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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 285

post #8521 of 9577
Quote:
Originally Posted by kbarnes701 View Post

 My advice to anyone who isn't comfortable with using REW with an HDMI mic: don't.

You mean USB mic?

Gear mentioned in this thread:

post #8522 of 9577
Quote:
Originally Posted by artur9 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

 My advice to anyone who isn't comfortable with using REW with an HDMI mic: don't.

You mean USB mic?

 

Yes, sorry. Good spot. Post corrected.

post #8523 of 9577
Quote:
Originally Posted by artur9 View Post


3) Are you doing the test-tone based mic positioning every time you start a measure session? Or do you have some other means of locating the mic after you have used test tones to determine correct position?
Fwiw the latest build of the software I use (acourate) has a real time mic alignment tool for this purpose. It plays high frequency clicks (Dirac pulses I think), rapidly alternating l and r, and shows you the mis alignment in no of samples (so 1 sample at 96kHz is about 3.4mm) in real time. It definitely makes a difference getting this right.
Edited by 3ll3d00d - 1/31/14 at 3:45pm
post #8524 of 9577
Quote:
Originally Posted by kbarnes701 View Post

I was referring to your measurements and your research confirming the typical noise levels in a quiet, domestic room. Personally, I have no doubts about the usefulness of the UMM-6 mic, but for anyone who does have, I suggest they don't use it.

Fine. The next time somebody posts a conclusion that is at least questionable, I won't question it.

Jeff
post #8525 of 9577
Quote:
Originally Posted by pepar View Post
 
Quote:
Originally Posted by kbarnes701 View Post

I was referring to your measurements and your research confirming the typical noise levels in a quiet, domestic room. Personally, I have no doubts about the usefulness of the UMM-6 mic, but for anyone who does have, I suggest they don't use it.

Fine. The next time somebody posts a conclusion that is at least questionable, I won't question it.

Jeff

 

Why not pop over to HTS and ask the author of REW, JohnM, directly if he believes that his software, specially designed to be used with HDMI and a USB mic, is useless?  Or maybe pop over to the OmniMic thread here and ask Bill Waslo the same question?

post #8526 of 9577
Quote:
Originally Posted by kbarnes701 View Post

Why not pop over to HTS and ask the author of REW, JohnM, directly if he believes that his software, specially designed to be used with HDMI and a USB mic, is useless?  Or maybe pop over to the OmniMic thread here and ask Bill Waslo the same question?

What a thoughtful suggestion, Keith.
post #8527 of 9577
Quote:
Originally Posted by pepar View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Why not pop over to HTS and ask the author of REW, JohnM, directly if he believes that his software, specially designed to be used with HDMI and a USB mic, is useless?  Or maybe pop over to the OmniMic thread here and ask Bill Waslo the same question?

What a thoughtful suggestion, Keith.

 

Well it would certainly nail the worries you appear to have about the USB mic. I am guessing that John and Bill would not risk their reputations on creating industry-standard software specifically for use with a USB mic if the results were going to be compromised by the very use of a USB mic. But the only way to be sure is to ask them.

post #8528 of 9577
Quote:
Originally Posted by kbarnes701 View Post

Well it would certainly nail the worries you appear to have about the USB mic. I am guessing that John and Bill would not risk their reputations on creating industry-standard software specifically for use with a USB mic if the results were going to be compromised by the very use of a USB mic. But the only way to be sure is to ask them.

I don't understand how my questions about the calibration accuracy (of the UMM-6) with respect to level, and my questions about what seems to be the thread's "conventional wisdom" that the mic has a self noise level of 50dB could be misconstrued as worries, much less mischaracterized as me claiming that the UMM-6 is "useless." But, yes, I do plan on visiting the HTS REW thread for the answers. And I'd wager that the answers will be easily obtained without anyone becoming hyperbolic and reacting like I have committed heresy.

Jeff
Edited by pepar - 2/1/14 at 5:04am
post #8529 of 9577
Quote:
Originally Posted by pepar View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Well it would certainly nail the worries you appear to have about the USB mic. I am guessing that John and Bill would not risk their reputations on creating industry-standard software specifically for use with a USB mic if the results were going to be compromised by the very use of a USB mic. But the only way to be sure is to ask them.

I don't understand how my questions about the calibration accuracy (of the UMM-6) with respect to level, and my questions about what seems to be the thread's "conventional wisdom" that the mic has a self noise level of 50dB could be misconstrued as worries, much less mischaracterized as me claiming that the UMM-6 is "useless." But, yes, I do plan on visiting the HTS REW thread for the answers. And I'd wager that the answers will be easily obtained without anyone becoming hyperbolic and reacting like I have committed heresy.

Jeff

 

I think it would be a good idea to visit HTS. It's not that anyone in this thread is regarding you in a heretical light - it is just that your question has been answered and nobody else in the thread seems to be interested in the point you keep raising. Once you accept that the USB mics cannot measure below -50dB, and once you accept that this doesn't actually matter, progress will, I am sure, be swift.

 

Another possible avenue for you to explore in your quest would be Herb at Cross Spectrum Labs. Herb sells all sorts of mics so he has no dog in the fight, and he is an expert in the calibration of these mics. Not only that, he is very consistently helpful.

post #8530 of 9577
Your explanation is appreciated, sir. I have a tab open right now on HTS.

Jeff
post #8531 of 9577
Is this going to be another thread where everybody with a technical background is driven away because of wrong-headed "firm belief"?

pepar/Jeff: which thread, somehow I'm missing it?
post #8532 of 9577
Quote:
Originally Posted by cfraser View Post

Is this going to be another thread where everybody with a technical background is driven away because of wrong-headed "firm belief"?

Take it from someone who has taken that path more than a few times, it will not achieve anything useful. Best to ignore or move on. Just my $.02.

Jeff
post #8533 of 9577
^ I know. But sometimes you have to pound away until the (contrary) evidence is accepted. This benefits everybody. See the Toole quote in somebody here's sig. smile.gif I'm not being mean and bear no ill will to really helpful people, just like to see the info straight...

You have to understand your tools, understand what you're measuring, and thus use the tools to their best advantage. It is annoying to go to the trouble of providing evidence and explanations and then having it completely ignored (standard practice, I'm not the only one who noticed based on other thread postings). Especially when it is of no personal use or benefit, as explained. Because some use laptops that have lousy USB interfaces, which vary hugely in ability and appropriateness for "quality" audio use, this should not be promoted as a limitation of a basically fine product. Face it if you have a lousy USB interface, it is easy to see, just look at a "good" one as provided.

Who uses REW to measure "noise level" anyway? Especially when they're "calibrating" REW with a convenient portable tool especially designed to do just that job. We use REW to measure at "individual" frequencies, which has nothing to do with broad-spectrum weighted noise level. I think we "pounded" through the concept that the higher the signal level, the more important the measurements. I would have hoped this is self-evident to everybody anyway. So we come up with a thread dB range for looking at waterfalls...reasonable, but some have other requirements, they're probably in studio-related threads/forums. Some might like to reduce room-specific noise if possible though, like me. But the concept that the mike noise floor varies by frequency a lot at the very low end (say sub-20Hz) was a little too much glossed over, and I now think this is because of the "firm belief" by "threadrunners" that the USB mikes are useless under 50dB anyway so why bother. For instance, I can clearly see the "noise signal" of an appliance (say the 59Hz spike...yes, not 60Hz [?]) when it turns on at well under 20dB, and see it disappear when it switches off. How is this not "measuring" validly below 50dB, for the purposes of REW? Pretty hard to deny that I'm not measuring anything valid when I can hear and see it when it happens. Look at my "quiet room" mike response.

Yes, I lied, and I'm still here pushing lol. But I'm back to ETC/reflections since I've got new panels/traps coming next week. Progress for me.
post #8534 of 9577
How does one determine if their laptop has a "lousy" USB interface and how, exactly, would that affect measurements?

Jeff
post #8535 of 9577
Quote:
Originally Posted by pepar View Post

How does one determine if their laptop has a "lousy" USB interface and how, exactly, would that affect measurements?

Jeff

As I'm trying to decide on a laptop purchase for use with REW, I would like to understand this as well. Is this in reference to USB 3.0?
post #8536 of 9577
Quote:
Originally Posted by KK in CT View Post

As I'm trying to decide on a laptop purchase for use with REW, I would like to understand this as well. Is this in reference to USB 3.0?

I don't know for sure, but I don't think so.

I thought USB was USB, as long as it was 2.0-to-2.0 or 3.0-to-3.0. It's digital data and not like the 1's and 0's from one are any higher quality than the 1's and 0's from the next one. We will have to wait for cfraser to reply.

Jeff
post #8537 of 9577

Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measuremen...

This thread has jumped the shark....can it be saved?


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post #8538 of 9577
Quote:
Originally Posted by kbarnes701 View Post

Once you accept that the USB mics cannot measure below -50dB

I have a hard time reconciling the above post with this post from jevansoh from which I infer that the USB mics can read below -50dB. On the other hand, since that post also says that most residential rooms measure at least 45dB, I don't see the difference making much difference.

That post is full of good information, as usual from jevansoh, but one of the money bits is
Quote:
The problem with the mic is that at certain frequencies and harmonics of those frequencies (100hz, 1000hz, etc, etc) there is a spike of way up to 50db so it looks like that's the overall noise floor of the mic. You wouldn't want to design speakers with this cheap mic as it is too noisy and not accurate enough for that, but again, for our purposes, the way we're using them, and coupled with REW and its design and ability to work through some noise, it is absolutely possible (without any issue at all, really) to measure a 35db or even 30db noise floor accurately.


But, please, I also think this discussion on noise (floor or level) should be allowed to fade away.
post #8539 of 9577
Quote:
Originally Posted by sdrucker View Post

Not so strange, Jerry. IIRC Artur9's Outlaw M8 subs are only rated down to 29 Hz +/- 3 db as per the Outlaw site (http://www.outlawaudio.com/products/m8.html), so if he moved the sub from a point where it may have benefited from room gain < 29 Hz, it's possible that you could get more impact from room gain around 30 hz and smoother performance from 25 to 50 Hz, but lower performance where the sub's not rated in the first place.

That is indeed the case. I moved the outlaw from a corner to the 1/4 point of the opposite wall. There was a great deal of low frequency boominess as noted by everyone eek.gif and that move eliminated it at the expense of low frequency extension. Before I went any further I wanted to be able to drive all 3 subs separately.

So, I got a separate sub amp so I could drive my 2 TBI Magellans separately with separate crossover settings as well. I now have 3 independently configurable subs. No separate delays but I don't know that I can handle another knob to twiddle right now.

But I'm left with a question. The Outlaw in the corner extended its bass quite a bit below what it is rated for. But the Magellan in the same spot does not. Would a different type of sub not be able to benefit from (IIRC) corner loading?
post #8540 of 9577
Newbie here....

I greatly appreciate the measured (no pun intended, maybe) responses of the members who, when more-or-less attacked by an argumentative person trying to pick a fight, deflect the attack and attempt to keep peace in the family and get back to the main topic. It surely requires a degree of patience and emotional maturity. Congratulations to you guys!
Jack B
post #8541 of 9577
Quote:
Originally Posted by artur9 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Once you accept that the USB mics cannot measure below -50dB


But, please, I also think this discussion on noise (floor or level) should be allowed to fade away.

 

Amen to that.

post #8542 of 9577
Quote:
Originally Posted by pepar View Post
 
Quote:
Originally Posted by KK in CT View Post

As I'm trying to decide on a laptop purchase for use with REW, I would like to understand this as well. Is this in reference to USB 3.0?

I don't know for sure, but I don't think so.

I thought USB was USB, as long as it was 2.0-to-2.0 or 3.0-to-3.0. It's digital data and not like the 1's and 0's from one are any higher quality than the 1's and 0's from the next one. We will have to wait for cfraser to reply.

Jeff

 

It is digital data and USB is USB like HDMI is HDMI. You don't get "good USB" and "bad USB". It either works or it doesn't.

 

I use the cheapest Windows laptop that I could find (Mac user for everything but Audyssey Pro, REW and OmniMic) and it works just great.

post #8543 of 9577
Well there is the difference between synchronous and asynchronous USB DAC interfaces, and the usual kinds of digital signal jitter similar to that seen in other types of digital audio sources. In general, of course, those kinds of influences are measurable, but at levels which are inaudible except as placebo, expectation bias and snake oil effects.
post #8544 of 9577
Quote:
Originally Posted by Selden Ball View Post

Well there is the difference between synchronous and asynchronous USB DAC interfaces, and the usual kinds of digital signal jitter similar to that seen in other types of digital audio sources. In general, of course, those kinds of influences are measurable, but at levels which are inaudible except as placebo, expectation bias and snake oil effects.

 

Yes, good point. I need to put this on a macro: "As far as I am concerned, if I can't hear it, it doesn't exist".  :)

post #8545 of 9577
Quote:
Originally Posted by KK in CT View Post

As I'm trying to decide on a laptop purchase for use with REW, I would like to understand this as well. Is this in reference to USB 3.0?

KK - another option to consider, and one that I have successfully used is to look at used Netbooks on Ebay that have HDMI & Windows capability. Other than a smaller screen, I don't think you'll find any limitations as far as REW goes, and the savings may be significant.
Examples: http://www.ebay.com/itm/Acer-One-Windows-8-Netbook-AO756-2840-/271387424961?pt=Laptops_Nov05&hash=item3f2ff378c1
http://www.ebay.com/itm/Acer-Aspire-One-A0725-Netbook-2-GB-AMD-C-60-320GB-Hard-Drive-Windows-7-FREE-SHIP-/121264041679?pt=Laptops_Nov05&hash=item1c3be66ecf
post #8546 of 9577
Quote:
Originally Posted by Selden Ball View Post

Well there is the difference between synchronous and asynchronous USB DAC interfaces, and the usual kinds of digital signal jitter similar to that seen in other types of digital audio sources. In general, of course, those kinds of influences are measurable, but at levels which are inaudible except as placebo, expectation bias and snake oil effects.

Ahhh, of course, jitter. Thanks for raising the bar, Selden, and thanks for supplying context.

Jeff
post #8547 of 9577
Quote:
Originally Posted by kbarnes701 View Post

Yes, good point. I need to put this on a macro: "As far as I am concerned, if I can't hear it, it doesn't exist".  smile.gif

There is nothing wrong with periodically rigorously re-examining what we hear or see to find out if there is something there that we are not hearing or seeing. That is the nature of SCIENTIFIC inquiry. At the end, it might be concluded that, as in Selden's example, there could be something there, but the reason we are not perceiving it is that it is ... imperceivable. But arriving at the conclusion before taking the journey is not scientific.

Jeff
post #8548 of 9577
Quote:
Originally Posted by ggsantafe View Post

KK - another option to consider, and one that I have successfully used is to look at used Netbooks on Ebay that have HDMI & Windows capability. Other than a smaller screen, I don't think you'll find any limitations as far as REW goes, and the savings may be significant.
Examples: http://www.ebay.com/itm/Acer-One-Windows-8-Netbook-AO756-2840-/271387424961?pt=Laptops_Nov05&hash=item3f2ff378c1
http://www.ebay.com/itm/Acer-Aspire-One-A0725-Netbook-2-GB-AMD-C-60-320GB-Hard-Drive-Windows-7-FREE-SHIP-/121264041679?pt=Laptops_Nov05&hash=item1c3be66ecf

Thanks!
post #8549 of 9577
Quote:
Originally Posted by pepar View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Yes, good point. I need to put this on a macro: "As far as I am concerned, if I can't hear it, it doesn't exist".  smile.gif

There is nothing wrong with periodically rigorously re-examining what we hear or see to find out if there is something there that we are not hearing or seeing. That is the nature of SCIENTIFIC inquiry. At the end, it might be concluded that, as in Selden's example, there could be something there, but the reason we are not perceiving it is that it is ... imperceivable. But arriving at the conclusion before taking the journey is not scientific.

Jeff

 

Very true. This is how I know that 'jitter' isn't worth even mentioning these days let alone worrying my head about.

 

Something that is there but imperceivable isn't there in any meaningful way IMO. I need to get that macro sorted :)

post #8550 of 9577
Quote:
Originally Posted by toofast68 View Post

This thread has jumped the shark....can it be saved?
 

 

What usually happens is that the guys who have been making the genuinely useful contributions and helping people improve their systems, just drift away.

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