Thanks for clarifying.
I was sure that I had misunderstood you, as with my initial assumption the time frame was in the sub nano second range, an area that your pragmatism would prohibit you from entering.
If you find the time, please post a link to your published results. 🙂
George
Ed - I had the same comments about some of the wire distortion tests, namely the needlessly large background noise that had to be ignored. We do offer these criticisms in the spirt of helping and getting to the bottom of things.
It's buried in some online archive. Here's the pictures 🙂. The spark gap was at the end of a 1 meter dowel and the push button piezo-zapper was another 1.5 or 2 meters behind that. Everything was dangled out in the room so there were no reflections for about 5msec. Pulse, raw spectrum, corrected response. It turned out the pulse is mostly a doublet up to about 10kHz. Above 10KHz there is a correction which takes about 20 pages of horrible maths to derive and of course involves Bessel functions. Luckily the 10-20kHz region is easily approximated because it falls below the first null of J0 (or something like that) 🙂
EDIT - The red line is my measurement offset by 10dB. My original reference had a less sophisticated derivation of the high frequency effects but was still accurate to 20K or so, you can sort of see the first Bessel null just before 30kHz
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http://wavebourn.com/images/audio/Proins/spark.pdf
Good. You have used the noise generated by the spark to produce a wide band acoustic signal with consistent and repeatable signature for to measure the frequency response of the Nakamichi CP3 microphone.
You verified the results (red curve) against the manufacturer’s data (black curve)
In your “to do list” is to repeat the same procedure but with one (or more) capacitor(s) in place of the CP3.
Yes? 🙂
George
I think you will find that French audio high-end people still understand and use N-rays. The rest of us have to manage without them, as they are not taught in English-speaking universities. Not Invented Here syndrome, I assume. We make an exception for Fourier, of course, although some audiophiles seem to (think they can) manage without him.bcarso said:
Yes, and I think this and my DIY piston chamber might make a good short article.
The problem is level. In the port of a reflex enclosure, I would expect one heck of a high spl, so the counter argument would be it's not sufficient compression.
Ed should just overwrap braid on the cap to get the far connection to the coax braid.
Then test with both zero voltage and 25 volts on the cap. If there is a measured signal and it is independent of capacitor voltage, then it is induced by the magnetic field, either by the changing magnetic field loop trapped, or by physical modulation of the loop within the static magnetic field of the speaker (or the half gauss field of the earth).
So simple, yet so hard.
jn
The table probably has huge magnetics, all your wires are moving violently in any fields present, etc. How about the tap test?
Sy,
I would imagine that is more tongue in cheek here, I would think a tap test would be much tougher actually than any audio type test could ever attain vs a direct impact of a device?
I would imagine that is more tongue in cheek here, I would think a tap test would be much tougher actually than any audio type test could ever attain vs a direct impact of a device?
This is the sort of thing my colleagues and I discuss in private. It's far beyond the level of what can be talked about here and is based on classified military developments that I did when I worked as a consultant to Einstein. Just the other day, Scott called me from his Rolls-Royce to discuss these issues. We did this 30 years ago. Works for me! ;-)
(If one of these has escaped your attention…) 🙂
http://www.bksv.com/doc/bv0054.pdf
http://www.bksv.com/doc/bv0051.pdf
http://www.bksv.com/doc/bv0048.pdf
http://www.bksv.com/doc/TechnicalReview1985-4.pdf
http://www.bksv.com/doc/bv0015.pdf
http://www.bksv.com/doc/TechnicalReview1977-4.pdf
http://www.bksv.com/doc/TechnicalReview1964-4.pdf
http://www.bksv.com/doc/TechnicalReview1965-1.pdf
http://www.bksv.com/doc/be1447.pdf
George
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