Yes the unpacking is proceeding, the problem is that all my stuff got packed and put into storage in haste and is quite a mess.
Unfortunately we were subject to the "American Rule" where recovering your legal fees is a rare exception.
What is the microphone in question guys. I would use a B&K for a test like this. What is it that is being used?
I might add a little about mikes used for measurement of speakers (take that grammar man). Most audio professionals use or would at least prefer a B&K condenser measurement mike, and really that is what is normally used, but many amateurs cannot afford them. The B&K or equivalent measurement mikes have a distortion chart or spec that is normally many times lower in distortion than any loudspeaker below 100spl or so. Higher levels depend on the following electronics used (just after the mike), whether a mike attenuation switch is applied (not a good idea for accurate measurements as it usually adds 2'nd harmonic), and the microphone capsule diameter. A smaller diameter capsule will usually go much higher in level before significant distortion is generated, so a 1/2" mike might be better than a 1" mike at higher spl levels.
Most here will not have the 'best' measurement mike, but you can use much cheaper and more available mikes that have been manufactured and tested against the B&K measurement mikes by the equipment manufacturer, even if it has a cheap, (hopefully selected) capsule from Panasonic or some other source and the mike manufacturer attests to its lowish distortion.
An old mike that you found in your great-uncle's junk box after his passing might be OK or it might not. Better not to trust it too much, without a comparison with another 'better' mike, and remember that normal dynamic mikes (the usual stuff) have very tiny transformers to step up the voltage from the moving coil (mike) itself which is just a few turns of wire. LOW FREQUENCY testing will upset these tiny transformers, so beware!
Most here will not have the 'best' measurement mike, but you can use much cheaper and more available mikes that have been manufactured and tested against the B&K measurement mikes by the equipment manufacturer, even if it has a cheap, (hopefully selected) capsule from Panasonic or some other source and the mike manufacturer attests to its lowish distortion.
An old mike that you found in your great-uncle's junk box after his passing might be OK or it might not. Better not to trust it too much, without a comparison with another 'better' mike, and remember that normal dynamic mikes (the usual stuff) have very tiny transformers to step up the voltage from the moving coil (mike) itself which is just a few turns of wire. LOW FREQUENCY testing will upset these tiny transformers, so beware!
Simple addition gives no sum or difference frequencies that was the point of two speakers to test the mic itself.
Sorry, was getting mixed up with RF frequency mixing.
I thought they added them but apparently they multiply them to get the multiple frequencies plus sum and difference out.
My mistook.
My measurements of the B&K preamp were pretty dissapointing, something like.5% distortion. I switched to HP preamps because .005% THD.
Electrostatic actuator came up with exactly the distortion spec'd by B&K (1.3%? I'll check my source) which makes sense since is single sided. I'll try the two speaker IM test. Building a tuned source like B&K' new high output one would be very interesting.
Electrostatic actuator came up with exactly the distortion spec'd by B&K (1.3%? I'll check my source) which makes sense since is single sided. I'll try the two speaker IM test. Building a tuned source like B&K' new high output one would be very interesting.
More FAKE NEWS to the people...
Trump wrote 'mike' instead of 'mic' — but here's why he's right - Business Insider
As it turns out, "mike" predates "mic" by several decades: The first known use of "mike" to refer to a microphone was in 1924, according to Merriam-Webster, while it wasn't until 1961 that "mic" first appeared.
Ps take it with a grain of salt, in case it's f... 🙂
Trump wrote 'mike' instead of 'mic' — but here's why he's right - Business Insider
As it turns out, "mike" predates "mic" by several decades: The first known use of "mike" to refer to a microphone was in 1924, according to Merriam-Webster, while it wasn't until 1961 that "mic" first appeared.
Ps take it with a grain of salt, in case it's f... 🙂
Not surprising, the classic mic guys are pretty wedded to their simple one or two FET open-loop impedance converters. FET + op-amp circuits using feedback can be far better for THD and still meet the noise specs. Of course they will speak with a new "voice".
Good.
Thanks for everyone's kind thoughts, I hope to be back up and contributing some interesting measurements in this thread sooner rather than later.
What mike preamp did you use Demian? A 2619? If so, you have a problem. If a portable sound level meter preamp, I can understand.
Most premium measurement mics today are Gras or Acopacific. Bruel and Kjaer of course are still around and careful shopping will get you some good buys on used equipment. One tip is to buy their first generation sound level meters with a working capsule for much less than the normal cost of the capsule itself.
However never buy one that is damaged or sold without return privledges.
Now I have purchased and repaired power supplies. The older ones use two gas discharge regulator tubes. A trimmer resistor sets the output voltage at a level between the two different tubes' ratings.
The mic preamps are a bit rarer but occasionally show up at reasonable prices. The wierd adapters are also handy to have.
The older General Radio or even Western Electric units are now quite rare.
But of course the low cost option is to use a pair of loudspeakers, taking advantage of reciprocity calibration.
However never buy one that is damaged or sold without return privledges.
Now I have purchased and repaired power supplies. The older ones use two gas discharge regulator tubes. A trimmer resistor sets the output voltage at a level between the two different tubes' ratings.
The mic preamps are a bit rarer but occasionally show up at reasonable prices. The wierd adapters are also handy to have.
The older General Radio or even Western Electric units are now quite rare.
But of course the low cost option is to use a pair of loudspeakers, taking advantage of reciprocity calibration.
Ok so we will refer to a mic as a mike. Capacitor will be now known as condenser and ghz will now be known as kilo-mega cycles. Any other retro terms we should be using?
Using two loudspeakers to produce separate tones for one mic has nothing to do with reciprocity.
Yes it is, really. Silly isn't it. I'm just following the lead of PMA and JC. I guess they know more than the rest of the wider publishing world and google too.
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