Dayton OmniMic Precision Measurement System - Page 14

The fact that Audyssey corrects both in the freq and time domain is a huge selling point of Audyssey, but Floyd Toole has stated in his book that simple EQ can help time domain behavior. Yes, Audyssey impulse response and frew response (you can convert between the two) to set their filters, but they are filters nonetheless, and any filter set wich will give a better freq reponse will tighten up the impulse response of a system. Audyssey cannot 'delay' certain frequencies to correct for improperly offset drivers in a speaker cab, it does not work miracles. Essentially, the 'magic' in Audyssey is the fuzzy logic it applies to determine where the cuts will be placed, to come up with the best EQ solution for the room as a whole...

Audyssey cannot fix glaring problems, like a first reflection causing comb-filtering, as it will pose a different 'signature' at every seat...

If you have every single seat with very different freq responses, Audyssey will not do much. It can't, as a change becomes a rob Peter to pay Paul situation. Audyssey corrects problems depending on how many seats those problems affect. If a problem affects several seats, odds are it will be corrected. If a single seat has terrible response, it will not help it much, unless that terrible response has similarities with other seats.

It is great for what it does, save the low freq 'boost' problem. But saying that it works wonders is beyond it's job description.....it eventually must come up with a single filter set for each speaker, and that requires compromise...the graphs on the Audyssey site assume a pretty awesome room to begin with, with little seat to seat variability. Most have huge variability seat to seat, esp in the low frequencies. Multiple subs is the answer, so that Audyssey can better apply a single fiter set which will help all seats.

JSS

Quote:
Originally Posted by noah katz
I wish Audyssey would do that to my bass; I have to boost it 10 dB.


With the boost it still lacks weightiness/meatiness.

I have a Reckhorn B-1; after a healthy dose of boost centered at 20 Hz it sounded pretty good.

I sill need to do more tries w/Audyssey; I got something to my liking with it before on an Onkyo I had.

Where I want to take this discussion probably does not belong in this thread. I am going to take it to a new thread, I hope you will chime in.

Yes.




There are two types of sealed enclosure systems: the infinite baffle (IB) system and the air suspension (AS) system. The IB system normally uses a large enclosure where the compliance (or "springiness") of the air within the enclosure is greater than the compliance of the driver suspension.
Source

Just got the Omni-mic today and for some reason I have a 60hz spike and a smaller spike in the 180hz range with nothing playing?



I forgot to take a snapshot of my frequency response, I got distracted trying to find out why I had this huge 60hz spike in a totally quite room.

It's still there when I run a graph. I did put in the Mic ID and followed the instructions when the pop up came to select 2 channel DVD for the mic and know I followed the instructions right.

I did set-up my Galaxy CM-140 right next to it while checking the SPL levels and there pretty close to each other.

Who has had the most time to mess with it and what do you think so far? It was easy to set-up but a 102db spike at 60hz shouldn't be there with nothing playing. I might try this out on the older XP pro laptop to see if I get different results from the windows 7 laptop.

You didn't have it plugged into the wall outlet did you? The laptop that is.

Try using a cheater plug on your laptop if you are using it while connected to AC power outlet.

The first laptop was running off of battery. This is now from the XP pro laptop and I pretty much get the same thing, again just running off the battery and not plugged in. I stretched out the graph to show the entire response with 1/6th octave smoothing. You can still see the 30db 60hz jump right there and the room is quite when I took that snapshot.



Here is a freq. sweep:



I know wish i remembered if that was an Audyssey on blue and off red but it could be me messing with the bassis. That dip at about 1.6khz went away after passing by and sitting down so I am thinking I was fiddling with the bassis but took the snapshot before the mic had a chance to settle down.

I haven't really set-it up in the perfect spot yet and it's not in the audyssey position, forgot to get a micro-phone stand, just using the tri-pod. have to mess with it more but the 2 peaks on 2 different laptops (Windows 7 and XP Pro) isn't encouraging.

mjaudio,

How about lighting in the room? Any chance you could have some sort of EMI from fluorescent bulbs in the room? Had a friend who couldn't run frequency measuring sweeps until he turned off the lights, ended up replacing them. I think some flourescents operate in the 50-60Hz area...

I will try some measurements with the lights off but I have never had this problem with any other measurement software.

I have to do some more testing.

Anyone one else with the Omni-mic care to chime in on how it's working for you so far?

It bugs me too that the window can't be maximized, seams to be the biggest complaint from most so far but I think I am the only one with a 60 and 180hz bump in response in a quiet room.

A good measurement package should eliminate all room noises from the measurements.

I would recommend measuring at a higher SPL. If the 60Hz issue increases then its an audio problem.

I've had no such issues so far, and the more I use it the more I'm liking it.

PE has a thread here. However, there is very little activity there, however, Bill Waslo may monitor it.

Good luck

Hi mjaudio,

I'm not supposed to normally do tech support on these, but I saw your post and got concerned, so I checked some mics that PE had sent as samples. I also got a strong 60Hz tone (though only around 57dB level), and became still more concerned ...until my furnace's fan shut down. And the tone vanished just then! Could you check to see whether you might be picking up that fan noise? In winter we tend not to hear HVAC noise since it's almost always there.... it can be carried particularly strongly in floor vibrations, though mine were only airborne (since my testing area is on concrete slab).

Also want to point out that "frequency response" is measured with a stimulus applied, that graph doesn't mean much without the proper tone being played. To see just the level of ambient sounds, hum, or noise, use the "FFT" or "RTA" analyzer on the "SPL/Spectrum" page. (you would've see the the same tone there for low frequency stuff, but the level shown would have been more meaningful). Best Frequency Response measurements (best noise rejection) are with the 2nd CD track playing and the frequency response analyzer set to "sine sweep".

-bwaslo


That would be a nice trick, but mother nature is a.... how about settling for "should reduce room noise effects"?

Thanks for the tips Penngray, FOH and bwaslo.

I am going to do some more tests when I get some more free time.

I didn't have the heat on and even tried another room and got the same results so I am bit stumped. I just got home so no testing tonight and the rest of the week may be late nights but I will get to more tests by this weekend.

Hey Bill, any chance of a software update so the window can be expanded full screen?

Awesome work Bwaslo.

FWIW, HOLM does remove the noise from the measurement. I have a mini-split AC unit in my HT room and I can see it in the "NOISE" part of the HOLM measurements when its on. The impulse measurement is uneffected. I have no idea how they did it but noise is removed from the measurement.

mjaudio -- another possibility is your mic may have a defect or damage. If the grounding fails in the body (such as the long tube not making good contact to the main body or similar), that can show as a hum pickup. If this seems to be the case, contact Parts Express for a replacement. If the tube can be twisted, and doing so makes the hum change or go away, that would be the cause.

I haven't had a chance to try it out again but I was thinking it might be defective or damaged as well since no one else seems to be having this problem.

I will try it out again this weekend in both system which are in different rooms to see if there is something in the room I am not accounting for.

Thanks for the tips about possible grounding issues.

Warpdrv -

Great thead.
I'd like to see you use this product in New Berlin, WI in the HT room in this thread: "rotary woofer".
Thoughts?

Mike

Cool.
It would be great to see "in person" before I buy one.
PM back...

Mike

I have had this product for a week or so and it is great.

WAY WAY WAY better than XTZ. Very plug and play as the mic preamp is built into the base of the mic. And much, much easier to use that REW.

If you have a few thousand (or more) tied up in your speakers, $300 is a no brainer to provide tools to make best use of your speaker purchase.

The USB connector that came with it is only about 6 feet long so I purchased a powered 10 meter extension that works great.

You can average as many measurement as you wish

You can scale the charts horizontally (frequency range) or vertically (amplitude)

Bass ringing can be plotted; room reverb can be measured

And instead of using a RS meter with it's varying correction table, this can be used as a much more accurate SPL meter.

You can read the manual on-line at

http://www.parts-express.com/pdf/OmniMic/index.htm

Two improvements I would like: (1) the ability to move traces on the screen so that when two are compared, you can align them if the measurements were not taken at the same db level and (2) a more integrated approach for generating the test tones. They provide a CD and also have the test tone files in the program but no integrated way to play them. This second point is not a big deal but a nice to have.

I have tried XTZ, REW (which is great when I can get it to work), ETF, and a few others but this wins the functionality/ease of use war. May not have all of the functions of, for example, ETF, but I can get it to work 100% of the time and it will do all I want it to.

Great review thanks. Doe it have the ability to apply eq filters to a frequency response and see the resuts?

Thanks

Chuck, you lost me there. What do you mean by "no integrated way to play them"?

Thanks for the mini-review!

/Ken

That would sure be a great feature.

Do any other affordable packages have that?

I wonder if it's feasible to go in the other direction with MiniDSP; import the measured response and sum it w/filter response.

Barring that, I guess we just eyeball what filter has the inverse response, and try it and remeasure.

I bet that gets old fast.

REW does that. Noah I could email you a REW measurement file you could open it n REW and play with it. What REW does is impressive.

I wonder if REW can import measurements made w/OmniMic.

Assuming REW's PITAiness is limited to h/w issues.

REW can import .txt, .frd, .dat.

The omnimic manual says it can save and open .frd files.

Does REW work with the OmniMic microphone? I'd like to use both programs with the same mic, if possible.

I'd really like to A/B the two programs as I like REW just fine but I like the package deal that comes with the OmniMic system. If I were to buy another mic and preamp to do the same thing, I wouldn't call any inconsistencies conclusive unless I were using the same mic/preamp for each program.

That would be REALLY cool though. Anyone with the OmniMic and still has REW... lemme know, please.