Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 28

Like I previously said this thread will get derailed if you, Amir and I start going back and forth on the value of the ETC. It's blatantly clear to all and sundry that we have differing opinions, and I don't think this thread is the place to argue about them (yet again). Even if we did set up a separate thread on the very topic of the ETC it's highly unlikely we would make any progress on agreement and consensus anyway!

 

I only have one sub atm.  Placing it in the middle of the front wall could work but I'll have to do some rearranging with my current setup.  For a quick and dirty test, how beneficial would it be to sit the sub just outside of the framing?  This would save me having to remove my screen and disassemble the center speaker shelf to fit it behind the false wall.  I was just wondering if you would expect an improvement from my current front right corner location (not shown below but you can just see the size of the sub in the hallway to the right of the screen) by putting the sub approx. 22" from the front wall or if you were suggesting it would have to be against the wall?  In some previous posts regarding my room and REW measurements, it has been clearly demonstrated that I have a very strong null at 40Hz (not sure if you saw this before or not?).

 

 

 

I'll need to check on the distance of the L/R's from the side wall but my CAD model says the outside edge is 31" from each wall.  I assume you meant 28" to the middle (each speaker is about 10.5" wide).

Edited by jkasanic - 1/30/13 at 11:01am

concur 100%.

the fact that no one acknowledges amir's ridiculous commentary is all that needs to be said.
i've never seen anyone so adamantly and passionately illustrate ways to use a tool incorrectly.

but then again, he doesn't understand the need for BROADBAND treatments - as illustrated by the baby diffusers in his company's showroom. cute little things!

Likewise, I make do with what I have. My room width is similar to jkasanic's (roughly 14 feet). For future reference, whenever you see that number, think 80Hz mode (1130 ÷ 14), right at the most popular crossover point.

My right side wall ends 102 inches back from the front wall, L'ing off to a dining area. My left side wall ends 160 inches from from the front, opening into an archway to other rooms. Rather than lament the lack of a perfectly rectangular room, I decided to concentrate on how to achieve left vs right consistency/symmetry in my L-shaped room. To that end, the Mellor/Hedback paper turned out to be a helpful guide, since their views on early reflections and ETC usage were in line with mine. While the paper deals with L/R speakers up front, I applied Nyall's advice to my L/R side speakers and L/R rear speakers.

Since my left wall goes back 58 inches further than my right wall, I had to make those 5 feet disappear (or disappear enough to sound symmetrical). Absorbtion at that location did the trick, taking away reflections from my right side and right rear speakers that were dogging consistency. Were I in a rectangular room, I would never use absorbtion in the surround field. Same with my front soundstage, where my equipment rack on the left side of the room was inhibiting the soundstage from sounding as wide as on the right side of the room. Pulling the L/R speakers almost 30 inches away from the front wall did the trick, letting me light up the side walls evenly for a symmetrical soundstage. Were I able to place the rack elsewhere, I would never bring the speakers that close to the listening area.

So, as you said earlier, we have to make do with what we have; in my case, it meant using speaker placement and absorption that I would've prefered not to. The only things I like less are inconsistency and asymmetry, so the compromises were worth it for me. I'm guessing a lot of people are in our situation. Rather than lamenting an asymmetrical room, they should figure out how to improve consistency. Which becomes easier as measuring becomes more user friendly (thank goodness for this thread).

Good point, and one I should have clarified earlier: when I say middle of room width or quarter points of room width, it doesn't necessarily mean on the front wall. It could be anywhere along the length of the room: quarter points of room width could be on the back wall, middle of room width could be right behind your couch, etc. So, for a quick and dirty test, line your sub up at the middle of the room; don't worry whether it is against the front wall or outside your framing (couple feet from front wall) or on the back wall or just behind your couch (hmmm, nearfield bass). Hadn't seen that before, was just going by the chart you posted. Look at the width modes on your chart and check out what frequency you'll be addressing at the midpoint of your room's width. Correct, the middle of the speaker (technically, the middle of the bass driver, since we're dealing with low frequencies).

Roger that. I was specifically trying to find out what in the height could be causing that 89Hz dip/possible null in your FR. So, as one of the examples in the paper did, I assumed your walls are not 6feet thick concrete and came up with an acoustical height of 12'8" in order for height to be causing a 89Hz dip. Now where is that added acoustical height coming from, floor or ceiling? The ~3'3" sub height is if all additional acoustical height were caused by your ceiling (perhaps you're on concrete slab). In reality the added acoustical height may be coming from some floor and some ceiling so I think it is a little lower than that. In the end, try it and measure though.

I was serious when I said "wildly swinging in the dark" and am likely causing more confusion than assistance while straining my brain Interesting stuff though. I'm learning.

 

I think very few of us don't need to make compromises of one sort or another. For some it's WAF, for some it's an awkwardly shaped room and so on. For me, it's the smallness of my room and I am constantly amazed at how good it actually sounds considering the inherent problems. Up till now my method has been trial and error - I would adjust something, or move something (not that I have very much freedom to do that because of the size of the space), measure, listen, adjust some more and rinse and repeat until I could get it no better. Of course, as I have learned more stuff, the chances of getting it better have improved. I am very impressed with the possibility of learning how to measure and then interpret the measurements to tell me what I need to do - as in Sanjay's fantastic post to Joe where he tells him with inch-perfect precision where the sub might need to be to sound best in his room. Just awesome. My mic is en route. Your amazing SetUp Guide (which gets better and better) is printed out and at the ready. This is a very exciting journey! 

 

In the spirit of keeping this terrific thread on track, this age-old advice is worth remembering...

 

 

Edited by kbarnes701 - 1/30/13 at 1:18pm

Speaking of fun, it's here!

 

 

In the last two pic's, you can see the thumb drive on the left, which contains the calibration files.  The drive contents:

 

 

Here is the custom calibration report:

 

 

 

1280303_mic_report.pdf 505k .pdf file

 

And a ReadMe file:

 

 

 

Read Me.pdf 173k .pdf file

 

 

I am always very impressed with the product from Cross-Spectrum Labs, and Herbert Singleton.  Now off to discover the sectets of my new toy.....

Excellent - looking forward these next steps!

 

Geez, looks exactly like the OM kit I just sent back!  Now the only question is when will OM work with this setup?!

So far, fairly straightforward.

 

Plugged the UMM-6 into an available USB port and the drivers were loaded automatically.  Checking Windows Device Manager shows all is working properly:

 

 

In REW, the UMM-6 is a choice in the Input box:

 

 

On the Mic/Meter tab, simply select "Mic or Z-weighted SPL Meter", and select the calibration file from the thumb drive from CSL:

 

 

 

Now off to take some measurements, using both the HDMI output, and the Windows Audio 3.5mm headphone jack output.  What did I do to deserve having so much fun?

 

+1 to that!  I may have been a bit remiss in my previous response to Sanjay - so let me say THANKS for the awesome feedback (from everyone thus far)!  I can't wait to get my mic and start measuring again!

 

+2.  Sanjay's advice is on-target for this audience, and is moving us forward nicely.  More, please! 

BTW, the mic holder has a small plastic adapter that allows the holder to fit onto either a large threaded connection (like on the Pro boom mic), or a small threaded connection (like a camera tripod).  Nice.

 

BTW #2:  the supplied USB cable is 10 feet long.  Not real long--may need an extender.

 

Great report, Jerry.  I will be off to a flying start when mine arrives. Do you think it would be a good idea to add those screenies to the Setup Guide?

 

 

 

 

Yeah, the OM V2 kit was the same on both accounts.  I didn't realize it at first though and spent a while (well, way too long) trying to configure my Audyssey mic adapter to work with it since I only had the small threaded connection on my boom mic and couldn't get the mic in the proper orientation!

 

On a similar yet different note, does anybody "highly recommend" a particular boom mic for taking measurements?  I've tried a few now and they all have their shortcomings.  I want one large enough to clear my couch back (36" high) and it needs to have secure joints.  The last freebie that came with my OM kit (this one) never was very secure at the pivoting joint and I noticed my mic could droop over extended periods of time:

 

 

It didn't matter how tight you turned the knob as the washer seemed to just deflect making the problem worse.  Given the amount of measuring I plan to do in the upcoming weeks, I'm not afraid to spend a little more for something of higher quality!

 

Of course, just need a bit of time to take some updated screen shots and publish Rev 2.0.  Perhaps tomorrow.

 

BTW, I have run an initial suite of measurements using the HDMI connection.  Everything works OK.  Compared the measurements to what I was getting with the EMM-6 mic, and they are slightly different.  No time to research right now, I am running out of gas.  I'll dig deeper into it tomorrow.

 

When I tried the standard headphone audio connection, I was not able to get audio to the AVR.  This has nothing to do with the UMM-6, just my laptop being tempermental.  I'll work on this tomorrow as well.

 

I have two boom mics now, one that I purchased a while back, and one that came with the Audyssey Pro kit.  The Pro kit one has failed twice.  There is a thumb screw at the bottom of the stand that holds the vertical part off the ground.  As I was taking measurements, this thumb screw would never hold the vertical part solidly, so the mic height would gradually drift downwards as I proceeded with the measurements.  I kept tightening it, trying to prevent this behavior, and I ultimately stripped the thumb screw threads.  Audyssey replaced the thumb screw one, but it has stripped again.  It's not worth replacing a second time--I an going to throw it away.  It is made by these people:  http://www.samsontech.com/.  I tried to get a replacement thumb screw from them, and they never answered me back.  I would avoid them. 

It depends on your measurement approach. Some folks like to place the stand behind the couch measuring over the back of the couch, but that typically means that you can't extend the boom far enough for the forward most line of Audyssey calibration measurements (I'd assume folks want the strand to be usable for both Audyssey and REW).

This is what I personally use.
http://www.guitarcenter.com/DR-Pro-DR259-MS1500BK-Low-Profile-Mic-Boom-Stand-101810141-i1170321.gc

Big fan of low profile mic stands because with regular height stands, the minimum height tends to place the boom arm somewhere in a potential reflection zone for one or more speakers when the mic is positioned at seated listener height when Audyssey chirps all the speakers in sequence. With the low profile stand, the body of the stand and the boom arm can be positioned in a much more vertical orientation, out of the way of the speakers.


Max

 

Thanks for the link Max!  Seems to be a good choice and I like your point about having to reposition a regular height stand as well as the possible reflections.

You're a great help as always, thanks.

Hi Max, so the mic stand is placed on the floor in front of the seat?

 

Not Max but yes that is what he is saying with the low profile boom mic.

Yep, place the stand on the floor in front of the seats. That stand will easily extend to position the mic where your ears would be in the seat.

A couple of added tips:
1) if you have suspended flooring, vibrations can and will travel through the floor and up the stand to the mic (especially in the lower octaves). This can result in anomalous results with measurements and Audyssey calibrations (short sub distance measurements post Audyssey are one example).

You can purchase mic stand vibration insulators made to go on the tripod feet to reduce that. I found that making my own from car wash sponges works well especially to insulate the mic from the stand. Simply use scissors to cut a slot to slide the sponge over the end of the boom (no need to get the boom to camera mount adapter piece). Taper the end a bit with the scissors and tape the Audyssey mic to the sponge ensuring that the tape does not directly connect the mic and boom.

Look at various sponges available at your local store. You'll want the kind that's 3-4" thick, 5-8" wide and 8-10" long. Don't get one that's too firm as it can still transmit vibrations. If you get one that's too soft, it may not support the mic very well. For the REW mic, you can cut a slot in the end for the boom, and another slot to slide the mic into that will hold it upright. You'll need to set up the stand to get the 2nd slot right, but sponges are cheap.

Although we're aware that for new users, the "Audyssey killed my bass" comment is often due to not being used to flat bass, when I did an Audyssey calibration on sprung/suspended flooring, I noticed that the bass had been significantly reduced. The vibrations through the floor and mic stand led Audyssey to believe that there was way more bass than there actually was. Insulating the stand from the floor and later, the mic from the stand cured this.

2) The exact placement of the mics for measurement/calibration isn't crucial to the fraction of an inch, but for anyone looking to replicate a specific measurement pattern as precisely as possible for comparative reasons (or simply being OCD), here's an interesting solution:
Get a roll of nylon string. Tie a small loop at one end and tape it to the ceiling. Determine the correct length required to hang a plumb bob so it dangles down to ear height. You can get mini plumb bobs at hardware stores (full sized ones are too heavy), or you can simply use the screw off tips of cheapo ballpoint pens.

To use the bpp bobs, simply thread the string through the hole on the tip and tie a knot big enough that it can't slide off the string. The larger end of the cone should be down when it's hanging. Incidentally, it's pretty close to the size of the tip of the Audyssey and EMM-6 mics. Avid fishermen can also use lead fishing weights, although I'd suggest the clamp kind, so you can position it precisely.

Make 8 the exact same length and tape them where you want them. Let them hang for placement and you have position AND height potentially to 1/8". Tape the plumb bob end to the ceiling for actual measurement sweeps.




Max

Question about The digital out with HDMI. My Laptop does not have HDMI out but does have Optical out( Mac Book) will this output be able to send all discrete channels via REW?

Athanasios

that's cute, forget WAF, how about lung.AF and Dr.AF. I love commitment but this stuff ain't worth getin sick over. Glass doesn't do well in the lungs lol. I'm no expert but just spitballin... fused silica doesn't break down that well. reminds me of old stories about a little rock named asbestos. Just having fun guys but seriously don't let that stuff fly around too much. ok done preaching back to acoustics!!

 

I don't know, and have not heard of anyone trying this.  If you find that it works, please let us know.  Just using REW with a Mac Book presents some issues, although beta 13 is supposed to provide support.  

 

I agree 100%.  I actually wore gloves and covered my mouth while working with the R30.  Of course, what you see in the picture is temporary, but many DIY enthusiasts build treatments using R30.  I have always felt that these DIY solutions are fine for a dedicated HT, but they look somewhat crude in a living room.

 

I always enjoy your description of this technique, because it supports my long-time belief that a repeatable measuring process produces repeatable calibration results, or at least minimizes the microphone placement variable.

 

I use a similar approach.  I use a tape measure to mark the microphone placement spots on the floor using small colored adhesive dots.  I then use the plum bob technique by tying the string to the bottom of where the microphone is affixed to the end of the boom stand (I use a Pro mic).  This allows me to center the mic over the floor markings and results in measurements that are probably within a +/- 1/2 inch tolerance.  It is also important that the weight serving as the plum bob not be so heavy that it alters the mic height as the boom stand is moved around.  Similar approach, same repeatable results.