Dayton OmniMic Precision Measurement System - Page 62

Thanks Jim!

My received is a Yamaha and lacks any kind of advance SubEQ management, that was the reason I pulled the trigger on a SMS-1. Really happy with this little gadget. However, I know the mic on the SMS-1 has some limitations and your post made me realize that I can solve that issue by using the OmniMic and REW combination.

I'm not in position to buy / upgrade my receiver/preamp, but eventually I'll try to buy one with MultEQ XT32. So, I think the OmniMic is a good step forward without cashing out too much money.

So, if you don't mind, I'll touch base with you in the near future for advice on how to use OmniMic/REW/SMS-1.

Thanks again!

Guys,

You either optomsze one spot or get a compromise on multiple positions.

I once ran a poll here on AVS to find out what everyone else was doing and it was about evenly split.

Using the pseudo noise sequence, what are some of the best ways to see what this does to your system over just simply running sweeps?




I hear ya, I always go for one spot, no one else I have over can tell a difference, EVER, unless I make a major speaker change or something.

Do you guys use "fast" or "impulse" when using the spl meter on the omnimic? Neither matches up with my radio shack meter, fast is a few db's lower than the radio shack meter and impulse is a few db's higher than the radio shack meter.

In other words, the same volume test tone would get the following readings:

Omnimic "fast" = 80db
Radio Shack Meter = 82.5 db
Omnimic "impulse" = 85 db

I'm wondering which I should go with, I don't want to listen to music above 85 db's for extended periods of time.

Carp, did you use A, B, C or no weighting on the OmniMic? Did you use C weighting on the Radio Shack SPL meter and slow or fast?

C weighting on the Omnimic. C weighting on the radio shack meter, I tried fast and slow and neither matched up with Omnimic.

What frequency was your test tone?

I was using the receiver test tone, but I also tried it just listening to music and I had the same results, the radio shack meter level was right in between the fast and impulse setting on the omnimic.

I typically use c weighting slow.

Been testing out my new Omni Mic system...love it so far...however, I'm getting a steady hump at 60hz no matter what I play, whether it's pink noise, sine sweeps, or a steady tone at 20hz...is this the 60hz bug that Dayton had fixed? I thought that was water under the bridge by now...

Yep, it sure looks like it...you will need to send it back to PE.

You sure your equipment doesn't have a 60hz hum problem?

First sign of hum I got was when I got my amp for my home made sub (dayton SPA1000). I got a ground loop isolator for my cable line and it stopped...I guess I should try disconnecting the coax and see if the hump disappears.

the v2 omnimics aren't susceptible to the hum problem (different grounding structure ). Check your amp and try turning any HVAC off (they can make hum noise, sometimes refrigerators too). OM can hear 60Hz better than we can....

Good to know v2 is safe from that, I hate returns/warranty repairs.

Ah, sorry, I forgot to mention I turn off all unnecessary lights, A/C (at control panel), Fridge (fuse), and noisy annoying Aquarium filter (power strip off) when I measure...the only things I leave on are TV and BD player (when using CD tracks), receiver, sub amp, miniDSP and laptop...what else should I look at?

Your furnace. Many newbies to measuring have literally wet themselves with joy over seeing 20Hz and lower response that shouldn't have been there, and it wasn't, they were reading the furnace. Turn the thermostat down before measuring. And if you're within even a mile of a highway you can get spurious LF readings from traffic noise that you can't hear but the mic does.

Not just that; the noise floor is higher overall if you're in a highly congested urban area.

I once tried doing OmniMic measurements in between breaks of our Air and Water Show. You should have seen the peaks around 100 to 200 Hz with 1/24th smoothing when a jet flew ovef Lake Michigan right by our place...

I think I am going to make the move up to the v2 OM, anyone interested in my V1? I want the calibrated mic down to 5hz

you know they'll recalibrate your version 1 mic for free?

they recalibrated my v1 - it's an advertised offer on the bottom of this page.

http://www.daytonaudio.com/index.php/omnimic-v2-precision-measurement-system.html

turn around time is a couple weeks. in my understanding I'm now as good as a v2 setup with my v1 mic.

Thanks, as I said the A/C was off, it handles both heat and cold, and we live in a relatively quiet area.

do you see the 60Hz when the stereo is all turned off, powered subs unplugged?

Hey Bill, just wanted to say I really admire how attentive you are to this thread and how you back your product...

I haven't had time to do further diagnostics yet, as I have two young ones and I have to coordinate to get the house quiet enough to even try...I will update as soon as I can...

I used the "Save IR to Wav" feature for the first time in order to let someone else look at the data through there software. To make a long story short, there is a ton of noise in the recording. Now I know why my waterfall plots look so horrid. I tried to post the file here but this forum wont let me post a Wav file.

Interesting comments here - I wasn't aware of this until just recently. I've had REW for many years...unfortunately I have to relearn it everytime I want to use it...so I don't use it that often. I also have a family room system that I'd like to check sub EQ. Have worked through many individual test tones measuring response with a Radio Shack meter. For $300 plug and play whenever I want to use it, it's a no-brainer. Mine should be here Thursday!

I haven't purchased the omnimic yet, but I've got a question about the z-axis offset calculator. To get z-axis measurement, from what area of the driver do you measure from and to, i.e. dustcap to baffle? Same for tweeter? What exactly is the calculator doing to provide z-axis correction data to enter into PCD for example? Just a GUI to calculate the offset arithmetic? Thanks!

Nevermind, found it. http://www.daytonaudio.com/OmniMicV4/hs110.htm
Edited by robotbunny - 12/19/12 at 11:55am

Just stumbled my way through taking average measurements in the 15-120hz range at 3 listening positions, optimizing the OmniMic 6 band PEQ, and then exporting those to biquad eq values, and then importing those values into my MiniDSP. Fun way to enjoy my morning coffee.

I think it's pretty cool how when you select audio output from soundcard, it plays the appropriate track (once you rip it from the supplied CD) automatically.

Question, does it matter where i point the tip of the mic while measuring at listening positions for overall home theater EQ?
Edited by mfrey0118 - 12/20/12 at 8:09am

Pointed at the speakers, with a slight lift.

Tried to use the main maths function (Offset) to find the differemce between two frequency resposne graphs, but it doesn;t seem to be working.

Can someone please describe the procedure to do this?

Thanks in advance

I finally got around to playing with the minidsp today and this is all pretty new to me. I put in the cd and started to do some testing, but I'm honestly not sure what to do with any of the measurements I am receiving. I got the mic so I can test out my drivers to make sure they are working correctly and also use it to setup my minidsp. Can anyone explain to me how I might go about testing my stock pile of drivers I have lying around? Can I just mount my drivers to an open baffle and take the measurements from the same sine sweep and just overlay them and if they match up I should be good?

And if I'm doing a general freq response average using all 7.1 channels?