Kite Aerial Sound

I swear I had another thread about this, but I can't find it for the life of me. So if this is repetitious, I apologize.

After watching Nicolas Chorier's video tests in Pondicherry, India, I dropped a number of KAP projects I was working on, including re-packaging my transmitter, and went off on the tangent of kite aerial sound. Going in, I thought this would be a straightforward project. Now that I'm months into it, I realize there's a lot more to it than I thought.

I'm less than a week away from what I hope will be the last end-to-end test of my gear. I'm putting this out here because it may be of interest to anyone doing video from a kite, or to create ambient recordings for use with still photography slide shows, which is more along the lines of what I'm planning. Before getting into what I've done so far, here's a quick intro to sound. Skip if it's boring:

With video, at least, sound is as important as the moving picture image. I'd argue that it's not as necessary with a slide show, but that it helps. One of the most common complaints about videos that I see on the RCGroups forum is the choice of music for the sound track. (I think this has to do with the tendency to pair RC airplane videos with "Highway to the Danger Zone" by Kenny Loggins or to "Rock You Like a Hurricane" by the Scorpions. No takers so far on the Pachelbel Canon.) Music tastes vary, but people seem to be drawn toward videos with good ambient sound tracks. At least there are fewer complaints about them.

Sound requires just as much care and thought about equipment and technique in the field as photography does. But just as our KAP equipment is always a compromise between quality, weight, and cost, so too is sound equipment. There's no one perfect answer, and everyone's answer will be slightly different.

Recording sound requires a couple of pieces of equipment: A recorder, a preamp (if the recorder doesn't have its own), a microphone, a cable, and wind protection since we're doing this outdoors.

Recorders need relatively low noise, a decent feature set, the ability to save high-quality file formats, and a good interface for the mic. Fortunately, a recent proliferation in handheld recorders makes picking up a KAP-weight recorder straightforward.

Microphones also need to have low self-noise, but beyond that they tend to be selected based on the application (shotgun for isolating a sound source, parabolic for picking up remote sound, dynamics for recording loud sounds, condensers for recording quiet sounds, etc.) Since the ambient soundscape is such a broad subject, omni-directional condensers work great. Most pocket sound recorders come with a pair built-in, though I went a different route with mine, as you'll see.

Cables need to have good shielding to cut EM/RF noise, high quality connectors, and decent mechanical strength. These can be bought commercially, though it's easy enough to build your own with good quality microphone cable.

And then there's wind protection. Almost any time you use a microphone outdoors, you need wind protection of some sort. Since I'm planning to hang all this stuff from a kite, it's an absolute must.

Now on to what I've done so far:

I want to record ambient sound from the air. More specifically, I want to record stereo ambient sound. The recorder I'm using is a Tascam DR-05. It's about as heavy as a compact camera and will record 24-bit 96KHz audio, which is overkill for what I'm trying to do. But it has its own preamps, has built-in omni condensers, and you can get wind protection for the DR-05 on Ebay for not much money.

I tried flying my DR-05 and using the built-in microphones, but everything sounded flat. There was no stereo separation, and I couldn't locate myself in space just by listening. There's an idiom in sound recording: If in doubt, get closer. (Hey! Sounds like photography!) This helps isolate a sound from the background, allows you to turn down the gain and get lower noise, and it creates a stronger stereo separation. Unfortunately since I'm trying to do all this from a kite several hundred feet away, none of that really applies. So I went off on another tangent and built a stereo ambient sampling system (Try saying that ten times fast!)

The SASS was designed by Michael Billingsley for Crown Audio. They're not made any more, they're heavy for KAP work, and the mics weren't really suited for outdoor ambient recording, anyway. Over the years people have built their own so they can use the microphones of their choice. So that's what I did. It's a close compromise between weight and performance. It's made almost entirely from 0.2" birch plywood, the same wood I used to build my KAP 4x5 camera, and is filled with relatively high density foam.

DIY-SASS

The microphones I chose are Primo BT-EM172 capsules. They're about $10 USD apiece, and are about the lowest noise microphone in that price range. By way of comparison, Telinga sells matched pairs of lavalier mics for about $350 USD. Take them apart, and they're just a wire going to a BT-EM172 capsule. Even the pros use them. They really are nice.

I learned the hard way that omnidirectional condenser capsules need to be mounted flush to the front of their enclosure. My first set were mounted recessed by 4-5mm, as shown in the photo above. During testing I heard some weird resonances that I fixed by switching to a flush mount enclosure.

Flush Mount Mic Body

The whole mess comes in considerably under the weight of my DSLR KAP rig, so I'm pretty confident it'll fly just fine from practically any of my KAP kites. The only step left is wind protection.

Two companies manufacture the bulk of the wind protection used by field recordists and film crews: Rycote and Rode. If you ask on the sound forums, most people urge you to buy a windjammer from one of them. Unfortunately neither Rycote nor Rode make windjammers for DIY microphone projects like my SASS, so I'm making my own.

Windjammers use acoustically transparent artificial fur to cut the wind. Something between a 1"-2" pile is ideal. The backing is also important: the more porous, the better. Rycote includes a disclaimer with all of their windjammers: because the backing is so acoustically transparent, it doesn't have a rock-solid grip on all the furry hairs. So they shed. I found a company selling 2" gray artificial fur with a tendency to shed, and ordered a yard in the hopes it's at least sort of acoustically transparent. It should be here tomorrow. Sewing the windjammer is the last step before I can mount this to a kite and get it in the air. (I get the feeling this thing is going to look like a big gray sleeping tomcat hanging from a kite line. And people stare when I fly a KAP rig!)

Initially I'm planning to mount this to a long pendulum suspension. I think the pulleys on a Picavet will transmit too much sound to the microphones to be useful without isolating the microphones from the rig. My first rig will be a set-and-forget with no way to aim the mics in the air. (It's basically the ballhead off my PAP pole stuck on the bottom of a pendulum suspension.) My plan is to fly it over one of the beaches I frequent to see if it can record wind-free sound in KAP-grade wind, and to see if the SASS can create a strong enough spatial image given the distances involved.

Sorry to end this with a cliff-hanger, but that's all I've got for now. I hope to have some sound files to share early next week. Meanwhile if anyone's interested in what the SASS does with stereo sound on the ground, here are two samples:

Three cars moving from left to right on a wet highway:

https://soundcloud.com/tnbenedict/three-cars-left-to-right

Waves crashing on a rocky shoreline with a pebble beach off to the left:

https://soundcloud.com/tnbenedict/kiholo-bay-south

These are both relatively close-miced, so they'll sound better with headphones than speakers. Because the kite aerial sound will have more distance between the subject and the mic, it should sound fine either way.

Tom
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Comments

  • edited September 2015
    Tom,
    The kapers using kite in high wind have a surprise with the cable hanging their camera.
    With its length and very low area on the flowing wind, the cable is starting singing, as every body knows, it is a mechanical resonance !
    When I was young I was reading a french comic book of Lucky Luke,"Le fil qui chante " made by Morris.
    It is the story of the first communications with the morse telegraph !

    The french man who gave me some interest in kap was Bernard Hénon , a plane modeler living near Calais .
    This man realize one of the first radio controlled rig in France in early 1990 years !
    His favorite kite was using high winds and was using a winch to help to the coming back of the camera on the cable kite !
    When the kite was finding it's best position in the sky, this sound using high frequency with two tones appeared .
    José
  • WOW, I will have to go through more deeply in such matter,...
    I use often the TASCAM DR07 (the older version with two microphones 180°) but also the ZOOM H1
    surely the two problems 1) wind noise ; 2) structural noise coming from line, RIG, suspension are creating the need of some very specific solutions
    small separate microphones could be easier to deal with,... surprising good quality are those given as accessory for SMARTPEN, a combination of ear plugs and recording (you can record what you are listening) - the plug is strange but,...
    wind noise protections arranged just a a foam looks poor,... but what is used normally for outdoor recording looks like a furred bottle,... maybe that something made by some windings of mosquito net + thin synthetic knitted fabric,... ??
    good luck and thanks for subject !!
    SMAC from Italy
  • If you look at this video by Nicolas Chorier you'll see what inspired Tom. Nicolas has managed to capture street sounds without much wind noise. It can be done!
  • edited September 2015
    Dave,
    Thanks, Kite line is used to lift a system to record some external sounds.
    josé
  • josé, I'm glad you mentioned line noise. That's another sound project I'm working on: capturing line noise as cleanly as I can. I'm building some contact microphones I can attach either directly to the kite line or to the winder. I've tried holding both up to my ear to listen to the screaming sound, and both work. I figure I'll try both and see which one the contact mic gets better sound from.

    Ramon also suggested using spaced microphones, SMAC. I tried some experiments on the ground while recording coqui frogs out here. I had the SASS on a tripod under a tree, and a pair of lavalier mics clipped to tree branches on either side. I started with a fairly wide spacing, maybe 8-10'. I found there's a practical limit. The lag difference between the two microphones made the sounds a little confusing to listen to. Once I brought it in closer to 3-4' it worked better.

    I tried some 4' spaced mics in the air early on using a pair of Audio Technica lavaliers I borrowed from a friend. Unfortunately the microphones had a lot of self-noise, and came across as hissy. I set that experiment aside while I worked on other ideas. I've got some lavaliers I built around the BT-EM172 capsules, so I might give that another try. I still have the bar setup sitting around somewhere.

    As far as getting line noise out of the recordings, I think there are a number of ideas I can try: exhaust hanger line dampers, vibration isolators from multirotors, sticking a length of rubber tube in my pendulum rig, etc. But first I want to just try it and see how much line noise I get. All of my aerial experiments so far have been with a Picavet, which is how I know the pulleys make too much noise. I'd like to see how much the pendulum rig damps line noise simply because of its own mass.

    One other question I still have to answer is this: Does it even matter? Nicolas's videos were made from relatively low altitude (a great choice in my mind, because it makes them such an intimate view of the subjects). Could the sound have been recorded just as well from the ground? There's a regular beach volleyball game that plays here every Sunday. One test I want to do is to record a game from the ground as well as from the air to see which sounds better. If the ground recording sounds better, I'll have to try with a broader subject at a higher altitude. If that still sounds better from the ground, maybe there's no point in doing aerial audio after all. It's weird to still be asking this so late in the R&D process, but it's a question I don't have an answer for yet.

    One fun part about this, though, is that of all the aerial platforms aside from balloons, kites are the only one to pull this off with any kind of ease. A friend at work recently got a DJI Phantom, and wondered why the camera didn't record audio. When I told them that all they'd hear is the angry bee sound of the rotors, they laughed and admitted they'd never thought of that! There's an advantage to an aerial platform that doesn't make a lot of noise.

    Tom
  • Interesting topic and thoughts on aerial sound recording.
    I have done some videos with camcorders, but never went so deeply on the sound matter. However this is what I experienced.

    The wind reduction noise feature on the camcorder is sufficient when the wind is not strong.
    In elevation, all noises on the ground are easy to catch. It is possible to listen music, people discussing, etc, when it is difficult to catch the same at a much shorter distance at ground level. I noticed that when the camcorder is inclined downward the sound is much better. So I just added a microphone towards the ground. I like also when there is a little wind noise as background.

    The stereo is not so important during recording. On video on the ground, as already mentionned, only close sounds provide stereo effects. In elevation I guess it would be really difficult. A truck coming from any direction will be the same on left and right microphones.
    But with a mono recording, let's duplicate it on the left and right tracks meanwhile adjusting the left/right balance following the direction at which the truck is seen on the movie.

    I have a zoom H2n and do records on the ground. But I have not yet combined it with the aerial recordings.
  • Is noise from the kite itself not a problem? It seems some kites with flapping edges might not be a good choice for this.

    I'm amazed at Nico's videos. Not just the audio, but how stable his video rig appears to be. Is this just a regular picavet suspension, or something else? Or is it just absolutely perfect stable wind? (In my next life, perhaps.)

    Looking forward to your results, Tom.
  • edited September 2015
    As you write, the kite can make some noise . it can deliver some interesting message !
    If you doesn't choose the good one, the first kite used can tell you:
    First try with a delta can generate some loud noise on medium wind to tell you: I am not able to do the job , use another one.
    So you put a flowform and it flies smoothly and is really in it's element !
    José
    Ps : For recording sounds during a flight cession , flowform do not deliver any flapping sound and it's a good choice !
  • wayback, I'm pretty sure he was testing a brushless DC gimbal mount. Nicolas's suspensions have always been a source of interest and inspiration for me. He was building really cool damped suspensions before I even started doing KAP. I can guess at the gimbal he used for that video, but I have no clue what was between it and the kite line.

    Christian, one of the reasons I built the SASS is that it still provides a strong stereo signature, even on distant sounds. Some of my frog recordings are marred by traffic sounds several miles away. In one of them I can tell which direction the truck is driving on the highway. Encouraging for aerial audio work, but it cost me a good recording of some frogs.

    Tom
  • edited September 2015

    Tom,
    Some rig using two or three brushless gimbals generate for working a little electronic noise .
    We find it too on the new generation of radio controlled servo motor.
    On my ring using one, when i put the supply , there is still immediatly a very little noise :one oscillator circuit is working .
    One microphone can be installed on the opposite side, it is enough to have a normal result !
    José
  • Very cool Tom! I'd love to hear a lava flow cracking or some surfers waiting for waves. Wind through the trees. Birds. Looking forward to see what you do.
  • I stopped by the post office on the way home at lunch and picked up my yard of gray fur. Time to make a windjammer!

    Tom
  • edited September 2015
    Tom,

    Great work. Love to see the audio in action from a kite including the stereo sound with the custom microphones.

    As you point out, the video by Nicolas was done close to the ground. I can only assume the kite was high above and the camera was attached to the kite line 10-20 feet off the ground.

    I too am amazed at the audio you can pick up from a kite - even at height. This is an example take with my Canon S100 using CHDK KAP script above Antwerp, Belgium. You can clearly hear the cathedral bells and voices of people even at this height. The sound of waves breaking on the beach is one of my favorites.

    For a bit of cross fertilization....I recommend you check out some of the work by the hang glider folks who have been experimenting with different external microphones tied into GoPros with a focus on removing the wind noise.

    This video by Andy Long does a good job of explaining the custom set up as well as in flight testing.

    I also recommend sticking a GoPro on the side of your microphone and just shoot continuous video...this will give you some context while in flight.

    Enjoy!

    WW
  • Hey, thanks for both of those! Both videos are very encouraging. The bells in Antwerp were a lot stronger than I was expecting them to be. And the wave sounds in Andy Long's video, even at that altitude, are a good indicator that at kite height, sound should be quite clear.

    I like the idea of mounting a Gopro on the rig to get a visual context for the recording. Plus, that'll let me know how much motion the microphones are getting.

    Sewing fur in the morning.

    Tom
  • Really enjoying following this project Tom. I'm learning a lot and marvelling at your workshop skills.
  • I think my woodworking is better than my sewing. My first attempt at a windjammer was an utter failure. I started off trying to make a pair for my lavalier omnis so I can try them on the bar rig. One problem with making something smaller than the length of the fur: No matter what you do, it gets trapped between layers while sewing. I won't have this problem on the SASS windjammer, but I kind of wanted to prototype on something small first. I'll try again tomorrow.

    Tom
  • @benedict : hi, I'm glad that this subject is receiving great interest
    I do not plan to do so much but a trial for a furred windjammer small, maybe
    Recording structural sound (line vibrating, kite frame,..); maybe that a simple device already existing could be interesting at least for some good trials : the guitar tuners with pick-up on guitar frame are beautiful ready devices; some has OUT for headphones and devices area existing very smal with just a mini battery inside
    I have looked again to Chorier video:
    1) beautiful but it's already difficult to believe that is taken with a kite (too low altitude, too steady,...)
    2) assuming that is a kite, to put on the additional weight of a good recorder,... no
    3) the sound track could be also taken at ground level and ADDED, sincronized with the original video
    wishes of all the best possible to all trying this way
    SMAC from Italy
  • This Nicolas' video on kollam competition is the last of a serie of 5 in his kite aerial section.
    Hold at 1'32" and you will see the shadow of the rig in the bottom right corner passing at the toe of the ladder. Il seems to be a picavet suspension.
    That video has the best sound. There is less wind noise. I would consider it is because at this low altitude there is less wind and the buildings may shelter the microphone from the wind. Also, I don't feel any stereo effect.

    A single microphone well sheltered from the wind and , as already said directed towards ground is giving the best possible results.
  • SMAC, that's one question I'm still trying to answer: What's the benefit, if any, of recording the sound in the air. The hang gliding video Jim posted seems to indicate the aerial soundscape is interesting enough to pursue it. I've got a couple of test spots lined up that should answer that question pretty easily.

    As for the weight, it's pretty minimal. I'm not using a Sound Devices 700 series or anything, but I'm able to do 24bit 96kHz with relatively low noise with a recorder that weighs 170g. So not much more than a compact camera. The mics I'm using are even lighter (bare lavaliers without the array are 140g). The SASS array pictured above adds some weight, but the whole thing still comes in considerably lighter than my DSLR KAP rig. Considering how many times I've run dual rigs in order to do air-to-air photography of a KAP rig, I doubt any of my kites will have a problem with the weight.

    For my purposes (doing still photography KAP and recording ambient sound to act as a soundtrack on a slide show), I don't even have to run the two at the same time. It's important for video, but not for stills. (Though I like Jim's idea of hooking my Gopro to the sound rig, just to provide a visual record of what the microphones were doing. So yeah, maybe video, too.)

    I ran into some problems shielding the SASS array from the wind. I know it can be done since other people have been using these for field recording for decades. But I get the feeling it's tough to do in wind suitable for KAP. I'm experimenting with another array design from a guy named Curt Olson that may lend itself to KAP better than the SASS. I hope to have that prototype built and flying by next weekend.

    I know a single microphone directed at the ground produces good results. That style of micing is popular in theater for just that reason. But I find I'm drawn to stereo soundscapes. Quasi-binaural arrays like the SASS and the Olson Wing work remarkably well with distant sources. As I said I've recorded sources from a distance of several miles and still preserved the stereo information with my SASS. The several hundred feet of altitude from a KAP rig should work fine.

    Tom
  • interesting! about basic question to do or not to do,... :
    A) structural sound (line, kite,..) looks more peculiar, more specifically linked to the KAP - KITE situation and it is somehow easier, with a proper transducer and signal processing amplifier - recorder
    B) probably in most conditions the sound track (air - sound) at ground level is best option (KAPer's feeling), ok it's not bird feeling but human for other humans
    Curt Olson / SASS / PBB / winged arrays ; good , very good to try ; they are all somehow ways for a kind of artificial head using at best possible the directional effect of cardioid condenser microphones and searching a stereo effect good enough

    Wind noise on microphones / windjammer need: maybe that good results are arriving with a simple configuration of two microphones facing each other and spaced 1 or 2 " within one furred tubular (one for both, saving space and maybe trubles)
    the extra simple recording with ear-plugs of ECHO-SMARTPEN mentioned before are a way for using personal head as best possible artificial head,.... (joking wound sound as "use YOUR head")
    SMAC from Italy
  • I add something else from comments of a friend that deals professionally in recording :
    for the recorder Zoom H1 works well the windjammer furred offered as option (few grams)
    Good quality from Rycote P/N 055406 33,00 Euro.
    recording the wind residual and suppressing from recording with a dinamic digital filter iZotope:
    https://www.izotope.com/en/products/audio-repair/rx/
    SMAC from Italy

  • Going through your comments in order:

    A - I've got three Alex Rice impedance matching buffers built and ready to go for doing contact mic work. I just need to solder the piezo elements and cables, and I should be able to do contact mic recording of kite line sing. I'm about two weeks out on this. (Waiting for XLR connectors and a DR-70D to show up.)

    B - I'm reserving judgement on the utility of aerial recording until I can do a set of side-by-side comparisons between aerial and ground-based recording using the same mic setup. Several months back I ran the idea past a number of field recordists, and they said sound from altitude is significantly different from sound on the ground, and that it's worth pursuing.

    C - I should have a prototype Olson Wing ready to fly either this weened or early next week. I'm going to order more mics so I can build it out as a permanent self-contained array, but I can do the aerial tests sooner than that. (I'm mounting the mics and installing the windjammer tonight when I get home.)

    D - Having two mics facing each other 1-2" apart is basically a coincident pair. I can test it, but it'll be very similar to some of my earlier experiments. I don't think the stereo separation will be all that strong. I'm going to wait on this until I have exhausted other avenues.

    E - I did something similar to your second post when I started all this. Rather than a Zoom H1 I used my Tascam DR-05 with a windjammer. It worked in that it reduced the wind noise to something I could work with, but the stereo image was relatively weak. That's part of what motivated me to go down the path of partially baffled boundary arrays.

    Since I've got some tests lined up I'm going to hold off posting further on this thread until I have some side-by-side audio to share. Specifically I want to test the SASS against the Olson Wing, and test the Olson Wing on the ground and in the air. I think having those will answer most of the questions that are rattling around at this point.

    Tom
  • Well I ALMOST waited until my tests were done before posting. But this weekend is looking promising.

    I finished out a contact mic and tested it with a Tascam DR-70D. Works GREAT. I'm planning to fly with some #100 cored Dacron and try to record line scream.

    I finished the Olson Wing over the last weekend and tested it in windy conditions on the ground.. Thanks to the input from some folks on the Yahoo! naturerecordists group I've got a low-cut filter set up that should get rid of the residual wind noise enough to try this in the air.

    Finally, I built a damped pendulum suspension. It's a lot simpler than the one I posted about several years ago (one pivot point instead of five, and no parallelogram section), but it's done and it works fine on the ground. As with any KAP gear project, as soon as I tightened the last screw the skies opened up and it started raining. So I haven't had a chance to fly the thing yet, either to carry a camera or to carry microphones, but it's ready to go.

    So unless something truly dire happens, I should be able to test out almost every idea presented in this thread: ground, air, coincident pair, partially baffled boundary array, contact, etc. The only one I won't be in a position to test is a widely spaced pair since my stereo omnis are currently tied up in the Olson Wing (new mics haven't come in yet).

    I'll post the results as soon as I have some to share.

    Tom
  • Tom,
    https://www.facebook.com/projectbasepage/videos/944053775655956/
    Not sure these are kites (don't see the line), but they might be interested in your mic setup... :-)

    Cheers, Hans.
  • YIKES!!!

    Not sure anything I've done would hold up to those wind speeds. :)

    Tom
  • I think the screams would cause some volume overload issues.
  • edited September 2015
    Agree with Tom - impressive speeds from these aerial dare devils.

    I have been tinkering with a bit of KAP sound experiments using my GoPro Hero 3 with an inexpensive external microphone with at wind screen.

    The audio results were not bad given the wind (very high) conditions. Wind noise still dominates the audio track.

    I spent some time on the Atlantic Ocean beach in Avalon NJ. The wind was blowing 20-25 knots with big surf rolling in. Given the big blow I used my Nighthawk kite which was happy as a clam and provided a solid anchor in the sky.....on the other end of the line I tied the kite line to my life vest and along with a couple of my sons we went for a drift in the high surf....with the Nighthawk kite pulling me along in the waves....

    Bit of a risk to the auto KAP rig with the Hero....floating above the waves under the Nighthawk kite....naked Hero 3 with no waterproof housing....as the external microphone plugs directly into the on camera USB port. The ocean surf and strong rip tide pulled me along....sometimes I could stand briefly between waves...other times ...just swimming between waves in deeper water. Thus limited ability to rescue the KAP rig in mid ocean if the KAP rig came down.... I disabled the auto KAP controller and fixed the pan and tilt angles to capture a fixed point of view (back down the kite line). The KAP rig was set fairly high above the waves for a bit of safety.

    The Hero 3 was in standard video mode shoot continuously. The Hero 3 automatically run for 17 minutes and 25 seconds prior to a file save and automatically starting the next 17 minute and 25 second video clip.

    The first 5 minutes of the video show the quick KAP rig attachment and launch....with the audio picking up the ocean surf along with the sound of a bulldozer working near by. The next 12 minutes or so of the video shows the the drift in the waves and occasionally picking up our voices over the sound of the waves on the audio track.

    YouTube now has the option to "de-shake" the video on upload....This works fairly well...but does break up the video flow periodically.

    Enjoy the KAP video clip with audio from the external microphone here on YouTube.

    WW
  • Hey, cool! I looked at the ports on my Hero 3 and didn't see a mic in. I just assumed it didn't have the capability. I should've known there'd be something on the USB port since that's how I get live video out for my downlink.

    I finally had the chance to try everything in the field. I took your advice, Jim, and flew my Gopro with the sound rig. It'll take me a while to go through all the video and audio files, get everything synced, and edit it into something passable. I'll share that once I do.

    In the mean time, the contact mic / line singing worked GREAT. The sound should be familiar to any KAPer who's flown with 100lb or lighter line on a hoop winder. That's pretty much exactly what the contact mic picked up.

    Contact Mic Recording

    I tried connecting the mic two ways. The first was directly to the kite line:

    Contact Mic on Line

    https://soundcloud.com/tnbenedict/kite-line-scream-contact-on-line

    When I took the mic off the line I found out that the blue poster adhesive stuff I was using doesn't like to come off of kite lines. Bleah!

    The other was to attach the mic to the carabiner I was using to anchor it to the ground:

    Contact Mic on Carabiner

    https://soundcloud.com/tnbenedict/kite-line-scream-contact-on-carabiner

    The carabiner recording cuts down some of the higher frequencies and lets in more of the bass. The only gotcha is that it also picks up a fair bit of noise from the anchor strap. I think wrapping the kite line around a standalone carabiner and attaching the mic to that would give the best of both worlds by isolating it from the anchor strap.

    The one thing I didn't try was to put the mic on the winder! I'll try that next time I go out.

    Just for grins, I took a look at the spectrogram of the attached-to-the-line recording:

    Line Scream Spectrum

    Harmonics! The primary frequency is somewhere between 500 and 1000 Hz, varying with line tension, and then every 2x, 3x, 4x harmonic shows up. Kinda neat. Anatomy of a scream.

    Unfortunately I already know at least some of my other recordings picked up line scream in them, and won't sound all that good. That's something I should've thought about when I went with a pendulum suspension. Without some kind of damping in there (reinforced Tygon tubing?) every vibration in the line conducts straight down the pendulum to the microphones.

    It's a work in progress.

    Tom
  • @benedict :

    WOW great, YES gives "the feeling", I have one line that is singing more than others,...

    about putty between carabiner and piezo transducer,... probably better hard and thin, a two component epoxy,...
    about separation between rig and microphones a good simple solution tested in the past is a O-ring 3-4" dia with string dia near 3.1 mm ; looking to O-ring connect with slim string North and South and than separately East and West; the 3 D shape NS ; EW works well as separating element

    great work SMAC from Italy
  • Hey, that's two great pieces of information. Thanks!

    I'd wondered about epoxy and piezo transducers. I'd seen one person who epoxied them to the back of large magnets, but I wasn't sure what that would do to the sound. The transducers themselves are relatively inexpensive, so dedicating them to a task by epoxying them in place makes sense. I just need to put connectors on the preamp board so I can swap out the transducers.

    On the o-ring, once you connect the strings to the o-ring, do you put this in-line with the kite line? So the kite line would go:

    Winder -> Lower O-ring N/S
    Lower O-ring E/W -> Rig
    Rig -> Upper O-ring N/S
    Upper O-ring E/W -> Kite

    If I'm imagining this right the o-ring would wind up in a zig-zag shape (looking at it sideways), kind of like a microphone suspension?

    Thanks again for the feedback.

    Tom
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