Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 14

Hi again,

First of all I’d like to thank Jerry for not sparing his time and effort again for providing different graphs showing test mic behaviour with different orientations. Highly appreciated!

Of course, I do agree that the best is to have a set of calibration files with different orientations prepared by specialists, but I’d like to talk a bit about the UMIK-1 (or any other mic with only 1 cal file) as an example with an idea to discuss how a self-generated cal file can be produced for 90 degrees when only the 0 degree file is provided by the maker and how the UMIK-1 owners or wannabee owners can regain their self-esteem and feel like half a man no more before cancelling their orders or shipping back/selling out their stock.

Before going into details, let’s review again some aspects of measuring mics:

1. I think we can easily agree that the directionality of the mic is only relevant at the high frequency end of the audio spectrum, while the lower we go down the importance becomes less important in view of sensitivity. Finally, down at the Bass Department the orientation makes no difference, for such large wavelenghts the mic can be in any position, up or down or on-axis or even showing it’s back side to the sub.

2. As it was mentioned by Jason in an earlier post, most of the commercially available test mics use a Panasonic capsule, therefore the basic characteristics will be more or less similar, while some deviation may be attributed to the housing. Namely they will have a pretty flat response up to about 3-4 kHz and the curve will have a peak around 13 kHz, from thereon it will start to rolloff. This 13 kHz peak will be somewhat higher for on-axis and somewhat lower for grazing incidence.

3. The range above 10 kHz will be of less importance when it comes to measurements of seating positions because that range is less sensitive to in-room speaker placement. Although a non-calibrated mic position may show HF roll-off, it won’t (shouldn’t) inlfuence waterfalls and spectrograms, it will just not look right ont he SLP charts.

4. Nonetheless, in order not to worry about the HF rolloff (seen on the charts but not present in reality) caused by non-calibration it’s advisable to load the relevant mic file into REW.

OK, not let’s take the UMM-6 mic with two response curves ( 0 and 90 dgerees) as an example and let’s have a closer look at this graph:



We can see that the lower end below 3-4 kHz is pretty much the same regardless of mic orientation, while the 0 degree curve (red) will need more compensation than the 90 degree curve (blue). (For the time being we may omit the 45 degree curve from our discussion.)
Here’s the table from CLS site for 0 degrees of the above chart with numbers:



Since the UMIK-1 usb mic is shipped with only 1 cal file for 0 degrees (on-axis) and more or less will show the same or similar characteristics on the occasion of being another Panasonic capsule type mic, my idea would be to modify the supplied table starting from 2.5 kHz and up by simply reducing the dB values by approx. 50%.

When done, the new figures can be copied/pasted into a notepad file which will be saved with a .txt extention. This .txt file will be the new cal file for the UMIK-1 for grazing incidence and can simply be loaded into REW. Job done.

Let me know what you think, please.

^ I think your approach is very reasonable, Feri, and well thought-out.  I think if you follow this logic, you will have meaningful measurements using the Mini-DSP. 

Thank you Jerry.

As I told before the most (if not all) of the difference between 0 and 90 degrees is not from the capsule, but from it's enclosure, it's size and shape, the way how sound reaches the capsule, and for transferring 0 to 90 degree calibration you need not divide decibels, but subtract some known values (decibels do not like multiplication and division, they like addition and subtraction ). It is better to subtract the difference of the known mic with same enclosure, but you might as well use data from a similarly shaped mic. Otherwise very right idea!

Thanks for your comments and compliments Igor.

I just learned that I will be able to use REW and not worry about microphones, sound settings or HDMI connections.

I have ordered a Dual Core 2.0 as a supplemental room correction device for my subs and learned that the measurement file I save on it can be loaded on my laptop and read by REW :-)

And by the time I learn how to read and interpret all of the charts and graphs, maybe someone (s) will have solved all of my other issues so I would also be able to use REW direct!

Life is good!

Sorry didn't think it was an issue. I don't have much knowledge on pc stuff. Just though sound card on laptop was an easy replacement like a desktop. I have a laptop thats not being used and was going to give you the sound card if it was easy to remove.

Since I now have found a way (see above) to get data into REW without need of USB mics and HDMI cables, I am going to sell my actually never used MiniDSP UMIK-1 mic shipped anywhere in the continental US for $70. PM me if interested.
Edited by audioguy - 1/18/13 at 8:14am

 

I just read the manual for the Dual Core 2.0. Wow! What a sophisticated unit it is - way more so than the 8033. I would imagine that XT32 plus this unit would give a fabulous bass result. It also has far more sophistication in its features than Audyssey Pro does (although it corrects only for the bass frequencies,, but can measure the full range, which is how you will be using it with REW. 

 

When it arrives, how will you be using it - as a bass EQ or simply in conjunction with REW. I would be massively interested in how you get on - maybe you'll start a new thread for your experiences with it?

Edited by kbarnes701 - 1/17/13 at 7:45am

A day or so ago, I graphed the front two SubMersives by themselves and the rear two by them selves and all 4. With all four, I get a very flat response without Audyssey: See below



But what I noticed is that there is a fairly wide (and deep) dip in the front two subs (see below):



That broad dip is "corrected" by a slight rise in the same area with the rear two subs. (see below).



I began to think that I am being robbed of some of the output of my 4 subs since the back two are spending much of their output "fixing" the front two.

So a few nights ago, I ran a quick Audyssey run of 5 positions (with just the rear subs) and listened to some demo cuts and I have never had that kind of bass response in my room. So much more power and impact than I had previously had running all four. While I could not hear the rear subs (much closer than the fronts), the energy they produced (at or near reference) created what was almost like having transducers mounted under my seats BUT, it seemed to be more from the rear. My objective would be to get that same tactile feeling but not be so location specific,

So I will use the AntiMode 2.0 to fix the front two subs so that they are flat (and maybe the rears as well) and then run Audyssey the way I always have which is to have the front two on one output (Integra 80.2) and the rear on the other output. Then do some listening and see what I end up with.

One of the things I am most impressed about with the most recent version of Audyssey (X32) is how much better it removed bass ringing than the previous versions. So as an additional experiment, I am going to set up a 2.1 experiment where I correct all four subs with the Dual Core up to about 120hz, use the Integra for getting the crossovers and trims and delays set correctly with my mains but listen without Audyssey and then do the same but only use Audyssey (no Dual Core) and compare. I used to own a TacT 2.2XP and Audyssey X32 did a better job of controlling the ringing than the TacT did. I am curious just how good this Dual Core thingie really is.

If you read the most recent TAS, Robert Green reviewed this product and raved about it. I used to work for SigTech (the first digital room correction system) and Robert reviewed our product and loved it. (As an aside, he is one of the very few reviewers I pay any attention to - Kal being another). So if he says it is a good product, it probably is.

I will post my results but this is probably not the best thread. Any recommendations on a better one?
Chuck

 

I shall so look forward to your impressions and test results. I am interested in the AntiModes myself (mostly academic at this stage). I would start your own thread for it if I were you - and be sure to post the link to it here!

 

Do you have a link to the Robert Green interview?

@ Audioguy,

The purpose of having multiple subs is so that some of the subs correct for the other subs, so I don't think there is anything wrong there. However, not sure why you would get better results by running Audyssey for just the two rear subs. The response of the front subs should not be canceling out the rear subs.

However, the path to the best bass response is experimentation, and the Dual Core exercise should be interesting. I encourage you to share your progress in this thread. The ultimate purpose of this thread is to develop measurement techniques that reveal response issues, and then collaborate on various remedial actions. Your case is perfectly in line with this objective.

One question, since you have four identical subs, did you follow Craig John's process to gain-match the subs before the calibration?

What's this "Dual Core" stuff?

Googling didn't cough up much other than dual core intel processors.

DSPeaker Anti-Mode 2.0 DualCore Digital Signal Processor (see http://www.dspeaker.com/en/products/20-dual-core.shtml)

Is there a US/NA distributor?

Let me start off by saying I am no audio expert, though I have been a hobbyist for almost 40 years and in and out of the audio business for about 20 years (10 of which was travelling around the country installing the original digital room correction system).

And my room sounds very very good as is: CraigJohn has been here as have other AVS members, and all were reasonably impressed. And the bass in my room is quite remarkable, as is.

I cannot give a guaranteed explanation for what I heard. And I am intimately familiar with why one uses multiple subs and gain matching. (mine are gain matched, level matched, finish matched, color matched and manufacturer matched ).

I only tried what I did because (a) the rather broad and reasonably deep dip in the fronts was very obvious and the rears fixed it (as can be seen in the graph when all 4 subs were operating) so I “assumed” that part of the bass that normally might be projected into the room was not. That may or may not be an accurate description of what is going on; (b) I am always on the quest of gaining new audio knowledge and (c) I have the measurement tools necessary.

So, as noted previously, I re-ran a small number (5) of Audyssey positions utilizing just the back subs, put on the same demo Bluray I always use and sat down to listen. The differences were startling. The overall bass presentation was astonishingly better. Just more off it. Not in the sense of amplitude but just more uniform (but clearly the measurements for all 4 and the back 2 were virtually identical). Most notable, however, was the feeling that someone had snuck into my room and attached ButtKickers under my seat. It was quite un-nerving. Movie clip after movie clip after movie clip did the same thing. I can show you the plot of just the rear subs and all four subs after Audyssey does it’s magic and there is very little difference – certainly nothing of the magnitude that would explain both what I heard and what I felt. The only negative of what I was “feeling” was that it was more toward the rear of the seat than evenly distributed or from the front. I was not able to actual hear or localize any sound from the subs.

Since, for the most part, I like what I heard/felt and since I already owned two additional SubMersives, I decided to try and fix the fronts and then run Audyssey. The DualCore has been shipped so I should know more next week. It was a very low risk investment. If it does nothing (or makes it worse) then I will sell it and might lose a few hundred dollars. If it does what I am reasonably confident it will do, then I will have more than gotten my money’s worth. If I can replicate what I have with the two subs operational from the rear but more evenly distribute that tactile sensation and greatly improved bass, then I will have increased my investment in speakers, etc by 4% and I will assure you that it is way more than a 4% improvement.

But I could be wrong or I could have done something different when I ran Audyssey last time or any number of things. We shall know soon.

I know Robert Greene of TAS from my SigTech days and communicated with him on this product. For what I am trying to accomplish, I believe it is the right solution.

Stay tuned!!

Call Tim at SIMPLIFI AUDIO (see http://www.simplifiaudio.com/). He is the US Distributor. From the website (CALL SIMPLIFI audio Sales and Support (619) 849 9615)

If you call him, I would appreciate you mentioning my name (Chuck Gerlach). I am not a dealer but if this does what I hope it does, I plan to become one. This technology at this price is incredible. The SigTechs I sold started at $6,000 and the user could not program it (I did the programming). That model costs $13,000 (for two channels I might add).

And while this product is not totally plug-n-play , it is a lot easier to set up than the SigTech or even theTacT.

follow up to post 369

asio tool box describes the status of the hdmi and the mike input as " beyond logic'

anybody? reinstalls hasn't changed anything. java still shows the input and output correctly.

Hard to give any better advice without being there with you personally than to read Jerry's excellent REW setup guide and follow it to the letter.

Unfortunately, you are experiencing why REW has a terrible reputation of being a nightmare to get working properly. REW relies on various PC components and software to work together. When these components don't play nicely together, what results may digress into the frustration of PC trouble-shooting.

I don't have any advice to resolve your issue.

"beyond logic" is an actual error message?

Yes, in the ASIO4ALL control panel, evidently equivalent to "fatal error".

As I struggle to follow along with this thread and decide if this route is right for me, might I suggest that when someone posts interesting links as in the quoted post above, that they be "archived" and listed in one of the "reserved" posts at the beginning of this thread? The problem is that, otherwise, they get buried in the ether of the every expanding thread and are difficult to recover later.

Perhaps one of those reserved posts could be dedicated to "background theory and education" or whatever with just a bullet-point type list of interesting links for reading. Some of those FAQ posts are already becoming gargantuan, and having a condensed list of relevant links will be useful IMO.

ASIO maual says.

Beyond Logic You get this if the device for some unknown reason refuses to start and/or
displays erratic behavior of any kind. Sometimes, closing and re-opening the
control panel may cure the situation, as may unplugging and re-inserting of USB
devices. Sometimes, this can also mean the same as “Unavailable”, whenever the
device does not report its current availability or the lack thereof back to
ASIO4ALL.
Note: If the device list is empty, this means that you do not have a single WDM audio device in your
system. Please check with your audio hardware manufacturer for a WDM driver!

I would like to re-raise the issue earlier for those us of without HDMI outputs on our laptop, who will end up using the standard "headphone jack" of the laptop with an analog RCA connection to the AUX IN inputs on the receiver to generate tones for measurement. My earlier question in response to Jason's originally reply has long since been buried in this thread.

To recap: I asked if using a simple male-to-male RCA "y-cable" with a 3.5mm mini jack on one end and two RCA male jacks on the other end would be sufficient (with the understanding that I would only plug in one at a time to individually test FR/FL speakers, both at the same time with PLII Cinema engaged to test the center speaker).

Jason commented that I should instead use an RCA splitter, 3.5mm male to two RCA FEMALE, and then use an RCA male-to-male cable from the splitter to the AUX IN input on the AVR.

I still cannot understand for the life of me how a male>female y-splitter cable, then connected to a male>male cable is any different than simply using one male>male y-cable. Isn't male>famale>male>male the same thing as male>male.... but with one cable instead of two?

Any clarification would be much appreciated

Hi Chuck,

That second graph of the front subs... is that the subs PLUS one or more speakers? If so, what do the subs look like alone? If the speakers are running at the same time as the subs, I would suspect a Distance mismatch causing a dip around the crossover, something we've both seen and corrected before. If that's the case, rather than trying to correct this with some external EQ device, first try changing the subwoofer Distance setting of the front subs independent of the rear subs. I've had some luck changing the subwoofers' Distances independently. Might work for you too.

Craig

Not answering your cabling question, but raising a different concern. You cannot run REW in "legacy mode" using the audio in your laptop. You need a separate outboard USB sound card. This sound card would be connected to the AVR using a simple RCA-to-RCA audio cable (the sound card has RCA out, and the AVR has RCA in). Please read the REW cabling basics help file on the REW web site (a link is referenced in the intro in my guide).

Subs alone; no Audyssey; no main speakers!

The dip I am looking to deal with (front speakers) is from about 22hz to about 60hz - the main part of the LFE range
Edited by audioguy - 1/17/13 at 6:19pm

WTF? So now we are going backwards? When this discussion started it was specifically in reference to using the basic built in sound (headphone jack mini plug) output of the laptop. And it was specifically noted that an external USB soundcard was unnecessary. What changed? If all I am doing is outputting simple analog sound (test tones) why do I need an external soundcard?

 

I am the messenger here, so there is no cause to get upset.  I don't know where you got the idea that you would be able to use your laptop's audio if your laptop has no HDMI port.  This thread was established to specifically leverage a new capability in REW 5.0 beta 10 that added support for laptops with HDMI and USB mics.  AFAIK, nothing has changed with regards to how to do a legacy connection.

 

If you read the REW documentation, it states:  "Equipment Needed:  A soundcard (internal or external) with line inputs and outputs. Note that most PC and laptop mic inputs are NOT suitable and should not be used (they have too much gain and most suffer from high noise levels and limited bandwidth)."  You may read the complete description of requirements for a legacy REW kit here:  http://www.hometheatershack.com/roomeq/wizardhelpv5/help_en-GB/html/gettingstarted.html#top.

 

Also, from the Cabling and Connection Guide: 

 

Important notes:
You will require a soundcard with a line-in and a line-out jack.
 

A microphone input (mic-in) on a soundcard is not suitable (many laptops only have mic-in).

LAPTOP Note:
If your laptop is limited to a mic-in port with no line-in, then you'll require an external USB soundcard.