MiniDSP UMIK-1 Microphone - Page 21 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #201 of 887 Old 02-11-13, 08:47 PM
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Re: MiniDSP UMIK-1 Microphone

I'm really glad you took the time to graph those responses... now I can better see what's going on... and what I'm seeing is quite bizarre.

Obviously it looks like the calibration curve beyond 802Hz has simply been transposed by some constant (but arbitrary) amount, however what is really disconcerting, now that I can see the relationship visually, is just how eeriely flat the "curve" is from 802Hz down to 21Hz... much too flat, much too perfect and on so many mics? that simply cannot be for real. Even those that were shipped UMIKs with better looking calibration files have now got to wonder if their super flat response calibration file is actually even true. Then of course there is the question of what happens to the response down below 20Hz... it's still going to be a big mystery but from the last recorded calibration level it also appears that it might be the beginning of a new transposition of the curve below 20Hz but we really don't know for sure since the data just ends abruptly at that point. There simply is no calibration correction value below 20Hz. And the mystery thickens...

I really want to hear an explanation from a miniDSP tech about what's up with these crazy calibration files... what a time to be off on a 5 day weekend. At this point I can't help but believe these UMIKs have to be shipped back to Hong Kong so they can make this right... but we'll have to wait and see what it is they suggest be done to fix the problems. By consulting the serial numbers (assuming they were shipped out in sequencial order) there's got to be more than 100 of them that were shipped out last week... that's gonna be a lot of money in shipping returns.

Last edited by monomer; 02-11-13 at 09:13 PM.
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post #202 of 887 Old 02-11-13, 09:38 PM
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Re: MiniDSP UMIK-1 Microphone

Forgive me for being super curious about your plot of the five calibration curves. How was it generated? Are all five of the curves exactly superimposed below 800 Hz? And what is the additional horizontal straight line? And what caused the offsets of the curves above 800 Hz? Was some of that offsetting done manually for your plot, or are there actually discontinuities in the data at that frequency, actual jumps in the calibration curves? Thanks, I am just trying to understand what I am seeing.
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post #203 of 887 Old 02-11-13, 10:03 PM
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Re: MiniDSP UMIK-1 Microphone

I believe those are the cal files without transposition or adjustment. It looks like an acoustic measurement above 812 Hz was spliced onto some sort of "null" measurement below, the numbers 802 Hz and below are probably just electronic noise. However, the above-812 was done at seemingly random levels....

My initial tests of a UMIK indicate that it's fairly flat down to 20 Hz, possibly within its +/- 1 dB tolerance even without a cal file.
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post #204 of 887 Old 02-11-13, 10:15 PM
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Re: MiniDSP UMIK-1 Microphone

Thanks, I had to see for myself, so I downloaded the calibration files for those serial numbers plus a few others, and sure enough that is exactly the way they plot out in REW.
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post #205 of 887 Old 02-11-13, 10:29 PM
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Re: MiniDSP UMIK-1 Microphone

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AudiocRaver wrote: View Post
Thanks, I had to see for myself, so I downloaded the calibration files for those serial numbers plus a few others, and sure enough that is exactly the way they plot out in REW.
There was no adjustment what so ever, just imported in.
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post #206 of 887 Old 02-11-13, 10:33 PM
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Re: MiniDSP UMIK-1 Microphone

So I see. Thank you.
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post #207 of 887 Old 02-12-13, 12:13 AM
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Re: MiniDSP UMIK-1 Microphone

Hopefully this is just a glitch in the files themselves and not something that happened when they were measured, although that's probably a long shot. If the actual measurements were skewed at measurement time, say by an improperly calibrated rig, then the mic itself would probably have to be sent back to be remeasured. Mine should arrive in a few days, it will be interesting to see what I end up with.
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post #208 of 887 Old 02-12-13, 12:17 AM
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Re: MiniDSP UMIK-1 Microphone

Received my UMIK today. Serial 7000237 and exactly the same calibration issue.

I am really looking forward to seeing the response from MiniDSP on this one!
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post #209 of 887 Old 02-12-13, 12:24 AM
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Re: MiniDSP UMIK-1 Microphone

I tried to check my order status on the miniDSP site and can't log into my account at the moment, it keeps telling me I don't have one or wrong username/password, hopefully this is just a "Holiday" system issue. Anyone else having trouble?
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post #210 of 887 Old 02-12-13, 02:55 AM
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Re: MiniDSP UMIK-1 Microphone

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I tried to check my order status on the miniDSP site and can't log into my account at the moment, it keeps telling me I don't have one or wrong username/password, hopefully this is just a "Holiday" system issue. Anyone else having trouble?
I can log in without a problem.. try the "Forgot password" or "Forgot username" links

http://www.minidsp.com/component/user/reset
http://www.minidsp.com/component/user/remind
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