You don’t actually need to do SPL measurements, just adjust volume until its high but not so high that it starts to produce room-distortion like shaking windows or rattling stuff around
Generally speaking, you should use the volume you use when playing music high, but pink noise will sound higher at same SPL.
The important thing from a room-correction perspective is that the volume is high enough so any background noise don’t affect measurements. I would guess you can get good measurement at 60dB if its very quiet.
Gentlemen, different microphones have different characteristics and frequency response. even reference measurement microphones have calibration files. in order to make the transmission characteristics as flat as possible. For fun, any available microphone can be used. you can experiment. but these will not be measurements, and there is no room calibration. ps. @Magnus great job.
Please I’m newbie on room correction and I’ve just followed the guide with mic. And I think I’ve a not bad flat line trend via REW but what is house curve,why and how should I apply it in REW.
Any step by step instructions?
By default you have a house curve in REW already (the slopes), but you can disable that and use your own. The default one is perfectly good though, so I recommend waiting with that and using the default one until you get a good working room correction. Then you can decide if you want to fine tune anything.
If/when you want to try your own house curve, you disable the default one in REW from EQ window (see picture) and go to preferences -> house curve and load one from disk.
Wow. @Magnus what an excellent guide and I have been getting everything together to give it a go. The Umik mic is proving difficult to get hold of in the UK though so I’ve gone for a Focusrite Scarlett Solo and a Beyerdynamic MM-1 mic.
I’ve just been having a final fettle of the room layout before I get cracking but it also looks like I may have bagged the services of a room acoustics expert who has offered to come and help me through the process and also advise on physical room correction treatments.
Think I’ll give the guide a go and then compare the results with how it all sounds after the consultation
Quite excited as this is not a step I’ve taken before but now I have a dedicated listening room it makes sense to take it as far as I can and because I have the wife’s blessing to take over the room I have complete freedom to do what I want to it.
@ Magnus and all contributors: many thanks for the guide and the willingness to support all of us here. I have tried a few times in the past to follow the guide but was not convinced about the results. Last week I tried again and for the first time I thought that the change was on average better. I did so with a combined L+R measurement and 20-800 Hz corrections only. Comparing the pre- and post- measurements corroborates (shown below with artificial SpL separation to avoid overlap) what I hear with the red+yellow curve (with convolution on in Roon) much smoother than the violet curve (convolution filter off):
Now, I am trying to do things properly with separate L and R measurements. They look very different because my room is L shaped (7.83m x 8.86m x 2.82 H with a 4x4 area carved out) with the R speaker in the apex corner of the “L” shape 1.12m from the back wall and 0.63 cm from side wall (all distances from woofer front baffle center) and the L speaker located along the 7.8m wall with 2.2m (tweeter distances) from the R speaker. As this is a living room more optimal positioning of the speakers is ruled out for the usual acceptance related reasons.
I would appreciate your feedback on:
the parameters I try to set up for correction (currently focusing on low end < 300 Hz, unless you advise to go higher). I have used Magnus’s home curve but then the target level (by the way it appears that the two speakers produce different SpLs …), the boost parameters etc will produce very different results so selecting them carefully is crucial.
I seem to get three “null” points especially the R speaker (33.8Hz, 82.5 HZ, 198 Hz) which I presume are due to the room and thus incorrigible (the speakers fire along the long 8.86m dimension), is this correct?
A good first step is to turn on “Var smoothing” filtering in EQ, it will make it easier to identify problem areas as well as help REW with a good correction. Can you show the L and R measurements with var smoothing turned on? (a good range is 50-100dB and 20Hz - 20khz which can be set with the button with 4 arrows up to the right in EQ window)
Target level looks good, I would correct 20 - 700Hz since both channels are on target there and it looks ok afterwards. The problem is that REW might try to correct to much (the small peaks and dips) so maybe disable some filters, which you do by opening the EQ filters window and un-check filters. I suggest to try a conservative “only fix the worst” kind of correction in this case, so try with only 5 filters enabled and experiment.
You usually don’t want a totally flat curve, but a correction that fixes with “broad strokes” so that the overall level is ok. You can see my correction which I posted May 26 as an example. This is one of the things I have learnt since I wrote the guide.
Hi Markus, this is also what i have somehow “sensed” by trying this method in the past. s there a way to restrict the Q’s or restrict the gains in REW? I understand “flatness curve” acts as a minimum deviation threshold but I have not seen “max deviation allowed” type of settings? Is that the reason you revert to manual (and yes, I have seen the relevant post of yours).
I have also noticed that REW cannot correct the major dips (especially the R channel ones). I understand this should not be attempted for null points but I cannot tell if my dips are due to null points or not (have not done the excess phase analysis to detect them)
Gains can be restricted but thats not the biggest problem, steepness (high Q) is. But try auto-correct with only a few filters available and then you can see the details in the EQ filters window. Its typically the narrow corrections that requires high Q so with to few filters available REW will only correct the bigger problems.
Or experiment and do it manually, Q=5 filters should work pretty good in your case except for a less narrow filter (q=2.5 maybe) to lower 150Hz and surrounding in first channel, and similar Q in second channel to raise 200Hz with surrounding. No need to touch anything above 300Hz. But I think you can get good results by lowering available filters and let REW do it.
I never experimented with “modal” filtertype in REW so not sure how that works, and with var-smoothing which does very little at lower frequencies its hard to see because of all the small dips and peaks. Maybe you should use 1/12 or even psycho acoustics.
Try this:
Set smoothing to 1/12
Disable all but 5 filters in EQ filter window
Let REW do auto-correct betweem 20 and 700Hz
I think that should give a conservative but good result
