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Re: short pickup range options

 

The definitive close range mike is the .
?
This is a cardioid (IIRC) with a highly sloped response that is compensated by Proximity.? The exact proximity is set by the bar that is supposed to be placed on the user's top lip.
?
The highly sloped response kills the LF ambient noise and the very close distance set by the bar does most of the rest.
?
There's other juju too.? IIRC, there is a BBC Engineering Monograph which details the design of this iconic beast.? Please post if you find a link to this document.
Re: short pickup range options

 

Some time ago I had a conversation with someone who was making a video about sewing, and wanted to include the actual audio of the sound of needles passing through cloth!
They had been advised that using a low noise, high quality, highly directional shotgun mic? was the way to go.... They had been advised to look at the Sennheiser range!
?
I pointed out that the inverse square law (already described in this thread) made the proximity of the mic to the source the most important factor in determining how successful they were likely to be in getting a useful result - especially when recording such tiny signals.? ?
That of course doesn't automatically mean using an expensive mic!.... I suggested using a Primo EM172 -? located only a few cm. from the source? - might work, and made a short video clip to illustrate the point ...
?
If it is an option to locate a small mic slose to the source, then I would suggest that's likely to produce the best 'selective' audio recording results.
Even a highly directional, very low noise mic will? - at a longer distance - almost certainly produce inferior results.??
As Jerry has already commented - you can't 'twist the laws of physics' !
??
Re: short pickup range options

 

Due to the reverse square law, a useful signal will distinguish itself better from the background when going close to the source. That's the main thing. Radio people sometimes opt for dynamic mics. Due to the higher mass of the membrane and the resulting inertia, distant, weaker sounds, don't come through so well. It's a case of trial and error, and I wouldn't hope for a high-quality result. Coles lip microphone (ribbon) makes use of the proximity effect to reduce far-away noises, especially the lower frequencies.
Sensitivity is misleading here.

Op ma 13 jan 2025 om 19:21 schreef cx b via <clistburnham=[email protected]>:

certainly there are "less sensitive" microphones, though, right?
i suppose the most obvious example would be something like a piezo, where there would actually need to be direct contact with the element in order to produce a voltage.


On Sun, Jan 12, 2025 at 5:52?AM Jerry Lee Marcel via <jerryleemarcel=[email protected]> wrote:

Le 12/01/2025 ¨¤ 09:40, Johan Vandermaelen via a ¨¦crit?:
> ?In live radio, they sometimes opt for a dynamic mic and going very
> close to the sound source.
In this case, the nature of the transducer (dynamic, electret or
condenser) does not make a difference. It's only the distance that matters.

Putting the mic as close as possible to the source increases the level
of desired sound, when parasitic sounds are identical, so it increases
the Wanted-Signal-to-Unwanted-Signal ratio.


> You miss out some details and the frequency range is rather limited,
> but it's a way to lift ou your subject out of it's environment
Dynamic microphones have an undeserved reputation for being less
sensitive to ambiant sounds or feedback, when they only attenuate high
frequencies. Actually most condenser mics have a better directivity
control than dynamics.







--
Johan Vandermaelen

6 Moon Parrizal
sonic scenography
Hofveldweg 47, 9420 Aaigem
Belgium
+32(0)473 343 880
Re: short pickup range options

 

Yes but that¡¯s kind of different than having a physical distance limitation. I think most applications to accomplish what you may be trying to achieve use filters and gates.?

Like dynamic vocal mics on a stage use high pass filtering and sometimes a noise gate or another type of threshold to determine when to allow signal through, especially in loud reverberant spaces with loud heavy drums.?

On Mon, Jan 13, 2025 at 10:21?AM cx b via <clistburnham=[email protected]> wrote:
certainly there are "less sensitive" microphones, though, right?
i suppose the most obvious example would be something like a piezo, where there would actually need to be direct contact with the element in order to produce a voltage.


On Sun, Jan 12, 2025 at 5:52?AM Jerry Lee Marcel via <jerryleemarcel=[email protected]> wrote:

Le 12/01/2025 ¨¤ 09:40, Johan Vandermaelen via a ¨¦crit?:
> ?In live radio, they sometimes opt for a dynamic mic and going very
> close to the sound source.
In this case, the nature of the transducer (dynamic, electret or
condenser) does not make a difference. It's only the distance that matters.

Putting the mic as close as possible to the source increases the level
of desired sound, when parasitic sounds are identical, so it increases
the Wanted-Signal-to-Unwanted-Signal ratio.


> You miss out some details and the frequency range is rather limited,
> but it's a way to lift ou your subject out of it's environment
Dynamic microphones have an undeserved reputation for being less
sensitive to ambiant sounds or feedback, when they only attenuate high
frequencies. Actually most condenser mics have a better directivity
control than dynamics.
Re: short pickup range options

 

¿ªÔÆÌåÓý


Le 13/01/2025 ¨¤ 19:21, cx b via groups.io a ¨¦crit?:
certainly there are "less sensitive" microphones, though, right?
Yes, and so what? The sensitivity of a microphone can be altered by changing the preamp gain.
Whatever the sensitivity/gain combination, the ratio between distant and close sounds doesn't change.
i suppose the most obvious example would be something like a piezo, where there would actually need to be direct contact with the element in order to produce a voltage.
You'd be wrong. Piezo microphones were quite popular in the 50's and 60's. they didn't require contact between the capsule and the person who talked.


On Sun, Jan 12, 2025 at 5:52?AM Jerry Lee Marcel via <jerryleemarcel=[email protected]> wrote:

Le 12/01/2025 ¨¤ 09:40, Johan Vandermaelen via a ¨¦crit?:
> ?In live radio, they sometimes opt for a dynamic mic and going very
> close to the sound source.
In this case, the nature of the transducer (dynamic, electret or
condenser) does not make a difference. It's only the distance that matters.

Putting the mic as close as possible to the source increases the level
of desired sound, when parasitic sounds are identical, so it increases
the Wanted-Signal-to-Unwanted-Signal ratio.


> You miss out some details and the frequency range is rather limited,
> but it's a way to lift ou your subject out of it's environment
Dynamic microphones have an undeserved reputation for being less
sensitive to ambiant sounds or feedback, when they only attenuate high
frequencies. Actually most condenser mics have a better directivity
control than dynamics.
Re: short pickup range options

 

certainly there are "less sensitive" microphones, though, right?
i suppose the most obvious example would be something like a piezo, where there would actually need to be direct contact with the element in order to produce a voltage.


On Sun, Jan 12, 2025 at 5:52?AM Jerry Lee Marcel via <jerryleemarcel=[email protected]> wrote:

Le 12/01/2025 ¨¤ 09:40, Johan Vandermaelen via a ¨¦crit?:
> ?In live radio, they sometimes opt for a dynamic mic and going very
> close to the sound source.
In this case, the nature of the transducer (dynamic, electret or
condenser) does not make a difference. It's only the distance that matters.

Putting the mic as close as possible to the source increases the level
of desired sound, when parasitic sounds are identical, so it increases
the Wanted-Signal-to-Unwanted-Signal ratio.


> You miss out some details and the frequency range is rather limited,
> but it's a way to lift ou your subject out of it's environment
Dynamic microphones have an undeserved reputation for being less
sensitive to ambiant sounds or feedback, when they only attenuate high
frequencies. Actually most condenser mics have a better directivity
control than dynamics.
Re: Active noise cancelling for microphones in noisy environments - techniques?

 

Do you know the mic level you need for the Garmin GNC255? Turning your pot mostly towards to zero means, that you are using a low level close to the 70mV you specified?
?
Sorry, I meant I turned the pot mostly towards zero resistance.

I've not measured the output amplitude properly during typical use with the foam on, but I'd shot for about 300mV peak-to-peak at zero pot resistance on the oscilloscope to close proximity normal speech when it was in pieces on my bench. The Garmin GNC255 requires 70mV - 1000mV depending on what its mic input gain has been set to.
?
There's plenty of scope to increase the amplitude on my mic setup. The second op-amp stage is just a buffer so could easily be given gain via a feedback resistor.

For reference, the Bose A20 mic outputs 600mV at 114dB SPL.
?
?
Re: Active noise cancelling for microphones in noisy environments - techniques?

 

And there is an MEMS mic called ICS-40800 from TDK with a front and back hole.?
Regarding this Figure-8 mic, it has an undamped membrane, meaning the frequency response has a +6dB/decade slope. The datasheet is a bit misleading, showing a "Typical Omnidirectional Frequency Response", i.e. with the back port covered. With the back port uncovered, it has this slope, which can be seen in Figure 16 of
?
?
The application note proposes compensating with an electronic filter.
Re: Freshwater Soundscapes...

 

You can order PCBs from PCBWay - link in Jules' instructable - and order the components locally.
It's easy to build.
Be advised - the default quantity in the order form is 5 pieces. But 10 pieces cost the same money :)
Also pay attentionbto shipping method - there are less expensive ones (though slower) than the default.
?
You can also order populated PCB but it costs substantially more. You'd need to compare prices.
?
The difficult part is cylindrical piezo element. These are expensive and hard to get.
But it is the best option. Top tier :) You can also use more common piezo elements.
Re: Freshwater Soundscapes...

 

I'd love to build the Gladys Hydrophone. Any chance to get the parts or DIY kit in Europe?
Udo


Jules Ryckebusch via groups.io:

Heinz, these will work fine in a pond. They are designed almost identical
to a NOAA paper on them and, like Naval Hydrophones. I have not measured
<ryckebusch@...>:

Yes! these: they
work really well and I have gotten great sounds with them as have several
renown field recording people.
Re: Freshwater Soundscapes...

 

I recently discovered many small and very old ponds and would like to take a listen. Some are very small. I will try your suggestion.?
I would find it a bit of a schame to use Jule's well-built hydrophones in ponds, where even wild boars sometimes wallow. From my humble opinion they're better suited for naval environments..?

Am Mo., 13. Jan. 2025 um 03:41?Uhr schrieb Johan Vandermaelen via <johan.vandermaelen=[email protected]>:

It looks like a piezo disk microphone. It's easy to build one for a handful of dollars. To make them watertight I use nail varnish instead of the more common plastidip. Be aware you should use an impedance adapter for best results. E.g. Triton, but I have had good results with a BSS DI. Waterinsects in a pond. This os a cheap way to start your journey. But Jules piezo with his adapter will clearly outperform my suggested - cheap- solution.

Op zo 12 jan 2025 10:24 schreef Heinz via <heinz.hartfiel=[email protected]>:
Hi Johan
Many thanks for your advice.?
I have a modest question. I own a Shadow (12mm). It sounds quite nice. Even on a classical guitars. Would it be possible to turn this pickup into a (small) hydrophone. I'm just wondering.
?
Btw: I didn't forgot that you might be interested in a HM-200 (#36096). But sadly I didn't came across another one yet.
?
On Fri, Jan 10, 2025 at 08:20 PM, Johan Vandermaelen wrote:
I have built electret hydrophones in the past. They have serious limitations. Noise/sensitivity is one. Another is the huge change in pressure on the (protected) membrane when passing from air to water. It asks for care to release this pressure. Condens is one more concern. In general, except for experimentation I wouldn't advise to use electret for hydrophones.
Re: Active noise cancelling for microphones in noisy environments - techniques?

 

¿ªÔÆÌåÓý


Le 12/01/2025 ¨¤ 19:36, Jerry Lee Marcel via groups.io a ¨¦crit?:
EDIT:wo omnidirectional capsules oriented in whatever direction always result in omnidirectionality.
Two omnidirectional capsules may result in some directivity, but polarity and level must be adjusted.
What you suggest would be two cardioid mics placed back-to-back and wired out-of-phase.
Could be an interesting approach I guess. What do you think?
A figure-8 microphone has the same directivity index as a cardioid (4.8dB), so both placed in diffused field receive the same amount of non-desired signal.
A hypercardioid mic has a directivity index of 6dB, and rejection is optimal at about 110¡ã on both sides. Sounds from the back are attenuated only by 6dB.
It is theoretically the most effective at rejecting ambient noise. However, if the main noise source is at the rear it may be less efficient than a simple cardioid.





Re: Freshwater Soundscapes...

 

It looks like a piezo disk microphone. It's easy to build one for a handful of dollars. To make them watertight I use nail varnish instead of the more common plastidip. Be aware you should use an impedance adapter for best results. E.g. Triton, but I have had good results with a BSS DI. Waterinsects in a pond. This os a cheap way to start your journey. But Jules piezo with his adapter will clearly outperform my suggested - cheap- solution.

Op zo 12 jan 2025 10:24 schreef Heinz via <heinz.hartfiel=[email protected]>:

Hi Johan
Many thanks for your advice.?
I have a modest question. I own a Shadow (12mm). It sounds quite nice. Even on a classical guitars. Would it be possible to turn this pickup into a (small) hydrophone. I'm just wondering.
?
Btw: I didn't forgot that you might be interested in a HM-200 (#36096). But sadly I didn't came across another one yet.
?
On Fri, Jan 10, 2025 at 08:20 PM, Johan Vandermaelen wrote:
I have built electret hydrophones in the past. They have serious limitations. Noise/sensitivity is one. Another is the huge change in pressure on the (protected) membrane when passing from air to water. It asks for care to release this pressure. Condens is one more concern. In general, except for experimentation I wouldn't advise to use electret for hydrophones.
Re: Active noise cancelling for microphones in noisy environments - techniques?

 

Le 12/01/2025 ¨¤ 18:40, aauer1 via groups.io a ¨¦crit?:
And there is an MEMS mic called ICS-40800 from TDK with a front and back hole. Regarding the datasheet, it picks up the sound from the front and back side. But mostly ignores the sound from the side (90 degree).
It's a bi-directional microphone, a.k.a. Figure-8.
So, I think this is similar to using 2 omni-directional capsules oriented in the opposite? direction.
No, it's not. Two omnidirectional capsules oriented in whatever direction always result in omnidirectionality.
What you suggest would be two cardioid mics placed back-to-back and wired out-of-phase.
Could be an interesting approach I guess. What do you think?
A figure-8 microphone has the same directivity index as a cardioid (4.8dB), so both placed in diffused field receive the same amount of non-desired signal.
A hypercardioid mic has a directivity index of 6dB, and rejection is optimal at about 110¡ã on both sides. Sounds from the back are attenuated only by 6dB.
It is theoretically the most effective at rejecting ambient noise. However, if the main noise source is at the rear it may be less efficient than a simple cardioid.
Re: Active noise cancelling for microphones in noisy environments - techniques?

 

Hello all.
I found this group while searching for directional microphones. Especially for an headset similar to the one in the above post for the aircraft.
?
On Sat, Dec 21, 2024 at 11:17 PM, <michaeljtbrooks@...> wrote:
It works pretty well! Happens to be at the right mic level with the pot mostly towards zero.
Do you know the mic level you need for the Garmin GNC255? Would be interesting for me to know. Turning your pot mostly towards to zero means, that you are using a low level close to the 70mV you specified?
?
Has anybody ever thought about using an MEMS microphone for this application? Because I think the output impedance might be lower. And there is an MEMS mic called ICS-40800 from TDK with a front and back hole. Regarding the datasheet, it picks up the sound from the front and back side. But mostly ignores the sound from the side (90 degree).
So, I think this is similar to using 2 omni-directional capsules oriented in the opposite? direction. Could be an interesting approach I guess. What do you think?
?
BR
Andreas
Re: short pickup range options

 

Le 12/01/2025 ¨¤ 09:40, Johan Vandermaelen via groups.io a ¨¦crit?:
?In live radio, they sometimes opt for a dynamic mic and going very close to the sound source.
In this case, the nature of the transducer (dynamic, electret or condenser) does not make a difference. It's only the distance that matters.

Putting the mic as close as possible to the source increases the level of desired sound, when parasitic sounds are identical, so it increases the Wanted-Signal-to-Unwanted-Signal ratio.


You miss out some details and the frequency range is rather limited, but it's a way to lift ou your subject out of it's environment
Dynamic microphones have an undeserved reputation for being less sensitive to ambiant sounds or feedback, when they only attenuate high frequencies. Actually most condenser mics have a better directivity control than dynamics.
Re: Freshwater Soundscapes...

 

Hi Johan
Many thanks for your advice.?
I have a modest question. I own a Shadow (12mm). It sounds quite nice. Even on a classical guitars. Would it be possible to turn this pickup into a (small) hydrophone. I'm just wondering.
?
Btw: I didn't forgot that you might be interested in a HM-200 (#36096). But sadly I didn't came across another one yet.
?
On Fri, Jan 10, 2025 at 08:20 PM, Johan Vandermaelen wrote:

I have built electret hydrophones in the past. They have serious limitations. Noise/sensitivity is one. Another is the huge change in pressure on the (protected) membrane when passing from air to water. It asks for care to release this pressure. Condens is one more concern. In general, except for experimentation I wouldn't advise to use electret for hydrophones.
Re: short pickup range options

 

sorry, I see I misunderstood your question. As Jerry Lee Marcel says it's difficult. The microphone is not intelligent to make an interpretation of the distance. In live radio, they sometimes opt for a dynamic mic and going very close to the sound source. You miss out some details and the frequency range is rather limited, but it's a way to lift ou your subject out of it's environment
Re: short pickup range options

 

¿ªÔÆÌåÓý

"Short pick-up range" does not exist.
Sound propagates with attenuation that is related to distance. There is nothing like a distance where sounds magically disappear.
Directive microphones allow separating on-axis sound from non-axis, though. There are even microphone arrays that allow better rejection of non-axis sound, but nothing can twist the laws of physics and make sound disappear after a distance.

Le 12/01/2025 ¨¤ 09:08, cx b via groups.io a ¨¦crit?:

hi all -
i'm wondering if anyone has any suggestions for electrets (or possibly other forms) with an extremely short pickup range. i'm looking to do some experiments and i want to minimize all non-essential sounds.

thanks!
Re: short pickup range options

 

Hello,
?
Your message sounds a bit like a contradiction to me. The best lows you will get from an omnidirectional capsule are often way lower than what we hear. On the upper range, most go into ultrasonics. This topic is a recent treat.
If you want a more directional response you will have to sacrifice the lows. Pressure gradient microphones have a roll-off in their lows. Can you be more precise in your question?
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