New analyzer...

Well I got some gear ripped off, including my Phonic PAA2.  It wasn't bad, but it wasn't great.  I want something different.
Steve suggested once the NTI AL1.  I like this and might pick it up with a behringer ecm8000.  But for a little cheaper on ebay (a buy now option) I can get the Avlex 4U2SET.  It looks really great but I've heard nothing about it.
Thoughts?

I can't figure out if the ecm8000 is class 1 or class 2.

I can't figure out if the ecm8000 is class 1 or class 2.

It's not classified, and neither would it be. The cheapest class 2 mic I can find costs $241 just for the capsule (you need the rest of the electronics to go with it), and it doesn't meet the spec with very much margin at all. An ecm8000 costs about $50, and despite all of the advertising claims for it, it  would need to be improved on quite a bit to meet the class 2 standard. It's not got a flat enough response for serious measurements as it stands. One of its problems as a measurement mic is that its output varies according to the amount of phantom power you send it... not good. Even the class 2 spec is quite demanding.

My class 1 measurement mic cost about $1000, and you can pay more than that for them without too much difficulty. And to make sensible measurements with either class of mic you need a calibrator, and that will cost as much again, nearly. Another of the ecm8000's problems is that the end diameter is non-standard, and won't fit into a standard calibrator fixing...

You can use any mic you like for 'measurements', but that does not make it a measurement mic, I'm afraid - the spec for those is rather demanding.

Your Avlex 4U2SET meter I know nothing about, and I didn't see a price for it either. How much are they selling it for?

List is around $1200 I believe. I can get it for $700.  Here'a a website:
http://www.4u2smart.com/home.html

It comes with two ECM999 microphones. If nothing else I figure it ought to be better than my phonic.

It comes with two ECM999 microphones. If nothing else I figure it ought to be better than my phonic.

AFAIK, ECM999's are the Superlux/Tenlux branded version of the ecm8000 - which isn't made by Behringer anyway, of course, but by Tenlux for them.

It's this one, not the Sony stereo mic with the same number!

Well for now I think I'll go with the NL1 and miniSPL and get the AL! crossgrade at a later time.  I want to make sure I at least have a class 2 unit.
Any additional thoughts?

[M]

Well for now I think I'll go with the NL1 and miniSPL and get the AL! crossgrade at a later time.  I want to make sure I at least have a class 2 unit.
Any additional thoughts?

The basic box has a class 1 spec - It's only the MiniSPL that gives it a class 2 spec anyway. But in order to count even as a class 2 reading, you still need to have a mic calibrator and use it before making an SPL measurement that has to stand up to any scrutiny. It's also the only way to be absolutely sure about the absolute value of SPL you are measuring - just relying on the inherent calibration value for the mic isn't good enough at all.

And I presume that you meant ML1... the good thing about the crossgrade is that you can, in conjunction with a PC, utilise the instrument in either mode - as an ML1 or and AL1, (but not both at the same time). I have other instruments that do the ML1 functions that the AL1 doesn't do, so for me it's not a problem, but if you don't have them, it's a good idea.

But in order to count even as a class 2 reading, you still need to have a mic calibrator and use it before making an SPL measurement that has to stand up to any scrutiny.

That's understandable, but what does a calibrator cost? Also, since calibration obviously won't physically change the microphone how do I tell the ML1 that "this is the frequency response of the microphone, adjust your readings"? I guess I just don't know anything about callibration...

BTW I received a calibration certificate with the microphone (which shipped directly from NTI, so no grubby hands were all over it). Of course It's already fallen from an 8' stand...

It looks like this:
http://www.nt-instruments.com/uploads/MiniSPL-Certificate.pdf

This doesn't seem very flat to me... Maybe you can explain?

I guess I just don't know anything about callibration...

My experience is that you stick your microphone into the calibrator, turn tthe calibrator on and look at the display. It should show the same number which is printed on or supplied with the calibrator. 93.8 dB in my case. If it does not - you turn a little screw somewhere on the analyzer/SPL meter until it does.

I think that if you need your measurement to be legally valid you should always calibrate your instrument before and after the measurement.

For  normal use, the calibration interval is specified by the manufacturer - one year in your case.

On the other hand, I recently checked an SPL meter which probably has been not calibrated for 5 or 10 years and it was fine. But it was a B&K meter.

I understand that much, but what about frequency response? It seems to me that NTI would have to take both my minispl and ML1 and match them.

You have to bear in mind the range over which a calibrated mic is supposed to work as far as building acoustics and noise is concerned - virtually all of the measurements that you are seriously interested in are based on 1/3 octave bands up to 8kHz. And if you really need to know answers to within a dB or so, you have to look at the mic's cal cert and make allowances in your measurements.

But most of the time, things aren't anywhere near that critical. For instance, if you make IEC-approved reverb time measurements, which are averaged over loads of readings, you'll find that measurement errors rather greater than those of your mic can slip in almost without you realising it - unless you are very careful. But when it comes to calculating the end result, which is an Rt figure (time), it hardly makes any difference at all. And if you are measuring a live venue, the absorption of people can vary the room response where you are measuring rather more than the mic error just when they stand up!

For normal use, the calibration interval is specified by the manufacturer

Actually, it's specified in the international standards when legally binding measurements (the sort of stuff you have to do for public enquiries) are being presented - and a year is the maximum amount of time that you are allowed to leave between calibrator calibrations... it's generally accepted that barring damage, the particular response of a mic won't vary that much over 5 years or so, but since the calibrator is not only calibrating the mic, but the whole measurement system as far as level is concerned, it's rather more important to have this checked and recertificated regularly - especially if you use extension leads, etc with the mic.

Most modern measurement instruments have an automatic calibration routine - the NTI ones certainly do - so you don't have to fiddle with presets inside the meter any more. Those early B&K meters were something of a nightmare to calibrate sometimes...

the particular response of a mic won't vary that much over 5 years or so

Good mics seem to be pretty stable, I like B&K's statement of EXPECTED LONG-TERM STABILITY: >1000 years/dB at 20°C

 

Good mics seem to be pretty stable, I like B&K's statement of EXPECTED LONG-TERM STABILITY: >1000 years/dB at 20°C

 

Yes, they say that about the externally polarised ones, certainly, but I think that they are a little more circumspect about the electret ones. It's a reasonable claim to make about a stable construction that's essentially non biodegradable where you have to produce the electrical charge that ultimately determines the output, but where you are relying on the long-term stability of a built-in electret, I think that the output degradation per year is rather less certain.

And so, the fact that B&K know how little the performance of their mics vary, but still insist that you use a mic calibrator just goes to show how much they ultimately trust the rest of the system, doesn't it?

Incidentally, decent calibrators (I have a Casella, which can be compensated for temperature and pressure) cost around £250-300 in the UK.

Thanks for all of your help, but now I'm rather skeptical about my purchase...
I'm having problems with my ML1 and the people at NTI America seem to think it's normal behavior...  Perhaps someone with one of these units can verify, or even better, tell me if it's gone with the AL1.
Firstly, if I input pink noise into the line input (two different sources of noise, btw) it looks like white noise on the analyzer: Equal level across the spectrum.  A representative tells me he gets the same result from various models there. He says: "The definition that I have for pink noise is equal energy across the spectrum, whereas white noise is more random, which is why I (he) notice a slight slope DOWNWARD in the lower frequncies with white noise."
Perhaps I'm wrong, but I thought that pink noise was equal energy per OCTAVE.  Maybe I'd get a flat reading on a 1/1 scale, but certainly not a 1/3 scale. Correct?
Also, I'm getting two seperate response times on the analyzer! There's a cutoff point somewhere in the low/mid range (I haven't checked the frequency, but it is one point) where the upper frequencies have a fairly (realistically) quick response time and the lower frequencies are about 200ms laging.  This gives me very confusing readings...  He again noticed the same things with his units and so came to the conclusion that this is somehow "normal behavior".  I don't think so...

On top of this, since he doesn't believe I have a defective unit, they expect me to pay for send and recieve shipping and wants to take at least two days looking at the unit.  I guess that's over two weeks that I don't have the unit, just so that they can return it back to me...