Bamboo housing for nature recordings
Hi MicBuilders!
I'm new to this group. Many greetings and hello to everybody!
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I would like to give it a?try to build a special 'Sound Sleuth Bamboo' version. The aim is to achieve the most natural-sounding recording possible in combination with natural and sustainable materials. Like bamboo! :-) I'm wondering if anyone could give any advice regarding the optimal selection of electronic components. Is the article at??still the way to go? Or are there any improvements or changes I should know about before I start ordering parts?
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I really love to work with bamboo from time?to time but I'm not so?familiar with?electronic?circuit board? design. Sound Sleuth looks so simple. Is it really that simple? How is the recording quality? To give you an idea of what the?sleuth bamboo version may (or better not) look like, I would like to send you some pictures of a prototype bamboo mic holder that I built two years ago and that has served me well. The holder can be attached to a long bamboo pole if necessary,?to record closer to the tree top. The orange strap is a replacement strap for an 8mm film projector. which was not expensive and works just fine. The microphone is a Sony ECM-678 that I found in a junk corner of a reuse store with a 'No tone' sticker on it. It works well again.  
My image of the mic housing for nature recordings is a kind of bamboo blip(upright), which can be attached to bamboo poles to record more close to the roof top without disturbing the environment too much. Perhaps leaning against a tree and fastened. Available recording devices: Sony PCM-M10 or USB powered audio interface with phantom power.
If you are interested in listening to sounds I recorded, you can find some on the YT-channel I recently started at:??(created?for fun...no monetizing...no commercials...).?
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In case you have any questions, don't hesitate to drop me a note. Or if you need any information about bamboo.
As for the design of the bamboo housed microphone circuit board, it would be great if someone could point me in the right direction.
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Many thanks!
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Heinz (amateur photographer, field recordist, hobbyist, former SysEng...respecting the diversity of nature...)
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
Of course to go with the tetrahedral cardiod array, you could use the TSC-1 LDC from JLI since they are single diaphragm.
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
That is awesome! I look forward to seeing the new Instructable. I have a contact at Ningbo Electroacoustics in China and bought one of their last year. It is a clone of the old AKG C426B. That body might work, or something similar. Or as I mentioned earlier some of the many U47 bodies might be large enough. The challenge is not so much the body itself, but the PCB rails inside!
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
My challenge is the body to hold them as well. I¡¯m going to design a custom PCB for multi channel OPA circuits ?? Best Regards,
Jules Ryckebusch?
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On Jan 15, 2024, at 08:36, Mark Day <neowalla@...> wrote:
?On Mon, Jan 15, 2024 at 09:02 AM, jack wrote:
Nevaton VR mic
Wow, I have not seen this mic before. This is exactly what I want to build, and after seeing the price of the Nevaton, building my own makes sense. Just have to figure out if I can get it all to fit into one of the U47 bodies on Aliexpress.
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
On Mon, Jan 15, 2024 at 09:02 AM, jack wrote:
Nevaton VR mic
Wow, I have not seen this mic before. This is exactly what I want to build, and after seeing the price of the Nevaton, building my own makes sense. Just have to figure out if I can get it all to fit into one of the U47 bodies on Aliexpress.
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
You can do this with three dual diaphragm LDC¡¯s at this point you don¡¯t need a tetra array you do X, Y, and Z axis. Google ¡°native B format ambisonic array¡± ? You still have the fact that things aren¡¯t fully coincident. This project is actually on my ¡°to do list¡± although I have a few other things ahead of it.? Best Regards,
Jules Ryckebusch?
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On Jan 15, 2024, at 07:45, Mark Day <neowalla@...> wrote:
?Hello everyone,
I have been bouncing an idea around in my head and wanted to throw it out to the collective wisdom of the group and see where it goes.
I built Jules' ambisonic mic from his and it is a great mic. But I would like to design one that uses large diaphragm, externally polarized condenser capsules, and takes advantage of both front and back diaphragms.
I'm thinking of a combination of the "multitrack microphone" idea, like , but with enough capsules for 3D first order ambisonic.
I spoke a bit with Arienne about using her ?
Initially I was just thinking of 4 cardiod capsules in the tetrahedral array, but she suggested with dual diaphragm capsules, I wouldn't need four of them.
I have read through the Springer ambisonic document but can't figure out how to arrange dual diaphragm capsules to get the correct alignment for ambisonic pick up. Any ideas?
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Re: 1st order ambisonic mic utilizing both front and back LDC diaphragms
You can sort of make an ambisonic mic using dual diaphragm capsules in native B-Format arrangement of three orthogonal fig 8 capsules and one omni. The trouble is the capsules need to be perfectly coincident, which is impossible with four capsules. Horizontal B-Format is easier, with a blumlein pair of fig 8s and an omni but still not perfect.
For A- Format, single diaphragm cardioids would be fine. A bit like the Nevaton VR mic, but I think that uses edge terminated CK12 type capsules.
J
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1st order ambisonic mic utilizing both front and back LDC diaphragms
Hello everyone,
I have been bouncing an idea around in my head and wanted to throw it out to the collective wisdom of the group and see where it goes.
I built Jules' ambisonic mic from his and it is a great mic. But I would like to design one that uses large diaphragm, externally polarized condenser capsules, and takes advantage of both front and back diaphragms.
I'm thinking of a combination of the "multitrack microphone" idea, like , but with enough capsules for 3D first order ambisonic.
I spoke a bit with Arienne about using her ?
Initially I was just thinking of 4 cardiod capsules in the tetrahedral array, but she suggested with dual diaphragm capsules, I wouldn't need four of them.
I have read through the Springer ambisonic document but can't figure out how to arrange dual diaphragm capsules to get the correct alignment for ambisonic pick up. Any ideas?
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Re: Reducing the sensitivity of electret capsules with built-in fet
This is the challenge with built?in FET electrets. I have successfully?used the?TSB2555B with a 220pF capacitor across the capsule as a pad. THey make excellent drum mics. This works great for snares, toms and hi hats.?Overheads actually don't?need a pad. I am using my OPA circuit and the impedance buffer, which replaces the fet and associated circuitry. It is not as easy a solution as what you are looking for, but they sound great. See this for how it works:?
Jules
To be more specific, my goal is to have a microphone that is closer in sensitivity to "instrument" mics so I can use it at least as an overhead over drums. As it is now, it's pretty much unusable even with the PAD activated on the preamp. Simply the microphone output is too hot.
-- Best Regards,
Jules Ryckebusch
214 399 0931
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Re: Reducing the sensitivity of electret capsules with built-in fet
Since you already have a 3-wire capsule, the simplest solution is
to use the FET as a source-follower. It would decrease the overall
sensitivity and keep the max SPL. Even then you may have to use
the preamp's pad.
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To be more specific, my goal is to have a microphone that is
closer in sensitivity to "instrument" mics so I can use it at
least as an overhead over drums. As it is now, it's pretty much
unusable even with the PAD activated on the preamp. Simply the
microphone output is too hot.
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Re: Reducing the sensitivity of electret capsules with built-in fet
I think you came to the right conclusion. Any modification of the
circuit without changing the capsule's configuration (3-wire vs.
2-wire) would not change the max SPL significantly.
Le 11/01/2024 ¨¤ 01:09, Zander a ¨¦crit?:
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Thanks for the advice and sorry for not being clear about what I
want to do ¡ª I was hoping to increase the max SPL that I can
capture without overloading the mic, to make a quite sensitive mic
more versatile. However it it seems like that's a limitation of
the capsule and I should stop trying to make it be something it
isn't... or get a FET-less or 3-wire capsule with similar
properties that I can use one of the suggested approaches with.
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Re: Reducing the sensitivity of electret capsules with built-in fet
To be more specific, my goal is to have a microphone that is closer in sensitivity to "instrument" mics so I can use it at least as an overhead over drums. As it is now, it's pretty much unusable even with the PAD activated on the preamp. Simply the microphone output is too hot.
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Re: Reducing the sensitivity of electret capsules with built-in fet
If you want to increase the amount of acoustic?signal that your microphone can handle there are many circuit approaches that you can use. One of them involves bootstrapping. Use capacitors to bump the supply voltage up as the signal output swings positive and make?the source voltage go lower when the signal swings down.
On Wed, Jan 10, 2024 at 4:09?PM Zander < zanhulme@...> wrote: Thanks for the advice and sorry for not being clear about what I want to do ¡ª I was hoping to increase the max SPL that I can capture without overloading the mic, to make a quite sensitive mic more versatile. However it it seems like that's a limitation of the capsule and I should stop trying to make it be something it isn't... or get a FET-less or 3-wire capsule with similar properties that I can use one of the suggested approaches with.
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Re: Reducing the sensitivity of electret capsules with built-in fet
Thanks for the advice and sorry for not being clear about what I want to do ¡ª I was hoping to increase the max SPL that I can capture without overloading the mic, to make a quite sensitive mic more versatile. However it it seems like that's a limitation of the capsule and I should stop trying to make it be something it isn't... or get a FET-less or 3-wire capsule with similar properties that I can use one of the suggested approaches with.
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Re: Reducing the sensitivity of electret capsules with built-in fet
Here is my actual schematic:
/g/MicBuilders/message/32232
Why do you need to reduce the sensitivity?? You only need to do this if the mike itself is overloading.? Otherwise just turn the preamp gain down.
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Re: Reducing the sensitivity of electret capsules with built-in fet
Zander, can you tell us what circuit will use with the EM258?? What recorder?? What recording situation etc? The 'best' solution to your problem depend on these. IMHO, the options are
- convert to a charge amp as from page 10 of simpleP48.pdf? You need to get at the Gate & Drain of the internal FET
- Rene's solution as page 12.? You need to convert the 2 wire capsule to 3 wire
- Jerry Lee Marcel's mod as page 7? You need to convert to 3 wire
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Re: Reducing the sensitivity of electret capsules with built-in fet
As per James, I'm wondering about this too - whether the ones posing the question are trying to raise the max possible sound pressure level they can accommodate (ie their mic is being overloaded by desired sounds), or that they're simply finding the mic's output too hot compared to their other mics (eg overloading their preamps).
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Re: Reducing the sensitivity of electret capsules with built-in fet
Is "recreasing" the opposite of "inducing"?? :)
-Scott
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On 1/9/24 22:22, Jerry Lee Marcel wrote: "decreasing", not recreasing.
Le 10/01/2024 ¨¤ 05:14, Jerry Lee Marcel a ¨¦crit?:
Have you tried recreasing the resistor ?
1kohm should reduce level by 6dB, 620 ohms by 10dB, and so on.
Le 10/01/2024 ¨¤ 01:57, Zander a ¨¦crit?:
I've got this problem also, but with a two-wire Primo em258 capsule ¡ª since I believe drain and ground are already connected inside the capsule, is there another way to reduce the sensitivity, or is that an impossibility for such a capsule?
Here's the diagram from the em258 spec sheet:
--
---- 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: Reducing the sensitivity of electret capsules with built-in fet
is there another way to reduce the sensitivity, ...?
_______________________________________
While I believe this was mentioned previously, ... I generally use an L or T attenuation pad made from appropriate value resistors. I make a simple L pad circuit to attenuate hot computer type electret condenser capsules so they better match and seem like a dynamic cartridge to amateur radio transceivers - which tames hot condenser capsules so they do not overload and leave plenty of headroom for adjusting volume, EQ settings, etc.
Just my take ... James
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Re: Reducing the sensitivity of electret capsules with built-in fet
Le 10/01/2024 ¨¤ 10:04, Goran Finnberg
via groups.io a ¨¦crit?:
Jerry Lee Marcel:
>Have you tried decreasing the resistor ?
>1kohm should reduce level by 6dB, 620 ohms by 10dB, and
so on.
The drain resistor also sets the dc operating point of the
inbuilt JFET transistor.
There is only one optimum value of that resistor
that nets you reasonably symmetrical?
clipping at high spl levels from the jfet.
That would matter if the voltage source was a stiff one, but in most
cases it has some resistance, which tends to average teh bias point.
It is always possible, when teh optimal combination of voltage AND
resistance, to split teh resistance in two and bypass their junction
point with a capacitor of suitabe value.
In fact that resistor should be adjusted
individually for each capsule for symmetrical?
clipping at high spl?level and not be
changed at all for other reasons.
That's true, but the values indicated in teh datasheet seem to work
reasonably well without adjustment.
If that resistor is adjusted to decrease the gain
of the JFET then the?dc operating point is
wrong that the clipping point is severely affected to become
highly asymmetrical clipping?
on one side of the output signal only.
"Severely" is debatable.
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Mark Day
Zander