Acoustic treatment

jon_5912:
"Has anyone ever tried having a single big sub and a few more smaller ones? I'd think a single sub that goes to 20hz would be enough and then 3 smaller ones that only maybe go down to 30hz could be used to even out the response. Locate the big one in the best spot for very deep bass and the other three can even out the response from 30-80hz. There tends to be a huge price difference between subs that will go to 20hz vs 30."


Hello jon,
     Very good question.  I've never tried this myself but I don't believe there's any reason this wouldn't provide accurate, detailed, smooth and natural bass with deep bass extension down to 20 Hz.  I suspect, however, having only one sub extending down to 20 Hz might limit the power and impact heard and felt at that deep bass frequency.  But It may be possible to compensate by having the volume set higher on the sub that goes to 20 Hz or you could always use two and still be saving money, just a bit less.  
     You should also probably go look and hear some subs, 30 Hz sounds and feels quite deep and may be sufficient for some.


Tim       

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.

I'm not going to address the reasons why you might, or might not want bass traps.  I'll just answer your question.  I've used Cotton Batting panels, Rockwool and Pressed fiberglass panels to make acoustic panels and bass traps.

I prefer making panels out of Owens Corning 703 & 705 fiberglass.  It cut's more easily and straighter than the other two options.  Additionally, when covering it with cloth, I find it comes out smoother than with the other two options if the cloth has contact with the insulating material. 

If you wear long sleeves, disposable respirator and safety glasses you will not be bothered by the fiberglass. 

Here is a link to a project that I did with fiberglass panels;
https://photos.app.goo.gl/1oKg2mjmU1tcBe4V9

geoffkait:
">>>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! - 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."

Hello geoffkait,

Yes, I did miss your point. Maybe if you didn’t wear that huge hat, your point would be more easily seen. Oh, Wow! Wowie Wow Wow! Now that you’re hat’s off and I’m closer, I can see you obviously have a very significant point there. Oh my god! No way! What the....Wow, maybe you should put your huge cowboy hat back on now, that point you have there on your head is really freaking me out!
Anyway, I completely agree with you that CD recording and playback does have its problems and has the capacity and potential to be of much higher quality. Those issues you mentioned and the serious issue of compressed dynamics (Loudness wars) caused me to now use less CD content and more 24bit/96KHz FLAC downloads, especially those recorded direct to digital.
However, this thread was started inquiring about bass room treatments and my suggestion was to invest in a better bass system like a DBA instead. While I believe the subjects of the quality of CD recordings and playback are very valid and important ones, I think it may be better suited for its own thread or threads.

Tim

Tim, I think you should find a job as a used car salesman, excuse me salesperson.
Actually summed bass below 100 Hz is an advantage in most acoustic situations you would have in the typical home.
Jon, It would be easier with identical subs. But if you have to use the large sub midway between your speakers and the small ones flanking. I would mono the lot. 
Geoffkait  you did not answer the question, how big? Wikipedia has the equation. I'll give you a hint. It is highly unlikely that anyone here has a room large enough to fit a Tube Trap that large.
Back to Tim, The term "room control" is a misnomer. You are not controlling the room. You are controlling the speaker to correct response abnormalities of the speaker/room system, to make both sides have exactly the same response and correct timing so that the sound from each driver hits the listening position at exactly the same time. With a good unit the listening position can be any where in the room! Where ever you plant the microphone. You still have to minimize acoustic aberrations in the room or you will waste a lot of power and even bottom out a sub driver. Any sub woofer system is going to sound better because you can correct and improve the sub inherent frequency response which is hardly ever flat. Every uncorrected smaller (12" and less) sub that I have ever measured has a response curve that falls off as you go down. 
This can be correct and I even give them a response that rises to +3 db at 20 Hz then at 28 Hz falls off like a rock 10th order! Tim, if you want your bass to really perk up you want to make sure each one is exactly the same distance from your listening position. You can put them anywhere in the room as long as the distance is the same. They should preferably all be up against a wall. It also helps if your speakers are also that same distance assuming everything is phase correct.