Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
easy to measure the low frequency response of omni microphone capsules. You only need a small woofer mounted in a small enclosure.
_______________________________________
Sidebar Question ---> How do we know variations in measured frequency response are caused by the variations in microphone frequency response or by variations in speaker reproduction response? Do speakers have uniform, linear frequency response throughout their working frequency range? (A serious question - not trolling for an argument.) James
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
On Thu, Feb 22, 2024 at 03:06 PM, Richard Lee wrote:
An omni electret's LF response is usually limited by
- the small hole which prevents it acting as a barometer
- the electronics.
The hole is easily seen on the side of a B&K capsule but should be easily identified in eg a PUI 5024.?
So - I just had a good look at one of my unused 5024 capsules.... I'm not seeing a small vent hole. Can anyone confirm this? Do they maybe vent through the front spacers? I did see some open thru-holes on the back of one of my Primo EM172 capsules.?
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Heaps of thanks Ken. I¡¯ll make those changes and yeah, verify with my younger son¡¯s gf who is a double major: computer engineering/physics. She has lots of electronics experience. But having all your input is fantastic since you will have far more specific insights.
I believe I am going to make one for myself (based on this diagram) and help my guy make one (utilizing the Alice board) in the format of the youtube tutorial. Let¡¯s see what can go wrong!
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On Feb 22, 2024, at 8:32 AM, kennjava < ken@...> wrote:
Hi David, ?You're pretty close with your circuit redraw. Notes:
- USB sockets supply 5v DC
- your output connections are unclear, and possibly incorrect. The output is after C1
- as Jerry mentions, R1 in mine was 5.6k (5600 ohms). And it's teeny - a 1/4w resistor that costs pennies (or less). Because you're now using 5v instead of 9v, the R1 value of 5.6k might still be OK with your mic... or it might need to be reduced a bit, to ensure enough voltage across your mic capsule. Something to try on the bench. Review the simpleP48 and other notes here to see how one measures the voltage at the mic.
- The small C1 (0.2uF) would somewhat reduce the bass. (Which was the point of my bass cut switch. I liked having the ability to roll off some bass in the field, when using small omni capsules). Anyway, since you don't want that rolloff, use a larger value for C1. Somewhere around 2.2 to 4.7 uF would be appropriate. Assuming an electrolytic cap, the positive end would connect to R1.
Parts - what part of Canada are you in? The larger cities usually have decent electronic parts stores where you can just pick stuff off the walls. A bit easier than Mouser or Digikey, though both those are great too. I hope we're not messing you up too much. Ask 10 people, you'll get 11 opinions. I'm assuming that your #1 criterium is a successfully working project with your son. If you wanted some really-fast success with your first attempt (and maybe tackle something more difficult later) consider the USB adaptor suggested by Jules. I believe that the USB adaptors that have 3.5mm mic in's already provide the voltage for 2-terminal electrets, which means that all you would have to do is wire the mic as a 2-terminal electret to the right 3.5mm plug... and it would immediately work (no battery box required). You could still do the fancy mount of the DIY-perks project.
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
A bit off-topic, perhaps, but since the subject is being discussed:
(I don't know anything about this; just something I came across in internet wanderings.)
-c
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
It would have been a list or two ago, and long gone from my archives.? But at one point somebody (I think Mark Strong from JLI) suggested putting a long piece of tubing behind an omni capsule instead of plugging up the pressure equalization hole.? That would allow lower frequencies without risking damaging the capsule with pressure imbalance.
-Scott
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On 2/22/24 17:06, Richard Lee wrote: An omni electret's LF response is usually limited by
* the small hole which prevents it acting as a barometer
* the electronics.
The hole is easily seen on the side of a B&K capsule but should be easily identified in eg a PUI 5024.? Just put a SMALL drop of cyanoacrylate to seat it off and the acoustic bits will go down to 0Hz
In SimpleP48.pdf, making C1 = 22u should get you at least -3dB @ 4Hz and probably better than that.
Most modern preamps using THAT 15xx etc will have LF limits set by the input capacitors to deal with LF current noise & hot plugging ... usually 22u too so with 3 of 22u in series, -3dB @ 12Hz
There's also the capsule capacitance and the FET input but in PUI 5024 etc and SimpleP48, that's way below the above factors.
=======================
None of the other suggestions have the inherent subsonic performance of an omni electret.
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
It's pretty easy to measure the low frequency response of omni microphone capsules. You only need a small woofer mounted in a small enclosure. There needs to be a sealed hole to connect to the capsule. For a typical electret capsule the whole thing can be placed inside the enclosure. The resonant frequency of the woofer should move above 100 Hz. The pressure inside the enclosure should be constant below the resonant frequency.You only need to have an oscillator that goes down and a meter that goes to the lowest frequencies of interest.
Le 22/02/2024 ¨¤ 19:12, Mark Day a ¨¦crit?:
> I did find the Behringer ECM8000. Very affordable an rated FR goes
> down to 15hz.
Do you really still believe the manufacturer's specs?
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
Hello everyone, small insert here - I like using low frequency tactile transducers, also known as bass shakers for the reproduction of infrasonics. Attached to a structure you sit or lay on, you ¡°feel¡± the bass. Regards, Jonas
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On 23 Feb 2024, at 00:06, Richard Lee <ricardo@...> wrote:
?An omni electret's LF response is usually limited by
- the small hole which prevents it acting as a barometer
- the electronics.
The hole is easily seen on the side of a B&K capsule but should be easily identified in eg a PUI 5024.? Just put a SMALL drop of cyanoacrylate to seat it off and the acoustic bits will go down to 0Hz In SimpleP48.pdf, making C1 = 22u should get you at least -3dB @ 4Hz and probably better than that. Most modern preamps using THAT 15xx etc will have LF limits set by the input capacitors to deal with LF current noise & hot plugging ... usually 22u too so with 3 of 22u in series, -3dB @ 12Hz? There's also the capsule capacitance and the FET input but in PUI 5024 etc and SimpleP48, that's way below the above factors. ======================= None of the other suggestions have the inherent subsonic performance of an omni electret.
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
An omni electret's LF response is usually limited by
- the small hole which prevents it acting as a barometer
- the electronics.
The hole is easily seen on the side of a B&K capsule but should be easily identified in eg a PUI 5024.? Just put a SMALL drop of cyanoacrylate to seat it off and the acoustic bits will go down to 0Hz In SimpleP48.pdf, making C1 = 22u should get you at least -3dB @ 4Hz and probably better than that. Most modern preamps using THAT 15xx etc will have LF limits set by the input capacitors to deal with LF current noise & hot plugging ... usually 22u too so with 3 of 22u in series, -3dB @ 12Hz? There's also the capsule capacitance and the FET input but in PUI 5024 etc and SimpleP48, that's way below the above factors. ======================= None of the other suggestions have the inherent subsonic performance of an omni electret.
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
Le 22/02/2024 ¨¤ 19:12, Mark Day a ¨¦crit?: I did find the Behringer ECM8000. Very affordable an rated FR goes down to 15hz. Do you really still believe the manufacturer's specs?
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
At this point in time, I doubt I have anything that will reproduce 15HZ or anything below 20 for that matter, but the wish to capture these frequencies is really for some future when I may have a super-duper system that rattles the walls, as well as for making the recordings to be released in some way for the benefit of others who may have systems that can reproduce it.
I'm going to order a couple of the Behringer ECM8000's and I may experiment with subkick-style speaker/microphones. I have 8 inputs on my Mixpre10 so in addition to the four required for the? Ambi-alice, I have a few channels to play around with.
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
I'm just a punter, but I am amazed by the amount of low bass that even a 10mm omni electret will capture. It's usually too much. To explore this, i would look into the following:
- using an oscillator and a pad, try to measure the low-frequency response of your mic preamp and recording setup. No point in a subsonic-capable mic if your recording chain won't capture it. Modifications might extend the low response.
- try omni mic capsules with larger diaphragms. Turn larger cardioid capsules into omnis by enclosing or blocking the rear. Try loudspeakers, even subwoofers in their cabinets
I am stilll striving for an impressive thunderstorm recording, but it seems in the last 2 years that every time I set up for a coming storm... it turns out to be a weak one.
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
Question on this one: What will you use to reproduce the infrasonic?stuff you capture? ;-)
Jules
On Thu, Feb 22, 2024 at 12:12?PM Mark Day < neowalla@...> wrote: Interesting article. An MKH-20 would be a good choice, but alas out of production and no more affordable than an Earthworks.
I did find the Behringer ECM8000. Very affordable an rated FR goes down to 15hz. At less than $50CAD, that is worth a shot at catching some thunderous rumble.
Of late I have been recording all my nature ambience in ambisonic using my Ambi-Alice (thanks, Jules), and a Zoom H3n, but I would like to throw in a channel of subsonic to give the subwoofer something to do while it's raining ;)
-- Best Regards,
Jules Ryckebusch
214 399 0931
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
Interesting article. An MKH-20 would be a good choice, but alas out of production and no more affordable than an Earthworks.
I did find the Behringer ECM8000. Very affordable an rated FR goes down to 15hz. At less than $50CAD, that is worth a shot at catching some thunderous rumble.
Of late I have been recording all my nature ambience in ambisonic using my Ambi-Alice (thanks, Jules), and a Zoom H3n, but I would like to throw in a channel of subsonic to give the subwoofer something to do while it's raining ;)
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Re: Top secret Earthworks M50 capsule, or the Thunder Capsule!
Infrasonics!? That was a rat-hole I arm-chaired down into a decade or so ago.? Record meteors, landslides, volcanoes, etc. I did hang out with the local student section of the AES who had a project to make an infrasonic detector.? A local farm equipment company donated a 300(?) Gallon water tank, and an engineer from Shure Bros. was advising them, and providing an omni capsule with a much more restrictive capillary than they normally sell.? If there's no capillary on an omni capsule (or if the case is not sufficiently leaky, then your capsule is a barometer.
My tangent away from that project was to look at building a differential capacitance "microphone" (or microbarometer) ... when going for low frequency response, the physical size of the components grows from the microscopic, so that a DIYer might actually be able to hand-build such a device.
Even earlier, said University across town was selling surplus lab gear, and somebody beat me to the Sennheiser MKH 110-1 they had.? See?
-- Mike (ex-DAT head)
On Thursday, February 22, 2024 at 10:47:18 AM CST, Mark Day <neowalla@...> wrote:
Hello everyone, I was thinking how cool it would be to record a thunderstorm with a pair of earthworks M50 measurement mics seeing as their frequency response goes way down into subsonic territory. Then I looked at the price tag. Yeah I won't be taking a pair of those things out into the rain any time soon.
Does anyone know what top secret Roswell technology Earthworks is using here? Do they manufacture their own capsules or is there an omni capsule out there that is equivalent?
I've also thought about the old speaker-wired-as-a-microphone, sub kick idea, but I don't have any way to measure the frequency response of a speaker/microphone. At least not in any practicable way.
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Top secret Earthworks M50 capsule, or the Thunder Capsule!
Hello everyone, I was thinking how cool it would be to record a thunderstorm with a pair of earthworks M50 measurement mics seeing as their frequency response goes way down into subsonic territory. Then I looked at the price tag. Yeah I won't be taking a pair of those things out into the rain any time soon.
Does anyone know what top secret Roswell technology Earthworks is using here? Do they manufacture their own capsules or is there an omni capsule out there that is equivalent?
I've also thought about the old speaker-wired-as-a-microphone, sub kick idea, but I don't have any way to measure the frequency response of a speaker/microphone. At least not in any practicable way.
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Hi David, ?You're pretty close with your circuit redraw. Notes:
- USB sockets supply 5v DC
- your output connections are unclear, and possibly incorrect. The output is after C1
- as Jerry mentions, R1 in mine was 5.6k (5600 ohms). And it's teeny - a 1/4w resistor that costs pennies (or less). Because you're now using 5v instead of 9v, the R1 value of 5.6k might still be OK with your mic... or it might need to be reduced a bit, to ensure enough voltage across your mic capsule. Something to try on the bench. Review the simpleP48 and other notes here to see how one measures the voltage at the mic.
- The small C1 (0.2uF) would somewhat reduce the bass. (Which was the point of my bass cut switch. I liked having the ability to roll off some bass in the field, when using small omni capsules). Anyway, since you don't want that rolloff, use a larger value for C1. Somewhere around 2.2 to 4.7 uF would be appropriate. Assuming an electrolytic cap, the positive end would connect to R1.
Parts - what part of Canada are you in? The larger cities usually have decent electronic parts stores where you can just pick stuff off the walls. A bit easier than Mouser or Digikey, though both those are great too. I hope we're not messing you up too much. Ask 10 people, you'll get 11 opinions. I'm assuming that your #1 criterium is a successfully working project with your son. If you wanted some really-fast success with your first attempt (and maybe tackle something more difficult later) consider the USB adaptor suggested by Jules. I believe that the USB adaptors that have 3.5mm mic in's already provide the voltage for 2-terminal electrets, which means that all you would have to do is wire the mic as a 2-terminal electret to the right 3.5mm plug... and it would immediately work (no battery box required). You could still do the fancy mount of the DIY-perks project.
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I have serious doubts about the use of a 5.6 ohms resistor rated
at 10W.
Also C1 at 0.2uF will kill most of treble.
Le 22/02/2024 ¨¤ 07:07, David Lau a
¨¦crit?:
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HI Kennjava:
Thanks for the lead towards your document archive
and the hopeful suggestions. I studied the pictures, diagram and
docs. It's an interesting design. And, yes, I think we could
utilize the 5 vdc power source from the USB rather than the
battery. I redrew it with your electret suggestion and
components that are currently online at Mouser. I didn¡¯t think
that the functionality for the low pass and hi pass (I¡¯m
presuming they are that) were needed. I¡¯m unsure if that delete
breaks the circuit? maybe?
Being new here, I'm not certain if image files are
uploaded with emails but I¡¯ll attach what I did. I would still
lean toward using the Alice board if that¡¯s feasible but if not,
perhaps I can get one of my electrical eng friends to critique
the circuit changes I made to your battery-box design.
D
On Feb 21, 2024, at 9:37 AM, kennjava < ken@...>
wrote:
On Tue, Feb 20, 2024 at 07:10 PM, David Lau
wrote:
Where would I find a reliable
diagram/instructions for [a battery box]?
I built a battery box like, um 22+ years ago, that served
me for almost 20 years, and parked the details in the files
section of this site.You'll find schematic, notes
and pictures there.
A few caveats on this design:
- I used tantalum capacitors for the larger
values; they worked and are small, but to do again I
would use electrolytic caps instead.
- It's kind of small and cramped, and it was
hard to fit everything in there. A bigger enclosure is
recommended.
- I selected 5.6k as the drain resistor to
the 9v battery. It worked with the little omni
electret capsules i've used. But you should probably
make bench tests with your chosen electret to ensure
that the voltage @ current at the capsule are within
the maker's specs.
It gave me great service, but about 2 years ago that box
started going intermittent, most likely due to the tiny
switches. At that time i made a new battery box, this time
with bigger switches, in a slightly bigger aluminum
project box. But I've misplaced my notes on the new box
[blush] so i can't recall what circuit changes I made.
If/when I find them, I will update the notes on file here.
You also have the option of grabbing 5v from the USB
connection.
Last suggestions: save yourself the hassle of working with
a bare electret capsule and a separate FET, and select a
capsule that has the FET impedance converter already
included - examples: JLI-2590A, TSB-140A, PUI
AUM-5241L-HD. For your application (desktop mic with basic
USB audio adaptor) you will get very good results with one
of these, without needing to jump through all the hoops of
separate FET/opamp.
There are simpler preamp circuits than the "DIY-Perks"
THAT opamp with its +/-15v requirements, that would run
from the same 9v battery, or even from (USB) 5v. I don't
have one to recommend, but others might.
Good luck!
?
?
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I have serious doubts about the use of a 5.6 ohms resistor rated at 10W.
Also C1 at 0.2uF will kill most of treble.
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HI Kennjava:
Thanks for the lead towards your document archive and the hopeful suggestions. I studied the pictures, diagram and docs. It's an interesting design. And, yes, I think we could utilize the 5 vdc power source from the USB rather than the battery. I redrew it with your electret suggestion and components that are currently online at Mouser. I didn¡¯t think that the functionality for the low pass and hi pass (I¡¯m presuming they are that) were needed. I¡¯m unsure if that delete breaks the circuit? maybe?
Being new here, I'm not certain if image files are uploaded with emails but I¡¯ll attach what I did. I would still lean toward using the Alice board if that¡¯s feasible but if not, perhaps I can get one of my electrical eng friends to critique the circuit changes I made to your battery-box design.
D
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Show quoted text
On Feb 21, 2024, at 9:37 AM, kennjava < ken@...> wrote:
On Tue, Feb 20, 2024 at 07:10 PM, David Lau wrote:
Where would I find a reliable diagram/instructions for [a battery box]?
I built a battery box like, um 22+ years ago, that served me for almost 20 years, and parked the details in the files section of this site.You'll find schematic, notes and pictures there. A few caveats on this design:
- I used tantalum capacitors for the larger values; they worked and are small, but to do again I would use electrolytic caps instead.
- It's kind of small and cramped, and it was hard to fit everything in there. A bigger enclosure is recommended.
- I selected 5.6k as the drain resistor to the 9v battery. It worked with the little omni electret capsules i've used. But you should probably make bench tests with your chosen electret to ensure that the voltage @ current at the capsule are within the maker's specs.
It gave me great service, but about 2 years ago that box started going intermittent, most likely due to the tiny switches. At that time i made a new battery box, this time with bigger switches, in a slightly bigger aluminum project box. But I've misplaced my notes on the new box [blush] so i can't recall what circuit changes I made. If/when I find them, I will update the notes on file here. You also have the option of grabbing 5v from the USB connection. Last suggestions: save yourself the hassle of working with a bare electret capsule and a separate FET, and select a capsule that has the FET impedance converter already included - examples: JLI-2590A, TSB-140A, PUI AUM-5241L-HD. For your application (desktop mic with basic USB audio adaptor) you will get very good results with one of these, without needing to jump through all the hoops of separate FET/opamp. There are simpler preamp circuits than the "DIY-Perks" THAT opamp with its +/-15v requirements, that would run from the same 9v battery, or even from (USB) 5v. I don't have one to recommend, but others might. Good luck!
?
?
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Re: Help choosing biasing resistor for simple p48 AUM-5241L-HD microphone
It's likely PUI use the same FET in all their different capsules so the resistors you used in your PUI 5024 (and those in simpleP45.pdf) are also appropriate for your PUI 5241s It's likely your problems with 5024 are not cos they are omni but that they are VERY sensitive.? Cardioids will pick up MUCH more wind noise and also handling, clothes rustling etc in a lavalier.? And the proximity effect is terrible for voice.?? This is the biggest sin in amatuer and many pro PA systems.? All you hear is, "woo .. Woo..WOO"If your lavalier is for voice, my recommendations are
- use the omni PUI 5024
- get the lavalier high up, as close to the mouth as possible.? Lapel mikes can get closer but are more affected by the speaker looking away.
- use a windshield; eg one of your mini deadcats :)
- severely roll-off the bass.? Start with C1 = 100n and expect to go even smaller.
More recent datasheets for these electrets usually show specs for Vds 3V or even 1V5. Cos main use is smart phones & other Low Voltage devices, they have to guarantee performance at low voltages.
They invariable give much better performance at 5V and there are significant improvements at even higher voltages up to about 10V when some early LN NEC FETs will die.
?
Older, traditional datasheets for same device, will show performance at 5V or 10V and have a 'Reduced Voltage' spec with the deterioration of Sensitivity at 1V5 usually 1.2 ¨C 3.5dB
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Mark Day