however I think we are getting closer to the solution, the ideas are there, the only problem is the size, but we will solve everything
Bass reflex don't require large size to tune low, but to tune low and loud in a small size does requires large, long ducts, which will increase volume far beyond your target size.
The maximum VLF output in a 45 liter suitcase size will be achieved with very high power, high excursion drivers and passive radiators tuned to the lowest frequency desired.
Tom Danley's Contra Bass subwoofer was an example of that technology from last century, though his servodrive woofer's excursion potential was far less (only 19mm peak to peak) than those available shortly after, less than half that of Bob Carver's Sunfire subwoofer.
A doubling of excursion provides +6dB output, down in the <20Hz range, equivalent to more than "twice as loud".
Art
I wish! 'Smart': "having or showing a quick-witted intelligence"; there's too much proof to the contrary in my life, but over many decades have accumulated an above average amount knowledge about sound reproduction.
Regardless, it was a response to lcsaszar's assertion, cracked case's query.
'Suitcase' size, not a chance in this reality. Attached is the acoustical limits of various vented box sizes. 82 dB = 0.01%, so 80 dB is even lower. I've lost the math, but hopefully someone else will post it to calculate the 80 dB/10 Hz % eff., minimum box volume.
Attachments
so let's do one thing, for the bass reflex the maximum dimensions must be: height = 70 cm, depth = 40 cm and width = 45 cm. so from these dimensions I would like to build a bass reflex, so the frequencies, now do not matter much, but it is important for me to respect the dimensions, so any frequency (as long as infrasonic) is fine. obviously we take all the necessary precautions, high power drivers, passive radiators etc. to get the best result, so please send me the assembly instructions respecting those dimensions I wrote before, in order to immediately build the bass reflex, thanks friends
hi GM I had found formulas on the internet that told me that for a brass organ pipe with a length of 17 meters and a CSA of 37 cm I can get an SPL greater than 80 Db, so I think it is feasible, I want build both the bass reflex and also the tube, the dimensions are those written in my previous post and are also valid for the suitcase that must contain the tube, so I will build two suitcases, one that contains the bass reflex and one for the tube. so what should be the length and width of the tube, and with which drivers should I push the internal air? would a compressor be better?
A box of those exterior dimensions would work well for a Stereo Integrity HST-18, sealed.
You could expect near 97dB at 8Hz, 109 dB at 16 Hz at one meter at your feet.
Assembly instructions: Use 19mm Baltic Birch plywood, brace the interior similar to this:
Forget the pipe dreams, go for displacement!
Art
WOW! Wasn't aware of this monster! 😱 Definitely 'no replacement for displacement'!
100 L hits 80 dB/10 Hz w/23 W, 2pi, so not much power required either, though still don't see the point of this low a frequency @ so far below audibility. I mean even 14 Hz at this SPL just rattles small, loose objects in my house and that's mostly because it's apparently its Fs.
100 L hits 80 dB/10 Hz w/23 W, 2pi, so not much power required either, though still don't see the point of this low a frequency @ so far below audibility. I mean even 14 Hz at this SPL just rattles small, loose objects in my house and that's mostly because it's apparently its Fs.
The smaller ( in relation to it's length ) a pipe, the more pronounced the higher harmonics. That's why long organ pipes are also fat, the same principle is behind transmission lines having to be above a certain size. Shame you can't add density to the air in the pipe. I wonder what would happen if you put a passive radiator in an organ pipe. It's possible the wave would just bounce off.
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sorry i didn't understand because of the translation, so the project you sent me can create 16hz, or as you wrote at the end, must i forget the pipe dreams? I did not understand what should I do?
he talked about air density, so what if instead of "air" we put carbon dioxide in the tube? it is denser
Each pipe plays a single note. The reason there are so many is because there may be 100 or more “ranks” playing when a single key is played. Each rank is like it’s own instrument in an orchestra so the more ranks, the more colors of sound. Playback of a 2 channel audio recording of the organ is one thing. Playback from a digital organ is a different animal because there are usually a minimum of 6 channels of output for the very smallest organ on a tight budget in a small space. Most are at least 12 audio channels and as many as the hardware can support. You get all kinds of comb filtering if too much organ is jammed through too few of channels, but infrasonic comb filtering is very hard to solve and will blow up equipment. For perspective, here is the amplifier rack for a massive digital organ at Amalie Arena in Tampa Florida, USA. I think it has 64 channels of audio and I think 16 of them are just for bass.
