Dayton Audio OmniMic Precision Measurement System

[[email protected]]

i now have one of these. it will probably take awhile to learn to do proper testing.
i dont have a proper mic stand until the weekend (hopefully). ran some quick fr's on some drivers i have on hand.
i think somthing was wrong here because it seems everything dropped off at about 1500
sb29

rs28a

north28d

silky

gefco buyout

[critofur]

Re: omnimic

Well, what size baffle did you have them on? That will affect the FR...

[johnnyrichards]

Re: omnimic

If, like my first night with my measurement rig, you are holding the tweeter in one hand and the mic in the other, you will get miserable results. Good way to verify everything is plugged in and whatnot though.

[johnnyrichards]

Re: omnimic

The top end rolloff might be from holding the mic a touch too close to the driver, as well.

[[email protected]]

Re: omnimic

as i dont have the stand yet, i had the mike mounted on a piece of wood clamped to my workbench and the tweeters on the desk up aganist a os speaker box. so yes, no baffle. aka yes, i had no bananas.:eek:
so, you are saying that a baffle of sorts is needed to get decent fr?

[johnnyrichards]

Re: omnimic

as i dont have the stand yet, i had the mike mounted on a piece of wood clamped to my workbench and the tweeters on the desk up aganist a os speaker box. so yes, no baffle. aka yes, i had no bananas.:eek:
so, you are saying that a baffle of sorts is needed to get decent fr?

Absolutely. It will take some experimenting, and the larger the room the better. I stick mine in the corner of the garage, with a folded up "egg crate" mattress cover on the floor in front of it. This spring, I am going to put one up above too.

[[email protected]]

Re: omnimic

i did some rta in the livingroom too. audessey vs manual eq. the manual eq only has 5 band of adjustment so not enough to get it better then audessey.
off and on look alot alike.
and on.

[johnnyrichards]

Re: omnimic

Hmmm... Looks like you might be measuring with the furnace running or something, or you like it bassy like me

[[email protected]]

Re: omnimic

somthing was exciting the lows even when nothing was playing. i turned or the fishtank, the furnace, freezer, ceilingfan. the fan over the onkyo was still on.
i have concluded that i need to extend the mid a bit. no mater what i did to the eq on the sa1000, i could not fill the drop centered at 80hz. i tried full range, 40,50,60,80,100 and 120hz. maybe the room.

[johnnyrichards]

Re: omnimic

It could be the room, remeber how impressed I was with the bass from your aluminum MTM's?

[[email protected]]

Re: omnimic

i did discover that one of my os tweeters is not working. that my polks dont look so bad. my center channel is not to bad either.

[bwaslo]

Re: omnimic

Arlis,

The most straightforward way to deal with background noise is to turn up the signal from the speaker. Also, use the sine sweep (track 2) rather than the pseudo-noise, sine sweep is more effective against background noise (and better in all other ways, except maybe annoyance factor).

Bill

[critofur]

Re: omnimic

as i dont have the stand yet, i had the mike mounted on a piece of wood clamped to my workbench and the tweeters on the desk up aganist a os speaker box. so yes, no baffle. aka yes, i had no bananas.:eek:
so, you are saying that a baffle of sorts is needed to get decent fr?

If you have the tweeter on a reflecting surface (not IN the surface, as in a baffle) then there will be a deep cancellation from the reflected sound at the frequency at which is it out of phase with the direct sound.

Also the tweeter's faceplate being round with the source in the center will boost the high frequency with a sudden drop as the wavelengths become larger than the diameter of the face plate transitioning from "2 pi" to "4 pi" space. It's a little more complicated than that, and I may be incorrect about the specifics, but that gives you the general idea at least. There are other factors such as the size of the radiating surface relative to the baffle (which in this case is a combination of the tweeter faceplate, then a dip, then the surface behind the tweeter once again giving a boost at lower frequencies below the bounce cancellation.... :eek: Hehe, does anyone even come close to imagining how complicated speaker measurement could be, before they start?

[[email protected]]

Re: omnimic

To all Dayton Audio OmniMic owners....

If you own the Dayton Audio OmniMic and do not have version 2.04 software you can download it by visiting http://www.parts-express.com/pe/show...number=390-790

Thank you!
:D

[critofur]

Re: Dayton Audio OmniMic Precision Measurement System

When you use the OmniMic for SPL, how does the system know how to calculate sensitivity? I don't see any pictures of wires to connect to the speaker level to measure current/voltage?

Does it not have that capability included? If not, that would be something to include with the next hardware revision (along with the ability to measure over 20Khz).