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Post by durian345 on Jul 3, 2020 7:04:52 GMT
Been reading up on the QRD diffuser and contemplating to DIY To put up 3 panels sided by side on the front wall, should the 3 panels be identical frequency range ?
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Post by Hexspa on Jul 4, 2020 7:46:00 GMT
As far as I know, you only need to diffuse 4-8kHz.
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Post by Deleted on Jul 4, 2020 8:22:48 GMT
You're way better doing ONE diffusor that has more wells, than placing three side by side. Are you using QRDude for your design ?
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Post by durian345 on Jul 4, 2020 12:25:39 GMT
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Post by Deleted on Jul 4, 2020 14:22:06 GMT
I would recommend QRDude. How large you need your diffuser to be? Room dimensions ?
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Post by rock on Jul 4, 2020 15:50:59 GMT
Without any practical experience, I can only repeat what I have gathered so take this with a grain (or pound) of salt: First, I'm pretty sure your diffusors will be more effective behind the listening position on the rear wall. I mention this because you mentioned the front wall. (remember, I may be wrong) QRDs use a repeating pattern so I think you should look at the diffuser as one system rather than how many sections it has. I shouldn't put words in his mouth but think Pasim's comment : "You're way better doing ONE diffusor that has more wells, than placing three side by side." makes sense, but maybe he's suggesting using a larger "Prime Seed" like 23 instead of 7 which will yield a wider unit and therefor will require less units to cover a given width... But I don't know, hopefully he'll elaborate. Even so, to cover the appropriate width of the wall, it may still need more than one sequence. For practical construction, you'll probably need to build and install them in smaller modules anyway. In general, you're going need to cover a significant fraction of the width of your (back?) wall. You should also figure on making them 4 feet high and mount them centered on your ear height. Covering only a small area will not have much of an impact. Just like absorbers, you need more than a little to make a difference. Above and below the diffusers on the rear wall (and even behind) could have absorption. I believe the useful design range can extend down to 800 or 1kHz but can that limit or influence the effective high freq? Wow, there's a lot going on with these things! No wonder I never built one (or them)! I can only imagine how difficult it can be trying to determine all the parameters of design without practical experience. If you're doing this for the first time, maybe see if you can visit some studios that are using diffusors and see how different designs sound and see if you can adapt that to your room? If you have not see Ethan's here they are: realtraps.com/diffusor.htm It'd be a lot easier to buy them! (but where's the fun in that?) Also, there's lots of diffuser discussion here too: www.gearslutz.com/board/studio-building-acoustics/988813-where-all-2d-qrds.html
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Post by Deleted on Jul 4, 2020 17:52:35 GMT
QRDs use a repeating pattern so I think you should look at the diffuser as one system rather than how many sections it has. I shouldn't put words in his mouth but think Pasim's comment : "You're way better doing ONE diffusor that has more wells, than placing three side by side." makes sense, but maybe he's suggesting using a larger "Prime Seed" like 23 instead of 7 which will yield a wider unit and therefor will require less units to cover a given width... But I don't know, hopefully he'll elaborate. Even so, to cover the appropriate width of the wall, it may still need more than one sequence. Yes, that's what I mean. If you're going to custom build it to your room, there's no point to build 3 small side by side, performance is way worse. Acoustic companies have to do it that way, because they are not building specifically it you and your room dimensions and needs.
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Post by rock on Jul 4, 2020 23:54:46 GMT
Hey Pasim, thanks for confirming my hunch. I have not built or used diffusers so every time a related question comes up I dig into it a little more. The QRDude was at one time more interactive online but now seems to be a paid download but it's almost certainly worth it as it does seem to drill down to greater detail like slat width which I did not see mentioned in the site referenced.
What do you think about the OP's desire to diffuse the front wall? Is that even a thing?
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Post by durian345 on Jul 5, 2020 6:23:54 GMT
Thanks for those good pointers.
My own bedroom is very small, about 300cm x 270cm of space after less all items along the walls. The 300cm sides are where my speakers are at front wall and where my 20cm thick queen size mattress placed vertical at my rear wall (for absorption). My listening position is at the mattress. This leaves some wall space on either side of mattress (150 high bookcase on one side) The 270 sides is where my 200cm wide window on my right side and my external wardrobe cabinet on my left. Entrance door is at front wall left corner inner recess.
I'm looking at front wall with bass traps (2 adjacent panels 15cm thick) at left and right corners. Additional absorption panels (2" thick) at the door, recess areas, wardrobe cabinet. The 2 wall spaces on either side of my mattress could probably have single15cm thick bass traps on each side. There's no adjacent walls on either side. That leaves the wall space (about 200cm wide) between the front wall bass traps, that's why was considering the diffuser.
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Post by durian345 on Jul 5, 2020 6:24:59 GMT
Forgot to mention that my speakers are Magnepan dipoles
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Post by rock on Jul 5, 2020 14:17:40 GMT
If your ceiling height is near the typical 8ft, your room is nearly cubic. Have you taken acoustic measurements? Given the dimensions, it seems to me diffusion is the least needed treatment but if your present treatment has tamed the peaks and nulls, go for it.
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Post by Deleted on Jul 5, 2020 15:21:28 GMT
Hey Pasim, thanks for confirming my hunch. I have not built or used diffusers so every time a related question comes up I dig into it a little more. The QRDude was at one time more interactive online but now seems to be a paid download but it's almost certainly worth it as it does seem to drill down to greater detail like slat width which I did not see mentioned in the site referenced. What do you think about the OP's desire to diffuse the front wall? Is that even a thing? It should be still free software, I haven't paid anything and downloaded it.
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Post by Deleted on Jul 5, 2020 15:24:55 GMT
Thanks for those good pointers. My own bedroom is very small, about 300cm x 270cm of space after less all items along the walls. The 300cm sides are where my speakers are at front wall and where my 20cm thick queen size mattress placed vertical at my rear wall (for absorption). My listening position is at the mattress. This leaves some wall space on either side of mattress (150 high bookcase on one side) The 270 sides is where my 200cm wide window on my right side and my external wardrobe cabinet on my left. Entrance door is at front wall left corner inner recess. I'm looking at front wall with bass traps (2 adjacent panels 15cm thick) at left and right corners. Additional absorption panels (2" thick) at the door, recess areas, wardrobe cabinet. The 2 wall spaces on either side of my mattress could probably have single15cm thick bass traps on each side. There's no adjacent walls on either side. That leaves the wall space (about 200cm wide) between the front wall bass traps, that's why was considering the diffuser. How near you sit the front wall? You said you almost sit on the back wall, but still how much distance from your listening position to front wall? What is your ceiling height?
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Post by durian345 on Jul 8, 2020 15:53:26 GMT
I'm about 170cm from the speaker plane. And about 250cm from the front wall Ceiling height about 250cm
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Post by Deleted on Jul 8, 2020 17:14:06 GMT
I'm about 170cm from the speaker plane. And about 250cm from the front wall Ceiling height about 250cm Ok, the diffusion makes sense on the front wall then. I suggest downloading the QRDude, its free and really good.
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