Need to help Environmentalist in Africa
I’m hoping someone has done this, or can point to someone who has…
I need to put together equipment and approaches for recording birds and possibly other wildlife here in Tunisia, North Africa. I have a friend who is a professor here, and who has made it his mission to make people aware of the unique environment(s) here, and the ways they are endangered by ‘modern’ life and peoples carelessness. He would like to make high quality recordings of some specific birds. Some are migratory birds that stop briefly here at the north tip of Africa as they travel from Europe to Sub-Saharan Africa, and two are totally unique to Tunisia and possibly Algeria.
I have a long electronics and audio engineering background, but “pieces d’electronique” are sometimes hard to get here. Fortunately I brought quite a bit of parts, oscilloscope, signal generator etc…
(A) I need help to find a good technique for a ‘distance’ mucrophone. I assume I will use a parabolic reflector, hopefully salvaged from satellite receivers. Can anyone point to info about this? I have typical SM58’s and a small RCA BK6 that might be workable. I could use one of many small electrets, of course.
(B) I need some decent preamp with variable gain (probably not actual AGC, though). Probably a 5534 is enough.
© I need a portable A-D converter. My thought is to capitalize on 24 bit capability to ease the problem of wide dynamic range in the source, applying gain control / AGC later in CoolEdit etc. IsThere a decent 24B USB interface?
(D) Recording: I’d LIKE to record directly to a laptop, I think.
(E) Editing / Processing: I think this is easy in 2004.
So, I would really appreciate pointers to information, suggestions, comments. There is probably no funding other than my personal nickel, at least to start, so that’s partly a factor. Also a small interface that can go in a padded envelope thru the Embassy mail and avoid spending 2 months in customs would be Real Nice. This ain’t 42nd Street.
Thanks for your help!
Tascam US-122 interface. 24/48 Works great and built like a tank. Built in Phantom power is a bonus too. Extended sessions with the Phantom power on will NAIL your laptop battery though. Pack extras.
I would think an Audio-Technica “shotgun” mic would be ideal for you. Since there is not a dealer on every corner in Africa though…the parabloa and mic should work if you align things properly. I seen a website once with a bunch of info on building these things for surveillance purposes. I can’t recall the link though. Try a Google search?
TG
Really great nature-recording info at Yahoo Groups: naturerecordists. You need to have a yahoo login (free), if you don’t already.
I occasionally play with doing nature recording. I used to use a Walkman Pro cassette deck, now I use a minidisc portable.
Check out the new HiMD recorders - they’re now capable of full 16-bit linear recording. MD won’t be 24-bit, but they are inexpensive, have reasonable preamps for certain mic types, and would be easier to carry, set up and run.
Regardless of your final rig choice, I can highly recommend having an MD recorder and a small stereo mic (eg SONY ECM-MS907) sitting in your knapsack, for those once-in-a-lifetime situations.
A) There are many possibilities here. For one “works most places” mic, try a good mid-side stereo condenser mic. There are several available, starting with the above SONY, to models costing thousands.
I’ve got a parabolic and some Sennheiser electret shotguns, but I’m no expert in using them.
Watch out for wind noise. With a MS or a shotgun mic, you may need the full zeppelin/rycote solution.
B) I’ve had luck with a home-grown 5532-based preamp on electret capsules, running from a 14v NiCad battery pack.
C) Core Sound have a nice portable mic pre and A/D.
D) Laptop… well OK. Not as robust, portable or as easy to use as a dedicated recorder. Here’s a PDA-based option also from Core.
E) Editing: CoolEdit + nTrack, of course 
Good luck. You are now obligated to send me a CD of African ambiences.
For portability, I recommend the M-Audio Transit USB. It has a 1/8" stereo line input and supports stereo 24-bit recordings. It’s powered over the USB cable. Best of all, it’s inexpensive at about $80. However, with the Transit you’d also need a mike preamp.
Therefore, a US-122 or M-Audio MobilePre USB might be better overall (unless you can make a better, lower power consuming preamp, possibly powered off the USB connector). The MobilePre is “designed for laptop recording such as field recording and sampling expeditions”, according to the manufacturer. Unfortunately, though, it’s only 16-bit.
If you decide to build your own preamp, don’t forget to experiment just using the line inputs on your laptop. Some aren’t too bad, with a S/N ratio of 70dB or better. Sure, that’s not great, but most likely you won’t be processing these signals much, which is where you really need the extra bits. Of course, your point about not sweating headroom is valid, but you still need to sweat the levels in the analog domain.
I suspect you’ll get better overall results by focusing on easily portable gear. Small hand-held parabolics seem to be pretty useful on the football field, but the S/N ratio required there is pretty low. You might be better off to find a way to put a camera mount on your mike so you can use a light camera tripod. Assuming you’re far from ground-transmitted noise (e.g., roads, volcanos), the camera tripod should work great as long as you have quiet feet.
Personally, I’d be tempted to try to find a way so the parabolic can be easily backpacked – either small enough to fit in a pack, or else with removable capsule arm assembly so it can be strapped on your back. Or better yet, strapped to the back of a laptop-backpack along with the camera tripod, making it an easy 1-man operation.
The easier it is to get to the location, the more locations you’ll get!
Archimedes is probably right that a portable recorder will be better overall than a laptop, simply because it will be more rugged and cheaper to replace after it gets soaked or dropped in the mud. That rules out the USB solutions, of course.
There are probably some better solutions these days, but a while back I had a portable Sony DAT machine - loaned from a music store to do a digital album mixdown. From my experience with that machine I’d suggest looking for something along those lines. There were models available that had balanced in with phantom power. A lot of foley artists were using Sony portables to capture sounds in the field. Some of those machines can be pretty pricey, but when you consider the price of a laptop capable of being a great DAW you probably aren’t looking at such a high price.
Oh, yeah, great ideas! I’m 5 hours ahead of US ET so just got posts from yesterday/PM.
(Not in order):
(D) Recording: Laptop isn’t cheap but I have a Thinkpad already available and also Mac I-Books from the school. USB talks either.
(B) © RE: 24 bits – I expect the dynamic range of wildlike sounds is very large: very distant to possibly quite close. I HOPE that 24 bit recording, with the gain set for some headroom for a close sound, will allow recovering distant sounds afterwards. This is the only application I know of where the ambient acoustic noise may be down at 25 Db or so, and microphone, electronics and wind noise may truly be noticeable. On that:
>> Watch out for wind noise. With a MS or a shotgun mic, you may need the full zeppelin/rycote solution.
Can you explain this a little? Sounds like a small, tight tent??
gtr4him amd archimedes, thanks for those great pointers!
Learjeff, the TRANSIT sounds perfect for this; the US-122 is high-end, but probably uses more battery power, and there are quite a few reviews about failing mike pre’s. Hmmm… RELATED: Can you confirm that the Transit’s headphone output can monitor while recording at lower (24B / 48KHz) settings?
>> I suspect you’ll get better overall results by focusing on easily portable gear
Yes, this is important… most of this will be backpacked by two people, who may well have overnight gear also. The ruggedness is somewhat important too. According to the discussions I’ve had so far with Tarak we will be in the Sahara on camels (I’m not making this up!) and, even scarier, dropped off on LaGalite island by a Garde Nationale patrol boat.
Well. I was looking for adventure and unusual music recording possibilities in Africa. OOhhh…! I could do 24 bit stereo recording of Berber (Bedouin) percussion and flute music out in their big tents in the Sahara. Now I know why I need that mike that Archmedes suggested:
>> A) There are many possibilities here. For one “works most places” mic, try a good mid-side stereo condenser mic. There are several available, starting with the above SONY, to models costing thousands.
… as well as a distance mike of some kind.
Anyone know if a ‘Stereo’ mike, if positioned in a parabolic reflector, gives any kind of stereo image??
Many Thanks! I got what I hoped for from this group: Stuff I hadn’t thought about, info I didn’t have, and a good tech topic to talk with friends about…
OK, I’d like to continue this as we all hear each others ideas. I’d especially like to talk about the “24 bit advantage” in recording sounds that peak WAY below full level.
>> Good luck. You are now obligated to send me a CD of African ambiences.
You bet; I’ll definitely be posting some examples and expect to have a section on my website with this stuff, including photos of the locations. So you can see if I was kidding about the camels.
I’ll second a DAT. Dragging a mic and a DAT will be hard enough, but hauling a parabolic mic, a pre, and audio interface, a laptop, and whatever water, granola bars, and doo dads will be a hassle. I would keep it simple. As for stereo etc, how do the National Geographic guys do it? You know when they are filimg those specials they are a 1/4 mile off using telephoto lenses to get the images, so they are probably using some sort of parabolic/shot gun mic. There has to be some info out there on their methods.
Geez…I think Bill’s link answers a lot of questions…you da’ man Bill!
TG
Hi Terry,
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| >> Watch out for wind noise. With a MS or a shotgun mic, you may need the full zeppelin/rycote solution. Can you explain this a little? Sounds like a small, tight tent?? |
Here’s a Rycote. It’s a system for shielding a mic from wind, most often seen at outdoor movie shoots or press scrums. Directional mics, especially shotguns, are susceptible to wind noise, so this elaborate shielding is often necessary. Unfortunately, the windshield also compromises the pick-up pattern, and can introduce frequency anomalies.
One nice thing about using a parabolic reflector is that you can use a simple omnidirectional mic with them, since the directivity comes from the dish. Omni mics are far less susceptible to wind noise (so you can get away with just a simple foam windscreen), and generally have higher outputs and better response. The downside of using a dish is the bulk and that it’s low frequency is limited by the dish size.
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| Anyone know if a ‘Stereo’ mike, if positioned in a parabolic reflector, gives any kind of stereo image?? |
I actually spoke once with a British recordist who did almost exactly that - using a dish behind a pair of forward-facing crossed cardioid mics. This goes against almost all the mic theory i know… which mainly proves that I don’t do actual recording experiments often enough.
I think you’re putting too much importance on 24 bit in the field. The gear you’re looking at will maybe perform better than 16 bit gear, but the improvement will be like 19 to 20 bit, not 24. The limiting factors will be analog, which means you still need to pay close attention to gain settings. I would suggest that your money is better spent getting great mics, decent preamps and a good 16 bit system, than putting more into a 24 bit system and cheaping out on the mics.
I wouldn’t personally go DAT. It’s a dying format, and it’s awfully fragile in the field.
I have a buddy who does sound for video, it’s his main gig. He may have some ideas.
I don’t think you want to put a stereo mike in a parabolic setup, though it might be worth a try. I think you’d end up getting a mostly mono sound from it, and probably not as good a mono sound as if you’d used a mono mike.
You could probably build a good parabolic mike using those $3 capsules you can get at Radio Shack. They have those in Africa, right? 
Just don’t expect it to be flat; I believe that the size of the reflector will determine the low cutoff frequency. But the amazing thing about parabolics is how much gain you get from them.
BTW, you may have laptops available – but how many are they going to let you destroy before your supply runs out? You might pitch them two scenarios, one using a laptop and the other using a small recorder, and compare the cost. If they have laptops that aren’t quite up to par for normal use but are good enough for recording, then price isn’t much of a factor; you’ll have to use the laptops.
Remember that using 24 bits doesn’t mean you don’t have to adjust the level for each recording. You’ll need to adjust it so that your analog gear is in the green, or you’ll get noise from that gear. Make sure that whatever you use, you have good meters to see what you’re doing.
Sorry I can’t verify anything about the Transit, since I don’t have one. I thought I needed one for playing softsynths live, but then someone turned me on to Wuschell’s Asio4All, and now I use my laptop’s builtin soundcard and it works just great. But that’s just a latency thing, unrelated to this issue.
I also don’t know whether the Transit supports direct monitoring. A builtin soundcard does, so it might. But if not, you’ll have to use “Live” mode and all that entails (latency issues, more CPU required).
BTW, how cool. I’d love to have a good excuse to go “camping” in remote places where I’d never want to just “go camping”. That would be like a dream come true for me.
I’ve built a nice mono mic pre-amp in an “Altoids” box complete with 2-9v batteries that will power it for months without an on/off switch. A little re-work and it can be a stereo pre-amp.
Don
Terry, I hope we get to hear some of the results. And, be careful where you point that shotgun mic.
You may want to visit www.national.com and ask for samples. They will send you up to six samples of ASICs (Application Specific Integrated Circuits) anywhere in the world via FedEx. Tons of pre-amp schematics and application notes on all of their devices too.
PS2: I just went to National for an update…Take a squint at the LMV722 Dual Op Amp. 2.2v - 5v supply, drain is only 930uA/Amp. You can power it continuously for a year on two AA Alkalines. The circuit is very simple. Take a look at its app notes for the circuit.