DIY Digital Room Correction with Linux(th0ma5w.github.io) |
DIY Digital Room Correction with Linux(th0ma5w.github.io) |
That is, there are likely both issues induced by the phase response of the speakers themselves as well as issues introduced by reflections in the room which will cause uneven frequency responses in these measurements. These issues are inherent in speaker systems and acoustic spaces.
If you have a really resonant frequency in a room, notching that frequency can help, but then you're compromising that signal; a more typical solution is to address reflectivity in the space.
And I hate to be a snob about mics, but yee, I do not like that specific mic-- of the many dozens of mics I have used it's memorably bad. And you don't need an expensive mic to do these measurements; there are a lot of ~$60 omni-directional measurement mics that work fine, as their low/mid frequency response is good enough for these tasks.
So all in all: hooray for folks experimenting... once you start playing with frequency modification, start investigating phase response and modal reflections in rooms, as they are super interesting.
Like, if you want to hear something really neat, put on a recording of a 120hz sine in a very reflective room, and you can walk around and hear the nulls and additions. And then you can find different frequencies and start to come to terms with the complexity there. Quite a fun exercise.
PEQ can take you a surprising distance. Many perceivable issues can be substantially reduced by attenuating signal at problematic resonant frequencies. At no point ever (IMO) should PEQ be used to boost the level of any frequency to make it more audible.
FIR filters are where you can fix time-domain issues. The only problem is that, depending on the amount of filtering required, you may add quite a bit of latency to the signal. IIR filters (e.g. for your crossovers and such) are typically much lower latency approach. IIRC FIR filtering will also allow for you to correct for phase issues.
At the end of the day, the room and its treatments are the most important part of the equation. The number of LFE radiators and their positions are probably #2. Everything else you can easily fix in software.
Pareto's principle indicates that the biggest 20% of work will provide 80% of the expected results, whereas to get the last 20% of expected results will require 80% of the work.
Doing a basic room EQ with the equipment you have on hand would mean that the spot you EQ'ed from would have a listening experience calibrated to the quality of the microphone at that location (but with a margin for error since they were not using any heuristic other than "make line as flat as possible in a single pass")
That's ~20% of the work in making a pristine audio environment but with close to 80% of the end results. Room correction, reverb baffling, bass traps, better speakers, fancier receivers with complex auto balancing algorithms all could definitely improve the end result but will take far more time and effort (and money) to achieve any noticeable improvement.
I wonder if you just need a mic with a calibration file?
this one is less than $25:
https://smile.amazon.com/dp/B00ADR2B84
and you can use the serial number to download a specific calibration file
Calibration files can help you in the frequency domain (provided that mic is stable over it's lifetime), but the time domain is a different beast as in: if we play a square click how well can the mic reproduce the square and/or what kind of artifacts are added by it.
In the end the question is, how important calibration is for your purpose. If you are a hobbyist, I would even say, you don't really need it more than once. If you mix/master productions that have high budgets maybe spending a little bit more on making sure everything works makes more sense.
If you are the hobbyist, maybe renting is a good option?
(This is essentially why a lot of consumer electronics sound surprisingly good these days: onboard DSP is cheap and easy to implement. What a blessing!)
Conversely, even "high end" speakers can sound bad if not dialed in correctly, especially if your room is rectangular and there are a lot of reflections.
Today, I just have a miniDSP that does basic crossover duty. I haven't bothered to do any parametric EQ or more advanced filtering in my new office yet. The passive acoustic treatments have done such wonders that I probably can't be now.
I don't really like running anything above 80Hz through digital filters that I have constructed myself. I've had some success in a few areas, but you can instantly tell something isn't quite right with certain content.
I am using it as a USB DAC driving a pair of stereo monitors and 2x subwoofers at the moment.
[EDIT] In case it's not clear, the core problem is that for some seats, without a large buffer between the seating area and the speakers, the nearest surround speaker will be like 5-10% as far away as the farthest one. No amount of room-correction can help much for most of the seats in such an arrangement. All you can do is use a larger space so you can put the speakers farther away without changing the size of the seating area (so, add empty buffer space around the seating area) so the difference in relative distance between the farthest and nearest surround speakers is smaller.
Depending on the seating costs and budget and other things, I think it makes sense to go ahead and put seats around the sides... in case you end up having extra guests, they can sit in comfort, even if the audio isn't ideal.
On a small budget, you can do a lot with just two decent speakers rather than speakers built into an ultra thin flat panel. Thrift stores often have nice speakers that may not be visually pleasing but are likely to be aurally pleasing.
This is very true, almost any separate speaker is going to be better than TV speakers, especially in the age of flat panels.
And one thing software room-compensation can do is let you build a surround system with mismatched speakers, without having to lose a day manually tweaking levels. No need to buy a full 7.1 or 7.2 set at once. Thrift decent pairs of speakers and orphaned subwoofers and let the software figure it out.
I think there are a LOT of these. I wish I knew when "reasonable" or "plausible" pan out.
Sounds like you don't need a mic or anything other than the EQ to make movies watchable. Just reduce every frequency range other than that of human voices. No more having your ears blasted by loud music / explosions because, earlier, you had to turn the volume up to maximum in order to barely hear the dialog.
Gives me peace of mind knowing my EQ curve always is on even if I'm using software that's outputting direct to my interface.
However, it's still fun to geek around with acoustics.
I mix stuff that other people listen to, and I operate sound systems in a variety of locations. My interest in this is mostly professional, though I think that it's easy to get a long way in that business without a lot of specific exploration, so really it boils down to being a fun and kind of nerdy hobby.
To your point about mics, Rational Acoustics, maker of the popular Smaart analysis program, have advised users that high-end mics might not be the most important element in a measuring system.
This is because most of the useful elements of acoustic treatment happen at lower frequencies, where the cheapo omni capsules work just fine, and these elements are not generally creating lower-frequency artifacts.