In my last place I had them a bit higher where my ear was between the tweeter and the midrange driver. I'll move them up!
For this, and for everything else you do, run a REW test after each change, and make notes in it about what you did just before the test. That will give you a complete record of what you tried and what the results were. For example, for choosing the height, do a series of tests in small increments of maybe 1cm at a time, and see what that does. Then you can cycle through those incremental tests and spot trends fairly easily. It's actually very interesting to do that, and see what a difference such small changes can make. Ditto when you move the speakers and mix position: Do that in small steps of maybe 5 to 10 cm, and do a test at each position, then cycle through them quickly to spot trends.
I will try moving them closer to the wall as you suggested. I've read that it is not advisable to place speakers equidistant from the front wall and side wall. I fear that if I move them wider they will be in this range. Is this something I shouldn't worry about?
As with most generalities, it's not always true. Sometimes you might actually WANT to do that, to get a phase cancellation at a particular modal frequency. If the speakers are in a null for a mode, then they won't be able to excite it, and in a square room, for example (not your case, but hypothetically) it might be good to put them in the null in both directions. Or perhaps you get lucky, and in a rectangular room the same distance would put you in one modal nulls for the length axis and another modal null for the width.
That said, you also don't want to put the speakers too far away from the front wall, as that would move the first SBIR dip down too low.
In other words, it's a juggling game! You have to play with all of those parameters to find the best overall compromise that doesn't make any one factor too bad, or too good at the expense of others. You can do the math to figure this out, then test it... or you can just move things around in small steps, to see those trends, and maybe use the trends to predict a better spot. For example, if you see that the low-end response is getting flatter around 34 Hz as you move in one direction, then keep going in that direction! That will have negative consequences in other places, of course, but it might still be worthwhile. Try not to focus too much on one single thing, at rather look at the bog picture as you nudge things around: pretty much always one or two things get better, but others get worse.... it's all about compromise.
Of course, if you soffit mount (flush mount) your speakers, then you can eliminate many of the artifacts caused by just having the speakers in the room, but that's another discussion....
I'm not sure why the mid-range dropped so much. I was very careful not to move the speakers or mic while adding the treatment, but of course it's possible I may have bumped something.
Maybe something changed on your DAW? Perhaps you used a different setting on your mic pre-amp, or in the software some place?
The speakers are Adam S3x-V
Nice!
and the subs are NHT b-20
I found the manual for those on-line, and they only go down to 29 Hz, so that would probably explain what I saw with the 30 Hz roll-off. The S3x-V goes down to 32 Hz by itself, so the subs aren't really adding a lot, and that's also what I was seeing in your data.
I set up the subwoofer position / crossover with the treatment in place. So if you look at the "Treated" L vs L-S you will see that it filled in a hole in the 100hz area.
I did see that, yes, but if you look at the final LR and LRS in the current setup, with the room treated, you'll see that it didn't actually accomplish what you were hoping for:
MAXLOR--REW--FR--12..500--LR-vs-LRS--treated-V1.png
Purple is the LR result, and light blue is LRS. The dip is still there, except that it moved down a few Hz, from about 98 to 91, but there's now an eve larger dip at 200 Hz: that took a nose dive by more than 10 dB! The reason for that 200 Hz dip is also clear, when you look at the phase overlaid on top of the FR:
MAXLOR--REW--FR--12..500--LRS--treated-V1-plus-phase.png
You have a phase flip, right there at 200 Hz! It spins through 360° over a range of just a couple of Hz. That is almost certainly a phase cancellation caused by the something in the room, such as SBIR for example, since it is also there on the LR test, as well as the LRS, but is NOT there on the S-- test alone... so it is not related to the subs directly, only to the mains. But when you add the subs, then multiply the problem due to their location in the room, and the extra energy. Try flipping the phase on both subs, and see what you get...
Because the speakers are almost flush with the front wall, they are very full sounding already. So the subwoofers aren't needed to boost the low end much, I was just hoping they would activate a different part of the room and fill in some holes.
One question: from the manual I found on-line, it's not clear id the subs are set up as stereo, or if they are both summed to mono? In other words, is each sub getting the exact same summed mono signal, or are the each getting different signals, from the L and R channels? It might be an idea to do a REW test of the subs individually: first just the left sub by itself, with nothing else at all, then just the right sub by itself.
I did a little reading about the "Plane Wave" setup, but I'm not sure I understand it completely. Does this mean I should orient both the subwoofers on the same plane, parallel with the front wall?
Not really, sort of, yes, no!
This is usually done with several subs, but it can also be accomplished with just 2, to a certain extent. The idea is to have one set of subs on one wall (often the front of the room) and another set on the opposite wall, phase inverted. So the ones at the front are "pushing" a wave down the room, all in phase, and the ones at the back are pushing the inverted copy of that wave in the opposite direction... and sometimes this can be considered from another point of view: the ones at the back are "sucking up" the wave produced at the front. So that wave is produce on one wall, runs down the room, and is cancelled at the other wall. It can also be done
across the room: it does not necessarily need to be done lengthwise. Width-wise works OK too. Often, this is set up by four subs on one wall (eg, front), at the 1/4 wave points of that wall, and another four on the rear wall, in the corresponding locations. All of them acting together produce a plane wave that travels down / across the room. A plane wave is called that because the wave-front is flat, not curved: all of it would strike the other wall at once, with each part of the wave hitting the wall at the same time, rather than each part hitting at a slightly different time if the wave-front where curved. That has acoustic benefits that are rather complex to get into, but one of those is that you can cancel the entire wave at the other end of the room all at once, if you produce an identical wave that is phase inverted. That doesn't happen with a spherical wave-front.
Why does it work, and what does it do? It greatly reduces modal issues, because a mode that is triggered on the one wall, is cancelled on the other wall! It gets "sucked up", so to speak. So it doesn't get to resonate, like it would otherwise. That's the theory.... Exactly as the mode arrives at the opposite wall, the other speaker produces a mirror image, hopefully getting 100% phase cancellation, so the mode is stopped dead in its tracks. For a large room, you usually need a delay on one sub that is equal to the time distance across the room, ensuring total cancellation, but for small rooms and across the width, sometimes you can get away without that.
So, in your case, since your room is not symmetrical front-to-back (the ceiling rises and falls), that's not going to work so well. But it CAN work sideways, because your room is symmetrical that way. You would need to set up one sub o the floor, in the middle of the left side wall, and the other in the same place in the right side wall. Flip the phase 180° on one of them, set them both to the exact same level, send them both the exact same signal (in other words, the summed base signal), and you should get a reasonable facsimile of a plane wave like that. It should give you decent smooth bass coverage through the entire room. You might need to nudge things around quite a bit to get it to work, because there's always some non-symmetrical stuff going on, and you might need to add a delay as well (as mentioned above).
One drawback is that having the subs out to the sides might make them "localizable", meaning that you can hear the direction where the bass is coming from: that's why it is better (when possible) to do it front-to-back. It might be possible to reduce the localization effect by sliding both subs forward, closer to the front wall. You'll lose a bit of the plane-wave effect like that, but hopefully not enough to be noticeable.
Once again, it's a juggling game: playing to give one aspect priority over another, if something becomes objectionable.
If it works well, you get very even bass coverage throughout the room, and you minimize modal problems. It smooths things out.
However, furniture and non-symmetrical things in the room can mess it up, so try to minimize that. Keep your desk as low profile and acoustically invisible as possible. Ditto your chair, and the client couch at the back (if you have one). Minimalist is the key here!
It's very time consuming and rather boring to set up, but if you can get it to work, it's a really, really, really good thing!
- Stuart -
In order to get them aimed where they should be, you need to rotate them a little, so that they are both pointing at a spot about 30-60cm behind your head. If you do that, then axis of each speaker will be just grazing the tip of your ear pinna, or even better, just a bit beyond the pinna, and that's where you want it. So each time you move the speakers or the mix position, rotate the speakers so that they are pointing at that spot behind your head, and not AT your head.