An approach to "acoustic" drone, maybe

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thelowerrhythm
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An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Wed Jul 14, 2021 1:43 am

Had this idea and wanted to get some other perspectives on it. I am considering building a very small 5U (zissou 54hp) rack with a bunch of contact mic and electret 1u tiles, two Patching Panda Vibrazums for filtering, two Expert Sleepers Mikeys, and probably four or so three channel mixers. The idea is to pair this with four mono USB powered speakers driven by the mixer outputs. I feel like this relatively simple, if not too damn expensive setup could yield a lot of fun results regarding the transformation of the sonics of a 3D space. Lots of opportunities for feedback networks, redirecting environmental sounds, etc. Perhaps a kind of sonic installation for field recording, or just something to experiment with in terms of whoever is there to experience the space.

Just to head off all of the "don't use euro" comments, of which I'd be a purveyor, I just have a lot of this stuff already, and have recently fallen in love with the sturdiness of the zissou. I feel like I could drop one of these things down some stairs and only mildly panic.

And maybe this isn't even explicitly drone, but that's how I'm approaching it.
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Re: An approach to "acoustic" drone, maybe

Post by EATyourGUITAR » Wed Jul 14, 2021 10:17 am

Piezo disk mics are horrible in feedback setups because they have a very big boost at the resonant frequency of the transducer. This is related to brass disk diameter. PVDF contact mics are flat. Look at the datasheet for any disk transducer. They are all the same. Look at condenser mics with oval diaphragm. This is a countermeasure to mitigate resonant frequency of the transducer. What I do is low pass the piezo bellow the resonant frequency on the datasheet. The high pass slope of the transducer and the low pass slope of the filter cancel out. The resonant frequency is above the cutoff frequency of the low pass so that is attenuated -6dB or more.
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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Wed Jul 14, 2021 3:54 pm

EATyourGUITAR wrote:
Wed Jul 14, 2021 10:17 am
Piezo disk mics are horrible in feedback setups because they have a very big boost at the resonant frequency of the transducer. This is related to brass disk diameter. PVDF contact mics are flat. Look at the datasheet for any disk transducer. They are all the same. Look at condenser mics with oval diaphragm. This is a countermeasure to mitigate resonant frequency of the transducer. What I do is low pass the piezo bellow the resonant frequency on the datasheet. The high pass slope of the transducer and the low pass slope of the filter cancel out. The resonant frequency is above the cutoff frequency of the low pass so that is attenuated -6dB or more.
Thank you for that information, that's really helpful. I had a feeling they'd be shit for feedback, but with those pulplogic tiles it's such an easy thing to include. I'll give thet method a try before deciding whether that aspect of the case can just be put on the backburner altogether. Ordered a few pairs of these cheap speakers from adafruit so I can try some four or six speaker setups out before continuing.
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Re: An approach to "acoustic" drone, maybe

Post by EATyourGUITAR » Wed Jul 14, 2021 4:07 pm

If you do use them. They become oscillators at the resonant frequency of the disk. Not saying it won't work. Just that you get the same frequency of oscillation every time and gets very boring and limited. You can also notch filter them with a module. That makes them jump between two oscillation frequencies.
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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Wed Jul 14, 2021 4:30 pm

EATyourGUITAR wrote:
Wed Jul 14, 2021 4:07 pm
If you do use them. They become oscillators at the resonant frequency of the disk. Not saying it won't work. Just that you get the same frequency of oscillation every time and gets very boring and limited. You can also notch filter them with a module. That makes them jump between two oscillation frequencies.
Yeah totally. I feel like they're really just going to be there to scoop up some random surface noise here and there. But I wonder if maybe they could play a more interesting role by being matched with envelope followers as a means for modulating filter CV.
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Re: An approach to "acoustic" drone, maybe

Post by Grumble » Mon Jul 19, 2021 11:24 am

I used an accelerometer (3x3mm) in my mouth while playing a didgeridoo, amazing sounds it produced!

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Re: An approach to "acoustic" drone, maybe

Post by 3hands » Mon Jul 19, 2021 8:23 pm

Grumble wrote:
Mon Jul 19, 2021 11:24 am
I used an accelerometer (3x3mm) in my mouth while playing a didgeridoo, amazing sounds it produced!
Pics or GTFO!! Hahaha! :yay:

That made me laugh out loud!
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Re: An approach to "acoustic" drone, maybe

Post by Grumble » Tue Jul 20, 2021 1:09 am

I’m not kidding!
If I remember correctly I used the Analog Devices ADXL356, which has analog outputs up to about 5khz, enough for a didgeridoo.

https://www.analog.com/media/en/technic ... .pdf#page1

Okay, it was a little bigger as I remember :sstorm:

E6947FD1-DCA6-406D-AE61-E592233A316F.jpeg

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Re: An approach to "acoustic" drone, maybe

Post by EASYBOY » Wed Jul 21, 2021 12:35 pm

3hands wrote:
Mon Jul 19, 2021 8:23 pm
Grumble wrote:
Mon Jul 19, 2021 11:24 am
I used an accelerometer (3x3mm) in my mouth while playing a didgeridoo, amazing sounds it produced!
Pics or GTFO!! Hahaha! :yay:

That made me laugh out loud!

:hihi:

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Re: An approach to "acoustic" drone, maybe

Post by 3hands » Wed Jul 21, 2021 12:51 pm

Grumble wrote:
Tue Jul 20, 2021 1:09 am
I’m not kidding!
If I remember correctly I used the Analog Devices ADXL356, which has analog outputs up to about 5khz, enough for a didgeridoo.

https://www.analog.com/media/en/technic ... .pdf#page1

Okay, it was a little bigger as I remember :sstorm:


E6947FD1-DCA6-406D-AE61-E592233A316F.jpeg

That’s incredible!
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Re: An approach to "acoustic" drone, maybe

Post by JohnLRice » Wed Jul 21, 2021 1:59 pm

thelowerrhythm wrote:
Wed Jul 14, 2021 1:43 am
with a bunch of contact mics
I've had pretty good results with AKG C411 mics for processing gongs and steel tongue drums. I think the sound quality is far superior to the piezo I've tried. https://www.akg.com/Microphones/Condens ... 411PP.html This mic mainly picks up vibrations for items it is directly in contact with, so it is extremely immune to direct feedback oscillation, which may or may not be what you are looking for for your setup? Bass response seems to be noticeably less with the C411 than the average normal microphone.

Here's a marginally useful :hihi: test I did to compare a AKG C411 and a Crown PZM on a big gong in the studio. The C411 is in the left channel and the PZM is in the right channel so you can compare:



This video has audio and still shots from a mostly improvised live radio station performance I did where I had a AKG C411 on a gong and one on a tongue drum and did mild to extreme processing of the sound. I have mixed feelings about this performance . . . I think there are some sections that worked well and others that . . . I wish were a lot better! :oops:
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Re: An approach to "acoustic" drone, maybe

Post by Grumble » Wed Jul 21, 2021 2:35 pm

3hands wrote:
Wed Jul 21, 2021 12:51 pm
Grumble wrote:
Tue Jul 20, 2021 1:09 am
I’m not kidding!
If I remember correctly I used the Analog Devices ADXL356, which has analog outputs up to about 5khz, enough for a didgeridoo.

https://www.analog.com/media/en/technic ... .pdf#page1

Okay, it was a little bigger as I remember :sstorm:


E6947FD1-DCA6-406D-AE61-E592233A316F.jpeg

That’s incredible!
A little off-topic, but still audio related…
I was once working on a project about snoring and the use of dentures placed over ones teeth (does this makes sense?)
In these dentures I placed an accelerometer to measure the vibrations when the person wearing these dentures would snore, because a microphone would not work.
This worked nicely and I decided to play the didgeridoo and record the signals coming from the accelerometer.

https://somnomed.com/eng/

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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Wed Jul 21, 2021 5:01 pm

Grumble wrote:
Wed Jul 21, 2021 2:35 pm
3hands wrote:
Wed Jul 21, 2021 12:51 pm
Grumble wrote:
Tue Jul 20, 2021 1:09 am
I’m not kidding!
If I remember correctly I used the Analog Devices ADXL356, which has analog outputs up to about 5khz, enough for a didgeridoo.

https://www.analog.com/media/en/technic ... .pdf#page1

Okay, it was a little bigger as I remember :sstorm:


E6947FD1-DCA6-406D-AE61-E592233A316F.jpeg

That’s incredible!
A little off-topic, but still audio related…
I was once working on a project about snoring and the use of dentures placed over ones teeth (does this makes sense?)
In these dentures I placed an accelerometer to measure the vibrations when the person wearing these dentures would snore, because a microphone would not work.
This worked nicely and I decided to play the didgeridoo and record the signals coming from the accelerometer.

https://somnomed.com/eng/
I love this, wonderful. I didn't realize a sensor like that could be so... sensitive. I wonder if this could be used with a field kit. Either way, totally rad.
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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Wed Jul 21, 2021 5:06 pm

JohnLRice wrote:
Wed Jul 21, 2021 1:59 pm
thelowerrhythm wrote:
Wed Jul 14, 2021 1:43 am
with a bunch of contact mics
I've had pretty good results with AKG C411 mics for processing gongs and steel tongue drums. I think the sound quality is far superior to the piezo I've tried. https://www.akg.com/Microphones/Condens ... 411PP.html This mic mainly picks up vibrations for items it is directly in contact with, so it is extremely immune to direct feedback oscillation, which may or may not be what you are looking for for your setup? Bass response seems to be noticeably less with the C411 than the average normal microphone.

Here's a marginally useful :hihi: test I did to compare a AKG C411 and a Crown PZM on a big gong in the studio. The C411 is in the left channel and the PZM is in the right channel so you can compare:



This video has audio and still shots from a mostly improvised live radio station performance I did where I had a AKG C411 on a gong and one on a tongue drum and did mild to extreme processing of the sound. I have mixed feelings about this performance . . . I think there are some sections that worked well and others that . . . I wish were a lot better! :oops:
Thank you for putting all this together. I remember using the C411 years ago as an engineer and didn't even think about it. Far better than a piezo disc. If I remember correctly it requires phantom, which the Lil Mikey will be happy to provide. Though I'm still trying to figure out how much power it draws when phantom is on. Doesn't matter that much, as one of the changes is moving to a case with 10 amps, but curiosity.

I happened into a Field Kit / FX pair, which doesn't head completely in the same direction, but provides a lot of related tools. In the meantime I've redirected some of my mixers to another case that's experimenting with nothing but clocks, logic, squares, and pulses. Quadrophonic output, but instead of like surround it'll be four speakers on entirely different output channels arranged linearly. But that's a whole different ordeal.
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Re: An approach to "acoustic" drone, maybe

Post by JohnLRice » Wed Jul 21, 2021 7:35 pm

thelowerrhythm wrote:
Wed Jul 21, 2021 5:06 pm
JohnLRice wrote:
Wed Jul 21, 2021 1:59 pm
thelowerrhythm wrote:
Wed Jul 14, 2021 1:43 am
with a bunch of contact mics
I've had pretty good results with AKG C411 mics for processing gongs and steel tongue drums.
Thank you for putting all this together. I remember using the C411 years ago as an engineer and didn't even think about it. Far better than a piezo disc. If I remember correctly it requires phantom, which the Lil Mikey will be happy to provide. Though I'm still trying to figure out how much power it draws when phantom is on. Doesn't matter that much, as one of the changes is moving to a case with 10 amps, but curiosity.
The AKG C411 does need 48v phantom power but I'm guessing it sips pretty lightly on it? I've used small 8 channel Mackie VLZ mixer with them and even 9v pedalboard powered guitar pedal sized preamps and they have always worked fine. The pedals I've used are the:

"A Station" made by HotOne, about $160 list but can be found for far less and is easy to find. It is very feature rich, nicely made in a metal enclosure, and sounds fine although I was disappointed to find out after I bought it that the five EQ controls only affect the 1/4" guitar input, not the XLR mic input. HotOne is a 20 person company based in Hunan China, and probably very nice folks but I've never communicated with them.
AStation.png
AStation.png (284.64 KiB) Viewed 113 times


"Synapse V2" made by Revival Electric. I love this one, beautifully constructed in a small aluminum Hammond box, it lacks half the features of the HotOne and costs about twice as much, but if you can afford one it won't disappoint! I'm "guessing" it's specs are better than the HotOne, but Revival doesn't list complete specs and HotOne doesn't list any at all. The Synapse is made by a nice one man (?) boutique shop in San Francisco USA. Their site said "backordered, expect a 2 week delay before it will ship" but they shipped mine after only 5 days. :tu:
https://www.revivalelectric.com/synapse-v2
SynapseV2.jpg
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Re: An approach to "acoustic" drone, maybe

Post by Grumble » Thu Jul 22, 2021 1:15 am

thelowerrhythm wrote:
Wed Jul 21, 2021 5:01 pm

I love this, wonderful. I didn't realize a sensor like that could be so... sensitive. I wonder if this could be used with a field kit. Either way, totally rad.
Totally!
But an accelerometer works fundamentally different from the microphone: while a microphone works by means of air pressure variation between front and back of the membrane, the whole accelerometer must vibrate in order to measure signals.
So it makes a great contact microphone. I’m sure it has its quirks but that might be corrected by the used amplifier.

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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Thu Jul 22, 2021 1:39 am

Grumble wrote:
Thu Jul 22, 2021 1:15 am
thelowerrhythm wrote:
Wed Jul 21, 2021 5:01 pm

I love this, wonderful. I didn't realize a sensor like that could be so... sensitive. I wonder if this could be used with a field kit. Either way, totally rad.
Totally!
But an accelerometer works fundamentally different from the microphone: while a microphone works by means of air pressure variation between front and back of the membrane, the whole accelerometer must vibrate in order to measure signals.
So it makes a great contact microphone. I’m sure it has its quirks but that might be corrected by the used amplifier.
For sure, sorry, I was a little unclear in the way I wrote that. I plan on getting one for the field kit sensor input, but I'm wondering how to go about using it in the same way as a contact mic. Would it just need similar amplification?
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Re: An approach to "acoustic" drone, maybe

Post by Grumble » Thu Jul 22, 2021 1:24 pm

thelowerrhythm wrote:
Thu Jul 22, 2021 1:39 am
For sure, sorry, I was a little unclear in the way I wrote that. I plan on getting one for the field kit sensor input, but I'm wondering how to go about using it in the same way as a contact mic. Would it just need similar amplification?
https://koma-elektronik.com/?product=field-kit
If you are talking about the field kit, is this what you are talking about?
If so, there are a number of accelerometers you can use and if you will I’m happy to assist choosing your accelerometer but I have to read the manual to give answers that makes sense.
The first look at the schematics suggest that there are 3pin input connectors for sensor input.
562E28C3-9D14-4A10-84F0-45738D5499B2.jpeg
That provide 5 volt to power the sensors.
But first you have to decide if an accelerometer is what you are looking for, because the analog signals provided by the accelerometer is the integrated form of the movement of the accelerometer.
63A92946-B212-4C0A-9E14-12D6D4E351B1.gif
63A92946-B212-4C0A-9E14-12D6D4E351B1.gif (9.65 KiB) Viewed 75 times
If you look at this picture and assume that the signals on the left is the movement of the accelerometer (suppose you feed these signals to an amplifier powering a loudspeaker and the accelerometer is glued to the cone of the loudspeaker) than the output signal of the accelerometer is that on the right of the picture, while a contact microphone will output signals similar to the left signals.

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Re: An approach to "acoustic" drone, maybe

Post by thelowerrhythm » Thu Jul 22, 2021 9:22 pm

Grumble wrote:
Thu Jul 22, 2021 1:24 pm
thelowerrhythm wrote:
Thu Jul 22, 2021 1:39 am
For sure, sorry, I was a little unclear in the way I wrote that. I plan on getting one for the field kit sensor input, but I'm wondering how to go about using it in the same way as a contact mic. Would it just need similar amplification?
https://koma-elektronik.com/?product=field-kit
If you are talking about the field kit, is this what you are talking about?
If so, there are a number of accelerometers you can use and if you will I’m happy to assist choosing your accelerometer but I have to read the manual to give answers that makes sense.
The first look at the schematics suggest that there are 3pin input connectors for sensor input.
562E28C3-9D14-4A10-84F0-45738D5499B2.jpeg
That provide 5 volt to power the sensors.
But first you have to decide if an accelerometer is what you are looking for, because the analog signals provided by the accelerometer is the integrated form of the movement of the accelerometer.

63A92946-B212-4C0A-9E14-12D6D4E351B1.gif

If you look at this picture and assume that the signals on the left is the movement of the accelerometer (suppose you feed these signals to an amplifier powering a loudspeaker and the accelerometer is glued to the cone of the loudspeaker) than the output signal of the accelerometer is that on the right of the picture, while a contact microphone will output signals similar to the left signals.
Exactly, and thank you! I have a lot of experience with contact mics and microphones, zero with sensors. It seems fairly obvious what they will do, to a degree anyway... just still in the research phase of figuring out what might be interesting, what's compatible, and where to get it. Ex. I'd prefer to find out quality differences vs. just doing what's regularly recommended (ie. going with an arduino pack o' sensors and seeing what sticks). I imagine you can find hardware that has superior sensitivity, though I'm not sure to what degree will make any difference in this application. The Koma packs seem overly expensive, but then again I'm unfamiliar.
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