A World of Experience
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Yep.I was planning on making a 4" thick panel of OC 703, 24" x 48".
Do you think that will be sufficient?
Not so sure about that! Here's a comparison of your original baseline results, to where you are now:It appears to not have made a real impact on anything in the SPL graph, compared to the last test I ran after adding super chunks.
OK, that would explain why they aren't doing as much as I expected: they aren't as big as I thought they were. For superchunks, I usually go with 36" sides, or 24" minimum. 18" is not very deep. What you could do to improve the effectiveness of those traps at low frequency is to add a 4" layer of very light density insulation, such as Pink Fluffy, or even polyester (around 20 kg/m3) in front of them, with a 4" empty air gap in between. That would increase the absorption at low frequencies.The super chunks are triangles of roxul safe n sound about 18” x 18”
That's probably the typical studio "floor-bounce", coming from reflections off the floor mid way between the speakers and the mic. It's actually not such a big deal as some people imagine, since it has a positive psycho-acoustic effect: your brain uses that to help interpret the acoustics of the room. Not worth worrying about at present. The desk and chair will change that, and probably some of the other treatment too...Do you think the side panels will help the dip around 114 Hz or is that a result of something else?
What's above that? That is not the hard boundary of the room: the hard boundary is above that. You need to know how far above, and what is in the cavity up there...Soundman2020 wrote:OK, that would explain why they aren't doing as much as I expected: they aren't as big as I thought they were. For superchunks, I usually go with 36" sides, or 24" minimum. 18" is not very deep. What you could do to improve the effectiveness of those traps at low frequency is to add a 4" layer of very light density insulation, such as Pink Fluffy, or even polyester (around 20 kg/m3) in front of them, with a 4" empty air gap in between. That would increase the absorption at low frequencies.The super chunks are triangles of roxul safe n sound about 18” x 18”
I actually have 6” roxul from floor to ceilin. In the rear of the room. That has been there since my baseline test. I used hen remaining roxul I had leftover for the super chunks and they are in the front and rear corners of the room.
Also, it seems you only have those two traps in the front corners? Nothing in the back of the room? I'd suggest doing two similar traps in the rear corners, and also covering the rest of the rear wall with something like 6" of insulation, or if you really want good bass low-end acoustics, then put hangers across the rear wall.
In the meantime, to double-check the flutter echo thing, use the panels that you have behind the speakers right now on the side walls, exactly in line with the location of the mic, and do a REW test like that. That will confirm that the issue I'm seeing really is flutter from the side walls.
just to clarify, should I place the panels at the reflection points on the side walls (using mirror) or are you saying to put it in line with the microphone (horizontal axis)?
That's probably the typical studio "floor-bounce", coming from reflections off the floor mid way between the speakers and the mic. It's actually not such a big deal as some people imagine, since it has a positive psycho-acoustic effect: your brain uses that to help interpret the acoustics of the room. Not worth worrying about at present. The desk and chair will change that, and probably some of the other treatment too...Do you think the side panels will help the dip around 114 Hz or is that a result of something else?
Also, from that latest photo I noticed that you have a drop ceiling!
I explained this earlier in the thread, There are I beams and conduit etc above the drop ceiling and then a weird square wave type ceiling, I believe I attached a picture somewhere in This thread
EDITED TO ADD: You really do need to get those longer cables for your speakers! The desk needs to go into its final position, and it can't right now, due to the short cables.
cables are arriving Wednesday. I will definitely redo the test once that is situated
Also thinking about moving the mic up closer to 38% length and running test to see if anything improves
- Stuart -
In line with the mic, horizontally. That's where the flutter will be strongest. This isn't about reflections from the speakers on the side walls and back to the mix position, but rather reflections that are happening between the side walls themselves, rushing back and forth across the room. This is just a test with those panels, to confirm the diagnosis. I might be wrong about it, but it looks very much like side-to-side flutter echo. In fact, if you stand in the middle of the room and clap your hands sharply, you should be able to hear that as a sort of hollow "ziiiinnng" sound. It probably occurs all along the side walls, wherever you go in the room, so this test with the panels in line with the mic should show if that's what it is that I'm seeing. It's not the final location of where you need panels: just to check if that's the issue or not.just to clarify, should I place tre panels at the reflection point on the sidebar wall (using mirror) or are you saying to put it in line with the microphone (horizontal axis)?
I used the offset method and ended up with the following results...Soundman2020 wrote:For better effect, you could "offset" the panels a bit, so that the one on the left is a bit more forward than the one on the right. In other words, set them up so that the BACK edge of the panel on the left lines up with the mic, and the FRONT edge of the panel on the left lines up with the mic. That covers twice as much wall area, so it should have a more noticeable effect on flutter.
- Stuart -
Please don't get so hung up on frequency response graphs! I really wish that REW would NOT show that one by default: it isn't even the most important parameter of the room acoustic response...I don't think these are the results we were looking for... test results look very similar from the last test ran.
Here's you REAL results... the ones you SHOULD have been looking for. You wont find flutter echo in frequency response, because it doesn't have anything to do with frequency response! It's a time domain issue, not a frequency domain issue.test results look very similar from the last test ran.
I disagree;I don't think these are the results we were looking for...
this is DEFINITELY the results we were looking for! A classic text-book case of flutter echo, with a classic simple solution. Crystal clear. 
Wow thanks for breaking that down for me! I was misunderstanding what we were trying to correct! I thought you were giving me a solution to help resolve the dips in the frequency response!