In the earlier temporal distortion thread (about a week ago), the issue of microphone rise time was raised in one of John Curl's responses on that thread. It started me thinking about that the issue of microphone rise time (and of course its overall fidelity) as an important point which I would like to discuss seperately. To me there is no doubt that this factor (microphone rise time and microphone fidelity) could easily be one of the most significant factors in robbing us of the life of the music and leave us with the sense that dynamics are compressed, transients have been blurred by 'slow' (even though State of the Art) microphones. Even a 10 us microphone rise-time will significantly effect the shape of a 20kHz ((50 us period) or even 10kHz (100 us period)tone, let alone faithfully reproduce a complicated multitone signal or music.

There are many points in the recording/reproduction chain that effect the overall result, but allow me to suggest that the sound energy-electrical energy transducers (the loudspeaker and the microphone)have the greatest effect. This leads me to number of questions:

1. What are your thoughts on this?

2. Is anyone aware of an information source which collates microphone rise-time test data?

3. How is microphone rise time determined?
All I can think of is that the microphone signal would be feed to an oscilloscope and a time difference determined, but what would be used as a test (sound) signal? This is interesting, because I believe it would require using a sound signal of either known rise time(what?) or extremely fast rise time (like a spark discharge, explosion or hammer strike), which would need to be orders of magnitude faster in rise-time than the microphone rise time for accuracy. If a spark discharge is used and ZERO rise time is assumed for this sound signal(i.e: maximum SPL achieved in zero time(????-yeah-right) then one could simply read the rise-time of the associated electrical pulse on the oscilloscope.Does anyone know the method used by test labs?

Thanks in advance for an interesting discussion.

HAVE FUN,

JOEY.

 Re: Microphone Rise Time- Is this the key? - Maiello 08:43:47 12/02/02 (5)
 Re: Microphone Rise Time- Is this the key? - JOEY. 12:53:53 12/02/02 (4)
 Re: Microphone Rise Time- Is this the key? - john curl 14:37:00 12/02/02 (3)

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 Re: Microphone Rise Time- Is this the key? - Maiello 08:43:47 12/02/02 (5)
 Re: Microphone Rise Time- Is this the key? - JOEY. 12:53:53 12/02/02 (4)
 Re: Microphone Rise Time- Is this the key? - john curl 14:37:00 12/02/02 (3)
 Re: Microphone Rise Time- Is this the key? - JOEY. 01:00:53 12/03/02 (2)
 Re: Microphone Rise Time- Is this the key? - john curl 11:28:13 12/03/02 (1)
 Re: Microphone Rise Time- Is this the key? - JOEY. 01:03:29 12/04/02 (0)
 Re: Microphone Rise Time- Is this the key? - john curl 17:13:25 11/30/02 (1)
 Re: Microphone Rise Time- Is this the key? - JOEY. 20:58:59 11/30/02 (0)

My own fax is down, but you could fax it to +61 3 9523 1046 for collection, or email it (if convenient). Thanks for the offer.

HAVE FUN,

JOEY.

I use a pair of large-diaphragm condensers (ADK). Given the greater mass of their diaphragms, they probably have slower rise-times by comparison... BUT the results are musically and soncially superior to many mics with better specs. (I'll refrain from naming names.)

There's something else at work here, and I think it has a great deal to do with a mic's harmonic "rightness," something that's difficult to put our collective fingers on. A mic with great tone allows the music, as well as the sound, to survive the recording process.

And complex multi-mic'ing/multi-tracking? After making a fair number of two-mic recorings, I'm pretty sure it's a devil's bargain!

-Frank

It is possible that rise-time isn't the most important paramaeter, but just like a poor frequency response, slow rise-time will effect fidelity in a negative way. Too slow a rise-time will blurr the leading edge of notes and limit the height of the musical peak, this could be demonstrated on an oscilloscope, particularly with rise-times in the tens of microseconds. That some fast rise-time microphones may by amusical, may also be due to a poor frequency response, or poor dynamic range- these would need to be compared sonically and electrically to really pin-point the offending parameter.

I agree with you 100% on the issue of multi-miking vs good twin mike technique. Not only does multi-miking confuse the sound field, but it paints a completely different dynamic picture of the music, particularly when close miking is used. The piano, guitar, drums, whatever, etc.... are never that loud compared to the rest of the ensemble in real life. Lets not even get into multi-track, recording booths, etc... YUKKKKKKK.

HAVE FUN,

JOEY.

With 10 us as typical of the fastest practical rise-time for microphones, let alone loudspeakers, it is now clear to me that this factor (along with frequency response and dynamic range) must surely be one of the greatest impediments to recreation of the live event. Imagine even a 10 kHz tone (100us period) having its 'leading edge'(1st 1/4 cycle of 25 us duration) delayed by 10 us AT BEST. No wonder a trumpet never sounds real. Horror of horrors, imagine what happens with really slow microphones. Thanks again for the offer of the microphone info- there is no hurry.

HAVE FUN,

JOEY.

I think I got the wrong end of the stick. Now I take your point, earlier on I understood you be referring to a type of delay and hence my concern about blurred leading edges since 10 us represents a significant time period compared to the period of a 10 or 20 kHz tone, BUT NOW...I understand (hopefully) what we are really talking about is the fastest possible SIGNAL rise time that can be tracked by the microphone (quite a difference!). If that is the case then I am happy and would withdraw my contention that rise-time is a VERY significant issue, especially where the rise-time allows a 20kHz+ signal to be tracked accurately. (unless of course someone can prove that we can hear OR perceive frequencies greater than 20kHz).

HAVE FUN,

JOEY.