Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 20

Jerry - thanks for the updates & kudos for the entire project! The "Cabling Basics..." section is especially helpful in clarifying the various options available. So - just to be clear (in my own mind at least) - I have an HDMI capable Windows 7 net book and am waiting on the delivery of my UMIK-1. In the meantime - are there are any additional measurements that I can take until the USB mike arrives? If not - then I'm going to visit my grand kids and hope the UMIK arrives when I return home in early Februrary!

Only if you can get the Audyssey mic working, and those measurements won't be very accurate without a calibration file. Visit the grand kids! They grow up quickly.

So if going with the Behringer EM8000 (mic) + Behringer Xenyx 502 (mic pre-amp) + a Creative Labs Sound Blaster Live (sound card), what would need to be calibrated in that series of components, and how can that be done? I have a regular EM8000 that I would like to use with the Xenyx 502 and a cheapo sound card, but the mic isn't calibrated. How do I get the EM8000 to be calibrated? How do I get the sound card calibrated?

Are there any other cheap sound cards that would work with the EM8000 and Xenyx 502, and if so, can anyone suggest any brands/models?

There have got to be some simpler ways of doing this! I saw someone mention that a usb mic does not need to be calibrated, is this true, and if so, which is the cheapest and most effective? If going with one of these usb mics, does that mean that I could use my old laptops' internal sound card and that it does not need to be calibrated?

 

The first part of your post is OT for this thread which is specifically for USB Mics/HDMI input to AVR. Sorry to sound difficult on this but it is important this thread stays focused.

 

To the second part of your question - if you read this thread and download the Guide created by AustinJerry, your questions will be answered in detail. Basically, your assumptions are correct.

You can download a generic calibration file for the ECM8000 from the HomeTheaterShack web site:  http://www.hometheatershack.com/forums/downloads-area/19-downloads-page.html#axzz2Ip9pt61y.  Scroll towards the bottom of this page.

 

Cross-Spectrum Labs sells the UMM-6 USB mic, which comes with custom calibration files, for $90+S&H.  CSL also provides calibration services, so if you want a custom calibration for your ECM8000, call them.  I am not sure what they charge for these services, but I think the cost is reasonable.

 

I use the Soundblaster X-Fi USB sound card, which can be purchased at various on-line sources for around $45.

 

Having lived with the complications of the external sound card, the Xenyx mixer, and all the associated cables for several years, I strongly recommend that you consider purchasing a USB mic.  If your laptop has an HDMI port, use an HDMI cable to connect to the AVR, otherwise you can use the headphone jack (see the Guide linked in my signature for cabling instructions).  You will spend close to $100 for the Xenyx plus the Soundblaster, so why not keep it simple and just order the USB mic?  Heck, if you wait another couple of weeks, I'll sell you my old REW kit for dirt cheap...

Hi Jerry and Keith, as always great info. Still waiting for the USB mic so decided to play around with Audyssey mic. Moved sub to MLP and going around the room with mic at ear level to graph different position. I know its not accurate but at least know what my best position might be.

You've got hum at 60 Hz JChin!! LOL (And repeats itself at 120 Hz, first harmonic, while the one at 200 Hz puzzles me, coz it should be 180 Hz, right??!! Although there is something at 180 Hz which gives me more puzzles.). Look at those fellows that don't decay as time elapses on you waterfall graph. On a second note, this questions how accurate the frecuency scale of REW is. Any thoughs welcome.

Q, is it aubible at the MLP? Witout a source you may turn up the MV to 0 dB and listen carefully. If you don't hear the hum at MLP it's all ok. At this frequency our ears are less sensitive to sounds at such low levels as can be seen on the "equal loudness curves". Worry not.

Meantime, in case the 60 Hz mains hum shows its harmonics your sub may be affected by harmonic distortion. Let's try to investigate this case together. Anyone?
Edited by mogorf - 1/24/13 at 8:16am

Just had an e-mail from Herb @ Cross Spectrum:-

UMM-6 mics are available again, he hopes to begin shipping early next week...................................................let the measurements begin

Regards, Mike.

Ah, excellent. I've been waiting to hear this before ordering one.

I would like to post a big THANK YOU to AustinJerry (and team), for the new REW step-by-step guide!

About a year ago I was over on the HT Shack learning REW with the old-fashioned set-up (tried several different preamp, phantom-power setups).
After several efforts, and no small amount of frustration; I was finally successful in getting some reasonable graphs and waterfalls. However when finished, I put everything away and forgot most of what I had learned.

Fast forward to last month:
I finished my first DIY speaker build, and was dreading the prospect of re-learning REW in order to graph my DIY speaker FR.

Then this month, I learn about the new USB MICs, and as a result I have in my possession; a new UMIK1 USB microphone.
And then this wonderful step-by-step guide from Austin Jeryy and Team shows appears.
Last night i read the entire document >>> VERY NICE WORK.

Although I do not have an HDMI equipped laptop >> thanks to this new guide >> I am actually looking forward to revisiting REW

 

Feri, it's possible that mains hum may find its way into the graphs via the laptop is it not?  In which case it won't be audible in any circumstances. For this reason I always make my measurements with the laptop on battery power (not that I know of any mains-induced 50Hz hum here, but it pays to be cautious).

 

It is always great to hear back from people who have been helped by something they found here on AVS. I am sure Jerry will be delighted you took the time out to say thanks. It really is a great piece of work (and getting better with each revision).

Who knows: maybe after I start getting some experience with the new setup - perhaps I can somehow contribute to the USB related revisions?

Welcome, and thank you for your kind words. Your feedback will be welcome here in the thread.

Thanks!
I will carefully share my observations and what I learn along the way - but will also not get in the way, or derail ....
:-)

Hi Keith,

The hum actually finds its way into the graph via the test mic that picks up SPL of the sub in case affected by mains hum. Of course troubleshooting can start by swithching laptop to battery, but usually that doesn't resolve the problem. Each and every severly audible hum problem is different, in case user can not solve it the power companies are willing to come to your house and the technician can make a thorough investigation and can get rid of the source.

Although my major is in telecommunications, not power electricity, but some general considerations I'll try to describe. First off, hum is always caused by a "ground loop". Since obviously one ground can not make up a loop it always needs at least two separate grounds in a household. In the beginning I also had serious (read: crazy loud) hum in my sub with my old Toshiba laptop (non-HDMI) when I connected it to the Denon AVR via stereo headphone jack. Also started out with laptop on battery, but to no avail.

Then I found the second ground in my home which was an independent ground from the one the electricity company provides. Guess where this is? In the cable TV box. Yeap, the ground of the cable TV incoming coax cable was on a different potencial than the ground of the electricity company. From there the solution in my case was very easy. I have a Belkin power strip with surge protector and it also came with a plastic imitation plug with plastic prongs but metal ground terminals and coax-in/ coax-out sockets. Installing it into one of the power sockets galvanically connects the power company ground to the cable TV ground. Result? Crazy hum went away.

The installed imitation plug looks like this:

 

 

 

 

 

I'm not making myself clear, Feri.  What I am describing is mains-induced hum that is finding its way through the laptop and into the measurement. It would still be there even if the mic was disconnected and if all the speakers were disconnected. In this case, removing the mains power from the laptop and running it on battery power solves the problem.

 

 

 

 

 

Yes, I agree with all of the rest of your post - just didn't make myself clear in the first place. There's a very useful thread here on AVS for those affected by hum issues:

 

The Hum FAQ

I see Keith. Care to expand a bit on this one, please?

Though the topic may seem OT, but I think we can relate it to REW if we'd like to have a clear picture of what is happening with our systems. I'm sure severe hum can easily throw off the measurements if untreated.

I apologize, but I seem to have lost the point. Why are we discussing hum?

 

It's the laptop itself that is generating the hum which is then showing up on the graph in the software running on the laptop - IOW it's nothing to do with what the system is measuring.

 

As Jerry says, this is way OT and we ought to take it elsewhere if we want to continue.

I just exchanged emails with CSL.  My mic is in the first group, with expected ship date next Monday.  With luck, I could have the mic by the end of the week.

Mine too - just checked. Just when I had the time to look at the OmniMic USB mic with the latest REW beta over the weekend. Oh, well.

Because we can't carry a tune?

(Running as quick as possible away from the office keyboard - sorry, couldn't resist)

Guys, was my reasoning so bad?

"Though the topic may seem OT, but I think we can relate it to REW if we'd like to have a clear picture of what is happening with our systems. I'm sure severe hum can easily throw off the measurements if untreated."

If so, it was bad.

 

Placed my order today and CSL says although there is a backlog (presumably CSL stil has to do the calibrations when they receive the mics?) mine should ship by end of next week.

There actually is minor relevance: if there's a hum produced by a laptop connected to an electrical power source that's being picked up by the mic, it might also represent a problem for someone conducting REW measurements on a desktop PC. Hence Keith's advice to measure REW ONLY with a laptop running on battery. While AFAIK most if not all of us are running laptops for measurements, it's conceivable that a future REW user (and thread participant) might be using a desktop with an HDMI out that doesn't have battery power, and be measuring effects that are artifacts of connecting to a wired electical source. But it's still a sidebar issue.

I vote we table this discussion until we have evidence of a measurement with a clear issue exactly at 60Hz (50Hz outside of the US). At this point, the discussion is too theoretical for me.

 

I'm trying to use the guide (great work BTW!) to see if I can get my OM mic and REW working with my non-HDMI laptop.  I've got a cabling solution I pieced together from some old parts (getting the LCR speakers to play in PLIIx so something must be right!) but I'm having a little trouble making sure my Windows setting are correct as well as the REW configuration.  It seems like you started the guide using some non-HDMI screenshots but on some of the finer points (like pages 17 and 18 for the Windows portion and pages 32-34 of REW configuration) you focus more on what those screens look like with HDMI.  I was wondering if you might be willing to revisit these sections and go into more detail (i.e. screenshots of configuration settings) for those of us without HDMI laptops but still trying to use USB mics?  Let me know if you need any screenshots but I'm guessing you can grab these with your laptop just as easy?  Thanks again for this guide...I consider myself fairly windows savvy but I would've been lost without it. 

Fair enough. I actually _do_ have an older desktop PC that I'm toying with using for REW and HTPC with an HDMI-based card of some sort, so that I don't have to worry about downmixing due to multiple HDMI devices being connected (I have an HDMI input 21" monitor that I usually have connected to the laptop when it's plugged in). But it's easier to use my Dell laptop's Display Port and convert it to HDMI (or a D-sub connection) if it comes to that. Tabled it is.

@jkasanic: I quickly re-read the Windows audio output section, and there really isn't anything different using the headphone jack output versus using the HDMI output. That's why I wasn't concerned which screenshots I was using. Basically, for the output device, you set the output level to 100%, disable any effects, and make sure you are sampling at 48k. Is there a specific problem you can describe?