Dayton OmniMic Precision Measurement System - Page 54

The 5 graphs above are subs only.

I agree that position 2 has the most variance in it.

Below are two screen shots showing the measurements being overlayed each other.

The black trace is from 1-14-2012
The red trace is from 3-26-2012

As you can see if I move the red trace up by 3db most of the position 2 is pretty close and position 3 is almost dead on. That is what I was looking for since I know the mic location was different between my measurements from January and this month.

James

how do you overlay two different graphs in OM like that?

BA,

If you notice in my screen shots the little window where it shows the colors and stuff, there is the "offest" section.

So I load the first frd file, then when I load the second one, I increase or decrease the offset and it raises or lowers it.

Hope that help.

James

I've got an updated mike and my graphs still only go to 10 Hz.

Yours go to 5?

Noah,

Did you download the latest software?

James

Can you give me some idea of how you do this?


So, aside from your point above about running the sub full range, are you saying that for the most part based on the steps I described above I am at least using the OmniMic correctly?

elee532,

A few things to suggest for your measurements are:
1) Have your receiver or pre in stereo mode
2) Scale your graphs to either a 5db or 10db size
3) Change smoothing to 1-6th or 1-12th

To scale the graphs use the little icons in the top left of the screen. I have attached a screen shot with the icons highlighted in yellow so you can see what I mean.

James

[quote=elee532;21844763]Can you give me some idea of how you do this?





I don't know how your receivers (Onkyo) way, but usually there is a switch on the front panel to control speaker A or B or both, off or on. Also there is normally a button on the remote control. The way i do it is turn both off so the only channel is the LFE.
Also i can turn my centre and surrounds off, which is not unusual.

What model is your Onkyo?
You are on the right track bit of fine tuning, take note of James post and post your results back.

There is no need for you to measure anything above 1/12 smoothing.
Omnimic defaults to 1/6 smoothing, and i normally leave it at that, with the odd accasion going higher.

Thanks James. Here are my next two tries at this. I did turn ON stereo and scaled the graphs to 5db. I forgot to change smoothing from none, but hopefully this still gives a good idea.

Phillips751, I actually have a Denon receiver. Anyway, I unplugged all the speakers execept for the sub. I am thinking this gets the same result that you were suggesting, correct?

The black line is with Audyssey turned off. The red line is with Audyssey turned on. Am I using the OmniMic correctly now? If so, any general thoughts about this reading?

Thank you both!

elee532,

There you go, looking better. Just to clarify did you have the receiver in stereo mode? I only ask due to this statement "I did turn off stereo".

Now that you are getting the hang of it for your next reading I would look at changing the smoothing to 1-12th and end your graph around 100HZ since you are not getting much past that.

Also, just to give yourself an idea of what happens when you move around in the room. Move the mic to different locations and take a measurement, save it, move to another location, measure, save, etc (do not change the master volume level though). Than you can load the saved frd file(s) and compare different areas of the room and what kind of response you get.

James

I would guess your crossover is set at 80 Hz based on the FR. When I measure my subs I set the crossover as high as it goes so I can evaluate the subs entire FR.

Yes you do get the same result but alot easier/quicker to push a button on the reciver or remote.

What is your model Denon?

Have you found speaker A and B?

Using the frequency response tab is great to use for finding the best position for speakers & subs, mainly because it is continous.

A good graph to check bass is in the bass decay tab. I have adjusted my subs using this tool and has made some great improvements.

Ooops. Yes, that should have read "on." Corrected.

Thank you for the help!!

Phillips761, Gooddoc, Exojam,

Thank you for the very clear instructions!!


Denon AVR-990


I have not, but I'll dig a little deeper into the manual.


I look forward to giving it a try. And, if I can't figure it out, I now know where to come and get a good answer.

elee532,

No problem with the help, glad you are moving forward.

James

Has anyone made a comparison with the new hardware mic etc (V1 vs V2)?

Phillips,

I think I saw that in the last 10 pages. The comment was that it was very slight.

You can more easily find it by going to the parts express website, find forms and drill down from there.

So if someone likes the ease of hooking up the Omnimic but want the filters through REW, they can pause the frequency screen, save the curve, open it in REW and calculate filters in the regular REW way....., right?

elee, there is no speaker a/b on the denon that I am aware of. I just simply put the AVR on stereo like you, and unplug the mains, leaving the surrounds in since there is no content being sent to them anyways

That is the way I do it to generate filters for my BFD...

Yep you save as a frd file and import into REW.

You need the impulse to use the Find Resoances/Waterfall features (plus all the mesurements) in REW, which could be very handy especially if you have PEQ. I have tried this saving the Omni Impulse to a WAV file and importing into REW but it doesn't give a accurate result.

I believe that Bill is working on saving the Impulse in the next update, hopefully that will be suitable to import in to REW. If this is able to work it would be fantastic.

Are there any guidelines for where to set the volume when taking readings with OmniMic?

~30 dB above your room's noise floor would be good.

Or whatever it takes to get stable response

elee532,

To expand a little on what Noah is saying (and Noah please correct me if I am wrong).

Before you start taking your measurements, what you can do to check for how much noise is just present, is go into your SPL tab and see what it is showing. I have attached a screen shot of the noise present in my room at the listening position before I started my measurements on 3-26-12.

The other thing I usually try to do but sometimes forget is to run your receivers test tone (for subs) as an example and make sure I get 75db at my listening position. I do this to make sure no changes in my subs trim need changing, which once set should not need to be changed.

One last step I do is to always take measurements with the master volume at the same level. That way I feel confident in comparing measurements from different days, months, etc. If you notice in some of my measurement screen shots they start with _5, that’s my way of noting that the frd save was taken with the master volume at -5.

James

Noah,

Were you able to get your graphs down to 5HZ?

One thing I have noticed is that even though the frequency response tab will take measurements down to 5HZ now, other sections will not.

As an example even though the SPL readings will allow you to go to 5HZ the measurement itself does not go down that far. I have not had a chance to look at other sections to see if this happens but I hope to do some measuring tomorrow and will look at see how it is working. I believe this is something Bill will need to address.

James

How would you recommend the process of adjusting a graphic eq?

I want to go back to the drawing board and try something else.

What about the RTA?

Do you measure/eq one speaker at a time (to find the affending channel) then combined or just combined?

Actually, in the strictest sense, a graphic really has no place in home audio. It way too course below the transition frequency. And above the transition, one shouldn't typically EQ. A parametric EQ should be used down low and a combo of acoustic treatments, speaker design and placement should address problems above the transition frequency.

I've got several EQ's,...including 1/3 octave graphic, several parametrics. Parametric EQ's are essential for subwoofer adjustment in HT's.

Good luck

Thanks for that.

It is built into the receiver.

I have attached a graph that has NO eq at all.

The black response is both main speakers playing and the others are seperate (red is left, blue is right).

I have also included indvidual graphs on seperate images (both & left, right).

If anyone can tell there thoughts it would be appreciated.

The sound is absoluteley horrible, extremely dry, drony, honky etc. I wonder if they are out of phase?

Has Bill replied to any questions about the orientation of the mic?

Nope, ya done good, James

Hmm, your room is about 10 dB quieter than mine.


Just tried (no mike connected) and sure enough, if I just keep clicking the graph expander arrow, it goes down to 5 Hz.

Does Omnimic have a correction other than the Mic calibration file?