Transient Response

[sr1200]

I've been going down the rabbit hole lately with all the research I've been doing into various microphone designs and companies, parts, etc. etc.
One thing i keep seeing come up is something I can't quite get my head around, and its making me think its not a real thing, similar to how old timers used to use the term "mic reach", which is certainly NOT a real thing. I'll tie it into all the buzz words that the marketing department throws into their ads and brochures. And something I see on this forum all the time...

How a mic has a "FAST TRANSIENT".

I see it written, i hear it said, but never explained.

The words make me think "response time" as it employs the use of the word FAST (time). But that can't be it, since the speed of a transient is tied directly to the frequency itself. A transient can only be as "fast" as the frequency that is being picked up.
Then i started thinking, "maybe they're talking about amplitude and how loud the transient is..." but that can't be it either since the amplitude is a result of the frequency response of the mic in relation to the spl level hitting the diaphragm. But that is frequency dependent and can't be attributed to the mic or capsule overall.

The only thing that I've noticed in testing this stuff, is that some mics (and preamps for that matter) seem to have an issue AFTER the transient, or what I would consider a recovery time. Some seem to "ring" a bit more. I would maybe associate that with either the rigidity of the diaphragm or possibly things at the component level (transformer, transistor, tube etc.). Is this what is referenced? The total time from the transient back to full rest?

Perhaps someone here can point me to some hard data or tests that can be performed to be able to show/prove what a "fast transient" actually is.
Or is it just a BS term that people throw around like "mic reach" that mean nothing to sound more knowledgeable about the topic?
Please enlighten a dummy!

 

[ccaudle]

Or is it just a BS term that people throw around

It is an imprecise term which does not have a formal technical meaning.
You are probably on the right path thinking about ringing after a transient. That would be related to Q factor of resonances.
Various other things which could possibly be related, in no particular order:

• amplitude distortion on peaks
• various forms of distortion from signal frequency/amplitude combinations which stress the feedback gain available
• susceptibility to RFI on large peaks
• lack of any of the above in comparison to another device

like "mic reach" that mean nothing

I think that "reach" is generally understood to refer to off-axis rejection capability of a microphone, which changes the direct to ambient balance.
But there are quite a few terms like that which get thrown around a lot in conversation or in audio press which are difficult to translate to precise technical terms.

 

[john12ax7]

"Fast" does have general implications for electronics, usually having to do with rise time and settling time. I suspect it could be more about settling time with mics. One parallel is speakers, where a sealed box design is typically considered "fast". The sealed box typically has a cleaner waterfall plot, less ringing and decay ( faster settling time).

One complication is the perception of sound. An API pre is not really that fast, can even have insufficient slew rate leading to distortion. But this can actually sound great on the right source and perceived as "fast" and "punchy".

 

[john12ax7]

The diaphragm material properties almost certainly play a part as well, directly impacting the speed of stopping and starting motion. And then the circuitry. Transformers tend to be slower and less accurate than transformerless.

 

[sr1200]

But what does SLOWER mean... that word means that something doesnt move quickly. If a sound wave is 1k the diaphragm doesn't move slower than 1k. Theres no build up of time to get the diapragm to start moving at 1K CPS. Is there some inherent lag between a transformerless mic and a mic that has iron? I haven't seen that actually happen. If it does, is there some way to quantify or show that? I've placed all types of mics on the same source (snare drum) at the same distance at the same time and EVERY transient arrives at the same time. Again, I have seen the stopping part of it, but never anything on the start.

 

[Voyager10]

I'm very much with you on "slower" having no physical meaning, but it comes up over and over again. Two recent threads which haven't completely descended into chaos yet:

• https://groupdiy.com/threads/preamp...-rate-and-not-the-harmonics-what-is-it.87436/
• https://groupdiy.com/threads/what-is-responsible-for-soundstage-in-a-preamp-design.83950/

 

[john12ax7]

But what does SLOWER mean... that word means that something doesnt move quickly.

Yes, or rather less quickly than something else. Look at rise time, fall time, settling, time propagation time, reaction and recovery time. There could be frequency dependence involved. There could be hysteresis involved.

If a sound wave is 1k the diaphragm doesn't move slower than 1k.

A single 1k steady state sine wave is an insufficient test condition. Stress testing things with transients is much more useful and informative. Also consider that the ear can discern timing in the uS range, a good bit less than 20 kHz BW would suggest.

 

[sr1200]

the rise time would have to be exactly the time it takes for the frequency of the sound coming into it, if it were slower it would be a different pitch, and that goes for sine or other complex waveforms.

 

[sr1200]

I'm very much with you on "slower" having no physical meaning, but it comes up over and over again. Two recent threads which haven't completely descended into chaos yet:

• https://groupdiy.com/threads/preamp...-rate-and-not-the-harmonics-what-is-it.87436/
• https://groupdiy.com/threads/what-is-responsible-for-soundstage-in-a-preamp-design.83950/

I replied to the OP on the first link privately, as i just did a comparison of a bunch of mic pres on my YT channel... the differences are negligible and as soon as you reach for compression and eq, whatever the pre did is out the window anyway.
The second one is a rabbit hole, OMG. Gonna have to hit that when i have some "ME" time after a spicy meal!

 

[garp]

The transcient is by definition a short period of time (around 30/50ms ) where the sound is closer to a noise than having a precise frequency. Therefore it is ultra wide frequency range, by definition a sine is useless to determine the response of a circuit to transcients except maybe at super high frequencies.

 

[sr1200]

The transcient is by definition a short period of time (around 30/50ms ) where the sound is closer to a noise than having a precise frequency. Therefore it is ultra wide frequency range, by definition a sine is useless to determine the response of a circuit to transcients except maybe at super high frequencies.

My test was a snare drum, so...

 

[Gold]

I know that 'fast transient' can't actually exist for the reasons stated. Yet I know what is being discussed and heard when the term is used. Best I can tell it's a dynamic characteristic having to do with overshoot, overload recovery time, and with power amplifiers current limiting. Probably other stuff too.