When I used a USB mic, it was for the purpose of using it with REW.
I didn't find clocking errors to have significance at all, until i started using FIR, where fixed delay timing can literally be set to the sample.
If I was into passive crossovers, I can't see how clocking differences could matter at all.
My problem with the USB mic, was not the mic at all.......but the fact REW uses an acoustic timing reference for timing, that keys off upper frequency response to determine timing. Fine if you're you're measuring tweeters, but sucks if you're measuring woofers.
Dual channel struggles with low freq too...its innate in the linear FFT math.....
And the linear FFT math dependency totally swaps minor clocking errors....for low freq work.
So I say USB mics themselves are great, ....... and would love to see how they work well implemented dual channel.
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They are both analog? (that's a rhetorical question btw)
The only difference with a USB mic the usb interface is build-in and with the other one it's not?
Besides that it's the same thing.
(I know that as a fact because I have helped designing a couple)
Except that if someone decides to maybe invest a bit more into this, and want's to use a much better microphone like a beyerdynamic MM 1, a Audix TM-1 or eventually even something like a Earthworks, you're completely stuck with a USB microphone.
Impedance measurements are also not possible with a USB mic, which I think is absolutely essential in somebodies toolkit!
I personally just find USB mics a very poor investment.
It just has one dead road, plus has some known potential problems beforehand.
They are also not that cheap, somewhere between $80 and $120 or so?
That is not much different compared to a audio interface with two proper inputs + mic
So why even bother putting limitations right at the start for just not having to connect one additional XLR cable?
Makes very little sense.
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Valid points... I am only following up on the point that you can have DAC and ADC on same clock using an audio interface (which, by nature, must use an XLR mic) vs the common complaint that USB mic interface won't have the same reference clock.
All academic if one has an audio interface already, but the USB mic is usually significantly cheaper if one does not.
All academic if one has an audio interface already, but the USB mic is usually significantly cheaper if one does not.
I was talking about two separate interfaces, which don't share the same clock.
I have actually measured this a few times, and sometimes you can actually see this difference very clearly in how the signal shifts.
I gave a general price in the post before.
For about $100 (give or take) you can also buy a separate interface + mic.
Even more so when you look at the 2nd hand market.
Maybe you end up slightly higher, but the options and upgradability are also much greater.
Anyway, I will put this to rest, since I think more information isn't much more relevant to this topic and I don't want to make @hifijim grumpy
Re: Stable timing with mics that use a USB interface in REW.
It can be done.
1.
https://www.avnirvana.com/threads/acoustic-phase-measurements.13300/post-99941
2.
It can be done.
1.
https://www.avnirvana.com/threads/acoustic-phase-measurements.13300/post-99941
2.
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It’s not only about the synchronous DA/AD, it’s also the second (line) channel that serves as an absolute timing reference. Also a no-go with USB mics.
Yes its very used and the most common usb Mikes have lots of users sharing methods. Probably much on Facebook these days😐
We get it that experienced builders prefer non-usb mikes, but you already have them😄.
For beginners a handy little usb mic and its possible limitations, but without outboard soundcard to worry about is often more tempting I think.
Cheers!
We get it that experienced builders prefer non-usb mikes, but you already have them😄.
For beginners a handy little usb mic and its possible limitations, but without outboard soundcard to worry about is often more tempting I think.
Cheers!
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Agreed.
But I hoped I made it clear that there is a difference in what serves to make an absolute timing reference,
and what people have come to associate with USB mics...
.
And again, I will claim it's due to REW being the proponent of USB mics...and that REW's single channel, uses an acoustic time reference which requires HF content.
That simple really, imo.....
Somebody please tell me why a USB mic couldn't be used dual channel if such were properly implemented....
and I mean properly implemented, other than a pliss-ant sample or two of timing difference...
Don't get me wrong...I think it's near nutz to be using anything other than dual channel and XLR mics to measure, nowadays.
I just don't see why USB mics couldn't be made to work
Windows blablaba ..."Windows" is not an argument to prove that I wrote something wrong.
Just everything was already there ...year 2009:
HD 'cone resonance amplification' @5th element
https://www.diyaudio.com/community/threads/audax-hm130c0-opinions.153064/#post-1944482 #4
Just everything was already there ...year 2009:
HD 'cone resonance amplification' @5th element
https://www.diyaudio.com/community/threads/audax-hm130c0-opinions.153064/#post-1944482 #4
Question for you Hörnli,
Do you use any form of test instrumentation? Have you used this with the Windows environment at all?
Some of us actually have and are commenting from direct, personal experience. USB is not intended to maintain timing between channels, never was. The Windows OS introduces other issues on top of that.
No one is attempting to prove anything you said was wrong. In fact you rarely say anything concrete, so you can relax. Now if you were to say you have no timing issues using a USB interface between two devices, I'm going to call you on that.
Do you use any form of test instrumentation? Have you used this with the Windows environment at all?
Some of us actually have and are commenting from direct, personal experience. USB is not intended to maintain timing between channels, never was. The Windows OS introduces other issues on top of that.
No one is attempting to prove anything you said was wrong. In fact you rarely say anything concrete, so you can relax. Now if you were to say you have no timing issues using a USB interface between two devices, I'm going to call you on that.
Dear Chris Bridge,
Please consider that I rely on my limited knowledge of English and Google translate. Personal perception could be misleading.
https://www.diyaudio.com/community/...eeded-for-speaker-design.410219/#post-7625845 #9
https://www.diyaudio.com/community/threads/drive-current-distortion-measurement.402566/post-7555802 #146 and the following postings
...
Best regards
Bernd
Please consider that I rely on my limited knowledge of English and Google translate. Personal perception could be misleading.
https://www.diyaudio.com/community/threads/drive-current-distortion-measurement.402566/
https://www.diyaudio.com/community/...eeded-for-speaker-design.410219/#post-7625845 #9
https://www.diyaudio.com/community/threads/drive-current-distortion-measurement.402566/post-7555802 #146 and the following postings
...
Best regards
Bernd
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Hi Bernd,
Well, you didn't list what you are using. I see you're using a balanced input for current.
Are you using an audio analyzer (if so, how many channels?) or a sound card? Do you use a good bench meter (what is it?) or anything else? Amplifier? Signal source?
I'm not sure why you put a 20R resistor in series. I use a 1 Kohm resistor to do impedance sweeps and even that can become significant. The 20 ohm is not high enough to mimic a current source. Your 0R77 resistor for current sense is high and again significant. I'd be using 0R1 at the most to sense current. I use current clamp probes normally. I can also use a network analyzer that gives me phase.
I use an audio analyzer and 5 19" rack bays of bench test equipment, plus more on shelves.
Anyway, at least you are making measurements.
-Best, Chris
Well, you didn't list what you are using. I see you're using a balanced input for current.
Are you using an audio analyzer (if so, how many channels?) or a sound card? Do you use a good bench meter (what is it?) or anything else? Amplifier? Signal source?
I'm not sure why you put a 20R resistor in series. I use a 1 Kohm resistor to do impedance sweeps and even that can become significant. The 20 ohm is not high enough to mimic a current source. Your 0R77 resistor for current sense is high and again significant. I'd be using 0R1 at the most to sense current. I use current clamp probes normally. I can also use a network analyzer that gives me phase.
I use an audio analyzer and 5 19" rack bays of bench test equipment, plus more on shelves.
Anyway, at least you are making measurements.
-Best, Chris
A phase plot with a network analyzer gives you the reactive properties of the device. The test circuit should be published with any data when published so that the results can be duplicated by others. That includes test equipment used along with signal levels.
A loudspeaker can go inductive and also resistive (at resonance). When voltage and current are in phase, you have a resonant point - exactly.
A loudspeaker can go inductive and also resistive (at resonance). When voltage and current are in phase, you have a resonant point - exactly.
No, you combine the signal and the driver response, together with the way the source interacts with the driver impedance, to get the response phase.