|
Post by kcatthedog on Jan 3, 2022 12:20:59 GMT -6
REW recommends a calibration of the sound card basically sending a sweep out and in on a loop. So, all internal nothing to do with mike, pre room etc.
Graph should be flat.
My aurora N isn't .
All its I/o is on a patch bay so I patched Channel 2 out to its in.
Any ideas why its not flat ?
hmm screenshot is too big so can't load, do I have options for loading the screenshot ?
|
|
|
Post by Tbone81 on Jan 3, 2022 12:31:36 GMT -6
It’s been a while since I used REW but I wouldn’t expect any converter to be ruler flat. There are analog stages on both ends, AD and DA, and they’re doing “something” to the audio.
The idea is that you do a loop back on your converter and use that to create a calibration file. That way REW can correct for your converters sound when taking measurements. So I don’t think anything is probably wrong with what you’re seeing.
|
|
|
Post by kcatthedog on Jan 3, 2022 12:46:09 GMT -6
Makes sense, I see a sort of long slope then see 3 peaks starting around 4k and a few 1,000 freq apart, that surprised me ?
|
|
|
Post by Guitar on Jan 3, 2022 13:26:03 GMT -6
Can you post a picture of what you're looking at? I'm curious.
TBone is right, a converter will have a sub frequency roll off, and a supersonic frequency roll off. But should be flat within a few fractions of a decibel in the human hearing range.
I'm going to say it again, because why not. When you calibrate for your sound card, then REW can factor that into your measurements and essentially be ruler flat and "invisible" for the other things you measure with it. It takes the sound card out of the equation. Pretty ingenious.
If you can, it's best to measure at 96 KHz or 192 KHz when doing these sorts of tests, for the most bandwidth.
One of the beautiful things about REW is you can see past the mythology. No gear is truly flat, or truly noise/distortion free. It's a beautiful thing to be able to have a look see at it.
|
|
|
Post by Guitar on Jan 3, 2022 13:28:31 GMT -6
You can use a program such as IRfanview to resize your pictures on Windows. For mac, I'm not sure.
|
|
|
Post by kcatthedog on Jan 3, 2022 13:33:35 GMT -6
I’m on a mac.
I thought REW defaults to 44.1, didn’t realize I could reset.
I’ll try again.
John kenn can you combine this with my other room measurement thread as it’s all related ?
thx.
|
|
|
Post by Guitar on Jan 3, 2022 13:35:51 GMT -6
On Mac, Fotor or GIMP should have you covered for free image editing and resizing.
|
|
|
Post by kcatthedog on Jan 3, 2022 13:57:20 GMT -6
|
|
|
Post by Guitar on Jan 3, 2022 14:02:58 GMT -6
Not sure what's going on there, it looks like an impulse response test to me, rather than what you want, which would be a sweep test.
There's a series of Peterson Goodwyn videos I could link you to if you have 20 or 30 minutes to train yourself with them.
|
|
|
Post by kcatthedog on Jan 3, 2022 14:17:33 GMT -6
|
|
|
Post by Guitar on Jan 3, 2022 14:23:09 GMT -6
The soundcard calibration test should be done as a loop back. Route one of your outputs back to your input with a TRS cable. Then you can get into microphone / speaker / room measurements and etc.
I'm not clear on what's going on here, I am not "looking over your shoulder."
But that's clearly not a DA / AD loop back measurement.
|
|
|
Post by Tbone81 on Jan 3, 2022 14:46:12 GMT -6
at first glance it looks like you ran the measurement test for your speakers, not then calibration test. Meaning it looks like the sweep you recorded was intended to be played by your speakers and measured with your measurement mic.
|
|
|
Post by kcatthedog on Jan 3, 2022 14:53:15 GMT -6
Yes, the last graph was not the calibration test of sound card.
It was a measurement test with no sound card calibration but with mike calibration .
The freq sweep doesn’t show it but the rt60 in 1/3rd octaves has delay mostly below 250ms other then very low bass like 50 cycles or so. I have a fair bit of treatment up so I would expect some ok results .
I just find when REW generates a graph that doesn’t seem to make much sense It raises more questions thsn answers snd I worry I am just misunderstanding REW and the methodology .
|
|
|
Post by kcatthedog on Jan 3, 2022 14:56:50 GMT -6
Sorry to switch hit on you guys, I was just curious what a sweep at 96k would register like.
I find it hard to believe there is anything wrong with the linearity of Aurora converters so was comfortable running measurement test with no sound card calibration file , although, I understand it’s theory.
|
|
|
Post by christopher on Jan 3, 2022 15:49:26 GMT -6
Long ago I tried REW, loopback from RME was perfectly flat. And my console+RME was barely a difference, did it 5 times or so because it didn’t even measure. Until I realized I had to zoom in very deep. That was the exact moment I learned FR is an overrated spec actually.
Yeah that room sweep looks like the kind of stuff I’ve seen, lol..
IK ARC makes you do 21 positions iirc, so be sure to move the mic 12 inches in each direction and remeasure
|
|
shawnh
Junior Member
Posts: 59
|
Post by shawnh on Jan 3, 2022 19:49:00 GMT -6
Oh man welcome to a deep dark rabbit hole. I think I mentioned in the new gear thread I had recently also picked up some kh310s - I really like them.
I have also been working with rew and working on my room and listening position etc. An ongoing battle now for a few months.
Like you I had a fair amount of treatment up in my room - first reflection points etc. I was really disheartened by my first measurements.
I’m not an expert but I’ve learned a few things and I have made very meaningful improvements over the last few months. Here are some things I’d point out.
-you need to measure left and right speakers separately - any frequency response above about 300 hz is best looked at that way. Unless your mic is perfectly positioned you get cancellations from sound arriving at slightly different times. It’s good to measure both together to look at your bass response. above that look at each speaker separately and use more smoothing.
-your treatment is most likely doing next to nothing under somewhere around 300hz. And honestly it can be depressing how little difference a lot of treatment makes overall - esp on the frequency response graph.
-the big peaks and nulls in your bass response are related to room modes and to boundary intereference. The only practical way to address these for most of us is to experiment with positioning of both the speakers and the listening position. For me the biggest change was moving my speakers right up against the front wall and then tweaking width and distance to listening position. It’s always a compromise and it’s lots of measuring and taking notes.
-try to get a basic understanding of the other graphs, esp the impulse response, the spectrogram, and the rt60. It’s a lot to get your head around but you need to have some idea of what’s going on in the time domain.
Long-winded post. It’s a complex subject. I’m happy to share more of what I have learned if it’s of interest.
|
|
|
Post by craigmorris74 on Jan 3, 2022 20:07:12 GMT -6
Based on how I've heard the newer Lynx products described by several different sources, I'm not surprised by that frequency response measurement at all. They're definitely a bit colored, and that may be just what you're looking for.
|
|
shawnh
Junior Member
Posts: 59
|
Post by shawnh on Jan 3, 2022 20:30:50 GMT -6
I haven’t seen anything posted that could possibly be the loop back response of an interface??
|
|
|
Post by tripalot on Jan 3, 2022 20:48:39 GMT -6
|
|
|
Post by Guitar on Jan 3, 2022 21:18:23 GMT -6
I've attached a couple of REW interface AD/DA loopback measurements for an example of what they look like. Here's a Clarett Octopre and a Tascam UH-7000. You can see the Tascam is a tiny bit bass shy. And I did the MOTU Ultralite MK 5 where you can see the frequency as well as the phase response. You can also measure noise and distortion with REW which is pretty incredible!!
|
|
|
Post by svart on Jan 3, 2022 22:05:41 GMT -6
All this is the reason I decided to forget about room calibration and just get some expensive monitors, trust them, and trap the room well and get to mixing.
You can't learn your monitors and room if you keep chasing the rabbit and changing things all the time.
|
|
|
Post by kcatthedog on Jan 4, 2022 2:24:11 GMT -6
Ha, that’s why I stopped using monitors and just used my cans for 2-3 years.
I bought the used focal shape as an experiment and had been considering some better headphones instead of monitors.
My rt60 x1/3 octave shows room ms around 250-300, above 100 cycles generally: pretty good.
my deep lower bass problem isn’t really much of as issue as practically speaking I hpf a lot.
Although I cancelled my Sonarworks order, it would help with more level frequency response and phase and would benefit my speakers and cans, so I might reorder.
Getting monitors again was an experiment, I may sell them and just get better headphones but the monitors do have that spaciousness soundstage and better bass.
|
|
|
Post by kcatthedog on Jan 4, 2022 2:29:25 GMT -6
I haven’t seen anything posted that could possibly be the loop back response of an interface?? Actually, the first post is and it looks all wrong and I don’t understand why? It’s just the sine wave sweep looping through the Aurora but I have my m1 mini on tbcables, the Aurora on db25 cables, a Samsung s patchbay and my patch cable which shouldn’t be affecting anything ,but that LB test looks all wrong. So, I did the sweep with no sound card calibration.
|
|
|
Post by svart on Jan 4, 2022 8:53:03 GMT -6
Ha, that’s why I stopped using monitors and just used my cans for 2-3 years. Anything will work as long as you learn it. That's why so many past pros could walk into any studio with NS10's and mix hits that sounded like *them*. Because it didn't matter what room, it mattered that they knew what the music should sound like from the speakers. It's like that old anecdote that I've read a hundred times but never really knew the source of.. Some engineer would put his hands on the NS10 woofers and feel how much they moved. When they moved a certain amount, he knew the low end was too much. That's the lost art of it all.
|
|
shawnh
Junior Member
Posts: 59
|
Post by shawnh on Jan 4, 2022 9:06:30 GMT -6
So here was my initial measurement of my room: Like I said pretty depressing for a room that I thought was well treated and that I had already put a lot of time into. The problems in the bass response were easily verified by loading up a basic synth patch and just playing up the keyboard - crazy swings in volume of the notes. Flat is approx 78dB on all these charts. 1/24 smoothing on all charts. After a lot of experimenting with positioning, upgrade to KH310, and "some" additional treatment: The finishing touch was some basic EQ done with RME total mix EQ on the master out - it's limited to 3 bands and it's all under 600Hz. 2 Small gentle cuts and 1 boost:
|
|