Could you clarify what this is? I found the spark technique to match a lab calibration to ~1dB but it needs some care and slight correction. After reading about it on the Earthworks site the actual literature was not that easy to find. If the energy of the spark is too low the high end rolls off as a first order Bessel function too soon and there can be a null.
A couple of mic calibration articles:
https://earthworksaudio.com/wp-content/uploads/2012/07/how-earthworks-measures-mics.pdf
http://acoustique.ec-lyon.fr/publi/ollivier_cfa12.pdf
https://earthworksaudio.com/wp-content/uploads/2012/07/how-earthworks-measures-mics.pdf
http://acoustique.ec-lyon.fr/publi/ollivier_cfa12.pdf
Figure 2b in the second one is what I was talking about. You can get this response (first null >20kHz) with a BBQ grill starter from Home Depot. The literature was sparser 12yr. ago but someone found a thesis from MIT with the derivation of the N wave for me.
The black line is a B&K chart that came with a calibrated electret capsule that Nakamichi sold in the late 70's. The red line is what I measured.
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I meant, I've never used one. Trial by fire as it were.
Without seeing the bus structure, I didn't understand my options well. The aux sends for example, aren't labelled front panel to indicate pre fader/post. The 2222 documentation helps a lot, but nothing beats a block diagram for clarity of signal paths.
When The 2222 arrives, I'll play with it to get a good feel.
It was funny, the videographer couldn't believe I ran the entire room with a Lepai 20/20 watt digital amp, all of 4 inches by 2 inches to cover 100 plus people, SRO. Danger zone (top gun theme) played nice, still had plenty of headroom.
Jn
Ps. Also liked the 2222 as it has sub outs on independent faders as well as phones/control room outs. Given I do only volunteer work for a non profit, it was a reasonable mixer at the price. And owning it means no borrowing, no more learning curves on other equip, no learning that one line level mono in wasn't feeding both main busses (broken)
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I will defer to your experience..
Can I assume you butt dialed a taser??
Jn
No, I was waiting in line at the bank a few days ago and the guy in the line in front of me had a small automatic pistol in the back pocket of his blue jeans.
Paying a bit of attention to his transaction as a result, all he did was deposited a few checks.
Haven't really checked to see if carrying a firearm into a bank is a felony no-no.
Also not sure of the stopping power of a handgun that small.
So another issue arises, are there limits to where you can take a taser?
Probably a really good idea not to have one in your back pocket when using a parachute.
Pavel,
I suspect your loudspeakers cost more than $20.00!
I'm using one of these:
Amazon.com: Camco 57533 Olympian GM12 RV Multi Sparker: Automotive
With a weak battery so the sparks don't repeat too fast. With a stronger battery the null doesn't move up noticeably, but I suspect the risetime of the HV supply isn't enough to increase the spark energy. Maybe I should try and increase the capacitance?
Attached is the response of the spark recording.
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I don't know exactly why you guys are spending so much time with this, but the way that I approach it is to use a REAL calibration condenser mike from the start, that has been built by people who know what they are doing. Then, IF I should have to use a different mike, I might put the new mike next to the test mike and note the DIFFERENCE. It is easy, and fairly reliable.
For distortion, I would also compare the two mikes with a relatively CLEAN speaker, even a horn, and compare the two. I did this more than 45 years ago between my reference B&K 1" and a Neumann KM-84, using a K-horn. There was a difference, but it was fairly slight. Of course the speaker will always have some distortion, but you can pick your frequency range to minimize it. Not too low, not too high.
For distortion, I would also compare the two mikes with a relatively CLEAN speaker, even a horn, and compare the two. I did this more than 45 years ago between my reference B&K 1" and a Neumann KM-84, using a K-horn. There was a difference, but it was fairly slight. Of course the speaker will always have some distortion, but you can pick your frequency range to minimize it. Not too low, not too high.
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Markw4, you are not helping things. MY first measurement mike (the mike in the measurement) was made from a B&K 1" capsule that a friend got at a Lockheed auction, it was worth, at the time, $200, I got it for $25. Then I made my own follower, power supply, and had the mike tube made by a machinist. DIY enough for YOU? I had it independently tested by B&K when they came through and they found it one of the most accurate 1" mikes they had ever tested. (at least for frequency response) I know that the follower preamp composed of two RF fets, one as a constant current load, the other as a follower was very low distortion, and being class A was predictable at typical measurement levels as almost perfect. You guys should show some enterprise in doing your measurements properly, or just forgetting it. Yes, it can be done cost effectively.
The ACO pacific 7052PH is probably the least expensive ISO standard compliant measurement microphone available. About a grand new and half that used with a bit of luck.
Then there was the time one of of my guys dropped a measurement microphone and it landed a level below on the concrete floor capsule first. Good thing I had six of them. Then there was the fellow leaving who though he could get away with the one in his tool kit. Also lost a few in the flood following Hurricane Ivan.
These days for most field work we use the cheapie electret condenser microphones that have been checked against a better one.
Then there was the time one of of my guys dropped a measurement microphone and it landed a level below on the concrete floor capsule first. Good thing I had six of them. Then there was the fellow leaving who though he could get away with the one in his tool kit. Also lost a few in the flood following Hurricane Ivan.
These days for most field work we use the cheapie electret condenser microphones that have been checked against a better one.
Ed, I agree that IF you can find an acceptable inexpensive electret microphone that MEASURES well against a measurement microphone, even in a comparative review by someone else, then use it. Just don't buy a TOY, disguised as a measurement mike without comparing it with a known reference.
I tried the taser. Unfortunately the HV supply squeal is too low frequency and interferes with the measurement. Also I think the static pulse from the taser is causing a LF step in the recording. The taser spark might actually have lower energy than the sparker pulse, the null is at a lower frequency.
Thanks I see now, the grill starter (manual, one of those push button clickers) that I got had that first null at 25K or so which was fine for me. I had to make sure I windowed out the button.
BTW guys this is DIY with an attempt to be accessible to as many as possible, I know senior EE's that retired and bought $50K Aglient spectrum analyzers to tune up their ham rigs.
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I have 7 different B&K mikes 3HP mikes and some others but mostly use the $1 Primos or Panasonics because they work.
I'm really interested in ways to calibrate that don't depend on existing calibration references. I'm building an electrostatic calibration setup but the correction curves are really involved. Free air reciprocity is best left to NIST but spark discharge is accessable. The nearby structures probably affect the acoustics. I was thinking of a spark plug flush in a panel.
I'm really interested in ways to calibrate that don't depend on existing calibration references. I'm building an electrostatic calibration setup but the correction curves are really involved. Free air reciprocity is best left to NIST but spark discharge is accessable. The nearby structures probably affect the acoustics. I was thinking of a spark plug flush in a panel.
What are you making school sandwiches now? What’s with so much damn jelly?
Let people do their own thing.
OS, I really don't know what you expect, but I recently have been trying to give serious advice, instead of just negative comments. Now, I have a serious measurement microphone and some experience with it, but I don't want to make this measurement, as it takes time and trouble, and I did not volunteer for it, like several others. However, I have been thinking about making some rudimentary measurements just to get updated with my latest test equipment, so I might drag out the B&K Mike and test the LS3-5a vs the Met 7. It might be interesting because they are two good sounding small speakers, but designed with different parameters in mind.
Oh Demian, did you remember about the B&K mike preamps? I know what a hassle it can be to chose them, so why not find a couple at random, and let me worry about it? Do you need something? Some months ago, Al Lashers Electronics on University Ave in Berkeley had some sort of B&K mike calibrator that they wanted to sell me cheap! Might be worth looking into, as it is a rare item. Unfortunately, I just could not conceive of what I could do with it back then, so I turned it down.
Oh Demian, did you remember about the B&K mike preamps? I know what a hassle it can be to chose them, so why not find a couple at random, and let me worry about it? Do you need something? Some months ago, Al Lashers Electronics on University Ave in Berkeley had some sort of B&K mike calibrator that they wanted to sell me cheap! Might be worth looking into, as it is a rare item. Unfortunately, I just could not conceive of what I could do with it back then, so I turned it down.
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