Where to place bass traps?

Well, I have ears so I can tell when everything snaps into focus and the imaging is spot on. I guess if "perfect" is the goalpost, that can never be known. But I think anyone with decent ears knows when the imaging and soundstage has snapped into focus.

Maybe they are crap speakers though.

 

Pretty sure that was meant as tongue-in-cheek response to Brian's earlier thread that described Wilsons as "crap" speakers.

 

Oh, okay I saw no emoticons that would help me interpret that.

 

In addition to careful speaker/listener placement and floor to ceiling corner traps, I found soffit traps around the entire room to be quite effective in taming bass modes.

Bill

 

I got a few big dog beds recently. Was planning to take one to the office an put the other in my listening room for my pup. Instead, I've got both in the listening room covering us the tile between the speakers and the tile in front of my rack. I put some pillows down on the other side. I alos put some pillows on top of the fireplace. Improvised floor & wall treatments seem to help a bit.

Turns out the place I bought my rug will let me exchange it for a bigger size, so I'll get more of the floor covered.

Hopefully Glenn will get back to me soon. THe soffit traps are ugly, but easily removable so no biggie. Are you placingthem at specific room nodes?

Well, looks like I'll be delayed a bit of doing the room measurements. I bought the mic and other equipment that Glenn at GIK suggested, but it's not the same as what they are using in their video and I'm not sure how to calibrate what I have. I'm a bit under the weather and lacking the patience to deal with figuring it out right now, so just going to listen to some tunes. I want to measure and get some feedback before changing the entire room around.

That said, something occurred to me last night while listening. It might just be certain music that is causing this "boxy" sound I'm hearing. I'm realizing that my older albums with lots of dynamics sound amazing. It's my Shoegazey stuff that mastered to be loud that is sounding boxy. Of course, that could also be because there is more bass energy in that music and the waves are cancelling each other out making what's left sound funny.

 

Either way, I have thick skin. Some people call it fat, but I'm sure it's just thick skin.

 

Mine's fat, and I'm proud of it

 

Nope, they're around the entire perimeter of the wall/ceiling junction.

 

This may not be relevant to you Brian but it addressed the issue for me after a lifetime of trying (you mention a "perfect" goalpost)....

There is a different route that in my experience fixes pretty much any room - DEQX speaker/room correction. It's a digital Preamp/processor that measures, calibrates and corrects the phase/timing of speakers to 'flat' and then allows you to adjust out the room nodes using a mic at the listening position. Very clever and effective, it even takes reflections from all the furniture and other objects in the room into account

Expensive but in the 3 years since I got this, I am able to play any type of music at pretty much any volume without those annoying frequency humps and dips. The system has 4 presets selectable by remote and I have calibrated the system for 'well mastered' albums at preset 2, bass heavy albums at preset 1 and bass-light albums at 3 & 4

I really do feel that my room is now as "perfect" as it could be (....to me & it seems to amaze anyone who visits)

 

no. Great it works for you,but its doing nothing for bass issues and time domain issues.It wont fix reflections,lol, how do you know this,cause it told you so? Have you measured what its doing? Sorry to be harsh but this stuff is such a fallacy for so many reasons. Heres a important one:
If you have nulls 3dB deep or more, and you will in an untreated room, thats double the ouput and more your asking from your power amp, thats eating up a lot of headroom. Not to mention the potential damage to speakers. I hope your wiz bang software is accounting for users with no clue and wont let them do this.I could go on and on, but if it sounds better to you great,but its not how to fix acoustic problems by a long shot.You sit in a properly treated and tuned room you realise this.
If you have a peak around 40z or so, NOT a null,EQ is ok to use there due to the long wavelength. Other than that, your band aiding a artery bleed. Almost literally.The low end swirling around unababted and taking ages to decay is the blood! You absolutely definatley cannot fix that with EQ period.
Been there done that. Treating the room as brian is doing is the way to go.

 

Yeah, unfortunately you can't EQ away room modes. If you have a null at X frequency at the listening position because there's phase cancellation at that frequency as a result of competing standing waves in the room, no amount of adding more energy at that frequency via EQ can change that. You'll still have that null (and more complex comb-filtering kind of cancellations at different points as you move through the room especially if you're trying to have a wide listening spot). Also, as Tim mentions above, you can't change room reverb times with EQ. Not to say that EQ'ing to get flat frequency response at the listening position can't be a useful part of specing a room if that's they way you're going. But it can't deal with many of the things that room treatment or altering room dimensions or materials deal with.

 

Guess I'm lucky as I have a solid wall/floor listening room with one chair and everything well away from walls. I only have to eq below 150hz, reduce by a max of 2.5dB & boost by max 1.75dB in a couple of places. The processor focuses mainly on time & phase alignment at the chair and eq is very subtle so I guess I'm not pushing the amps too much

Anyway, not here to hijack the thread so good luck....

 

By the way, I checked on the cost to do my room with that cork flooring. Looks like it'll be less than $500. I know you don't think it will help with low frequency absorption, but you think it will help with other things, right? You think it's worth it?

 

I would think it would help with HF reverb times, and you can still throw a mat and the carpet on it too, esp. in contrast to tile. Just based on the absorption coefficient data for the wall tile -- which may or may not be similar to the floor tile -- I wouldn't expect miracles, and w/ low frequencies, they just kinda pass through everything. Absorbing those tends to require some kind of special material or air gap installation or something using a tuned resonator or something. I do really like the look of the tile though. Tough to bridge the aesthetic/sonic gap sometimes in a home setting.

 

A retailer here used to have cork walls in one or two of their audition rooms. I am certain that the cork used on the walls would not hold up as flooring. We refloored our kitchen last spring and looked at cork as an option. It was not the same material or thickness that was on the wall at that audio dealer.

I found one product with listed absorption coefficients using cork and at 40mm thick it absorbs from 500hz on up. At 60mm thick it works down to around the 350hz range. It is not exactly broadband.

Start with broadband absorption and wait for Glenn to return before spending any money.

Also, there is a very helpful forum on HTS that will help with instructions on how to load the calibration file for your mic.

 

Brian,

Your room is no doubt going to need taming in the HF region, but just be careful not to kill it dead. The overall goal is an even decay across the range, maybe a little higher in the low end, but thats the goal.

And what mic and software did you buy?

 

I'm starting to think that Glenn isn't going to return my emails. I've sent a few over the last two weeks and he hasn't responded. I have stuff in my cart, just waiting to hear back. I've probably spent $2K+ with them already, but I guess he doesn't want anymore of my biz.

 

I got a PreSonus AudioBox and a Dayton Audio EMM-6 Electret Measurement Mic. Both were recommended by Glenn. Unfortunately, they use a different AudioBox in their "How To" video that has more inputs for calibration. I haven't had a chance to figure out how to calibrate this one and I'm pretty sure I don't have the proper cables to hook it up to my MacBook.

Unfortunately, I don't have enough free time to figure it out on my own right this minute. Hoping to get to it this week/weekend. My new pre-amp arrives tomorrow, so this will likely take a back seat since I didn't get it figured out yet. I'm gonna be doing some serious listening sessions for the next week.

 

You might get better responses on HTS. They have two forums that will help you. Start with the REW forum to get up and running, then move to the Home Audio Acoustic forum to receive help deciphering your graphs.

GIK has a presence on the HTS forums, Bryan. He has answered my questions on targeted frequency problem locations and trap design questions in the past.

 

When you are on the GIK site look at the test results for Monster Traps and compare them to Soffit Traps. You'll see Soffit Traps go down lower. This is what you need in the corners. They may be ugly but with a choice of colours you might be able to hide or make a feature of them. I suggest getting as many as you can afford. In order of effect in a typical rectangular room my understanding is: wall/wall corners behind speakers, wall/wall behind chair, ceiling/wall and ceiling/floor on all walls. If you stick your ear in a corner whilst playing bass you should hear the effect. Positioning of these corner bass traps is regardless of where you position your speakers.

The Monster panels can be used on the back walls to prevent reflections from there. They can be hooked onto the wall or feet standing which makes for easier positioning and helps with experimentation. The wooden feet work well.

This gives an idea for speaker/chair positioning to reduce bass problems - 'The Thirds'. You could also try 'The Fifths'.

I use an equaliser to tidy things up after room treatment, speaker/listener positioning and copious measurements. Room treatment and positioning should get you nearly there but there will always be compromises. Using EQ through the full range I have improved my sound. I know people doubt this out, often out of principle, but I hear an improvement.

 

I tend to put my bass traps behind the bushes in the back of my house where the bass tend to congregate. During the winter months, bass try to sneak into my basement (for warmth and maybe beer), so I put a trap in the stairwell.

Once I catch a bass, I will throw the trap in the back of my truck and release the bass in the wild. While I have a fondness for bloated bass and treat them humanely, I kill shrill highs on sight.

 

Hmmm... unfortunately, I invested in GIK's Tri-Trap corner bass traps per their recommendation. I didn't realize the Soffit Traps were THAT much better. I have one Tri-TRap in each corner, but need to order 2 more so that I can extend all the way to the ceiling.

Since Glenn hasn't called back, let me ask you this... my ears tell me I need additional Monster Bass traps. I was thinking of having them built with scatter plates and placing them on the front wall on either side of the regular monster trap that is in front of my fireplace OR placing both behind my couch on each side (I have some absorption right behind my head currently). Would scatter plates likely help keep the monster traps from sucking all the life out if placed in these spots?

 

I think 'yes', but of course Glenn or his colleagues could answer better.

I have 242 panels with scatter plates, as that is what GIK advised me for my side walls. In fact I use a pair of them on my front wall along with two diffusors. The scatter plates seem to me to act a bit like diffusors so you need a decent distance (8' or more) between them and your ear. When I put them on the side wall they were too close and I didn't like what they did.

GIK have their own forum here and Glenn responds as do his colleagues:

http://www.audiocircle.com/index.php?board=183.0

 

Any pics of your room?

Thanks for the link. Didn't realize that they had their own forum.