If the room starts to have too much high frequency absorption you can also break up flutter echo by scattering it with hard surfaces. I like taking something thin like luan and bending it into a semi circle or arc. Where the wall meets the ceiling is a good place to put them. They can also work mounted in front of absorption panels.
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john12ax7
Well-known member
Since you have REW I would suggest doing waterfall plots with the sub positioned. Getting even low frequency decay will most likely be the biggest control room challenge. If possible make the entire back wall one big absorber as deep as possible, 24" is not unreasonable. The 24" can be a full fill or absorber plus air gap. You can use a porous absorber calculator to estimate the optimal fill % based on the properties of the material you are using.
Things like flutter echo are easily solvable once you get the low end right.
Things like flutter echo are easily solvable once you get the low end right.
Im hoping that I have enough low end management in the room at this point. I dont have a lot of experience with subs in CR as Ive never had one in my own rooms bu there is a MASSIVE bass trap in the back of the room.
I left the RTA mic in my garage like an idiot so I will do some shooting once I grab that thing. Im also waiting on the sub, which is going to change the whole set up. Then I will need to add the NS10s.
The flutter echo is gone with some basic initial absorber placement and ill probably move things around to accomodate furniture.
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Sounds like it's coming together - congratulations! You are lucky to be able to iterate and explore the changes as it happens - most people don't have that ability or luxury!
I wouldn't worry about too much HF absorption, but once you get a waterfall plot like john12ax7 noted, you will see how your decay time works across all frequencies.
In the studios that I tune, the main thing I notice is that the HF contour (almost always some kind of linear roll-off from 1kHz up to 20khz) that I apply will vary based on how absorptive the room is at HF. A slightly more dampened HF room will take brighter voicing, whereas a more reflective room will usually feel better with a slightly more subdued HF voicing. That's the fun part, once you get the big stuff (modes, symmetry, and first-reflections) taken care of.
A lot of companies are selling "scatter plates" these days, to help with some random-ish HF reflections. They can work well, but so can simply hanging your gold plaques or family photos or other knick knacks. even the thin vertical pieces of wood, like you have as trim over your fabric do something nice.
I wouldn't worry about too much HF absorption, but once you get a waterfall plot like john12ax7 noted, you will see how your decay time works across all frequencies.
In the studios that I tune, the main thing I notice is that the HF contour (almost always some kind of linear roll-off from 1kHz up to 20khz) that I apply will vary based on how absorptive the room is at HF. A slightly more dampened HF room will take brighter voicing, whereas a more reflective room will usually feel better with a slightly more subdued HF voicing. That's the fun part, once you get the big stuff (modes, symmetry, and first-reflections) taken care of.
A lot of companies are selling "scatter plates" these days, to help with some random-ish HF reflections. They can work well, but so can simply hanging your gold plaques or family photos or other knick knacks. even the thin vertical pieces of wood, like you have as trim over your fabric do something nice.
Here are some initial shoots wihtout the sub.
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Definitely some early reflections to take care of- probably sidewalls. Be sure to include the rulers on your screenshots.
Below 300 hz the decay time is much longer than above. Have you treated the ceiling yet? Also something is creating some steady tones- like a fan or computer or something running that you can see in the waterfall.
Lookin great so far!
Below 300 hz the decay time is much longer than above. Have you treated the ceiling yet? Also something is creating some steady tones- like a fan or computer or something running that you can see in the waterfall.
Lookin great so far!
I just updated the screenshots with another more accurate placement of the RTA and cleaned up the scale of the images and added the rulers. I think my Makita battery charger was humming along in the first set.
The ceiling has the original 6" of pink insulation with the thick plastic sheeting over it. I was hoping to not have to add more but absolutely can add a big trap to the front half of the ceiling above the desk. I have the material and the Fabric/wood to install it. Im so sick of doing insulation... haha.
Sound slike I need a bit more broadband absorption to catch the early reflections.
I think it could be coming from some of the random stuff int he room right now too.
The 1st reflections could be from the walls on the sides of the speakers or the ceiling. You can actually find the reflection point from the ETC curve. If there is a reflection at 1.1 ms, then the reflection path (spkr/wall/ear) is 1 foot longer than the direct path (spkr/ear). You can use a piece of string taped to the front of the speaker and then stretch it to the measurement mic. Tnat is the direct path, so mark it with a piece of tape. Then pull another foot of slack and attach that to the mic (so the string is 1 foot longer than the direct path. Now see where the string can touch a reflective surface between the speaker and mic. In the example of 1 foot, it would likely be a desk surface, but if it was 3 or four feet, it could be a side wall or low ceiling, etc.
Your first reflections will definitely be tamed by a cloud above you (along with some LF problems) and you should have absorbers on the side walls between your head and the monitors (4" or 6" would be great, but even 2" will kill 1st reflections).
The reflections you care about are the ones that happen during the 1st 20ms from the impulse and only worry about the reflections that aren't at least 20dB quieter than the impulse...
BTW, can you drop the 6" of ceiling insulation, so that the insulation is flush with the lowest part of the joists, leaving 6 inches of airspace behind the insulation? That will give you a huge low end absorption benefit.
Keep going - you are getting so close!
Your first reflections will definitely be tamed by a cloud above you (along with some LF problems) and you should have absorbers on the side walls between your head and the monitors (4" or 6" would be great, but even 2" will kill 1st reflections).
The reflections you care about are the ones that happen during the 1st 20ms from the impulse and only worry about the reflections that aren't at least 20dB quieter than the impulse...
BTW, can you drop the 6" of ceiling insulation, so that the insulation is flush with the lowest part of the joists, leaving 6 inches of airspace behind the insulation? That will give you a huge low end absorption benefit.
Keep going - you are getting so close!
john12ax7
Well-known member
I would make the 1st reflection absorbers as big and deep as possible. If you are building 2'x4' sizes then use 2 on the side walls right next to each other, so effectively 4'x4'. For the ceiling cloud you probably want at least 4'x8' effective. And then add an air gap behind all of them to improve the low frequency absorption.
Thanks for the explanation! I think I follow you on how to measure the time/distance but not sure how to read the data.
I’m planning to add another 6” deep absorber on the side walls, but I think the first reflection we’re seeing is from the floor. The desk isn’t populated yet and there is a giant cork floor which is definitely reflective at high frequencies. I’m trying to figure out the best thing to do for the ceiling.
I like the idea of just dropping the insulation and then floating a cloud above each speakers reflection point for the first reflections although I suspect the insulation that is already there is not reflective. I can see how easy it is to lower the existing stuff.
I was planning on just putting one layer of 3” safe and sound at the bottom of the ceiling joist bay on the first 4’ against the front wall and then covering with fabric. This would be about 6” of pink, 4” of air and 3” of sns. The joist bays are just big enough to not snugly hold a sheet of sns, so I have to get clever about mounting it. The idea of just removing staples and dropping the existing stuff is smart.
Welp, turns out I can do that with the ceiling insulation... so thanks for the new project! haha. I think this is actually an easy thing that will help a bunch.
It looks like the early reflections are at 4ms which would be 4ft past the distance to the mic. That puts it at the side walls.
It looks like the early reflections are at 4ms which would be 4ft past the distance to the mic. That puts it at the side walls.
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Good stuff!
The floor is no concern- you need it reflective for obvious reasons and also to keep the room sounding natural.
Sounds like you have the reflections figured out and dropping the insulation gets you lower absorption for “free” instead of adding more insulation.
The floor is no concern- you need it reflective for obvious reasons and also to keep the room sounding natural.
Sounds like you have the reflections figured out and dropping the insulation gets you lower absorption for “free” instead of adding more insulation.
Actually they do.
Spiritworks
Well-known member
Dec 23rd post, picture showing measurement mic: It's my understanding these mics, when used, should be placed at ear level, with the capsule pointing up towards the ceiling. I got this information from the instructions that came with my JBL LSR speakers. Seems to make sense to me. When pointing towards the speakers you would get a different reading than when placed as instructed. Is that only for calibrating the speakers, rather than reading the room? Am I wrong? What would be most accurate?
It's omni so it shouldnt matter, but Im sure it does.... Let me review the documentation.
Im doing it right, im using the 0 degree calibration file. . From the Umik1 site below:
"- 0deg: This calibration file is for Stereo and 2.1/2.2 systems. Point the microphone towards the sound source being measured. In the case of a Dirac live measurement, you'll point the microphone to the center point between the 2speakers. This calibration is a so-called on-axis calibration file."
The Neumann RTA mic used for the correction software is placed as you describe. (facing upwards)
I did some new tests with the room treated finally and with and without the sub.
Not sure what is going on in the impulse with the sub.
This is all without the Neumann software tuning. Im not sold yet on the sub. In the mix position it nearly disappears in a good way, but of course in the rest of the room there is a boomy sub presence. Bass players and drummers will love it!! haha
With sub.
Without sub
Not sure what is going on in the impulse with the sub.
This is all without the Neumann software tuning. Im not sold yet on the sub. In the mix position it nearly disappears in a good way, but of course in the rest of the room there is a boomy sub presence. Bass players and drummers will love it!! haha
With sub.
Without sub
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The sub is not causing the boominess- the room is. You need to find the best place for the sun in relation to the listening position. You can do this two ways:
1. Place the sun at you listening position and play seeep tones from 30 Hz up to 100 Hz and then crawl around when you want the front of your room and find the most even bass response.
2. You can predict the location with REW or other software and then fine tune the location from there.
The best location will probably not be 50% between the side walls or 25%. It will probably be close to the front wall, not more than 30 inches from the wall or you will get SBIR problems. Sometimes a corner is actually the best location.
Once the location is sudsed, you should fine-time the volume, phase and crossover of the sun so that it extends the response of the mains without being obvious that the bass is enhanced.
Don’t worry about what the room sounds like outside the listening position - there is only one best place so listen in any room (regardless of what some hype-peddlers will try to tell you).
Bass pressure will always be stronger at a boundary and modes will always exist- your treatment only dampens them, it doesn’t eliminate them.
Shoot for an even decay time at all frequencies, measured at the listening position.
The measurement mic, as you mentioned is calibrated to a specific orientation and some mics proved 0, 30, and 90 degree cal files. Doesn’t really matter which you use- it will slightly affect the high freq measurement, but it want affect decay time or impulse measurements in amy meaningful way.
1. Place the sun at you listening position and play seeep tones from 30 Hz up to 100 Hz and then crawl around when you want the front of your room and find the most even bass response.
2. You can predict the location with REW or other software and then fine tune the location from there.
The best location will probably not be 50% between the side walls or 25%. It will probably be close to the front wall, not more than 30 inches from the wall or you will get SBIR problems. Sometimes a corner is actually the best location.
Once the location is sudsed, you should fine-time the volume, phase and crossover of the sun so that it extends the response of the mains without being obvious that the bass is enhanced.
Don’t worry about what the room sounds like outside the listening position - there is only one best place so listen in any room (regardless of what some hype-peddlers will try to tell you).
Bass pressure will always be stronger at a boundary and modes will always exist- your treatment only dampens them, it doesn’t eliminate them.
Shoot for an even decay time at all frequencies, measured at the listening position.
The measurement mic, as you mentioned is calibrated to a specific orientation and some mics proved 0, 30, and 90 degree cal files. Doesn’t really matter which you use- it will slightly affect the high freq measurement, but it want affect decay time or impulse measurements in amy meaningful way.
OK, thanks for the info. I placed the sub in the position I simulated as "best" in REW and its actually pretty good. I moved it around a bit. It is dead center between the two speakers as close to the front wall as I could get it. I'll play around with it some more.
Just to clarify, the boominess isnt present in the mix position. It actually sounds really good there.
The Neumann software actually does a lot of phase and crossover stuff depending on the room reading and placement so I might get a bit closer with manual adjustments and then start using the tuning SW. I wanted to try and get as close as possible without the tuning SW.
Right on- room EQ/speaker processing is the icing after you’ve dialed in your setup and acoustics. Get it the best you can without any processing and then see if the processing feels better or not. I use SoundID (software) in many of my setups and I like what it does to the stereo imaging, but some people prefer no DSP processing and that’s valid, too.
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