Ever stand in front of a large satalite dish. Notice how everything sounds wierd? This is ridiculous.
A long time ago, a co-worker decided that he could build an anechoic chamber the size of a phone-booth for measuring loudspeakers, thus replacing the six-figure price tag with a three-figure one.
I was conscripted to make some audio measurements of the little enclosure, and to try to find a way to subtract its frequency response from that of the speaker under test, so that we would get the true frequency response of the speaker system (and not the mini-chamber).
I was not a believer in the idea, but when the boss tells you what he wants you to do to earn this week's pay, and it looks like it might be fun, you do it. 🙂
The mini-chamber was built pretty much exactly as you described, with plywood and lots of fibreglass insulation inside.
I started my measurements by mounting a woofer with a known frequency response to a plate mounted to one wall, and a calibrated measurement microphone on a slender wand stuck into a hole in the opposite wall.
I was not surprised to find that the acoustic response of the box itself had a vast array of enormous peaks and dips in its frequency response. Basically it was the inside of a giant loudspeaker enclosure, and suffered from all the internal acoustic standing waves that any speaker box would. All that fibreglass stuffing inside didn't even come close to controlling this problem.
I think if you build a car-sized booth for audio, you would have the same issue: the acoustic response of the mini-room would be very far from flat, and that would colour all the music you listened to in there. Like listening to music (or singing) in your bathroom. Big honking resonances everywhere in the frequency band.
My suggestion is to try near-field listening instead. It gives you the same kind of intimate listening experience, without the damaging acoustics of a tiny listening environment (and it's cheap and easy, too!)
Here is a convenient how-to from Sweetwater: https://www.sweetwater.com/insync/techniques-setting-up-nearfield-monitor-speakers/
Here is another how-to (it's flawed - the speakers should be at head height, not chest height - but the pictures might be helpful): https://www.musicradar.com/tuition/...monitors-correctly-in-a-project-studio-645713
In a nutshell, the idea is to have the speakers at head-height, within 3 - 5 feet of your head, and placed so that (seen from above) your head and the two speakers form an equilateral triangle.
If you've never tried this before, the results are amazing when you first hear it. The effect of room reflections and room modes is reduced drastically, and most of what you hear comes directly from the speakers. If you have good speakers, the result is detail and clarity that is almost startling. It's a bit like using a pair of really good headphones, but with better bass and proper stereo imaging.
You can give this a try at zero cost and with minimal effort, so why not try it? All you need is something the right height to place the speakers on, say a pair of bar-stools.
I listen to a lot of music in my vehicle, too, and enjoy it while I'm driving (and most of my mind is occupied with that task, rather than critical listening.) If I park the vehicle and listen to music, however, I quickly become aware of the poor acoustics and general low quality of the audio.
-Gnobuddy
Exactly! cbdb posted this while I was typing up my reply above. We're both making the same point.
-Gnobuddy
Maybe the nearfield setup will do - my "Kallax" Synergy is really great even when not finished and playing in mono (I tried it this afternoon). A pair of these in nearfield should sound like giant headphones, only need to sort out the bass.
IMO, it sounds much, much better than headphones. Headphones tend to collapse much of the stereo image into one loud noise that appears to come from inside the rear of your skull, instead of being spread across an invisible stage in front of you. I find it a very irritating auditory illusion, though young'uns who grew up listening to nothing but ear-buds seem unbothered by it.
With qood quality speakers and near-field listening, you get the opposite of collapsed-stereo headphone sound: you get a spectacularly good stereo image, with crisp placement of sound sources from left to right.
A lot of over-the-ear headphones also produce considerable bass rolloff, so the music ends up light on deep bass. Near-field monitoring doesn't suffer from this problem. You get all the bass your speakers are putting out.
Combine the superb stereo imaging with the dramatically reduced effect of imperfect room acoustics, and this is why a lot of music is mixed down on near-field monitors. Unless you have a huge, acoustically-treated listening room, near-field listening is about the best you can get.
I actually do all my music and TV listening through a pair of near-field studio monitors, moved a little further away and further apart, so my wife and I can both share the sweet spot. More mid-field than near-field, but it still works well. Deep bass is augmented by a Velodyne subwoofer.
-Gnobuddy
I have one SLOB with 2 12" - all awaits a proper measurement session. My CNC spindle is broken, so my free time will go into measurements. Unfortunately, the CNC gave up before I built a spinning table for that.
Another vote for the Sonic egg chair. Done right with something like 6.5" coaxials or equivalent and a woofer mounted free air to the bottom of the chair and you have ****s and giggles for years.
Thats such a smart concept. Ultra near field for smoother bass response. Higher SPL with lower power and distortion and less bass leak.
I couldnt find the thread. Anyone have a link?
I think you mean, if someone else builds something as silly as a Sonic Egg Chair you will have ***s and giggles at his expense for years. 😀
-Gnobuddy
I remembered wrong, it was on Audio Circle! Took some searching to find it.
https://www.audiocircle.com/index.php?topic=54844.0
And here is my build: https://www.diyaudio.com/community/threads/slob-2x12-subwoofer-for-near-field.384529/
Wait a goddamn minute! Yes rule of thirds placement is often near perfect but makes the room useless for other purposes.
The TigerFox's beneficial outcome seems to be much more from nearfield rule of thirds type placement then the materials itself.
FYI i have these chairs that I never really used for hifi listening... perhaps i should measure the response versus the Ikea Poang I use...
![kpMebrR[1].jpg](https://www.diyaudio.com/community/data/attachments/961/961345-f485f4920067470ca66e928c9a35bfc4.jpg?hash=9IX0kgBnRw "kpMebrR[1].jpg")
The TigerFox's beneficial outcome seems to be much more from nearfield rule of thirds type placement then the materials itself.
FYI i have these chairs that I never really used for hifi listening... perhaps i should measure the response versus the Ikea Poang I use...
I have fantasized about the "pod" idea for some time, inspired by having heard pretty impressive sound systems in cars, also built-in comfortable seating.
One thing that is great about cars is that the sound isolation is actually pretty good. The main reason for this is that the doors have to be completely air/water tight, so there is no sound leakage. This initial reduction of say 30 to 40 dB could be a huge advantage where you have neighbors or family members nearby. If you are listening in your "car" at 110 dB, then this can step down to a much more manageable 70 to 80 dB in the room where your "pod" is located. Ordinary walls and floors have some chance of stepping this down to normal 40 dBA background level.
Another thing is you will want is for your "pod" to be isolated from the floor structure with some high-deflection rubber isolators so the natural frequency will be down in the 8 to 10 Hz range. Pneumatic tires could actually do a pretty good job of this, right?
Also, you want your "pod" to have windows, right? You want to see what's going on around you.
So I was trying to think of the best kind of construction to emulate the positive things about a car as a listening/isolation environment, perhaps build it like the way you would build a voice-over booth, isolated floor, double glass, sound-rated door, etc, or at least a budget-friendly version of these things.
Then I started thinking, couldn't you just buy a totaled car with the passenger cabin intact, maybe chop off the front and back and that would be your prefab "pod" ready to go. Of course getting it in your house (or especially your apartment!) could be challenging . . .
As for sound quality, you don't really have any "modes" in the low bass range. It's more of a compression chamber since you are well below any room modes. If 8 feet is your largest dimension, then 70 Hz is your lowest axial mode. You at least have a chance of absorbing these frequencies. Sure a car stereo may not be equivalent to a serious listening room, but I have to say I have listened to a couple car systems with pretty amazing performance.
One thing that is great about cars is that the sound isolation is actually pretty good. The main reason for this is that the doors have to be completely air/water tight, so there is no sound leakage. This initial reduction of say 30 to 40 dB could be a huge advantage where you have neighbors or family members nearby. If you are listening in your "car" at 110 dB, then this can step down to a much more manageable 70 to 80 dB in the room where your "pod" is located. Ordinary walls and floors have some chance of stepping this down to normal 40 dBA background level.
Another thing is you will want is for your "pod" to be isolated from the floor structure with some high-deflection rubber isolators so the natural frequency will be down in the 8 to 10 Hz range. Pneumatic tires could actually do a pretty good job of this, right?
Also, you want your "pod" to have windows, right? You want to see what's going on around you.
So I was trying to think of the best kind of construction to emulate the positive things about a car as a listening/isolation environment, perhaps build it like the way you would build a voice-over booth, isolated floor, double glass, sound-rated door, etc, or at least a budget-friendly version of these things.
Then I started thinking, couldn't you just buy a totaled car with the passenger cabin intact, maybe chop off the front and back and that would be your prefab "pod" ready to go. Of course getting it in your house (or especially your apartment!) could be challenging . . .
As for sound quality, you don't really have any "modes" in the low bass range. It's more of a compression chamber since you are well below any room modes. If 8 feet is your largest dimension, then 70 Hz is your lowest axial mode. You at least have a chance of absorbing these frequencies. Sure a car stereo may not be equivalent to a serious listening room, but I have to say I have listened to a couple car systems with pretty amazing performance.
Okay. It certainly won't be the first time. 🙂
But only on diyAudio would people actually think it was actually a good idea to build a giant speaker-box and stick your head inside it. 😀
Actually I did that when I was about 15. I had built a working record player from odds and ends, but my first pass at the audio amplifier had too little voltage gain, and my home-made platter drive wasn't working yet. The only way to play a record and hear what was coming out of the loudspeaker was to wear the open-back speaker box on one's head, while turning the platter at roughly the right speed with a fingertip. 😀
-Gnobuddy