Alright Guys-at-Bose,

Can you talk a little about what makes a bass trap, both intentional, and unintentional? Maybe a little about how to recognize, by sight?? by sound??

Thanks, Oldghm

I've heard of a bass boat, a bass lure and even a singing bass, but I've never heard of a bass trap.

Can anyone help me out?

OK, I'm over there trying to answer your question and you're over here trying to be funny. "BASS TRAPS", not to confused with fishing, bass are sport fish and unlawful to trap in my part of the country.

Anyway, bass traps are room acoustic configurations that absorb sound energy at low frequencies. Mostly that's done intentionally to make rooms less boomy and reverberant. That’s especially important when the walls consist mainly hard material (brick, stone, log cabin), because these tend to absorb no bass at all.
There are a couple of different ways to go about that: Objects that can vibrate at those frequencies can easily absorb the energy and turn it into heat. Drywall in most American residential homes tends to do that. The actual dry wall is not particular stiff and can vibrate on the underlying framing and thus makes a good sound absorber in the frequency area around its resonance frequency.
Another method is to put panels with absorptive material at a certain distance in front of the wall. Using distance, mass and stiffness of the panel and thickness of the absorber one can tune the “trap” pretty accurately to a certain frequency range.
Certain objects in the room can also form bass traps: Large pieces of furniture with the right weight, stiffness and upholstery, heavy drapes that are not close to walls, large reflecting surfaces (that are not the walls themselves) with absorptive material between the surface and the next wall.
If you suspect that your basement has too much bass traps, it might help to move the B1 into a corner. That not only increases the efficiencies but also tends to provide a smoother frequency response in the bass region. If on the other you think, its too boomy, you should move the B1 away from any wall.

Hope that helps

Hilmar

This message has been edited. Last edited by: Ken-at-Bose,

Oldghm,

There are several articles linked from this page that you may find interesting.
http://www.realtraps.com/articles.htm

You might find this one poignantly apropos
Bass Traps - Not Just for Fishermen! by Ethan Winer

Thanks Hilmar, for the serious side.

Do you know why Bass don't sing in four part harmony?...............Because they are all singing bass.

I think you just described my basement as a BIG bass trap.

Oldghm

ST,

Thanks for the link, in reading that first article it would seem that my problem is actually the oppisite of a trap, too many reflective surfaces causing standing waves, thus I don't hear the bass.

Is this a proper interpretation? In my basement the Games in the middle of the room and the rectangular cabinets on either side all have reflective surfaces and are different distances from the speakers so they would effectively reflect different wavelengths causing multiple dead spots in what I hear, or don't hear, as the case seems to be.

When I brought the extra stereo speakers in to do the experiment with the recorded tracks the other day, I set them up facing across the narrow diminsion of the room rather than the long diminsion and was close while monitoring the recorded tracts, that might explain partly why I heard more bass from them than I did the PAS with 2 B1's.

Of course they're trying to sell product, and need to convince me only they have what I need, but that's what makes the world-go-round.

I sure didn't plan on all this when I decided to get the PAS, but hopfully I'm gathering information that will reward me many times over in future situations.

Thanks again, Oldghm

To all,

I went in last night and took the seat cushions from the sofa and placed them in front of the cabinets, didn't solve the problem but did make a noticeable difference. I feel like I may be on to something that will not only improve the PAS performance in the basement, but improve the overall music experience as well, and music is the primary thing in the basement.

Great links ST.

Oldghm

Oldghm,

Sorry I haven't been around too much lately, but yes, bass traps make a huge difference in the acoustical properties of your room, whether it's a studio, practice room, home theater/listening room, etc. If a room has not been specifically designed with acoustics in mind (i.e. the room has parallel walls, low ceilings, reflective walls, etc.) bass trapping is a great "band aid cure all" solution.

If you can get rigid fiberglass panels such as Owens Corning 703 or 705, cover them with fabric and put them in the corners of your room as well as along the walls, you'll notice quite a huge difference especially in the low end response. Things like sofas and mattresses help some, but they do not absorb down very low so they don't have quite the "wow factor" of rigid fiberglass.

You can probably treat your whole room for less than $300 if you make the traps yourself. Or if you have less time and more money, you can buy some... I'd highly recommend Ethan Winer's company, RealTraps. Ethan also has some great articles on acoustics and bass trapping, including DIY plans, on his web site, as ST already mentioned in this thread.

quote:

Originally posted by Oldghm:
...it would seem that my problem is actually the opposite of a trap, too many reflective surfaces causing standing waves, thus I don't hear the bass....

You're close. The furniture doesn't have much effect on the bass stuff, but....

There are two things going on in your basement - and any other normal room. First, the dimensions of the room will cause standing waves of specific frequencies at specific locations no matter what you do. Speaker location can exacerbate this effect. These low frequencies tend to roll around long after their useful work is done, and mess up following bass notes. Although the concept of reverberation time is not really useful in home size rooms, there is still a decay period to trouble you.

The second thing going on is "seismic" vibration. Don't worry. You don't have to check your Home Owners Policy. I'm talking about things like passing traffic outside, refrigerator compressors, wind shaking your home, and etc. All these things create a low frequency rumble of which you may not even be aware - until it goes away.

And that is the key: absorbing the LF stuff that is either not related to the music, or has outlived its usefulness. That is a job for the Bass Trap.

Now, the first thing to know about bass traps is that they need to be big, because the dimensions of the frequencies they are dealing with are big (i.e. measured in feet). The second thing to know is that it is really easy to absorb high frequencies, and really hard to absorb low ones. Most room treatments do exactly this; suck out all the highs, and do nothing for the lows.

The best product I have ever used is the "Tube Trap". Note that I have not used all products - Real Traps, for instance. Note that I also have no affiliation with Tube Trap except as a user. Tube Traps are a product of Acoustic Sciences Corporation. They are expensive. They really, really work. I have them in my listening room. I use them on projects.

The difference is unbelievable. Quite literally. No one believes it. Here is a Truth: Lets say you decide to spend the price of a Bose PAS Double Bass system on room treatment. What's that? $2600? OK. There is absolutely nothing - I say again - absolutely nothing that you can buy for $2600 that will give you the same improvement in sound that $2600 worth of Tube Trap will give you. Not a new amplifier. Not a new equalizer. Not a new microphone. Not a new mixing console. Not a new guitar. Not a new Pseudoacoustic Infector. Nothing.

Clearly, MacPhee has been taking too much pseudoephedrine, you say? See? I told you you wouldn't believe me. But it's true. Three things happen when you install Tube Traps.

First, the silence. You know the relief you feel when someone plugs in an instrument with a pick-up and it hums. Then something gets adjusted, and the hum goes away? Similar sort of effect when the bass gunge goes away in a room. There is a new kind of "black velour" silence. It is quite unmistakable. I swear, the room is actually "warmer" than it was before. (For those of you in hot climates, I don't know what your perception would be. But somehow, it is a more comfortable, enjoyable room to be in.)

Second, the bass. Oh yes! The bass! In one of those deliciously illogical truths that we stumble upon from time to time, to hear real bass in a room, you first need to remove all the bass. That done, a bass note from an instrument is finally able to stand (sorry) on its own, complete with its own series of harmonic complexities, unsullied by other bass gunge. Our hearing system actually makes a lot of judgements about the fundamental of a note from its harmonic structure. When you allow this system to work, the results are... unbelievable. Clean, punchy, warm, balanced, round, smooth, chocolatey bass.

Third, the dispersion. Earlier, I noted that one potential problem with room treatment is to absorb more high frequencies than low frequencies. Tube Traps take care of this by using a curved surface covered with a "limp mass crossover". As the frequency reaching the Tube Trap increases, the reflective property of the crossover increases, reflecting the HF energy back in the room where it belongs. Additionally, since the surface is curved, the highs are dispersed, creating a very dense early reflection field (that's a good thing).

There is really only one problem with Tube Traps. After you have spent the first $2600, you will be able to pinpoint some new acoustic anomalies which were completely unnoticed before. If I could put just one more over there and two more here....

The effects above are real. I do a convincing demonstration in my listening room. I simply remove all the Tube Traps and seat you in the room (you can stand if you like). We talk, and as I talk, I bring the Tube Traps back into the room one at a time. (Voice is an excellent test for this. We know when a voice sounds good.) You will hear a quantum improvement with each addition. Our voices will sound better and better. The noise floor of the room will drop. I'll play some music. Oh yes! The bass!

So why aren't Tube Traps everywhere (they work in rooms small and large)? They are unbelievable. No one believes it. Even after they have experienced it. Even after they have seen the before and after measurements. I am at a loss for an explanation.

Mike

PS Download the MATT mp3. Read the detailed description. Listen to the sound file on headphones first, to understand what it sounds like without room effects. Then play it in your basement. Start putting your spare change in a jar.

quote:

Lets say you decide to spend the price of a Bose PAS Double Bass system on room treatment. What's that? $2600?

It's $2,300 USD.

Thanks for the introduction to the Tube Trap ... very interesting. Did you buy them direct from ASC?

Steve

quote:

Originally posted by Steve-at-Bose:

quote:

Lets say you decide to spend the price of a Bose PAS Double Bass system on room treatment. What's that? $2600?

It's $2,300 USD.

Thanks for the introduction to the Tube Trap ... very interesting. Did you buy them direct from ASC?

Steve

Sorry about the price. CDN$2600. That's my story, and I'm stickin' to it.

I first got involved with Tube Traps to solve some severe acoustic problems in a hockey arena. A high Q sound system had been specified, but the civil engineer wouldn't sign off on attaching that weight to the ceiling structure.

So... there had to be a plan B, which turned out to be actually fixing the reverb time instead of trying to duck under it with directional loudspeakers. At that time, ASC had licenced a Canadian company to build the traps, as the US factory was struggling to keep up with demand. Avoiding the border crossing made them much more affordable in Canada as well. Since the Canadian factory, by sheer coincidence, happened to be quite close to the arena (both in the West Kootenays in BC), I was able to work with the factory for the design and installation details, and do the before and after tests. Right after I finished the tests, I ordered some for my home.

Unfortunately, the Canadian factory had a serious fire, and they just weren't able to bring it back on line again. Now I use product from Oregon. Many home theatre dealers sell the products, too.

I forgot to mention a couple of things in my last post. If oldghm thinks the high resolution PAS is making him a better performer, wait until he tries his high resolution speaker system in a high resolution room. The first thing he will notice is that he can be 3 feet or 15 feet away from the loudspeaker and it will sound the same. (This also works for recording, BTW. No longer do you need to weld everything in place if you need to stop mid session and resume later on. The room sounds the same everywhere. Just set up and go.) He will find that he will be able to play much louder if he wants, but he will also find that he will actually work at moderate levels, because all the detail is there. Need to set up your instrument? It's a lot easier when the room effects are gone. Finally, you can hear what all those twiddles do when yo twiddle them.

Highly recommended. Sorry for the advertisement, but they really are the perfect accessory for the PAS, both for rehearsal and gig spaces.

Wow MTM! Thanks for the info. I can't wait to research this stuff while saving my penneys.

Since my wife thinks the pas "looks" kinda nice in the living room, (and loves the sound), she should be thrilled to see this stuff arrive! LOL

I feel an audiophiliac attack coming on!

Thanks

These sound like exactly what I need for my cubical home studio. Thanks Mike!

One question, though: will my studio cat see these as being the world's most expensive scratching posts, or do they mount on stands up a bit from the floor?

quote:

Originally posted by Alan Steinberger:
These sound like exactly what I need for my cubical home studio. Thanks Mike!

One question, though: will my studio cat see these as being the world's most expensive scratching posts, or do they mount on stands up a bit from the floor?

Well, knock on wood, my cats have never bothered the Tube Traps. YMMV.

Having said that, Tube traps come in three "flavours"; full round, half round, and quarter round. They are four feet high standard, but they will do custom lengths. I think there is a tutorial on the website about how to apply them, but here is a quick primer.

First, do the corners. If you have the room, use full rounds. Nobody has the room, so use quarter rounds. Now, (and this part should sound familiar) you need to mount them so they are at ear level. Don't forget to account for seated and standing listeners. They are so effective in the corners that I like to fill them from near top to near bottom. This will probably require some custom lengths. They have a fastening/coupling connector built into the ends to deal with this. Next, put a half round in the middle of the wall behind your listening position (LP). Put a half round in the middle of the wall behind the speakers. Put a half round behind the speakers, or at about a 4' spacing, depending on room size. Now, get out a mirror and have a assistant move the mirror along the side wall until you, in the LP, can see a reflection of a speaker. A half round goes there. Soon you will see a reflection of the other speaker. A half round goes there. Ditto the other side wall.

Your room will now sound gorgeous. Generally, if your listening room is also your living room, your wife will have left you by now (even though they come in designer colours). If you have a surround speaker system, you may just as well go for the 4' spacing around the room and be done with it (this will cause her to serve the divorce papers).

If you are using point source speakers instead of a PAS, you may want to consider doing the mirror trick on the ceiling to catch that major reflection (this will cause her to apply for a restraining order).

I just said lots of money. Remember what I said, however. Whatever that dollar figure is, there is nothing you can purchase for that amount that will improve the sound of your system more. Well. Maybe a couple of those PAS studio monitors.

ASC has some other, lower cost products, but I have not used them in treating studio acoustics. Their premier product is the Tube Trap. A related product is the Studio Trap, which is a small, portable, stand mounted Tube Trap. If you do location recording, these do magic things for you, and you can take them back and do a room treatment with them when you are finished.

Mike

PS In proof reading this, it might sound like you need to buy all this at once. Not necessarily. As I said earlier, every Tube Trap that you bring into the room will improve how the room sounds. The first half dozen or so each make a huge difference. It's sort of like the PAS. Get one B1 now, and the other 15 as funds permit.

PPS ASC is always busy in the "skunk works". Make sure you chat through with them what you want to do. They may have some latest, greatest stuff. But there is nothing like a Tube Trap in my experience.

PPPA Warning! You are about to create a high resolution room. You won't believe how many things are not working properly. You'll hear hum and hiss and grainyness and fans and general gunge that you never even suspected before. On the other hand, you won't believe how easy it is dial in that mix.

quote:

Originally posted by J.G.Nelson:
Wow MTM! Thanks for the info. I can't wait to research this stuff while saving my penneys.

Since my wife thinks the pas "looks" kinda nice in the living room, (and loves the sound), she should be thrilled to see this stuff arrive! LOL



I feel an audiophiliac attack coming on!

Thanks

There *is* an aesthetic resonance between a Cylindrical Radiator and a Tube Trap.

However, note my comments about the WAF (Wife Acceptance Factor) in my reply to Alan Steinberger.

Great info, Mike! Thanks for the tutorial (and the morning chuckle!) I'm printing out your message for later reference.

I'm lucky in that so long as I understand my wife's obsession with horses and books (two Thoroughbreds and several thousand volumes, respectively), she understands my obsession with cool tools.