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"Why would anyone want to bother building a kit that costs $300 without any paint when he can add... - Page 10

post #271 of 280
Quote:
Originally Posted by carp View Post

Does anyone know where gating is on the omnimic? I don't see it. thanks

I don't have OmniMic, but in the manual on page 8 it says this about gating (though it doesn't use the word "gating"):
Quote:
Originally Posted by OmniMic Manual 
A frequency response is related to its "impulse response" (the pressure signal that a speaker or sound system would make if it were fed by an extremely short pulse). OmniMic can show impulse responses, and you can select how much of an impulse reponse you want the analyzer to look at when forming a frequency response. Click on the impulse response graph at the latest part of the impulse response you want OmniMic to include when it computes frequency response. The selected portion will appear as a red trace, the rest will remain black.

Reflections of sound in a room will appear as abrupt features in later parts of the impulse response (usually after about 3 to10 milliseconds from the main impulse response.). The response of the speaker without room reflections is smoother and less varied than when room reflections are included. Removal of room reflections is possible only at higher frequencies -- at lower frequencies, the reflections happen before even one full cycle of longer low frequency waves.
post #272 of 280




post #273 of 280
Those measurements were about 3 feet away. They were each SEOS built and all in the same place. The EMC 8000 was used with 0 degrees cal files(mic was pointing at the speaker) into a mobile pre(no sound card files) and then the output was HDMI into my AVR. No smoothing, no EQ. Tonight I will do more, tell me what! These take some time to do. The actual measurement is quick but moving speakers, and getting the results into the forum takes time.
post #274 of 280
I took one of the measurements from 2 pages ago and overlaid it with one of the ones you just posted. They look surprisingly similar for being at completely different distances.

post #275 of 280
You have to pretty much ignore 600hz and down using a 4ms gate. There's still a lot of reflections in there. Something does looks weird at 2khz. I'm wondering if something isn't wrong right there. I don't know what it could be though. Polarity flip wouldn't do that. Vertical mishap wouldn't do that. XO components out of spec would only be a couple db at most...

The only thing I can tell is there's a notch at 2.3khz in the design. If this was wired wrong you'd get that result. But mtg90 showed me his work and it was right as far as I could tell.
post #276 of 280
Still could be a reflection, but I'm now doubting that.
post #277 of 280
Well, the mic was sitting on an upside down clothes basket, maybe reflections off that? Sorry, it was late and needed to compromise. I will have to get the mic stand out.
post #278 of 280
Oh. Ya, I'd try a stand smile.gif Try to get the speaker and mic as far away from boundaries as possible. If you have to, put the mic at 2ft. Keep it a little more on axis with the tweeter than the woofer, but sorta split the difference. To close and you'll cause problems though. 2ft max. Try 3 ft first.

Measurements are a lot of work. Especially going outside. It'll take me half my saturday to measure a speaker sometimes if I want all the data. Perserverance biggrin.gif
post #279 of 280
Quote:
Originally Posted by andyc56 View Post

I don't have OmniMic, but in the manual on page 8 it says this about gating (though it doesn't use the word "gating"):

Thanks, I'll try it out.
post #280 of 280
Quote:
Originally Posted by tuxedocivic View Post

Oh. Ya, I'd try a stand smile.gif Try to get the speaker and mic as far away from boundaries as possible. If you have to, put the mic at 2ft. Keep it a little more on axis with the tweeter than the woofer, but sorta split the difference. To close and you'll cause problems though. 2ft max. Try 3 ft first.

Measurements are a lot of work. Especially going outside. It'll take me half my saturday to measure a speaker sometimes if I want all the data. Perserverance biggrin.gif

The speaker was on the floor, which is carpet over concrete.
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AVS › AVS Forum › Audio › DIY Speakers and Subs › "Why would anyone want to bother building a kit that costs $300 without any paint when he can add to cart on our Theater 10?"