Listening in an Anechoic Chamber - a report

[rdenney]

RF

In reality it attenuates both. But is designed, certified, and used for certain RF frequencies/signals.

The traps don't look deep enough to work at low audio frequencies. Every chamber has a frequency below which it does not attenuate effectively. Such low frequencies will really give a large space like that a sense of air.

By the way, here is entertaining reading on the construction of McIntosh's anechoic chamber back in the Roger Russell period. They also had a blind-testing room.

McIntosh Anechoic Chamber

Rick "54-inch depth low-passes at 65 Hz" Denney

 

[sarumbear]

40cm seams to be as good as 305

Gearspace.com - View Single Post - Basotect air flow resistivity numbers/thickness

Post 12900638 -Forum for professional and amateur recording engineers to share techniques and advice.

gearspace.com

Multi-layer Absorber Calculator

at these thicknesses you need a much less denser material to improove:

Multi-layer Absorber Calculator

that means bascily fluffy stuff you find in pillows

Thank you for these calculations. I thought as much from experience but never had a reason to calculate such an odd assembly. I really like to see it. 10’ is a huge thickness. The poster uses the word burrowed. Does that a miss used word or they really carved into a solid Basotect? If not how are the layers of Basotect stick together, how thick each layer?

 

[sarumbear]

The traps don't look deep enough to work at low audio frequencies. Every chamber has a frequency below which it does not attenuate effectively. Such low frequencies will really give a large space like that a sense of air.

By the way, here is entertaining reading on the construction of McIntosh's anechoic chamber back in the Roger Russel period. They also had a blind-testing room.

McIntosh Anechoic Chamber

Rick "54-inch depth low-passes at 65 Hz" Denney

Why were their speakers marketed properly I wonder? One expects McIntosh speakers to be all over the market at the time. I have never even knew they had a speaker range.

 

[rdenney]

Why were their speakers marketed properly I wonder? One expects McIntosh speakers to be all over the market at the time. I have never even knew they had a speaker range.

I think they were marketed--that cheesy photo of Roger Russell and Carl Van Gelder in the anechoic chamber was an ad I remember from the hi-fi press of the late 70's or early 80's. It was the only visual of an anechoic chamber most people ever saw. But their speakers were expensive--lots (and lots) of drivers hand-made and assembled in Binghamton, NY--so my interest was academic only.

By the way, Russell had done his design in reverberant rooms, and decided to build a proper anechoic chamber after visiting with and meeting Floyd Toole at the Canadian NRC labs in 1977. He said Toole had tested their premiere speaker and found it to sound good but measure poorly. Instead of complaining about how measurements suck, etc., he upped his testing game. Out of that came his work with column arrays of tweeters. But those were even pricier. Here I am, the owner of a pair of Advents, looking at speakers that retailed for $5,000 and up in the middle 80's.

Roger Russell's web pages are still up, though he passed away last year, and are must-reading for any audio enthusiast, it seems to me.

Rick "he stuck with the tall vertical column array of many small, full-range drivers right to the last" Denney

 

[sarumbear]

I think they were marketed--that cheesy photo of Roger Russell and Carl Van Gelder in the anechoic chamber was an ad I remember from the hi-fi press of the late 70's or early 80's. It was the only visual of an anechoic chamber most people ever saw. But their speakers were expensive--lots (and lots) of drivers hand-made and assembled in Binghamton, NY--so my interest was academic only.

By the way, Russell had done his design in reverberant rooms, and decided to build a proper anechoic chamber after visiting with and meeting Floyd Toole at the Canadian NRC labs in 1977. He said Toole had tested their premiere speaker and found it to sound good but measure poorly. Instead of complaining about how measurements suck, etc., he upped his testing game. Out of that came his work with column arrays of tweeters. But those were even pricier. Here I am, the owner of a pair of Advents, looking at speakers that retailed for $5,000 and up in the middle 80's.

Roger Russell's web pages are still up, though he passed away last year, and are must-reading for any audio enthusiast, it seems to me.

Rick "he stuck with the tall vertical column array of many small, full-range drivers right to the last" Denney

Here in the UK I have never heard of a McIntosh speaker, nor seen one even though I owned their amplifiers between 70s and 90s. The only Mac speaker I saw was a behemoth with zillion tweeters and woofers on two separate towers at a Russian oligarch’s house outside London. I assumed it to be a custom model. I looked at their website now and that model doesn’t exist anymore. They have some large speakers that seems to use CBT alignment. Does your towers use CBT alignment too?

 

[rdenney]

Here in the UK I have never heard of a McIntosh speaker, nor seen one even though I owned their amplifiers between 70s and 90s. The only Mac speaker I saw was a behemoth with zillion tweeters and woofers on two separate towers at a Russian oligarch’s house outside London. I assumed it to be a custom model. I looked at their website now and that model doesn’t exist anymore. They have some large speakers that seems to use CBT alignment. Does your towers use CBT alignment too?

What you are describing sounds like one of the XRT-xx models from the 80's.

Not "mine," though. Read Roger Russell's web site, and he spends a lot of time explaining it. I don't think he developed a phased array, though.

Rick "intrigued but not paying what those kinds of speakers cost" Denney

 

[sarumbear]

What you are describing sounds like one of the XRT-xx models from the 80's.

Not "mine," though. Read Roger Russell's web site, and he spends a lot of time explaining it. I don't think he developed a phased array, though.

Rick "intrigued but not paying what those kinds of speakers cost" Denney

I read Mr. Russel’s words but I didn’t know that yours was using the same design.

His entire premise is based on the following, which I do not agree. It is as subjective as it gets.

A preconceived notion about a long column is that it produces comb filtering and tweeters interfere with each other causing sharp narrow dips in response. Although this can be shown by producing sine wave response curves, it fails to explain why it is not heard. Our hearing process compensates for this by the Precedence or Haas effect.After hearing an initial signal, the brain will suppress any later signal, such as an echo, for a time up to about 30 or 40 milliseconds. This inhibition is called time or temporal masking. In effect, you do not hear the sound from the higher or lower drivers that would otherwise interfere with locating the nearest source of the sound. It is thought to have evolved as a survival response. The behavior explains why the highs in long columns like the McIntosh XRT20 and XRT22 seem to always come from the area opposite to your listening height.

 

[Inner Space]

10' absorption on almost all surfaces in a 30' x 30' x 14' room is not what is called a residential property.

The room is in a property in which I reside. Therefore it is what is called a residential property.

My imagination is fully engaged but your language skills seems to be less so.

My language skills? Consider the following:

Does that a miss used word or they really carved into a solid Basotect? If not how are the layers of Basotect stick together, how thick each layer?

This is completely incoherent garbage. "Does that a miss used word" - In English we say "misused", not "miss used" and what the hell does the rest of the clause mean? Why "or they"? Are you missing an "are"? Why "a solid Basotect"? What does the "a" contribute? And why not use the past participle "stuck" instead of the present "stick"? Is "how thick each layer" some kind of pidgin? And so on. In other words, check your attitude at the door, you patronizing and hypocritical git.

 

[sarumbear]

In other words, check your attitude at the door, you patronizing and hypocritical git.

I was considerate in my address to you as “they” because I do not know if you are a male, female or transgender.

I hope the moderator will take action for calling me names. It’s not called for and shouldn’t be allowed on a public forum.

 

[Raindog123]

for calling me names. It’s not called for and shouldn’t be allowed

I am just a happy bystander, but from where I stand you’ve totally started it with your “language skills”.

And I thought you both were gentlemen, no?

 

[sarumbear]

I am just a happy bystander, but from where I stand you’ve totally started it with your “language skills”.

And I thought you both were gentlemen, no?

Al I said was “a 30' x 30' x 14' room cannot be called a residential property.” Will you say “a” residential property to have 14' ceiling?

In any case I refuse to be called a git! No gentlemen will use that word.

 

[rdenney]

I read Mr. Russel’s words but I didn’t know that yours was using the same design.

His entire premise is based on the following, which I do not agree. It is as subjective as it gets.

I don't have a design and my only association with Roger Russell is what I read on those pages. If you don't agree with Mr. Russell--totally cool with me. But he is not without credentials in objective design and testing.

Rick "noting the previous mentioned of a blind-testing room at McIntosh, however" Denney

 

[Inner Space]

In any case I refuse to be called a git!

Then don't behave like one. Perhaps you would prefer "a persnickety little fussbudget"? Which is how you come across.

 

[sarumbear]

fussbudget - Google Search

You simply cannot stop using derogatory terms can you?

 

[Raindog123]

To be constructive, I‘ve just googled “vaulted ceiling height” and got “A vaulted ceiling in our definition is a ceiling higher than the typical 8-foot flat ceiling height. Typical vaulted ceiling height in previous projects can be anywhere from 12 - 25 ft.”

For what it’s worth. I‘ve run out of steam here…

 

[sarumbear]

To be constructive, I‘ve just googled “vaulted ceiling height” and got “A vaulted ceiling in our definition is a ceiling higher than the typical 8-foot flat ceiling height. Typical vaulted ceiling height in previous projects can be anywhere from 12 - 25 ft.”

For what it’s worth. I‘ve run out of steam here…

Correct, like in a church. Do you expect to see such vaulted ceilings in a residential property?

Anyone I run out of steam as well. Life is too short.

 

[EEE272]

Correct, like in a church. Do you expect to see such vaulted ceilings in a residential property?

Anyone I run out of steam as well. Life is too short.

Yes, in mine!
No joke... it's an attic.
BTW. It is actually the room that I use to listen to music.

@Inner Space would you mind describing a bit more how it sounds to listen to music/movies in this almost anechoic room?
Do you disagree with Toole's findings about the sound being in your head for surround sound? I wonder if his observation depended a lot on the recording.

I did make a similar experience to what you said before. Initially I had a very reflective room and then bought my first absorbers... The change in terms of precision and immersion was incredible and I got a bit addicted to adding more...
My room is certainly not anechoic but rather dry by now with around .2 reverberation time - thus at the lower end of what is often suggested. I still really like it.

 

[Raindog123]

We, Americans, must be lucky bastards without even realizing it: Through my adult life, I’ve [consecutively] owned four separate houses. Three out of four did have vaulted front halves. The last two — insanely high ones — needed professional help hanging lights… When we started talking about high ceilings here today, in my mind it was totally a common thing. I guess, taken for granted…

 

[Inner Space]

@Inner Space would you mind describing a bit more how it sounds to listen to music/movies in this almost anechoic room?
Do you disagree with Toole's findings about the sound being in your head for surround sound? I wonder if his observation depended a lot on the recording.

Music only in that room - I'm indifferent to the whole HT thing, and get by with a 2.0 + 55" OLED system in a normal living room for TV.

I absolutely disagree with Toole on the issue, and would note he offers only an unsupported anecdote, that conveniently fits his predetermined enthusiasm for so-called envelopment via controlled reflections. (Worth noting: "the science" shows the majority of listeners choose clarity over envelopment [Lokki 2012] but if you're in the minority who prefer envelopment over clarity, then yes, Toole's your man, and certainly his work is extremely valuable, including to those majority members forced by circumstance to live in the minority's rooms.)

Music in an almost-anechoic room is characterized by extreme clarity - no blurring, smearing or masking by late-arriving reflections. For once, the old audiophile stuff about never-before-heard detail etc is absolutely evident, with, e.g., reverb tails clearly audible, trailing away to nothing. Stereo spread is correctly limited to the space between the speakers. Phantom images are sharp and precise. Depth (if recorded) can be dramatic. I really enjoy it.

My pursuit of this (admittedly eccentric) approach came from two directions - first, a private definition of accuracy, that says the sound waves at my ears should be prompted only by the bits in the incoming file, nothing else, with nothing taken away, and certainly nothing added. Privately it perplexes me that folks obsess over fidelity in the electronic realm, and then completely abandon fidelity in the acoustic realm, to the extent of deliberately adding delayed and amplitude-altered tones to those exiting their speakers. And then enthusing about it! It's the biggest disconnect I can think of. Suppose a DAC or an amp did that? What would ASR say about that?

The second direction was trying to clean up room modes, which led logically to suppressing LF reflection as completely as possible. Hence the super-deep absorbers.

The only identifiable negative is that removing room gain and reflections takes about 10dB out of the sound power in the room, which means using very much higher levels at the speakers to achieve the desired SPLs. In practice that generally means using speakers with high sensitivity, running pretty hard.

 

[Axo1989]

Yes, in mine!
No joke... it's an attic.
BTW. It is actually the room that I use to listen to music.

@Inner Space would you mind describing a bit more how it sounds to listen to music/movies in this almost anechoic room?
Do you disagree with Toole's findings about the sound being in your head for surround sound? I wonder if his observation depended a lot on the recording.

I did make a similar experience to what you said before. Initially I had a very reflective room and then bought my first absorbers... The change in terms of precision and immersion was incredible and I got a bit addicted to adding more...
My room is certainly not anechoic but rather dry by now with around .2 reverberation time - thus at the lower end of what is often suggested. I still really like it.

Well, posting as 'Inner Space' we shouldn't be surprised by a large room. I'd also like to hear/see more about it.

We, Americans, must be lucky bastards without even realizing it: Though my adult life, I’ve [consecutively] owned four separate houses. The three out of four did have vaulted front halves. The last two — insanely high ones — needed professional help hanging lights… When we started talking about high ceilings here today, in my mind it was totally a common thing. I guess, taken for granted…

You don't paint your own own ceilings then. Btw my listening room has a raked ceiling and forms an open mezzanine at the high end around 3.5 metres, it's only a medium size at 5 x 7 metres, if it were a full size room the ceiling would be a fair bit higher. Any residential design with an open living space of that type will have a high ceiling. Or one of the Kardashian's ensuites.

I also like a more directional speakers in a dry-ish room (n my case T60 sits under 200 ms until the bottom octave/s) with floor and ceiling treatment but nothing specific for deeper bass, which I may get around to.