|
Post by rock on Feb 11, 2023 15:03:58 GMT
It looks like your piano is a digital on a stand. It really does not have a large "acoustical footprint" i.e. influence reflections/absorption etc. so leave it there if it's not in your way. If you want, you can run a couple REW sweep with it in and out of the room an see if a difference shows up but if anything it will be minimal and probably only in the HF. BTW, I don't think measurement (REW etc.) has been mentioned here; you can use it is as much or as little as you want but it can help identify or confirm issues you may (or may not) be hearing.
Looks like the desk will be behind the LP so it's my guess it's not a problem where it is either.
I like Hexspa's suggestion "in another room" but for the cupboard, yeah, I agree, I'd keep that wall clear for full absorption which will help to make the wall "disappear" acoustically. If you can't move it, so be it, like you mentioned, compromises need to be made...I think that's an issue for all of us. Again, measurements may help you make some decisions.
Cheers
|
|
|
Post by rock on Feb 6, 2023 19:11:19 GMT
First, one question: What's that thing across from the desk? Can it be moved? I'm mostly just wondering.
I think the most obvious answer is the speaker /listening position etc. Set up the speakers on the north wall. Exact positions need to be determined experimentally. I'm pretty sure Hexspa has a procedure in a post somewhere or in a youtube. Either search or he'll probably get back soon. Best way to minimize mix desk reflections is speakers on stands and a small desk.
Deep wide-band absorption on the 4 ft south wall. Absorption on the 8ft south wall too. Actually you know you need absorption everywhere, it's just where do you need it the most?
I like your idea of a complete ceiling frame. It takes care of LF floor/ceiling modes and reflections at the same time.
Squeeze in as many of your bass traps in the corners as you can fit.
Cheers
|
|
|
Post by rock on Feb 6, 2023 14:13:44 GMT
Good to have you back. Any war stories? Thanks but no war stories LOL. Seems I filled up my Bookmarks Bar and Ethan's got pushed off screen and down the list and since the site has been fairly inactive lately, I have gotten out of the habit of checking in. BTW, I've got a couple yet-to-be-deployed 2'x4'x4" mineral wool batts still in the package. I'm in the process of building thin wood (6mm Baltic Birch) frames. They're a little different in that instead of cutting holes in the sides, it's built out of 1" wide "rails" all the way around. I should take some pix. All the panels I've built so far are frameless and the fabric is not stretched tight and cosmetically they look a little shoddy. These should look better. We'll see... Cheers
|
|
|
Post by rock on Feb 1, 2023 13:55:42 GMT
Sorry, I've been away for a while.
Hex is correct! But add on and put it another way:
(cletuschrist wrote:) "Thanks! I was confused about whether the gap had something to do with waves hitting the wall and bouncing back into the insulation, or if it really only matters when the wave energy goes through the insulation once THEN AGAIN after hitting the wall coming back the other way."
I'd answer: It's BOTH!. Sound waves bounce off the wall from both going through the absorber first and then back again... and to a lesser degree from any sound waves reflecting off the wall from other angles.
|
|
|
Post by rock on Nov 26, 2022 15:25:15 GMT
Interesting point on gapping the sidewall adsorbers - do you mean spacing between the panels in this case, not the air gap behind them? On bass trapping behind speakers, why would this be less effective? I can potentially put them elsewhere, like under my desk etc, but I’ll try comparing with REW too. 1.) I think you are referring to this: "if you gap absorbers a distance equal to the thickness lowers their efficacy one octave." Here I mean the gap is the distance between the absorber and the wall (or other boundary). The primary reason for absorbers on the side walls is early reflections, but in your specific case, you note a resonant peak at 125Hz so I'm suggesting by using a thicker absorber and mounted (or positioned) an equal distance (gap) from the wall, you'll get more effective low end control with the same absorber. Regarding spacing between absorbers: You typically won't have complete 100% coverage (although you could) and therefore will want to spread a measured quantity of absorption over a given room or surface area after prioritizing specific areas like corners and RFZ. 2.) In general, the wall behind the speakers typically is an area that is not a problem and using resources in other places might give you more bang for the buck. It's not that they will be useless or undesirable there, so as Hexspa pointed out "you can add more absorption, as per your plan. With no cloud and stone walls, you're going to need all that you can get." I don't know if he was specifically referring to the absorbers behind the speakers but either way, I agree. Cheers
|
|
|
Post by rock on Nov 24, 2022 14:59:11 GMT
Hi kr1s1,
Thanks for reporting with your attempts but it looks like a head scratcher:( I'm sorry but I have not tried to do any sweeps like you're doing.
In the past, when I wanted to check a frequency response of analog electronics, I have simply hooked up my audio frequency sine wave oscillator on the input and O-scope and dB meter on the output and manually swept the oscillator and noted any level changes on the scope and the meter. This is admittedly primitive, but you can get a pretty good idea.
BTW, you really don't need both a scope AND a meter but the scope gives you an instant response and meter better accuracy. Some scopes have built-in metering but cost $$$. I got a good deal on a dual trace Craigslist some years ago, before that I had a single trace (that I never use anymore:(
|
|
|
Post by rock on Nov 24, 2022 14:30:31 GMT
Hi ufx, Great that you've read up and your plans are good. Yes, B is an improvement especially with the RFZ absorbers on the sides. Remember, if you gap absorbers a distance equal to the thickness lowers their efficacy one octave. Too bad you can't do a cloud. Absorbers behind the speakers are least effective there but probably won't hurt. If you want to see, run REW with and without them in place. The door corner, depending on clearances if any, is a spot for absorbers, one on the wall and one on the door OR a portable "roll around" bass trap you could position during mixes. The corner bass trap might not be as effective as the others because of the short 2.4' wall dimension and placed facing into the room might be as good, again, run REW. Overall your plan as drawn is good and the changes I point out may or may not make significant improvements. Here's the Amroc room mode calculator amcoustics.com/tools/amroc?l=11.4&w=8.9&h=8&ft=true&r60=0.6 Looks like that 125 Hz is the 2nd axial mode of short 8.9 wall to wall so gapping the wall absorbers or even using thicker 6" + gap will help here. Other than that, all the amroc data looks good for your room dimensions.
|
|
|
Post by rock on Oct 28, 2022 13:07:58 GMT
Thanks for getting back to us. Yes, it does look like the RTA tool in REW is the way to go. I'll have to try it. Thanks again!
|
|
|
Post by rock on Oct 25, 2022 23:28:50 GMT
One App we use for acoustic measurements is REW but it supplies it's own sweep which is applied to the speaker system and picked up by a mic which feeds the app the raw data and REW spits out all kinds of graphs. I don't know if REW can accept an audio sweep from from an external file like you have but if if did, that would be the answer. So we need to find you (and everyone else who would like one) an app that will take our sweep file and spit out a response graph. Here's someone who did that but it's almost from the last century pensa.fr/freqresplot/indexe.htm Who knows it might work for you! If it does, please let know how it works and share your results! If that doesn't work, I think if you search the internet for "Frequency sweep to graph converter" app or something like that you might find something. Again, please let us know, it's would be a handy tool. Another type of app I have seen are spectrum analyzers. They might possibly have a frequency graphing function too. Good Luck!
|
|
|
Post by rock on Oct 10, 2022 12:55:12 GMT
The site you linked gives good basic info. Keep in mind this can be rather expensive and it's unfortunately easy to end up with inferior or less than desired results.
"Soundproofing" is a misnomer. It is virtually impossible to eliminate all sound from entering or leaving a room. "Sound transmission attenuation" is a more accurate description.
This is a completely separate and extensively detailed subject than acoustic treatment. I'm not an authority either but I have looked into this and done some builds in the past.
Another question you have is building codes. Check with your city. I know different municipalities have potentially differing codes but I'll guess you may be required to use steel studs instead of wood.
Rod Gervais' book is a good resource. In short your wall should consist of three parts: Mass - Air - Mass. Flanking, another issue, is when sound goes around your "soundproof" wall so if you really want maximum sound attenuation, you probably need to build vibration isolated walls plus ceiling and floor; essentially a "room in a room".
There are a few threads here where I go into greater details I have learned so you might search this forum but better, check out Rod's book. Keep in mind that this in not absolute but more a question of "How much sound attenuation do you need?"
|
|
|
Post by rock on Sept 21, 2022 12:52:41 GMT
Great! I'm glad you got info from the designer so it confirms you're on the right path. In general, I don't think any given speaker is necessarily wrong for any given room but there are practical limits like the actual size and optimum positioning requirements like in your case. You could fit Klipsch Corner Horns in your room but there might not be much room for anything else (ha ha , not really but you get the idea).
|
|
|
Post by rock on Sept 19, 2022 20:31:24 GMT
Hi mtl,
First I should warn you that I have never tried this with a speaker like yours so I really can't say how well it will work at all. I'm just using the info I've learned here about passive absorbers. My lack of hands on experience with a situation like yours makes me suggest that you take acoustic measurements with software like REW to determine how well it improves your speaker response.
That said, I'm really wondering if this is a good idea at all so you really need to see how close you can have the PR to your absorber without affecting the system response. But yes, I suggested a 1" space between the absorber and the PR... BUT I do want you to measure (with REW) at other distances to verify your response. The reason I suggested 1" is because you "gave me" a total of 7" to work with. I'm suggesting a 6" absorber for best LF performance if we can "get away with" as little a 1 inch space but IDK, 1" might not be enough! Maybe it's more like a 5" absorber with a 2" space...IDK.
My best guess is to center the absorber on the passive radiator.
My understanding is to use one membrane (foil) on the front.
Remember to measure. AFAIC, you're in uncharted territory. If you have not purchased your speaker yet, there's probably a better choice. Maybe someone here will have a better idea. If not, try other forums or better yet contact your speaker mfg. and see what they say about all this.
|
|
|
Post by rock on Sept 19, 2022 13:13:39 GMT
Sorry to say but clearly, your monitor choice is not consistent with your room and set up; if this is temporary, maybe your next room will be better suited for you new monitors but hopefully an absorber will solve your problem and all will be fine. I'll share my best guesses.
What I'm describing below is basically a standard LF porous absorber that will fit between your monitor and mounted flush to the wall:
Using 3" thick mineral wool or OC 703 doubled in thickness to 6" is probably the best you can do. Sandwich two pieces together to get 6", no glue (if you can purchase it 6" thick, go for it!). Use kraft paper, thin plastic or foil on the front lightly glued with spray glue. Cover with you choice of acoustically transparent, breathable fabric. Frame or no frame, your choice. Typical size is 2 feet by 4 feet and at that short distance (1 inch), a 2x4 panel should be enough. If you want overkill, you could enlarge the panel to 4x4 and add a surrounding thickness of another 6 or more inches. If you do this, you'll want to leave some airspace of about an inch on the sides. I'm really not sure if and inch is enough behind and on the sides but a thinner absorber will be less effective at lower freqs.
If you want to optimize this, you may need to try this idea using various thicknesses with corresponding distances for space from the speaker. If you're going to experiment, you don't need fabric or a frame
For this project, I would certainly make before and after acoustic measurements especially if you're going to experiment with different thicknesses etc. For starters, measure 2 foot, 1 foot and 7" from the wall without an absorber just to confirm mfg. specs and to get a baseline.
Let us know how it goes!
|
|
|
Post by rock on May 12, 2022 12:45:48 GMT
...for the purpose of creating a flatter bass response then the concrete wall would produce.. What you should want to do is to absorb the sound and eliminate (as much as possible) the reflections. Resonant absorbers can be built and Ethan has a page describing them if you want to go that route but if you read the details, porous absorbers are recommended for DIYers. So, if you use porous absorbers, thicker = Better lower LF performance so go as thick as possible. Below ~8" use rigid rockwool or FG above ~8" use fluffy FG. Sorry, I don't have a recommendation for membrane. Maybe someone else here can help.
|
|
|
Post by rock on Mar 17, 2022 13:35:02 GMT
The only things I can say about resonant absorbers is mostly what I have read from Ethan. That is, resonant absorbers are by definition targeted and narrow band. This means that your data on your material properties and design calculations are critical. Broadband absorber designs, like Hexspa suggested are not critical and the larger and deeper they are the better they work. That's why they are recommended for DIY projects as you are more likely to get the results you expect.
Sorry to preach but if you're really invested in getting better acoustics, it's a good idea to educate yourself. Joining the this forum is a good start. If you have not read all or Ethan's material in the stickies, please do so. Using the search will help you see that there is a common thread that runs through many of the discussions and you'll pick up info there too.
One constant with acoustic treatment is that you need a lot of area coverage to make a significant influence or improvement. Like Ethan said, if you hang a washcloth on the wall it will absorb "something" but not much. So you might find you just need more than 4 big traps...but it may be a good start.
|
|