Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 30

My Samsung Series 9 has an "Intel Display Audio" listed that seemingly controls the HDMI output. I also have a "Realtek High Definition Audio" listed in the device manager. In fact the AISO wouldn't show the "power button" lit up for the Intel device until I disabled the Realek device. The ASIO also only recognizes the Intel if its actively plugged into my AVR (Denon 4311).

Bill

I've seen many comments in various threads stating that HDMI employs an 'end to end' connection protocol.
When I use my laptop to run REW sweeps via HDMI, I always ensure that the laptop is already connected to the AVR - and that the AVR is appropriately configured to send that i/p video to the screen, whilst ensuring that all audio is handled exclusively by the AVR/speakers. This appears to guarantee that the laptop offers access to the maximum of 8 channels.
My Anthem AVR only has one setting for audio output (TV, TV+AVR, AVR - as stated mine is set to AVR) - is it possible that others AVRs offer this option on an input by input basis - such that some may be set to TV (which normally only allows stereo) - would the HDMI protocol then only allow the 2 channel option in the laptop control panel.

Regards, Mike.

Also, has anyone else noticed audio 'drop-outs' lasting a split second during HDMI connected sweeps? I have not had the time to investigate further, so do not yet know if it's the laptop or AVR - but I do think my AVR is sometimes a bit slow to detect the digital data stream when starting a sweep.

 

I am fairly sure this is your issue Jerry. It seems clear from my experience that Windows detects whatever is connected to its HDMI port, presumably by using the EDID from the connected equipment. This is what my Windows dialog box reports the 5509. The 5509 is, as you say, telling the world at the other end of the HDMI cable what capabilities it has via the handshake. I remember saying to you at the time that I thought it odd that your Windows dialog did not say Denon 4250 or whatever the precise name is. So I suspect we have identified the problem but are unfortunately no nearer to discovering a solution. Do you have all that HDMI crap in the Denon turned off - you know what I mean - all that auto-control and RDI stuff or whatever they call it?  Can't see why it should matter but HDMI is one of the black arts so it might. I have all that stuff disabled in my Onk.

The Omnimic 5.1 DVD is at the duplicators right now. Hopefully the tracks will be available for downloading to burn onto one's own DVD. This is not to detract from REW, I still plan on using it at times.
Edited by Theresa - 2/1/13 at 3:21am

 

I just posted this in the OM thread before I saw your post here, so please forgive the cross-post:

 

There is so much more to REW than just that though, Theresa. Consider the ability, for example, to take one measurement, of the full spectrum, and then to later be able to graph that single measurement as a FR chart, a waterfall, an ETC etc. And to be able to select any frequency range for the graphs that you wish, from the full spectrum available.  Also consider the ability to upload your measurement data file to a thread, where people with greater expertise could load that data file into REW and make an analysis of it for you. These are just a couple of things that have drawn me to the 'new' HDMI/USB mic version of REW. OmniMic has the great virtue of simplicity, but it comes at a price.

I'll keep that in mind. I do know that REW is much more powerful than OM. I intend to get a SLM for REW use.

 

Don't get me wrong - I have been thoroughly impressed with my OM and I would never have got started on measuring without it. But I think that REW will prove ultimately more useful to me, and many of its features are without doubt very sophisticated indeed.

 

I thought of you when I read about REW's capability to make a sweep and then to import the results directly into certain EQ devices which then create filters according to REW's findings in the room. I could imagine you using such a feature. (I read it in the downloadable REW Guide from HTS).

I stay away from HTS because of their evangelical christian agenda.

 

IKWYM. I have attached the Help PDF for you - the section on programming Equalisers starts on p112. The guide does not cover the latest USB/HDMI version of REW but it is a goldmine of useful information. I have had to ZIP the file as it exceeds AVS max upload limits otherwise.

 

 

 

 

REWV5_help.pdf.zip 4,499k .zip file

I think I downloaded that guide a while back. I do know that it can automatically apply filters to the miniDSP as can OM. So far I've just done it "live" with OM running sweeps while I adjusted the miniDSP manually. I also use the miniDSPs as electronic crossovers and since I need to run three of them to do so (well, two as crossovers, one for R/L, one for C, and a third as a sub equalizer) complicates automating the process.
The advantage of this thread over the guide is that it focuses on simplifying the process.

I'd also like to add the ability to generate the test tones with the laptop as a plus over having to play a cd. I may be in the minority but I don't have a CD player in my rack and using a BluRay/DVD player means either having to turn on my projector or keep going back and forth to set the right tracks cause I can't count worth a darn! 

I prefer to use test tones recorded on a CD or DVD if you only need to generate FR charts. Much simpler in that no connections are required between the AVR and the PC. Plug the microphone into the PC. Place the CD / DVD in the DVD player. Calibrate for SPL level. Measure frequency response. Same procedure for REW, TrueRTA and SpectrumLab.

However, you can not generate REW waterfalls when a test disk is used for source material. That being said, 99% of the time I only generate multiple FR charts.

When I was messing with it the other night I had the same exact thought. I had no intention of watching a movie so the projector stayed off and I just listened to some HD Radio while I set everything up.

Bill

thx for the clarification. now i just need to find the cheapest SPL meter but I wonder if there are any specific limitations that may stop it from balancing the mic. What function/feature of the SPL is specifically used to balance the mic because I want to be sure the SPL meter I"m getting will be able to do the job, mainly for balancing the mic?

i.e. do i connect the mic to the spl meter? do i play the mic and set the spl meter next to it and press a record button on the spl meter or what? how?

No connections required.  Please read the instructions in the guide. 

I have been running a set of measurements using REW today, both with the legacy non-USB EMM-6 mic, and the new UMM-6 USB mic used with an HDMI connection.  I had no issues configuring the UMM-6 on the laptop, or in REW.  I am pleased to report that there is consistency between the two sets of measurements.  For example, here is a measurement of L+R+Subs:

 

 

The red line is the USB mic, and the green line is the legacy mic.  The slight vertical difference between the two lines is a result of my calibration of the two mics, and does not affect the comparison.  Note that the two graphs are virtually identical, which means that the readings, when used with the "narrow_band_response_90_degree.cal" calibration file, are consistent across both microphones.

 

I will work on updating the guide with the screenshots I captured during this exercise.  My conclusion is that we should be good to go with the UMM-6 microphones.

You definitely make a good point that people who have never optimized low frequencies in their room can have the impression that the correct bass performance is not right. Whether it is by use of EQ or acoustic products, reduction of resonances (peaks) in the low frequency response will take away low frequency energy and with it, give the impression of less bass. This is especially felt in movies where the reduction in ringing (notes lasting longer than they should) can reduce what one feels in addition to hears. Hopefully they notice the better performance with tighter low frequency notes.

That said, we have to be careful to not take the lead from Audyssey and/or going by our gut feeling that "flat" response is the correct one. It is not perceptually nor based on research in the field.

Think about our everyday lives. We live in closed environments that don't remotely resemble an anechoic chamber. As such, the sounds that we hear are all benefiting from "room gain," i.e. exaggeration of low frequencies. Let's agree that it doesn't get higher fidelity than hearing those sounds as is. Recording them, then taking out the effects of the room gain when we play them by flattening the response will therefore degrade from our memory of what the real sound is like.

Here is a set of published measurements performed on a number of "room eq" systems with the overall double blind subjective listening test results overlaid on them:



The dashed black line in the middle is the room response with no EQ. We see the room gain in the form of that peak around 50 Hz. Notice the system in the bottom in teal which did exactly what you said: flat response in bass. Now notice the winning systems at the top. None of them used flat response. They had a tilting curve where the bass output was distinctly higher than the frequencies higher than them. We see clear correlation between doing that and subjective scores and verbal feedback from listeners. This was across 6 listeners and the outcome was consistent across all of them. Here is the break down on per frequency basis:



We see that they indeed voted RC6 and RC5 that aimed for flat response as having too little bass. Again these are trained listeners and not newbies.

Net, net, the goal as you use REW to optimize your system should be to get a *smooth* response, not *flat*. We crave more low frequencies than flat response gives us. The more precise way to say what you are saying then is that we like to see a smooth response, not flat.

Stepping up a few levels, we should keep in mind that correlation between acoustic measurements and what we like can range from very good to absolutely dreadful. While low frequency measurements are in the "very good" range of that spectrum, there can be surprises like above.

Again, you made a good point regarding correct bass and hopefully I did not take away from it by expanding the point .

 

Yes, agreed. The guide is very dense. There is plenty of good stuff there but I found a lot of it was very hard-going. I think a lot of it will snap into clearer focus when I understand REW better - it is what I used to call at work PCIPU (perfectly clear if previously understood).

Hi Jerry, my Denon AVR-1909 show multi-channel connected via HDMI to HP laptop and Windows Audio does not see 1909. Don't know if it makes a difference but I have HDMI Control is turned off on the 1909.

 

:)  Yes, I had a similar issue with using a test tone disc too. My gear is in an external closet and the system is controlled by a Harmony 1100 in wireless mode. So in order to control two devices at the same time (the Bluray player and the prepro) I had to constantly juggle between them on the Harmony which, being an activity-based device and not a component-based device, is harder than one might think. Having the test tones generated by the laptop is immensely better for me.

The REW Guide has been updated to Revision 2.0.

 

This revision now has instructions on how to configure a USB microphone for use with REW.  The guide specifically references the UMM-6 microphone, but other USB microphones should work in a similar manner.  Click the link in my signature to download a copy of the guide.

 

Thanks for the tips.  Unfortunately, I have tried the AVR settings, and it looks like my laptop only supports stereo.

 

Wahey!  A revision up to a new whole number. Great work, Jerry.

What happens if you disconnect your display from the AVR? The way HDMI works is that the receiver is supposed to "lie" when the source queries how many channels the display supports. It needs to override the data passed to it from the display with its own capabilities (i.e. multi-channel instead of stereo that your display may support). When the AVR does the decoding of the stream (e.g. Dolby Digital or DTS), this obviously does not matter since it outputs the channels internally. Some sources also ignore the target capabilities and output in multi-channel anyway. Such is not the case with the PC however in this scenario. The suggestion is along shot as this day and age AVRs do this properly but might be something to try if you have time to kill .

We have a quantum data HDMI analyzer that makes this kind of troubleshooting very easy but it is an expensive box so not an option for you all in the field.

Jerry, can you do a simple test? Load a DVD film into your laptop and see what the Denon displays. DTS or DD 5.1 should come up. If so, your laptop is capable to output multi-channel bitstream.

In my case in the Control Panel -> Sounds I can choose and default to "Denon AVAMP" which means my laptop sees the Denon AVR. If you only can select "HDMI something" I think your laptop does not fully recognize your AVR. Just thinking out loud!

You need to think outside the box a bit more.

Create an activity called 'measurement' and add the controls you find yourself needing from both the Blu Ray player and the prepro to it.

Ooh, at 2:45 this morning the post office emailed me to let me know my microphone is on its way from CSL. Really looking forward to trying it out.

 

Excellent suggestion - thanks. But as soon as my new mic arrives, test discs will be a thing of the past. It does seem a bit antiquated to need a physical disc for the test tones when one has to use a laptop anyway, for the measuring software. I guess the only benefit is you don't need the HDMI cable hooked to the AVP - but that is a trivial thing to do.

I've just read the setup PDF guide.
Is the “narrow_band_response_90_degree.cal” file available for the mic ordered from Parts Express? Or it's only available from the mic ordered from Cross Spectrum Lab?

The guide also mentioned that SPL meter is required. Is it really required if I have the miniDSP UMIK1 mic?

 

That calibration file is one of the custom files provided for the UMM-6 by CSL.  From what we have heard, the UMIK1 mic has a calibration file, but it was taken with a mic orientation of zero degrees, not 90 degrees.  I'm not sure we know if this affects the UMIK1's ability to take accurate measurements or not.

 

The SPL provides a sound level reference point.  Here is my understanding of the relationship between the mic, the SPL, and REW.  When the mic picks up sound energy from a test tone, it generates an electrical signal that is passed to the software, i.e. REW.  REW sees the electrical signal, but has no way of knowing what absolute sound level the signal represents.  This is where the SPL comes in.  As the mic is hearing the test tone and generating the signal, an SPL held next to the mic measures the absolute sound level of the test tone.  This value, read from the SPL, is entered into the software, essentially telling the software that the electrical signal it is receiving is associated with a specific absolute sound level.  Thus, the software is now calibrated, and can calculate subsequent absolute sound levels from the mic.

 

It is not clear to me how a USB mic would operate properly without the calibration step, so my understanding is that an SPL is required.  Keep in mind that an SPL is a pretty important part of any audiophile's toolkit, and there are many times when you will benefit from having the SPL to take a quick measurement.  It is money well spent.