Acoustic treatment

Ya don’t get what I’m saying here. Look, it’s not rocket science. All you have to do, gentle readers, is compare the cassette version of almost any record with the CD version. Or the LP version. All will become clear.

In the case of the wretched CD there are two reason why bass response is really rather wimpy and apparently rolled off and otherwise unimpressive. It’s because of the two problems I have been pointing out of late regarding (1) scattered background laser light getting into the photodetector and (2) the fluttering, wobbly and vibratory nature of the CD itself that forces the laser servo mechanism such as it is to work overtime trying to keep the bloody laser on track. The geometry involved with how the laser reads the nanoscale data is extremely susceptible to vibration of the disc.

It wasn’t misonjin but you’re very close.

Huh? Didn’t you 🔙 post the equation last week? We already covered this last week. Does that refresh your memory?

Here’s a question for you - how can I hear a low frequency sound through ear buds if the wavelength is 32 feet?

Another question fir you - How can several tiny little bowls with diameters of 1” affect very low frequencies in the room?

Another question - How can a Schumann frequency generator affect the sound in the room when the wavelength of the Schumann frequency 7.8 Hz is 25,000 miles?

Even better!

Pretty smart!

From somewhere in cyberspace,

“We subsequently purchased the lot of lightweight frames and took them home with us and used them for many years. The idea behind the Room Tune was nothing new: a reflective membrane on one side and an absorptive material on the other.”

On the off chance nobody mentioned it already one key element of Tube Traps, the real ones, is that there is a reflective side that should face the room. This is also true for Michael Green’s corner tunes. Coincidence? In the immortal words of Acoustic Revive regarding the dodgy subject of damping, “One should be careful or else over-dumping can occur.” The other trick is to determine the actual standing wave location in room corners which may or may not be in the actual corner per se.

I’m filing your post under Whatever, Doc. And I have no idea what question it is I didn’t answered but I actually don’t care as the subject for today’s class is tiny little bowl resonators, not Tube Traps. Are physicians notoriously bad at staying on the subject? The last thing I mentioned on the subject of Tube Traps was most likely how difficult they are to set up, anyway. I have no idea what problems you had with Tube Traps. Most people don’t.

Earth to Tom - I know in space no one can hear you scream.

Enough jibber jabber. The reason tiny little bowls work is that the diameter of the bowls and corresponds to an acoustic wavelength AND an electromagnetic wavelength. That’s why Franck Tchang was able to *measure* effects up into the GHz range. In the acoustic domain the tiny bowls “equalize sound pressures” in the room by reducing (absorbing) unwanted high sound pressures like standing waves. We know that’s how they work because the high pressure zones in the room is where the tiny bowls are located ideally. Hel-loo! In the electromagnetic domain the tiny bowls absorb rf. It’s an acoustic resonator. And an electromagnetic resonator. It’s nothing so mysterious and goofy as shear wave velocity.

Deprogrammers are standing by. You can’t use that shear velocity baloney for everything. You can’t use it for isolation, much less tiny little bowls. It’s a nice day. Go out and get drunk.

“If I could explain it the average person they wouldn’t have given me the Nobel prize.”

You’re stuck in a rut. You need professional help. Deprogrammers are standing by 😳 😳 😳 😳

Who cares? I know you keep saying that. It simply doesn’t apply here. You can’t use it to explain everything. Anymore than repeating over and over, the sky is blue. Even if you say it a hundred times, which you actually have. Remember, one of us has a theoretical fluid dynamics and physics background. The other doesn’t? Go peddle your theory someplace else. How about visiting the library and come up with some new material?

Or it could be just the pressure equalization and electromagnetic wave absorption the review discusses. Hel-loo!

You can research the original Franck Tchang Acoustic Resonators. Here is one of the excellent reviews in 6 Moons,

https://6moons.com/audioreviews/francktchang/resonators_2.html

I must have gone farther in math than you did. No offense,

Huh? OK, I’ll repeat it. Maybe it will sink in this time. The frequency of operation for a Helmholtz resonator is a function of 3 variables - volume, nozzle diameter and nozzle length. Therefore, you would be able, well, maybe not you personally, but someone who knew what he was doing, to construct a Helmholtz resonator for 20 Hz that did not (rpt not) have a very large volume. You can also affect bass performance with tiny little bowl resonators. There’s lots of ways to skin a cat.

noble100
geoffkait:
"In the case of the much maligned CD not very much of the bass frequencies are coming through anyway so what’s the difference?"

Hello Mr. Rocket Science,

True RS, most cds and vinyl recordings only contain summed mono bass from 20 to about 100 Hz but reproducing whatever bass there is on the source material with high fidelity is still important for an optimum listening experience.

>>>I’m afraid you missed my point. The bass information’s there on the disc, and tons of it, it just isn’t being retrieved properly or completely - not by a long shot! Even when bass is mono it should have slam, go low in frequency and be articulate. It shouldn’t be wimpy, thin, rolled off or bland. As fate would have it the CD playback systems are plagued by a number of technical problems - even after all these years that prevent a lot of information from getting to the speakers. Primarily, scattered light and vibration of the CD itself, but also some other problems.

In the case of the much maligned CD not very much of the bass frequencies are coming through anyway so what’s the difference?

Size isn’t everything. I just got through explaining it. Hel-loo!

Helmholtz resonators’ effective frequency is a function of volume of the bottle, the diameter of the nozzle and the length of the nozzle so even a Coke bottle can be converted into a tube trap. It’s not rocket science! 🚀 The problem arises at shows where many Coke bottles and beer bottles litter the room randomly, creating acoustic chaos. 

I’m a big fan of tiny little bowl acoustic resonators as opposed to big ugly Tube Traps or mattress size panels. They’re much easier to set up, too. As it turns out corners aren’t even the right place for Tube Traps half the time.