|
Post by Hexspa on Jun 18, 2023 13:55:27 GMT
thinking it won't make any difference! Little do they know
|
|
|
Post by Hexspa on Jun 16, 2023 15:34:20 GMT
All I know about sound isolation is that even small gaps reduce a barrier's acoustic performance significantly. For example, small gaps around a door can reduce its effect on blocking sound by, say, 25%. I don't know the exact ratios of gap-to-performance decrease but it's surprising how little will ruin the effect.
|
|
|
Post by Hexspa on May 30, 2023 12:15:51 GMT
Thanks for the idea rock, I'll keep thinking of ways to mount my panels when they're finished. Ideally I'll be spacing them 8" off the walls. Also good point about the pro studio builds. I guess there really is no such thing as too much low frequency absorption. Cool to see your room and progress Hexspa! Glad to see this stuff does make a real difference. It's interesting that even a smaller desk can reintroduce nulls like those in your post-treatment graph, guess I'll have to swap out the big desk. Yes, I think it's a few things including the multi-tiered desk. It has the speaker riser that goes all the way across the front and doubles as a dual 19" rack so that's two levels plus I have a 27" monitor (though angled) and an 88-key midi controller between that and a QWERTY keyboard. Those nulls represent quarter wavelengths of under 2' so what else could it be? I'd love to remake this desk out of acoustically transparent material but, with all this other crap I don't know how much it would matter. I think in theory it should be fine to broadly boost the 2-300Hz range then raze off a few peaks, especially since my reference level is just 63dB but I'm going to change monitors at some point. If you look at the FR of these speakers, they're very boosted above 1kHz and that makes the lower midrange look scooped. I'm not trying to blame my gear but in this case it matters as far as I know; you mostly only want to EQ below the transition frequency and 300Hz is pushing it. Either way, if you look at the note-to-frequency values it's only like four notes that are sucked out (two per null) so I'm not that worried. But, yeah, nothing is ever perfect but we make the most of what we have. Sometimes that's resorting to headphones. EDIT: thinking about those lower midrange nulls, I may have left my stool next to the mic stand. My reasoning was probably "this is where it's going to be anyway" but once I wrap this room up, I'll have to remember to measure with and without.
|
|
|
Post by Hexspa on May 30, 2023 12:08:25 GMT
Here's a neat artefact. All I know about this diffuser type is from the video Ethan made where he was strumming the hell out of an acoustic in front of one I briefly read what Mr. Volkmann wrote but he kind of lost me talking about the Philadelphia Academy of Music and how the paneling re-radiates sound. Like, ok but I can't see that from any pictures so whatever. What I think is interesting is how he recommends similar reverb times for listening rooms that later papers do. Anyway, here it is if you're looking for dump material: worldradiohistory.com/ARCHIVE-RCA/RCA-Broadcast-News/RCA-40.pdf You can delete "rca-40.pdf" and browse the directory of other issues.
|
|
|
Post by Hexspa on May 19, 2023 22:42:32 GMT
Here's a shot from the rear right. From the left, you can see four 6" rigid panels which absorb a mini hall wall that borders the kitchen. Past those, you can see the rear corner of a 31.5" fluffy super chunk. These are doubled up to make 24" soffits. Continuing around, I'm actually missing about 24" worth of recording zone right now but past that you can see the 15"-wide, 12"-thick safe-n-sound panels made from vinyl drywall bead. If I was to do it again, I might use metal since the vinyl is a little wobbly. Continuing clockwise, there's a super chunk in the front left corner of the room gapped about 2'. Behind that is my subwoofer. The front wall is totally untreated and the right wall is a mirror of the left sans the rear panels. Let's not forget the cloud which I significantly enlarged from my last space. Instead of one 2x4' 4" cloud and then two more of those above my recording zone, we've done the entire studio area with 6" rigid, about 64ft2. Seeing others' results, I noticed that often those with the biggest clouds got the best results and I can confirm it's very helpful. There are about 6" gaps between the rigid panels due to us needing to mount them on joists instead of drywall due to weight. This is true for the recording zone and the RFZ monitoring zone. Since my speakers are less than 1m distance, I haven't noticed any negative effect on stereo imaging and the measured response of each is not drastically different. To reiterate, the listening position is about 45% the width and not centered. Subjectively, and backed by measurements, the bass is nice and solid here. Actually, the response is a little better about 1 foot behind my MLP but I'll just use that as an excuse to stretch my legs . I have a very thin carpet but that's mainly to damp my footsteps and other mechanical noise so my neighbors don't hear me as much. Probably doesn't really help but I like to pretend it does.
|
|
|
Post by Hexspa on May 19, 2023 21:43:39 GMT
Zejamin, by all means explore the calculator. I've already done that work and came up with the ideal thicknesses per absorber type: 24" for fluffy, 12" for safe n sound, 6" for rigid - each with a 1x air gap. The reason 8" vs 12" safe n sound-equivalent shows little difference is due to a few things: your air gap is not 1:1 in both examples, you haven't selected random incidence (which you get when gapping a panel in a room), it's absorbing more from 20-40Hz which is a significant difference. For absorption coefficients, anything above 0.15 is significant and that just about meets that difference. The final reason, which doesn't apply here, is that beyond a certain thickness (per material, technically its gas flow resistivity), you end up with too great of a resistance and the panel becomes increasingly reflective. Essentially, you begin to put solid walls up. Here are the pre-eq response images of my room. I didn't take a sweep after EQ because I'm using Equalizer APO and I'm not sure whether the filters are going to affect the sweep and I didn't want to deal with it at the moment. Bass peaks are easily tamable with EQ and, subjectively, they're having their effect. The reason I boosted my subwoofer, which is causing that 20dB bass boost, is because I planned to EQ later and I wanted maximum level at the lowest frequency possible. In any case, impulse response envelope and decay are where the real battle happens so just imagine a semi-Harman bass-boost on the bottom instead of the gigantic bass peak. This is a non-smoothed response with both speakers and sub playing so, really, the SPL is very good. Impulse envelope should be around -10dB within 40ms ( Mellor) or -15dB within 20ms ( Winer), my decay target is -20dB above 63Hz within 150ms ( Spencer). Decay plot values are 140 and 160ms. For the heck of it, I'll post the predicted EQ curve too which is applied to an average of several measurements in about a 1' radius of my main listening position. The three nulls from 125-310Hz are probably from the desk. I will be adding 24"-thick fluffy soffits to the front and rear walls to tame the 60Hz resonance. Let me note that the speakers here are two Yamaha HS50 and the HS8s sub (the older one with a thru out). You can see from the EQ image that a few dB is shaved off at a higher frequency. This should be fine because the directivity of these speakers is pretty smooth which is what you look for when applying EQ to mains. Please see the Audio Science Review Spinorama-based review. Attachments:
|
|
|
Post by Hexspa on May 19, 2023 21:35:28 GMT
Yeah, do that wherever possible (remove the drywall to expose the insulation). If not, you can search on here for Ethan-approved strategies for treating vaulted ceilings.
|
|
|
Post by Hexspa on May 14, 2023 20:40:59 GMT
SPL is overrated! Focus on decay and minimizing reflections if you want accuracy. Minimize nulls through placement and then peaks through EQ.
|
|
|
Post by Hexspa on May 11, 2023 19:56:51 GMT
Let me give it to you easy:
Larger room, forget 38%; go with 20, 32, or 45% - your choice (20% north side big room is probably best), use 6" rigid on ceiling, 12" safe n sound on side walls at 24"-thick front-and-rear walls. Treat windows like normal boundaries. Corners are just the convergence of surfaces and consequently 1/4 wavelengths. Other than that, they're not important (for speakers it's the same but for pressure instead of velocity which gives "room gain" but that's a different story).
That's how I have my room set up now and it's great. I was thinking about posting measurements but I want to get the extra 24" front-to-back dimension treated. I'm meeting or exceeding my targets 20dB decay within 150ms above 63Hz and energy time curve down at least 10dB within 40ms. Actually, I only have one remaining resonance at 60Hz which I'm assuming is front-to-back (easy to check but I just haven't) that exceeds that just by 3dB or so. With the 2' fluffy soffits, I'm sure that'll go away.
Keep it simple, you don't have to reinvent the wheel. I have 8 [edit: 12] 6" 4x2' panels [8 are cloud, 4 are rear], 12 12"-thick 15"x48" safe n sound side panels, nine 31.5"x48" fluffy superchunks (diagonal soffits) in the corners. If you do that, you'll get the result - guaranteed. Anything less and you're going to compromise. Actually, you get a little wiggle room but not too much. Like I said, try to do what I'm doing and you'll be happy.
|
|
|
Post by Hexspa on Mar 22, 2023 10:45:47 GMT
My flawed example was on the song It's My Life by The Animals. I said "the guitar plays a minor third while singer Eric Burdon goes back and forth between major and minor thirds to avoid a clash." You pointed out that Eric alternates between a normal and flatted fifth. I don't recall anything about a fourth higher. Well, that's convenient! I mentioned it in this post - from six years ago! Man, I can't believe this forum has been here that long. Anyway, I guess the song sounded like an Eb tonic and the bass was playing Eb-Ab. According to what I said, you may have thought the bass was playing an Ab chord with the Eb as the P5 instead of an Eb chord with the Ab as a P4. To be certain, I'd have to go back and listen. Overall, the song seems pretty complicated with double flats and blues scales so I'm wary to revisit it. If you want, I'm willing to accept a truce Cheers.
|
|
|
Post by Hexspa on Mar 16, 2023 8:01:00 GMT
Sounds like fun enjoy
|
|
|
Post by Hexspa on Mar 16, 2023 7:58:27 GMT
Hex, you have been a terrific resource in this forum. And I'm still grateful you caught the error in my music theory video, where I confused a flat 5 for a minor 3. Haha I don't remember that exact one. The one that comes to mind is where you decided to write the song a perfect fourth higher key signature because "bass players rarely pedal on I-IV" It was unusual, to be fair. heh
|
|
|
Post by Hexspa on Mar 15, 2023 10:46:42 GMT
I do not know. Maybe someone else will help.
|
|
|
Post by Hexspa on Mar 15, 2023 10:43:45 GMT
I'm finding this tread interesting. When I first joined this site, I had a similar question asking if insulation in a closet would affect the acoustics in the room on the other side of the wall or closed closet door. It seems obvious now but it didn't before. Thanks to Ethan, his forum and all the other contributors, I think I now have a pretty good basic idea of what's going on with sound in "small" rooms. (seems to me, priorities seem to change in "medium" and "large" rooms so I'll have to leave that for another day...most of us don't have those size rooms anyway. But now that I think about it, stano's room is on the big side for a "Small Room" and may be entering the "Medium Room" territory. IDK) So, the OP, stanodx5, asks: "Can I use room boundaries as a bass trap?" Well, the answer is no. A solid, rigid, reflective room boundary will not absorb and reduce room modes (to any significant degree if at all). One suggestion is that if the OP wants or needs low freq bass trapping on the rear wall, fill the space with insulation (2,5m is pretty deep so that would be a very effective bass trap). The fill need only be low density fiberglass since the space is so deep. Let's use the idea of 1/4 wave length as theory of the depth to frequency relationship even though actual acoustic measurements may give us even better results. We can calculate freq of 2,5m quarter wavelength to be 34.4 HZ. So if you build a wood stud wall, (or steel stud for fire safety) and fill the 2,5m space behind it, then cover the stud wall with acoustically transparent material, there you go! Now, in addition, Ethan has mentioned the rear wall being a good candidate for diffusion too. Ethan builds combination absorber/diffusors. I think the idea is that the low freqs go "through" the diffusor into the bass trap. So the question is "What are the properties of the diffusor material that will work for this purpose?" If you are going to build DIY diffusors, hopefully Ethan can share or suggest a material for this purpose... if of course it's not proprietary info. (sorry, Ethan may have mentioned this already in a post but IDK or just forgot:( "Just one more thing..." (no this is not a Columbo episode:) I notice the dimensions before and after are both well outside of the "Bolt-area" amcoustics.com/tools/amroc?l=953&w=730&h=350&r60=0.6 but even with that, the node distribution looks pretty good and the size of your room pushes the fundamental mode frequencies quite low. The ceiling/floor is, as usual, the highest first node (47Hz) and the idea of a well treated fully transparent ceiling trap is also as usual a good idea too. Ethan and others have noted that, depending on building material, walls can be about 5% more distant acoustically due to their absorptive properties. Often you'll see measurements which reflect this i.e. an 8' ceiling but ringing below 70Hz (or whatever it is). Additionally, the bass traps you add will contribute further to this. Please allow me to take this time to thank Ethan for creating a hospitable environment here - as much as I tried to burn it down . I've been exploring a few other forms and, let me say, it can be tough out there. Thanks, Ethan!
|
|
|
Post by Hexspa on Mar 15, 2023 10:40:30 GMT
I think the quarter wavelength idea is more theory than practice. I mean, if 2-inch rigid fiberglass measures as fully absorbing 400 Hz, then there's your answer. Of course, we know that spacing the fiberglass off the wall absorbs even better and to a lower frequency. And 1/4 wavelength spacing puts the fiberglass where wave velocity is maximum. Hmm, that's interesting. Right, I looked at the absorption coefficients and it's true that materials less than 1/4 wavelength have ratings of 1.0 for a given frequency. My guess is that this is due to the sound not arriving completely perpendicular to the absorber i.e. some comes in from an angle, some from the side, and some possibly goes "through" the absorber and bounces back and becomes totally absorbed. On one hand, acoustics can be dead simple. On the other hand, pandora's box.
|
|