|
|
Post by Boomzilla on Aug 2, 2016 7:58:51 GMT -5
So I have this microphone:    I'd like to measure my room. I'm not interested in making any corrections at this point - just want to have a look at the frequency response in-room. I'm hoping to find a SIMPLE software for either Mac or PC. Also, I'm assuming that I'll need a microphone preamp (I can borrow one from garbulky) with a USB output? How will I get the sweep signal from the computer software to the audio system? I'm new at this, so forgive me my ignorance. I've also looked once before at REW and found the learning curve steeper than I wanted to mess with. There's got to be something simpler? Thanks - Boomzilla |
|
|
|
Post by garbulky on Aug 2, 2016 8:02:23 GMT -5
Yes please help. I am also at a bit of a loss here. I think this was meant to work with a velodyne subwoofer that accepts the mini-xlr plug end of the mic. But the sub is not there. I have not seen a mini-xlr plug so I am confused here.
|
|
|
|
Post by Boomzilla on Aug 2, 2016 8:05:20 GMT -5
The microphone (I'm 99% sure) is a standard room measurement mic that Velodyne just silk-screened their name on. It will work with a standard XLR microphone cable (no need to use the Mini-XLR at all).
|
|
|
|
Post by millst on Aug 2, 2016 9:57:07 GMT -5
It's probably an ECM8000, which means you'll need a preamp with phantom power. That's probably $50+ (not sure, bought mine many years ago) if you don't have one. It doesn't have to be USB, but it's easier that way.
Of course, you don't have any calibration info for it. That's like measuring the length of your room with a tape measure that you know is wrong.
Most people use REW. I wouldn't call it user friendly, but it is popular enough that people could walk you through it. TrueRTA might be easier to use, but it's not free and Windows only.
-tm
|
|
|
|
Post by charlieeco on Aug 2, 2016 10:01:14 GMT -5
|
|
|
|
Post by yves on Aug 2, 2016 10:22:45 GMT -5
Setting up and using REW is not that hard because everything you need to know about it has been explained on Home Theater Shack in a language that even a child could understand, and it has a great userbase that you can fall back on. Learning how to correctly interpret the measured data is always the hardest part regardless of software choices.
You will need something like a Focusrite Scarlett 2i2 or Steinberg UR22 / UR22 mkII that can supply 48V phantom power on the mic input. If the USB audio device can't supply phantom power, then you could decide to add a separate mic pre that can, but IMO you will be better off going for the 2i2 / UR22 instead. Another option would be to replace your mic with something like a MiniDSP UMIK-1 USB mic or a Dayton Audio UMM-6 (USB) mic, but the downside of doing that is you won't be able to get very accurate frequency response calculations if using the socalled gated impulse response measurement technique. That's because you need to have a loopback cable hooked up whilst performing the measurement sweeps; only *then* does it make sense to have the "Use loopback as timing reference" option ticked in REW settings, and only *then* will the clock differences that exist between the DAC part and the ADC part [in the audio device used for measuring] be eliminated from the calculated frequency response results. (Please note, the "Use loopback as timing reference" option is not to be confused with "Calibrating the Soundcard"...).
|
|
|
|
Post by garbulky on Aug 2, 2016 10:24:09 GMT -5
It's probably an ECM8000, which means you'll need a preamp with phantom power. That's probably $50+ (not sure, bought mine many years ago) if you don't have one. It doesn't have to be USB, but it's easier that way. Of course, you don't have any calibration info for it. That's like measuring the length of your room with a tape measure that you know is wrong. Most people use REW. I wouldn't call it user friendly, but it is popular enough that people could walk you through it. TrueRTA might be easier to use, but it's not free and Windows only. -tm So this mic would need calibration info for it? How would we go about getting it? We just need to know the model number for it? I have a preamp with phantom power. |
|
|
|
Post by millst on Aug 2, 2016 10:42:06 GMT -5
I don't know of anywhere to obtain it. You could try Velodyne. It was probably batch calibrated, which I'd guess is good enough for what you guys are trying to do.
-tm
|
|
|
|
Post by yves on Aug 2, 2016 11:52:03 GMT -5
|
|
|
|
Post by yves on Aug 2, 2016 12:05:50 GMT -5
|
|
|
|
Post by Boomzilla on Aug 2, 2016 14:23:21 GMT -5
After you are ready to get serious about room measurements... Well, I'm NOT really ready to "get serious about room measurements." Instead, I just want a one-time overview of where the peaks & valleys (if any) are in the bass. After that, THEN I'll decide whether to "get serious" or not. My gut feeling is "not," but depending on what I see on the curves, then I'll decide. Background - I've tried multiple versions of room correction software before and none (NONE) made any improvement at all. In fact, most made the bass not only worse, but SIGNIFICANTLY worse. "Flavors" tried include the Emo correction on their first processor, Yamaha correction (three different receivers), Denon room correction, and at least one other. Each and every one sucked eggs. My room has far, far less bass than any other room I've heard. I don't mean that some frequencies are missing - the room response seems smooth, but it sounds like a bass tone control is turned down between one and two notches. The bass is clean, tight, & tuneful, just gradually decreased in amplitude (unless the two 15" subwoofers are also working). This has been true through multiple speakers, multiple speaker positions, and both before & after room treatment. It's a big room with ATS treatment panels on all four walls. But there's an opening in EVERY corner (kitchen, foyer, hallway, & open stairwell). I've heard the SAME speakers in other rooms where they produced LOADS of bass, but not in my room. So if the bass response rolls off smoothly (as it seems to by ear), then a slight bass boost via equalizer or tone control should restore roughly flat response. If, however, the bass has huge peaks & throughs in addition to being gradually rolled-off, then some judicious EQ of the parametric nature may be required. We'll see... |
|
|
|
Post by garbulky on Aug 2, 2016 14:41:50 GMT -5
If you are just looking for a general idea of the dips and peaks that method I wrote in the PM with the SPL mic and a frequency sweep would be much easier imo.
|
|
|
|
Post by Boomzilla on Aug 2, 2016 15:13:48 GMT -5
Your SPL meter has "weighting." It can't be turned off. It's either A or C weighting (that are OSHA required for measuring workplace noise), but they are NOT what is needed for room measurement.
|
|
hemster
Global Moderator 
Particle Manufacturer
...still listening... still watching
Posts: 51,952
|
Post by hemster on Aug 2, 2016 15:33:28 GMT -5
I would start with a plot of room modes to see where the peaks and valleys are (i.e. points of reinforcements and nulls). See if your seating is on/near a null.
As a one-time offer, if you send me your room dimensions (width, height and length) I will send you a plot.
|
|
|
|
Post by millst on Aug 2, 2016 15:34:05 GMT -5
I don't think there is an issue with that, especially considering your first choice is a batch-calibrated mic. The weighting curves are well-known and can be calculated out of the response. That's how many of us EQ'd our subwoofers when we couldn't afford measurement equipment. Sounds a bit silly to be able to afford the equipment, but not the tools to optimize it...perhaps, it was just before the software really existed.
-tm
|
|
klinemj
Emo VIPs 
Official Emofest Scribe
Posts: 15,098
|
Post by klinemj on Aug 2, 2016 15:37:05 GMT -5
I have to say - I know you have tried REW and found it not so user-friendly, but...for doing what you want...just measuring, it's the right tool. And, I will say...in just doing the basics of measuring what you have, it's fairly easy. To interpret all the fancier graphs and use them to decide on room treatments/setup changes...that's not so easy.
As someone above noted, you need the mic, you need a mic preamp w/phantom power, and a way to output a test tone from your PC or MAC to your system (channel by channel)...which I did with a single wire from my PC into single inputs on my preamp and I would manually move the cable from channel to channel and measure 1 channel at a time, recording the data from each into a file named appropriately. Easy but a bit labor intensive.
If you don't have a calibration curve for the mic, you will only get relative data - not absolute. If you want to know what your room is really doing, you need a calibration curve. The Home Theater Shack site used to have example curves for different mics on the site. But, it's really just a typical curve for a mic of specific brands...not "the" mic. And, their site also showed how huge the mic to mic variation can be. (Which is why I chose to get a UMIK from CS Labs to use with my XMC-1...)
And...there is also a sound card calibration you need to do, but the REW software leads you through that. Again, easy but takes the time to do it.
Mark
|
|
|
|
Post by Axis on Aug 2, 2016 15:40:07 GMT -5
Very cool thread. Watching to see how Boom gets his results. Interested in this myself.  |
|
|
|
Post by Boomzilla on Aug 2, 2016 16:23:53 GMT -5
OK - klinemj has convinced me. REW it is. Now a stupid question - Does a netbook have enough guts to run REW or must I have a "real" computer? I can do the latter if I need to, but since the netbook is just sitting around... Is REW smart enough to test the speed / ram of the platform it's running on & say OK or No? |
|
|
|
Post by Axis on Aug 2, 2016 16:28:47 GMT -5
OK - klinemj has convinced me. REW it is. Now a stupid question - Does a netbook have enough guts to run REW or must I have a "real" computer? I can do the latter if I need to, but since the netbook is just sitting around... Is REW smart enough to test the speed / ram of the platform it's running on & say OK or No? Boom do you have a USB Audio Interface yet ? A Focusrite Scarlett 2i2 for $150 is something you can use for more than you think. www.sweetwater.com/store/detail/Scarlet2i2G2And get a proper computer to do this. |
|
klinemj
Emo VIPs
Official Emofest Scribe
Posts: 15,098
|
Post by klinemj on Aug 2, 2016 16:35:11 GMT -5
I can't answer if the netbook is capable...not familiar at all the the Mac lineup. As far as USB, when I last used REW, I didn't use USB out from my PC. I just used the audio out that powers my computer speakers if I recall correctly. And, that was what the soundcard calibration was about...taking into account it potentially being "off".
Mark
|
|
