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PostPosted: Wed Jul 05, 2006 12:07 am 
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Joined: Tue Jul 04, 2006 11:48 pm
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Location: Italy
My 2 cents (and my first post...)

Hi all, reading you from Italy, and loving every word I read from SPCR!

Getting back to the point, I came up with an idea, don't know if it has already been discussed in the past or not, but here it is the same.

I read carefully both the old and new methodologies for getting sound/noise readings, adopted by SPCR staff, and if for some things I think I can agree with both methods, there are other things that make my nose tickle. I am no expert so maybe I'm completely wrong, please forgive me if this is the case, but my idea is this:

Wouldn't it be better to build a small aneconic enclosure where to put inside it the article to be noise-reviewed, with several mics installed in the strategic points (up, front, back, left side, right side) at a predetermined distance, so to be able to record noise produced in all directions regardless of ambient noise, external factors and so forth?

This enclosure should be in noise-dampening material, of course, and with a small pedestal in the middle where to install the article to be reviewed. Mics should be installed in the internal walls, encastonated inside the dampenind foam with conical shape (just like in an aneconic chamber, but smaller in dimensions). Overall dimensions of the enclosure should respect your methodologies (walls @ 1m from object, with the possibility to "push in" some mics to get 1ft readings).

What do you think of this? Please let me know your comments, I am willing to build such an enclosure this summer for my personal reviews (I am moderator of a modding website in Italy, btw).

Garacs1

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PostPosted: Wed Jul 05, 2006 12:34 am 
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Joined: Sun Aug 11, 2002 3:26 pm
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Location: Vancouver, BC, Canada
Welcome to SPCR.

It's an interesting but complex and ultimately flawed idea. The problem is "small anechoic enclosure". There's no such thing. Small enclosures suffer from boundary effects that cannot be overcome with tricks. They need to be a certain size for them for be truly anechoic, and have a decently low bass cutoff frequency to be effective. Which is why the anechoic chambers built in the last 2 years by Intel, IBM and nVidia are all ~20x24x14' and cost ~$200,000 just for the anechoic portion alone -- not the building / room in which it goes, nor the equipment. Multiple mics are good, but only if they are all very high quality -- the mics we're dealing with cost $350 and $600. How many do you think we can afford?

The mic array you suggest would not give us any more information nor info in any standardized format that jibes with established audio measurement techniques. It sounds like a vague hemi-spherical array of the typed used to measure sound power, but it would not give accurate results for that. Also, sound power is no longer regarded as having that good a correlation with human hearing.

We keep our test procedures as simple and consistent as we can, follow well-established rules and principles whenever possible, and totally repeatable. Even so, we still end up with some rather complex test procedures and setups. We don't need to make them any more complex than they already are.

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Last edited by MikeC on Wed Jul 05, 2006 11:59 am, edited 1 time in total.

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PostPosted: Wed Jul 05, 2006 4:12 am 
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Joined: Tue Jul 04, 2006 11:48 pm
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Location: Italy
I get the point, MikeC, and thank you for taking your time to reply. I was somewhat prepared for the costs, but did not imagine they were so HIGH!

Eventhough, taking by chance the fact that we (you, me, anybody) still could afford to pay for such structures, still remains the dimensional issue, as you pointed out. Not being a pro in sound relieving procedures, reading the fact that INTEL and so on build anechoic (sorry for the typo before) chambers spending as much as several thousand dollars astonishes me, specially if I think that we (noiseless pc enthusiasts) tend totry and build costless similar anechoic enclosures, much smaller in dimensions, and even "adaptable" to our needs. I'm mentioning our pc cases, which we tend to try and make noiseless at no or very little cost. Now, reverting the thing to you, could you (SPCR staff) try to build an enclosure a little big bigger than a normal pc case, which still corresponds to your testing procedures, using low cost noise dampening material, build still in correspondance with noise relieving procedures (at least trying to), so to give a much more professional approach to your reviews? Please do not feel offended by this last part: I am not judging nor criticizing your work, in many ways exceptional and extraordinary. I'm just discussing in a friendly manner on what could be done to improve quality and most of all, insert repeatibility to reviews regarding noise. I've been working for some time (approx 7 years) in the PC accessories market, focusing my attention in extreme air and liquid cooling, and I've always stated (that repeatibility and quality of instrumentation in reviews is the key to give end users a precise idea on how a heatsink, or waterblock performs. in the "noise" business, it should, and maybe it just could be the same.

Garacs1

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PostPosted: Wed Jul 05, 2006 11:22 am 
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garacs1 wrote:
......Now, reverting the thing to you, could you (SPCR staff) try to build an enclosure a little big bigger than a normal pc case, which still corresponds to your testing procedures, using low cost noise dampening material, build still in correspondance with noise relieving procedures (at least trying to), so to give a much more professional approach to your reviews?.....

My previous answer should have made this clear: There's nothing about such an approach that is at all professional. Following your suggested technique would lead to much less repeatable, much less professional, much less useful, much less realistic results than we have now. You simply cannot take audio measurements in such a constricted space and expect to have any kind of accuracy.

Sorry if I sound blunt, no slight is intended; I am simply trying to be clear, and appreciate that you're not communicating in your native tongue.

The rooms in which we conduct our measurements and recordings are very quiet (<20 dBA) rooms of average dampening, which means that real users in real rooms can expect results very much like our own when using the products that we test & review.

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Support SPCR by buying your gear through this link: Amazon


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PostPosted: Wed Jul 05, 2006 11:47 am 
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Joined: Wed Apr 26, 2006 9:11 am
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Location: frozen tundra
MikeC wrote:
garacs1 wrote:
......Now, reverting the thing to you, could you (SPCR staff) try to build an enclosure a little big bigger than a normal pc case, which still corresponds to your testing procedures, using low cost noise dampening material, build still in correspondance with noise relieving procedures (at least trying to), so to give a much more professional approach to your reviews?.....

My previous answer should have made this clear: There's nothing about such an approach that is at all professional. Following your suggested technique would lead to much less repeatable, much less professional, much less useful, much less realistic results than we have now. You simply cannot take audio measurements in such a constricted space and expect to have any kind of accuracy.

Sorry if I sound blunt, no slight is intended; I am simply trying to be clear, and appreciate that you're not communicating in your native tongue.

The rooms in which we conduct our measurements and recordings are very quiet (<20 dBA) rooms of average dampening, which means that real users in real rooms can expect results very much like our own when using the products that we test & review.



HERE HERE!!!

Mike is right on! to have a realistic recording you need space... space is important... have you ever heard the difference in your voice in the shower or other inclosed space... why would it be any diffrent for computer noise ;)

take it from an audio engineer space is neccessary


PS: SWEET NEW SHOTGUN :lol:

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PostPosted: Thu Jul 13, 2006 1:35 am 
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Joined: Sun Jan 16, 2005 2:59 am
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Location: Santa Cruz
I have helped build an Anechoic Chamber,the internal open area wasabout 7 ft x 8 ft x 11 ft. The baffles were stainless mesh triangles,stuffed with fiber,the walls a 2" thick sandwich of stainless steel and foam. The baffles consisted of triangles about 10" in depth. The structure was all Stainless,as it was at an oceanside Marine Lab. The purpose-to record the sounds of seals and sea lions. It had to be Echo-free so the details could be studied. The Size of a large seal like Bernice probably determined the scale of it. Price? I don't know but I'd guess well beyond $20,000.

I think for fairly small sounds-computer parts,a chamber could be 20% of that size. too small,and theres not quite the space to deflect/absorb sound which would tend to slightly exaggerate the gap between a relaively louder item and a quieter one.

For SPCR...it's not about trying to figure out language patterns of Harbor Seals...its about relative loudness of computer parts in a context that relates to what we'd experiance. A bit of room echo,if a constant,is barely measurable. The main deal is no irregular background noise. Rather than SPCR spending thousands to create a "perfect" chamber-I'd rather they test more stuff I'd be thinking of buying.


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