Why An Anechoic Chamber?

[das]

Many people have asked us why we use a true anechoic for our speaker measurements. To us it might be obvious, but to others it's not. Likewise, the designers at many companies get asked the same thing. As a result, for the latest instalment of our "SoundStage! Shorts" features, we've added one featuring Bob Johnston, GoldenEar Techonology's Director of Engineering. Enjoy!

Doug Schneider
SoundStage!

 

[amirm]

Another excellent production by you all Doug and 100% perfect message. I am amazed how many companies not only have no anechoic chamber but release products without ever testing them there!

 

[das]

Another excellent production by you all Doug and 100% perfect message. I am amazed how many companies not only have no anechoic chamber but release products without ever testing them there!

Frankly, it's shocking when they do. That said, sometimes one has to visit the facility to really know what they have there. I'm not sure many people knew the extent of GoldenEar Technology's design facilities until we did the first video there, which I've also linked:

Doug Schneider
SoundStage!

 

[amirm]

I didn't know they had one either until your videos came out.

 

[das]

I didn't know they had one either until your videos came out.

This is one of the reasons we like to do these factory tours and video -- show places many people never see.

Doug Schneider
SoundStage!

 

[andromedaaudio]

A study to where as a free standing Ls measurement in different rooms is done and is compared to a measurment in an anechoic chanber, i would find more interesting to read , may be an idea for soundstage , a Freq response measurement
Again measuring a loudspeaker freestanding in different rooms , not very close to a wall versus a loudspeaker measurement in an anechoic chamber .
I bet you wont see much diff above 400 hz until 12 , 15 kHz or higher up
YG measures freestanding , they lift the speaker they want to measure high above the ground in a factory hall and they produce one of the best measuring (freq response ) loudspeakers .
I ve heard also a lot of speakers that are measured in a chamber sound like crap, so ....mmmm

 

[das]

YG measures freestanding , they lift the speaker they want to measure high above the ground in a factory hall and they produce one of the best measuring (freq response ) loudspeakers .

Actually, you might be surprised to know that YG Acoustics has made use of NRC's anechoic chamber for several years now -- and was just up again a few weeks ago. The most credible companies have or have access to a proper chamber.

Doug Schneider
SoundStage!

 

[andromedaaudio]

The last time i visted their site they explained they did the measurement like that that was indeed a couple of years ago , sure its a good thing , but it would be nice also to rule out once and for all, how a freq response would alter if any in the region i mentioned under room circumstances versus anechoic circumstances , that the bassregion alters is fact but otherwise .
A ls that measures flat in the bass in a chamber can measure or better will measure different in room and sounds accordingly.
And off course there are much more interesting designparameters to speakerdesign then a chamber measurement

 

[microstrip]

History is filled with contradictory facts. In the UK, in the 70's B&W marketing campaigns were build around their use of an huge anechoic chamber - the Building Research Establishment facility - and in the other extreme Peter Walker designed his famous ESL63 based only on physics and calculations, using a mathematical model, without experimental measurements taken on prototypes. It is often referred that he said something like : "we built it after the project, but yes we listened to it after it was finished" ...

I have read that some speaker manufacturers say that thanks to the powerful analyzing algorithms of computer based measuring systems nowadays they need much smaller anechoic chambers.

 

[das]

I have read that some speaker manufacturers say that thanks to the powerful analyzing algorithms of computer based measuring systems nowadays they need much smaller anechoic chambers.

I think that if that were 100% true, I personally wouldn't be itching to get into another chamber in our city that is 6X the size of NRC's, which is already bigger than many use. The reason is bass accuracy -- you need a really big chamber to measure it and you're not going to be able to model it completely on computer. There's a reason these companies build chambers -- they need them to develop.

Doug Schneider
SoundStage!

 

[microstrip]

I think that if that were 100% true, I personally wouldn't be itching to get into another chamber in our city that is 6X the size of NRC's, which is already bigger than many use. The reason is bass accuracy -- you need a really big chamber to measure it and you're not going to be able to model it completely on computer. There's a reason these companies build chambers -- they need them to develop.

Doug Schneider
SoundStage!

I understand your point - but some people who have access to the large chambers, such as B&W, claim that currently bass modeling using computers and specif measurement techniques is more accurate than real measurements. BTW, as far as I know, in Europe the clients of these large acoustic chambers are not mainly loudspeaker designers, but the industry, mostly because we live in a world of "certification".

 

[das]

I understand your point - but some people who have access to the large chambers, such as B&W, claim that currently bass modeling using computers and specif measurement techniques is more accurate than real measurements.

I think the actually thing is that it's extremely hard to get accurate bass measurements. To be truly anechoic down to 20Hz, it has to be enormous.

Doug Schneider
SoundStage!

 

[amirm]

I think the actually thing is that it's extremely hard to get accurate bass measurements. To be truly anechoic down to 20Hz, it has to be enormous.

Doug Schneider
SoundStage!

Micro is quoting B&W's blog there: http://blog.bowers-wilkins.com/sound-lab/tools-of-the-trade-the-anechoic-chamber/

"The bass response of a speaker is now more predictable using modern computer modelling techniques, which allows us to use a much smaller chamber."

What he means is that if they don't use the chamber for bass, then it obviously can be much smaller. Not that there is a trend toward using small chambers.

He does not articulate there or in later blogs that I checked on what computer modelling technique he is talking about.

 

[microstrip]

Micro is quoting B&W's blog there: http://blog.bowers-wilkins.com/sound-lab/tools-of-the-trade-the-anechoic-chamber/

"The bass response of a speaker is now more predictable using modern computer modelling techniques, which allows us to use a much smaller chamber."

What he means is that if they don't use the chamber for bass, then it obviously can be much smaller. Not that there is a trend toward using small chambers.

He does not articulate there or in later blogs that I checked on what computer modelling technique he is talking about.

Yes, the subject is referred briefly in this blog. However my search was triggered by an article in an old HFNRR magazine describing the collaboration work between B&W and UK universities - not sure any more if it was Essex or Salford. KEF was also referred in this article for similar reasons.

 

[das]

What he means is that if they don't use the chamber for bass, then it obviously can be much smaller. Not that there is a trend toward using small chambers.

He does not articulate there or in later blogs that I checked on what computer modelling technique he is talking about.

That makes quite a bit more sense. If you can't use a big enough chamber, you resort to other means. And what they're saying is correct about the modeling today being better. However, if you can get in an appropriate-sized chamber, you'll be able to confirm what the model predicts.

Doug Schneider
SoundStage!

 

[Rodney Gold]

Yes.. I do know that there are actual advantages to having a very good anechoic chambers response etc .. but the fact is that the room so seriously mangles them makes them somewhat less relevant to a consumer.
anechoic is a level playing field in an area that resembles the craters of an artillery salvo (room/speaker interactions)

 

[ddk]

History is filled with contradictory facts. In the UK, in the 70's B&W marketing campaigns were build around their use of an huge anechoic chamber - the Building Research Establishment facility - and in the other extreme Peter Walker designed his famous ESL63 based only on physics and calculations, using a mathematical model, without experimental measurements taken on prototypes. It is often referred that he said something like : "we built it after the project, but yes we listened to it after it was finished" ...

I have read that some speaker manufacturers say that thanks to the powerful analyzing algorithms of computer based measuring systems nowadays they need much smaller anechoic chambers.

It might be the nature of electrostats or just that some people can accomplish great results without every tool at their disposal, for all intent & purposes Roger West is clinically deaf yet his A1/B1 speaker is among the best ever made, bar none!

david