# Are my Mic, Pre and SoundCard compatible with REW?



## tjswarbrick (Jan 11, 2014)

I joined primarily so I could download Room EQ Wizard. Before I do, I need to know if I NEED new equipment to run it, or if what I have is likely to work at least to get me started.
I should note, I have no signal processing in my home setup. I'm largely a stereo guy, though I do run my HDTV, DVD/VCR and Blu-Ray audio through my preamp into my 2-channel system. And I am quite happy with it.

I recently picked up my first autosound Digital Signal Processor. Tuning by ear and with various SPL and RTA files on my Android phone got me to better than without, but I feel I still need some fine tuning, and for that, more accurate measurements are required. Which leads me here.

I don't presently have a laptop.
My Desktop system is 64-bit Windows 7 on an ASUS card with I think a P5 or so Intel processor. (I built it myself a couple years ago, but have forgotten what I put in there.)
My sound card is an ASUS Xonar Essence STX PCI-E.
Microphone is a V-Tech VT-1009 unidirectional dynamic model.
Mic Pre-amp is a Behringer Tube Ultragain MIC100. I've managed to set the gain and limiter so my daughters can record themselves on RazKids and play it back through the Xonar Essence card over the stereo, so I know it works. I just don't know how accurate it is or have a calibration report for it. 

Does anyone have experience with such things? Can you offer guidance or tips?
Thank you.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, tjswarbrick!

Unfortunately, your equipment is not going to work well with REW. Acoustics measurements require small-capsule omni-directional condenser mics. By contrast, your vocal mic is uni-directional, and most likely has severe limitations at the frequency extremes (i.e., a steep roll out at the highest and lowest frequencies). Generally we don’t recommend tube pre-amps, as by their nature they are not designed to be transparent. 

Regards, 
Wayne


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## tjswarbrick (Jan 11, 2014)

That's what I was afraid of.
Thank you, Wayne.

I guess I'll keep my eyes peeled for that Dayton mic and a new pre... In the meantime, I'm pretty happy with the sound (finally), so I don't feel an urgent need for more tweaking.


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## tjswarbrick (Jan 11, 2014)

Well, I've finally done it.
I picked up a calibrated UMIK-1 from Cross Spectrum.
This allows me to bypass the mic preamp and, hopefully, get some accurate measurements.

I'm going to double-check his instructions, but does anybody know which calibration file I'm supposed to use? There were like 6 on there. Narrow-range or smoothed, at 0, 45, or 90 degrees. I'm sure I want 0 degrees (on axis,) but not sure from which range.

Also, has anybody calibrated an ASUS Xonar Essence STX with REW 5.01 on Windows 7?
I'm having a of a time, and either get too low a signal (like -47dB,) too high (clipping,) or too much variance (like 71 or 89 dB over the range from 20-20k Hz.) 
For loopback, I'm trying to run a patch cable from the "red" right line-level out through an RCA to 3.5mm converter and then a 3.5mm to .25" headphone adapter into the Line In on the card. Option for output is Speaker (not sure how I'd use the Digital selection for a loopback...) Input is Line In. I've messed with the input and output signals from .250 to 1.00 of max, and level from -3 to -40 dB. When it gets low enough to not clip, it's too low to register or has too large a volume swing. 

Just to see if it works, I ran an un-cal'd sweep with the UMIK. Once I got the volume to read 82.5dB on my RS SPL meter, and adjusted the REW SPL meter to match, it was +/- 1dB from 30-10kHz, with about a -3 dip at 10. Then is was a little spikey, but stayed within about +/- 2 to 20k.
But I'd like to get the calibration right so I know what I'm measuring is accurate, so I can correctly interpret any changes I might make.

I tried the search and didn't see a thread discussing cal with Xonar Essence - but if there is a pertinent thread, the link would be awesome. 

Thanks!


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## tjswarbrick (Jan 11, 2014)

Well, I just read that (on laptops, per the thread, anyways) if using a USB Mic that you would NOT use a soundcard calibration. So maybe I wasted 3 hours this afternoon for nothing!

Before I move stuff around and take additional measurements, can more experienced users confirm that no soundcard cal is required, necessary, or even desired when using a UMIK-1 for measurements?

Thanks again.


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## JohnM (Apr 11, 2006)

Correct, no soundcard cal with a USB mic since the soundcard is only used for output, not input.

The Cross Spectrum cal files usually don't have the UMIK sensitivity figure in them, you should insert that as the first line of each file, copying it from the MiniDSP cal file for the mic. It is the line that begins "Sens Factor = ..."


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## tjswarbrick (Jan 11, 2014)

awesome.

Thanks John.


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## tjswarbrick (Jan 11, 2014)

I added the UMIK sensitivity line to the CSLabs Cal file.
Frequency response looks a bit like this:


I have limited EQ capability, but have done what I can to tame the peaks. Sounds very good, but sometimes the bass doesn't blend well - particularly on kick drums. I've have a 10" sub crossing over to 6.5" / 1" passive 2-ways at right around 80Hz.
Trying to time-align the sub to the fronts before I get too deep into correcting modes/nodes with EQ. Did it by ear but I don't have control of T/A from the listening position so it's kinda tough. Steps on my processor are coars at ~ 1/3 msec per click.

I read that Impulse Response doesn't mean much with a USB Mic.
Does that mean this is useless:



Can I use Group Delay instead?
Red is phase; gray in minimum phase; black is excess:


Since I have a loopback cal for it, should I try to use my Xonar Essence card, VT-1009 uni-directional mic, and Tube Ultragain Mic100 to try the impulse response again? I'd keep the frequency range between 15Hz and 200 on the sub, and 40 and 200 on the mains, to keep it (hopefully) legible and useful.

Thanks for any advice you can offer.


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