needs to actually be louder than the direct signal! I have marked the 0 dB line indicating this (and the dashed/solid lines based on Haas and Meyer/Schodder research). This is obviously is not going to happen in any room unless it is the shape of a circle or something. So whatever you gut tells you here is wrong.

At the other extreme, the threshold of hearing if there is a reflection at all, is -15 dB or so. In other words, it doesn't take much for the side reflection to become inaudible.

In the middle we have image shift or spreading of the sound away from the speaker -- the very thing many listeners like.

Notice how the graph is composition of research by others plus that of Dr. Toole's team. And all of it is before Dr. Toole arrived at Harman.

So lets see: we listen to you or a man who has dedicated his 50+ year career to this topic. Thinking...thinking... I think I will go with Dr. Toole and all the other researchers instead of what you have to say.

Your patronising tone is not worthy of a reply. Don't fall off your high horse.

 

[edechamps]

While it's true that stereo has its obvious weakness and mono is actually better in some areas (no superposition), the question is whether we get closer to the recorded signal or mix with or without side wall reflections. And the answer here is clearly that we get closer without side wall reflections.

You say this as if it's obvious, but it's really not. Toole argues that side reflections actually allow you to hear the original signal more accurately, as evidenced by speech intelligibility experiments (Toole hypothesizes that this is because reflections allow your auditory system to get a "second look" at the signal).

You seem to be making an implicit assumption that a stereo signal is meant to be listened to without side reflections, i.e. that getting rid of the side reflections will bring you closer to the artist's intent. I find that to be a somewhat extraordinary claim and would love to see some citations for it.

A/B testing
(...) Now the alarming fact is that A /B testing may under certain circumstances give rise to completely wrong results when comparing the sound quality of two loudspeakers.
If pink noise is used as a convenient source, and a deep narrow crevasse (dip) produced in it, it has been shown that the effect will be almost inaudible.
If this is listened to for, say, half a minute as if programme were being used to judge a loudspeaker, and then the crevasse (dip) is switched out so that a uniform spectrum is produced, the ear will hear a strong colouration at the frequency of the crevasse (dip).
It seems that there are two mechanisms at work; the conscious one ignores the crevasse (dip) but the subconscious one detects it clearly.
When the uniform condition is suddenly heard the subconscious mechanism comes forward and points out that there is now a considerable amount more sound energy at the frequency of the crevasse (dip), and as that condition had been accepted as satisfactory the only conclusion to be reached is that there is now an excess in this region and that the sound must now be highly coloured.
Transferring this to loudspeakers it is implied that if one with a crevasse (dip) is first listened to then it will probably appear that one with a uniform response is coloured. (...)

Two things here:

1. The experiment you describe appears to be using pink noise as a way to test for preference (or perceived accuracy). This is a pointless experiment, as real material does not resemble pink noise. Pink noise is a useful signal to run some discrimination experiments (e.g. to determine worst-case just-noticeable-difference thresholds), alongside other kind of test signals (such as impulses), but that's not what's happening here.

2. Even if the phenomenon you describe (i.e. the preference of perceived accuracy of a loudspeaker depends on what was listened to immediately before) is real, any study worth its salt will control for this phenomenon anyway. Randomizing the order of loudspeaker presentation is an obvious way to do that.