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Lilmike's Mic - Page 2

post #31 of 119
Thx, Awesome stuff!!
post #32 of 119
lilmike--for the usb noise issue, I bet we could cook up a nice little filter circuit using a couple capacitors and a small inductor . That'd give you a 3rd order filter, and since SMPS switching typically is 50kHz-1MHz, we could probably knock it down most/all the way to 50dB.
post #33 of 119
Any comparisons yet, lilmike?
post #34 of 119
Thread Starter 
Not yet. I've not forgotten, just been extra busy this week.

In addition to pushing pixels so dB can make some sawdust and get started on the rest of this monster this weekend, I've been thinking about the methodology I want to use so that I can make things 100% repeatable.

Got some ideas that should work fine, I just have to get the time in the shop to make things happen.
post #35 of 119
I just recently discovered this lil mic as well. I was actually able to use this mic with no preamp. Just the capsule wired to an 1/8 inch jack, jacked into my computer. Didn't work for my laptop though. I guess my computer powers it

I also got something strange going on above 5khz. Not sure what it is yet. Drops like a rock. I think it may be my setup. I go digital from the computer via HDMI to my tv and from my tv to receiver via optical. From there the receiver converts to analog and the receiver should be pretty flat. However I think maybe the tv screws the signal above 5khz. Because it's very consistent and WRONG. Will probably try analog from the computer to the receiver and see if that fixes it. To bad my receiver doesn't have HDMI.

Any diyer should buy this mic. I gave it props in my build thread actually. I was extatic to use it
post #36 of 119
I got my 5 mics from digikey today, still waiting on some other parts to get them built. I am going to build 5 of these (if I dont screw anything up) so I can compare them to each other and my ecm. Not sure what I am going to do with the extras yet.

Wem
post #37 of 119
Haha I understand how projects creep up on you. Just working on my speakers, I've identified 3 other projects that I 'need' to do . (miter saw stand, dust collection system, and shop organization).

No rush, especially since I'm headed out of country for a few weeks. But I'll be looking to build a few of these when I get back!
post #38 of 119
Completed my first "lilmic" today, results attached. I am going to build a few more so I can compare them, but that won't happen today. Soldering to the Mic itself was quite the pain in the rear end, but the rest was easy. Kinda makes you feel like a fool when the mic that came with the audyssey reciever may be more accurate than the calibrated mic.

Wem

I attached the same graph but with the RS meter c-weighted and no cal file. Isnt it general excepted the RS meter needs a cal file to be accurate?
LL
LL
post #39 of 119
Mike, could a few parts be swapped out to be able to test much higher in decibels, up to say 160dB?
post #40 of 119
Quote:
Originally Posted by wembley2000 View Post

I got my 5 mics from digikey today, still waiting on some other parts to get them built. I am going to build 5 of these (if I dont screw anything up) so I can compare them to each other and my ecm. Not sure what I am going to do with the extras yet.

Wem

sell them?
post #41 of 119
Quote:
Originally Posted by wembley2000 View Post

Completed my first "lilmic" today, results attached. I am going to build a few more so I can compare them, but that won't happen today. Soldering to the Mic itself was quite the pain in the rear end, but the rest was easy. Kinda makes you feel like a fool when the mic that came with the audyssey reciever may be more accurate than the calibrated mic.

Wem

I attached the same graph but with the RS meter c-weighted and no cal file. Isnt it general excepted the RS meter needs a cal file to be accurate?


Interesting, since Lennon_86 had different results. His audyssey mic, RS mic with calibration, and his ecm8000 all gave very similar readings.

My audyssey mic also gave very similar readings to my RS mic with just C weighting, and the WM-61A capsule setup. I wonder how accurate your ECM8000 is since its a clear outlier of three different mics.

You should post these results in the RS meter accuracy thread.
post #42 of 119
How do you use your Audyssey mic with rew, on the mic in? I tried it and it didnt work. Maybe I needed to change the rew input, I might try again.

I completely forgot to do the spectral today when i got everything set up. That was the motivator to get it all set up again in the first place
post #43 of 119
yeah, it works in mic in.
post #44 of 119
Thread Starter 
Quote:
Originally Posted by kryptonitewhite View Post

Mike, could a few parts be swapped out to be able to test much higher in decibels, up to say 160dB?

Not exactly. Though I can add an attenuator to pad the output down, the capsule sets the maximum SPL limit, and that limit for a Linkwitz modded capsule is about 135 dB.
post #45 of 119
Lilmike, I am looking forward to your comparison results. How low is your mic calibrated? It would be nice if we could all agree on which mic is the most accurate, some people wont be happy to lose 10db off the low end of their graphs. I just want reasonable accuracy below 30, all the mics so far seem to be close above that.

Wem
post #46 of 119
Ok got the second "lilmic" completed. I reran the graphs again, here are the results.

Wem
LL
post #47 of 119
Quote:
Originally Posted by notnyt View Post

Interesting, since Lennon_86 had different results. His audyssey mic, RS mic with calibration, and his ecm8000 all gave very similar readings.

My audyssey mic also gave very similar readings to my RS mic with just C weighting, and the WM-61A capsule setup. I wonder how accurate your ECM8000 is since its a clear outlier of three different mics.

You should post these results in the RS meter accuracy thread.

Notnyt,

I know the ecm is the odd one out, but also it is the only one that has been calibrated by an outside source. I am looking forward to lilmikes comparison to his higher dollar mic. If i find out the ECM is wrong, no problems, I will use the one that is correct. I am using a soundcard cal file in rew for the mic in. The mic in port is not as flat (it still very good) as the line in, my line is is very flat, but the mic in calibrates just fine.

Wem
post #48 of 119
I'm interested to see as well. If they're not accurate I'll buy a mic that is *shrug*
post #49 of 119
Quote:
Originally Posted by fankietank View Post
If the ECM was calibrated by Cross Spectrum, shouldn't that be the reference point and not a DIY WM-61A? The Behringer coming from Cross Spectrum and it's specific correction should be accurate to 5Hz, no?

I mean, we're either saying the DIY mic is off by 15dB at 5Hz or the calibrated ECM from Cross Spectrum supposedly accurate to 5Hz is off by 15dB there.
Except someone else with an audyssey and a calibrated ecm8000 had them measure nearly identical. We need more data on this. Someone PM'd me that they wanted to send me a calibrated mic and the calibration info for testing, and then never did.

I'm going to build two more of these mics and probably give them away.
post #50 of 119
Wembly, where did you take your measurements? I guess this can affect calibration as well?

from ecm8000 box

post #51 of 119
lilmike has a calibrated mic as well so when he gets his graphs posted, that should provide some more info.

I wouldn't mind sending some of these out for calibration either.
post #52 of 119
I ran everything to mic in, without calibration, so they're all consistent.
post #53 of 119
I just modified another rwo of these capsules. It took about 30 seconds this time

Using the alligator clip not around the outside makes a big difference
post #54 of 119
lilmike, your diagram has an error. You should have the switch directly after the positive lead of the 9v battery, otherwise it completes a circuit and will drain the battery over time. I didn't notice this since I built mine off the linkwitz diagram. However, I was building another one and caught the mistake since I was using your diagram this time
post #55 of 119
So, I built another two mics, and one the capsules is WAY off from the first one.

I tried the second mic using a 10uF cap and a 2.2uF cap. The first mic uses a 4.7uF cap.



I then replaced the capsule in the second mic and it measures closer to the first, but a bit more sensitive.



I think it's time for me to order a calibrated mic to finish off these comparisons. What's the best mic with calibration to get for around $100 or under?
post #56 of 119
[quote=notnyt;20269278]Wembly, where did you take your measurements? I guess this can affect calibration as well?

from ecm8000 box

I do all my sweeps from the lp about 11' away.
post #57 of 119
I'm going with your ECM8000 being accurate, and these not. I'm about to purchase an EMM-6 from CSL and an m-audio box.
post #58 of 119
I am going to try something tonight, trying to run I through my head to see if it is possible maybe you guys can help. I want to try to make a cal file that includes my 502 mixer. If I run an rca from the line out to the mic in on the mixer via xlr to rca then out like normal I should get a cal file with the mixer inline correct? Maybe the mixer is messing something up.

Wem
post #59 of 119
I now have a CSL calibrated EMM-6 ordered along with an M-AUDIO preamp/phantom power box. Once I receive it, I will do a shootout between the Audyssey mic, RS meter, WM-61a linkwitz builds, and the EMM-6.
post #60 of 119
Thread Starter 
Good catch on the diagram. If I'd have drawn up what I actually made, there'd be no problem. I did not use a switch.

I have the diagram redone, the revised schematic is in post 1. Sorry for the oopsie.

Anyhow, I just moved the switch into the + lead, ahead of the resistors.

I have the EMM 6. It is only calibrated to 20 from the manufacturer. I've considered getting a nicer mic, but don't see the need right now. Since the tax man cometh, cash for toys is a little thin.

That difference in response between capsules is what happens when you get the Linkwitz mod wrong and damage the capsule seal. That's why it is a good idea to do several and compare them.
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