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Post by antonmcmillan on Mar 23, 2018 21:10:57 GMT
Hello there, Acoustic Experts, I hope you are doing well and the weekend is in proper positive mode. For me, unfortunately, it is a time for work and problem solving. But not for long, I hope.. I am writing this thread as a result of a build process that is now well underway and that I have certain doubts in. The room is a small production room that I will use to mangle with my synthesizers. It is 5.8x3.2 x2.4 meters (19x10,5x7,9 ft) (LxWxH). The room has rounded ceilings. You can see it here:
Therefore the room that im building has an angled ceiling profile. You can see the framework of the design here:
At this point I have done the framework, the walls and the ceiling. The walls are done with a layer of MDF covered with a layer of high density plasterboard. Every joint or panel is sealed with caulk very carefully. You can see the framing done here: Before the framework was installed, I have done the ventilation system for fresh air. The IN and OUT air ducts have been treated with silencer boxes. The inside of the boxes are shown here:
The floor has been done with underfloor heating and tiles. You can see the finish here: I have also received the first parts of my custom made table. You can see it here: So, so far I am at a point where only the basic first measurements have been made inside the room. I have measured the room with PSI A21-M and JBL P708 monitors, using RME Fireface UCX as my soundcard and Presonus PRM1 as my measurement mic. Both monitors have revealed similar problems. I have already installed acoustic hangers in the soffits, right under the speaker enclosure space. The hangers have fixed some problems in the low end. You can see the measurement of the empty room vs the room with hangers here: However, I feel something is not right with my measurements. For some reason my soundcard (RME FIREFACE UCX) has a very large internal deviation on the frequency response (around 12 db across the full range). You can see the full frequency response of the soundcard here: So my question is: can you maybe give me some insight on why might this deviation be so big? Maybe theres some kind of power or earthing ground loop thats is messing up my interface so that it gives this very strange response. I have watched several videos on REW and most of the soundcards have a variation of several dBs. And only in the lowest and highest frequencies.. Any advice will be very appreciated. For those that want to have a closer look on whats going on on my measurements or maybe have an interest to see how are PSI A21-Ms compared to JBL P708s - i have attached the measurement data in the following link: MDATA
I also made a screenshot of the measurements of both speacers for comparison: I would also like to ask the experts another question. Should I consider changing my monitors from A21-Ms to JBLs? They have much more power in the lower frequencies. Its not just visible in the graphs (10 dB difference at around 30 Hz), but is audible very clearly as well. I assume soffit mounting speakers that have more low end energy would be more beneficial than the PSI's, because I would have more low frequency presence in the room without adding a subwoofer. And that would be a good thing for electronic music. I hope my post is not too long and boring. Thanks in advance everyone who will have a minute to read through and maybe give their insights. You have a good weekend, Sirs. Sicerely, AM
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Post by antonmcmillan on Mar 23, 2018 21:15:04 GMT
I also hope its not a problem I created a new thread. Since my room is not a rectangular shape - I think standard thread advice might not be suitable. Also, this will be easier as I will be updating the thread as my build progresses.
By the way, I have a Skethup model of my room and some basic treatments that im updating frequently. So if anyone would be really into giving their expertise on my room - I could share it.
I also dont mind purchasing professional advice on treatment.
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Post by antonmcmillan on Mar 24, 2018 9:57:58 GMT
Also, I dont know if im not getting ahead of myself because im not sure if my soundcard is measuring properly, but since ive measured on 2 different monitors and they all came back pretty much identical in the low end - i made a small sketch of a slot resonator to put in the corners in the back of my room. They look like this: According to calculations these should work in different narrow Q frequency ranges between 29 and 92 Hz. You can see the inside of the resonator here: I know I have not added the insulation in the sketch, but it will be there. Since all of these are more or less my own knowledge based - I would like to ask any expert to take a look and tell me what they think. You can download the model here: MODELThank you in advance.
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Post by Hexspa on Mar 24, 2018 10:40:36 GMT
Hey, anton. Looks like an interesting project. I'm not sure how much I can help but I look forward to seeing this unfold.
Please reduce further image uploads to around 100kB.
Thanks.
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Post by antonmcmillan on Mar 24, 2018 14:14:30 GMT
Hey there,
Gotcha, Hex. All further uploads will meet the criteria.
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Post by rock on Mar 24, 2018 17:05:34 GMT
Since my room is not a rectangular shape - I think standard thread advice might not be suitable. Even though your room is not exactly rectangular, the standard advice still applies. From the photos and your graphs it looks like you could use lots of corner bass traps. That's standard advice. Also, I see you have RFZ absorbers on the sides, it's good to have them on the ceiling too. Your length and width are almost double (half, which ever way yo look at it), that's not great I took a second look and your dims are OK, sorry, but full thick absorption on the back wall will help anyway. With small rooms, you need lots of absorption to flatten out the low end.
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Post by antonmcmillan on Mar 24, 2018 17:43:04 GMT
Since my room is not a rectangular shape - I think standard thread advice might not be suitable. Even though your room is not exactly rectangular, the standard advice still applies. From the photos and your graphs it looks like you could use lots of corner bass traps. That's standard advice. Also, I see you have RFZ absorbers on the sides, it's good to have them on the ceiling too. Your length and width are almost double (half, which ever way yo look at it), that's not great I took a second look and your dims are OK, sorry, but full thick absorption on the back wall will help anyway. With small rooms, you need lots of absorption to flatten out the low end. Well yes, RFZ and first reflections are an obvious thing here. But the ones i put in the walls are just pieces of mineral wool that were left over from when i made the hangers for the soffits. They will eventually also be inside the soffits. But the whole room will be insulated nonetheless. The spaces between the studs of my framework are all 100 mm thick (4") and I am planning to compeletely fill every single space with insulation. At first I thought one type, similar to OC703 that has a density of around 49 kg/m3. But now im thinking of varying different types of insulation. Also varying insulation with film and without it. I know it will make the room quite dead, but Im planning to then add some variations of wood slats for liveness and esthetics. As for the back wall - did you check the post where i made a corner slot resonator? I will be putting two of those in the bottom corners. I will also treat the corners with superchunks (i will stack a superchunk on the slot resonator right to the angled ceiling). The back wall is also problematic because the door is inside it. You can see it here:
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Post by antonmcmillan on Mar 24, 2018 17:55:27 GMT
Oh, by the way, I have also designed and made the door myslef. The door is solid OAK multilayer, that has a step sequence on the door and the frame. This way I was able to add a double seal around the perimeter of the door. I have also added a mechanic door seal at the bottom. If you are interested in seeing - here it is: Here you can see a cross-section drawing of the door closed in the door frame: THanks for your input. Anyway, maybe you can answer the question about my soundcard? I feel a bit worried continuing measuring because of the 11 dB frequency deviation in REW..
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Post by antonmcmillan on Mar 28, 2018 19:03:22 GMT
So I actually found out why there was a feedback loop in my measurements. RME TotalMix has a monitor send that feeds back to itself and i did not mute it when making the measurements At this point I have made new measurements with my PSI A21M monitors and they look like this: I decided that my next move will be adding insulation inside the framework all though the studio and its corners. I know this will deaden the room, but I will later add some wood slats to bring back more liveness into the room. Plus it will have an array of synths that will be mounted on mutilayer stands, so some highs will reflect into the room nonetheless. I would like to know what would you reccomend to add as basic insulation? OC703 or maybe even 701? At this point im talking about basic absorbtion on all the surfaces in the room except the floor. After I do that I will definitely build some panels. I havent decided yet what type. I also decided to hold down on the resonators that i posted earlier. First I will treat the room with porous absorbing materials and then measure and see what problems are still inside. Then build first reflection point panels, a cloud and maybe some additional stuff, if need be.
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Post by Hexspa on Mar 29, 2018 0:19:04 GMT
So I actually found out why there was a feedback loop in my measurements. RME TotalMix has a monitor send that feeds back to itself and i did not mute it when making the measurements At this point I have made new measurements with my PSI A21M monitors and they look like this: I decided that my next move will be adding insulation inside the framework all though the studio and its corners. I know this will deaden the room, but I will later add some wood slats to bring back more liveness into the room. Plus it will have an array of synths that will be mounted on mutilayer stands, so some highs will reflect into the room nonetheless. I would like to know what would you reccomend to add as basic insulation? OC703 or maybe even 701? At this point im talking about basic absorbtion on all the surfaces in the room except the floor. After I do that I will definitely build some panels. I havent decided yet what type. I also decided to hold down on the resonators that i posted earlier. First I will treat the room with porous absorbing materials and then measure and see what problems are still inside. Then build first reflection point panels, a cloud and maybe some additional stuff, if need be. Cool stuff. If you're going to add wood slats then make them thin and try to get them in contact with the absorption. However much, they will help with your low end that way. Use OC705 if you can. It comes down to budget but I'm pretty sure that OC705 with FRK is going to be the best for low end. Regular kraft paper, applied later, is also good and works just like the wood will. The key to your broadband is GFR, thickness, and coverage. Ideally your whole room will be treated, barring any diffusion. The minimum thickness of rigid panels for music is 4" so, with those facts in mind, choose your material accordingly. I'm glad you've, at least temporarily, forgone the resonant absorbers. That's not a language I speak! However, for a permanent install, and after you've deployed your broadband, they can be just the ticket for final tuning. I have one question: you're going to build panels in addition to your in-frame treatment? Baffles and such can be functional but surely you're not going to have multiple layers of identical treatment, right? Some people start getting too creative but you seem more the rational type. Let me make a suggestion: since you appear to be going all in, or all out as it were, consider taking multiple measurements around the room. Take a few in a 1' radius around your listening position and then another few at points you may use for recording. You may discover some hidden gems or even aural termites.
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Post by antonmcmillan on Mar 29, 2018 8:44:13 GMT
Cool stuff. If you're going to add wood slats then make them thin and try to get them in contact with the absorption. However much, they will help with your low end that way.
Use OC705 if you can. It comes down to budget but I'm pretty sure that OC705 with FRK is going to be the best for low end. Regular kraft paper, applied later, is also good and works just like the wood will.
The key to your broadband is GFR, thickness, and coverage. Ideally your whole room will be treated, barring any diffusion. The minimum thickness of rigid panels for music is 4" so, with those facts in mind, choose your material accordingly.
I'm glad you've, at least temporarily, forgone the resonant absorbers. That's not a language I speak! However, for a permanent install, and after you've deployed your broadband, they can be just the ticket for final tuning.
I have one question: you're going to build panels in addition to your in-frame treatment? Baffles and such can be functional but surely you're not going to have multiple layers of identical treatment, right? Some people start getting too creative but you seem more the rational type. Let me make a suggestion: since you appear to be going all in, or all out as it were, consider taking multiple measurements around the room. Take a few in a 1' radius around your listening position and then another few at points you may use for recording. You may discover some hidden gems or even aural termites.
You are correct about the wood slats. I guess I will get more into analysing the concepts of them when i have the insulation in the framework. I know theres some really nice logarhithmic patterns to targed specific frequencies, so I guess ill see into them once the time is right. Im not in much of a rush so I can basically do the insulation, that I think I will cover that insulation with fabric and from there will move on with acoustic tuning and interior of the room. About OC705 - I Ihave read some forum threads where they reccoment porous 701 insulation for broadband treatment. I have downloaded the OC700 series insulation technical data sheet and you can clearly see there that 703 FRK is best at absorbing at 125 Hz. Check it here: Ok, so lets say I do the room with 4" 705 FRK. Do I buy 4" insulation with one layer of film or do I buy 1" insulation and stack them to 4" and have a multilayer of film? Which one would be acoustically better? I will be doing every surface of the room with 4" of insulation. I will be also adding a cloud with 4" thick insualtion. Answering your question: what I meant about adding extra treatment is building acoustical panels. Something like Ethans LOW-BASS TRAP, maybe MID-FREQUENCY ABSORBER. And maybe, like you said, some resonant devices. I have read quite a bit about those too, and since I have time and money - I think I would try at least one or two and see what happens. My idea was to do insulation, cover it with fabric, then build some panels and play with their placement and eventually finish with wood slats to liven the room up. Thanks for your advice! I will definitely make that.I just want to first add the insulation to give me a clearer view of the room when most of the high frequency reflections will be eliminated. After that I will definitely measure most of the places in the room. Ill post here as the progress goes by. Thanks for your input, Hexspa!
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Post by Hexspa on Mar 29, 2018 20:56:46 GMT
You are correct about the wood slats. I guess I will get more into analysing the concepts of them when i have the insulation in the framework. I know theres some really nice logarhithmic patterns to targed specific frequencies, so I guess ill see into them once the time is right. Im not in much of a rush so I can basically do the insulation, that I think I will cover that insulation with fabric and from there will move on with acoustic tuning and interior of the room. About OC705 - I Ihave read some forum threads where they reccoment porous 701 insulation for broadband treatment. I have downloaded the OC700 series insulation technical data sheet and you can clearly see there that 703 FRK is best at absorbing at 125 Hz. Check it here: Ok, so lets say I do the room with 4" 705 FRK. Do I buy 4" insulation with one layer of film or do I buy 1" insulation and stack them to 4" and have a multilayer of film? Which one would be acoustically better? I will be doing every surface of the room with 4" of insulation. I will be also adding a cloud with 4" thick insualtion. Answering your question: what I meant about adding extra treatment is building acoustical panels. Something like Ethans LOW-BASS TRAP, maybe MID-FREQUENCY ABSORBER. And maybe, like you said, some resonant devices. I have read quite a bit about those too, and since I have time and money - I think I would try at least one or two and see what happens. My idea was to do insulation, cover it with fabric, then build some panels and play with their placement and eventually finish with wood slats to liven the room up. Thanks for your advice! I will definitely make that.I just want to first add the insulation to give me a clearer view of the room when most of the high frequency reflections will be eliminated. After that I will definitely measure most of the places in the room. Ill post here as the progress goes by. Thanks for your input, Hexspa! Those spec charts will only take you so far. On the Bob Gold's resource, it says that value differences less than 0.15 or thereabouts are irrelevant. Than has performed tests and published them here using these materials and 705 appears to win. Also, like the image to which you've link mentions, specific implementation has something to say about absorptive performance. There's also variance from sample to sample. Regardless, sheer coverage seems to trump whatever minor differences result from similar materials. You just use one layer of FRK and it goes facing the room. As far as additional panels are concerned, Ethan appears not to be recommending those designs currently. A room full of 4" faced rigid broadband will get you pretty far. Just remember not to FRK your RFZ
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Post by antonmcmillan on Mar 30, 2018 12:00:56 GMT
Yes, I have read that report. But also there is a lot of people saying that lower density (below 20 kg/m3) insulation works much better on low frequencies.. Its quite frustrating, because in resonant defices the mass of a material works to lower the frequency when you increase it. Yes I know an insulated room will be quite good, but it will not be perfect. I want to achieve as good as a result as possible. My thought was that if you have insulation in the walls - it would advance the properties of that if you put a membrane panel over it. Not seal the insulation with the panel, but just add it a certain distance from the insulated framework to increase acoustic performance. Maybe I will ask Ethan on why he does not reccomend that and what are his thoughts. Anyway, I will experiment with my place a bit to see what best works for what im trying to achieve. And I will post here. So we will se in practice what type of stuff will eventually do the best for me
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Post by antonmcmillan on Apr 2, 2018 18:53:13 GMT
Hey everyone, So I have done the insulation during the weekend. Basically every surface is insualted except 2 framework slots where the ventilation ducts are. I will work on the interior details to have a nice finish on these this week and will cover them up with insulation as well. You can see it here: Another pair of untreated place is the speaker enclosures. My furniture guy has done the reinforced boxes to house the monitors and I have received the 12"x12" sorbothane pads for decoupling the boxes from the soffit frame. Once I will have the boxes and speakers anchored to the soffit I will add fluffy insulation inside the soffit construction. After that Im waiting for some MLV material to come and I will make a sandwich of MDFxMLVxMDF that has a natural oak finish to seal the speaked enclosure. After that Im thinking of adding acoustically transparent cloth all over the surfaces of thÄ— studio. And then build the cloud. And then build porous corner traps. What do you guys think? I have done acoustic measurements of the room after I put the insulation. You can check them out here (left speaker): You can compare to what has happened compared to the empty room: And if anyone wants to check out the measurements in detail - the mdat: HEREIf you look closely you will see that a dip at around 160 Hz has appeared where it was not present before. I think that is due to reflections of my desk. Is that correct? The desk will house a small digital mixing console so some more reflecions are going to appear later on. If anyone has some insights on what I should or shouldnt do at this point - you are welcome to chime in Have a great easter
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Post by Hexspa on Apr 4, 2018 4:36:11 GMT
164.81Hz = 209.33cm = 82.41" wavelength of E3. 82.41" / 4 = 20.6" = 1/4 wavelength of E3. 20.6" (1.7'), 60.8" (5'), 103" (8.5') = 1/4, 3/4, 5/4 wavelength of E3 and possible locations of surfaces contributing to your null. Since the null is so strong and that frequency is still relatively less directional, methinks the offending boundaries are those of the cubby holes in which your speakers reside. In other words, that frequency is radiating backwards, bouncing back then destructively mixing with it's kin. It'll probably get resolved once you stuff that corner. It could be the desk too, though. In fact, it's probably a combination of factors. You can be more sure by using some of the information I'm about to give you. You can use the links I'll post below to figure out whence the rest of your trouble spots come, if any. You can post graphs with 1/3 octave smoothing so we can see at what SPL you're measuring. Though measured positioning is best, remember than you can EQ below your room's Schroeder frequency to even out it's response so long as you confirm it's effect is balanced within a realistic listening radius. Another metric which may be of interest to you is the decay time of your space. You can use the waterfall and decay plots in REW to identify this. I could do this myself but I'll leave that fun for you The room looks great and you've definitely made improvements in the SPL response. If you haven't measured your listening area's radius then I suggest you do that. Also remember that covering your non RFZ absorption points in FRK should improve the low end response as well while adding back some mid and high reflections. Something just occurred to me. What kind of insulation did you use? You should know that, though you've heard advocacy for low density insulation, as far as I know that kind of absorber works best at thicknesses greater than 8". I'm saying this because it doesn't look like you used OC70x but instead chose a Rxx variant. pages.mtu.edu/~suits/notefreqs.htmlwww.google.com/search?sclient=psy-ab&site=&source=hp&btnG=Search&q=cm+to+inches&oq=&gs_l=&pbx=1amcoustics.com/tools/amroc?l=23.83&w=13.33&h=8&ft=true&re=EBU%20listening%20room
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