Dayton OmniMic Precision Measurement System - Page 56

Good to see hopefully this thread is moving again.
Has discussion moved somewhere else?

Funny you bring this up, i was reading Stereophile Rotel and Bryston reviews and XTZ was used and a liitle review on one of the pages (either Rotel or Bryston).

Its not a matter of "prettier" graphical interface its a matter of easier to look at/follow + accuracy.

I believe that there has been a big improvement in the hardware, which the reviewer comments on. XTZ looks very good for room eq and straight forward operating for Rooms

Also there is a time alignment for aligning the speakers with the sub.

What do you mean XTZ Pro is more suited to rooms? Isn't Omnimic also suited to rooms?

I guess I'm a little conflicted. Both programs look good, but I like the visual look of XTZ. I have no idea whether it's as accurate, or as accurate as REW or not. Perhaps someone who has the software can comment.

Thanks for the help Phillip.

Omnimic has better tools for speaker design, has more tools but it less convenient for the basic acoustical FR and decay measurements than is XTZ. Before buying a tool, you need to decide what your particular need is. After all, not all hammers are the same.

Hi Kal. My needs will be acoustical analysis, measuring frequency response and basic calibration (setting speaker/subwoofer levels, time alignment etc). I'm not designing speakers or anything like that.

So you reckon XTZ would be better suited for my needs?

Actually emailed the rep for XTZ and he told me that XTZ Pro II measures at 1/12th resolution (1/6 for XTZ standard) for the subwoofer analysis. That isn't that great, is it? REW measures higher than 1/48.

So basically this is going to be a very smoothed result. There is no unsmoothed option, as far as I understand it. If I'm adding acoustic treatment to my room and want to see what effect it had on frequency response then I imagine the measurement will not be very accurate.

Right. OTOH, given how we hear and what 1/12 octave constitutes in the bass range, I wonder if there is any value beyond that for standard setup/acoustics use.

The argument for high resolution, particularly in the lower Hz, ie. <20, has been argued in these forums ad nauseum. Bottom line is that some want to see the data points. They have worked hard to have numbers down there and they want to see it in all its glory .

As you said, different hammers.

But I do prefer to work at a higher resolution when trying to solve problems, then I smooth it at the end to admire my work. So my opinion is a bit biased since I don't have a whole lot to work with down there. When I add some more capability down there perhaps my opinion will change.

Are you saying there is little merit in using high resolution measurements (or high data points) in the low frequency range? Not arguing with you, just curious to know why. What's the point then of using high data points?

Yep. For typical HT rooms, most of what's down there is PVG as far as I understand it and there is very little that can be done to effect high Q (>1/12 octave) FR abnormalities in those regions. So I'm not sure what to do with the data if it was captured.

Forgive me, but what is "PVG"?

PVG = pressure vessel gain, which is what happens when the wavelength is so long that the wave is close to in-phase throughout the room, raising the pressure simultaneously everywhere.

This happens completely only at 0 Hz, and with a perfectly sealed room with rigid boundaries; the effect diminishes from there but results in very significant room gain.

Thanks Noah. What is your take on the high resolution measurement story? What do you use for acoustical analysis?

In addition, when the wavelengths become too large for the space (actually half the sine-wave), they change from cyclic propagation, to pressurization. One of the rare instances of free lunch. It's a wonderful thing. Another stellar benefit is the fundamental is rendered wonderfully, yet the harmonics don't benefit from the same acoustic reciprocity due to their shorter wavelength.

Thanks

Why in addition when it's the same thing?

I've shared this with many involved in audio,..explained it so many times. And oftentimes, until I say "change from cyclic propagation, to pressurization", many individuals will express that is what clears it up for them.


Also, in my experience, the effect of a room being sealed is much less important to the rooms boundary surfaces relative acoustic impedance. Admittedly, my sample size isn't enourmous,...like some installer that measures each room's LF transfer function. But, that's what I've found in each space I've measured.

Thanks

Does anyone have a contact at Dayton? I've emailed three three times and left two voicemails at their company, trying to followup up on my mic return (to have a cal file created), and no one is bothering to contact me...

gotcha

Noah, how dare you not respond to my question. I'm Goneten, I deserve royal treatment. Okay, let me reiterate : what is your stance on the high resolution/data point position? For acoustical analysis and calibration, is higher than 1/12 octave necessary? For all intents and purposes you can leave out applied EQ. Just analysis and calibration. What software do you use?

As a matter of interest, what software do you use for measuring?

Post 1549.

"As some of you know we made a recent hardware manufacturing switch from the original OmniMic to the recently introduced OmniMicV2. Unfortunately, during the changeover it appears the first batch of microphones were calibrated using a procedure that is not intended for the OmniMicV2 system. We know you are eager to use your new OmniMicV2 so today we are shipping replacement correctly calibrated V2 microphones. Since you may receive two OmniMicV2 please call Parts Express at 1-800-338-0531 so we can verify by serial number which is the right one. We will also be sending a postage paid label for returning the miscalibrated OmnimicV2 We apologize and again want you to know how much we appreciate you and your patience as we correct this problem.

Thank you.
Rich Taylor
Richt@daytonaudio.com

James

It depends on what I am measuring. If it can be done by XTZ, that is what I use. If I need more resolution and more tools (and that is rare), I use TEF25. http://www.gold-line.com/tef/t-tefkit.htm

Let's assume you're measuring frequency response. Do you use XTZ or TEF25? Why would you need more resolution that XTZ has to offer? Just being devils advocate here... is all.

Not sure I'm that qualified to answer on measurement issues, but I'd say it is.

Somewhere back in this thread Bill (bwaslo, author of OM) explained the resolution issue as regards OM, and IMO satisfactorily made the case that it is sufficient even at the lowest freq.

I have OM, no way I have the patience to deal with setting up REW.

As I said, I rarely have reason to use the TEF25 and mostly for functions, like impulse response and noise level, that are lacking on the XTZ. I cannot recall ever requiring it just for the increased FR resolution although it is available.

Thanks Kal. Your input is appreciated. So basically the consensus here is that 1/12 octave resolution is good enough at low frequencies for straight analysis, unless you need to apply EQ filters, then you need finer resolution.

Bump.

I didn't say that. In fact, I used the EQ filters from XTZ to set up the PEQ in the Rotel RSP-1572 quite successfully.
http://www.stereophile.com/content/music-round-53

Kal, you have used Omnimic and XTZ. Of the two, which software do you prefer to use 99% of the time?

xtz.

Kal, why do you prefer to use XTZ over Omnimic? Just a quick question. Can you set SPL levels for the speakers and subwoofer with Omnimic, and is it more accurate than using a Radioshack SPL meter?