Gear
| My samples are recorded on a 1997 vintage Sony Walkman D8 Digital Audio Tape (DAT) recorder.
The Sony D8
is about the size of the earliest Sony cassette Walkmans. It is easily
concealed and is popular with concert tapers. With a good set of
microphones a recording of very good quality can be made. The DAT format,
while never gaining consumer acceptance, was very popular with recording and
broadcast professionals and musicians with home studios. In recent years the
DAT format has begun to die off and now it is getting diffcult to buy tape. I hope to be
upgrading to a solid state recording system soon.
For microphones I have a pair of Core Sound Binaural microphones. They are very small, about the length of a jellybean but a bit smaller in diameter. I usually clip them to a piece of stiff fencing wire stapled to a large diameter dowel and use that as a handle. The mics can handle high sound levels without distorting. They are small enough to be placed inside engine compartments without interfering with things like throttle cables and fan belts. I'll run the cable around to the door and try to find a place where the rubber seal has a split. Failing this, I'll run it through the open passenger window. I've had some folks ask me about technique, and I've been hesitant to dish out information as I consider myself to be an amateur. Nevertheless, here's roughly how I go about it. For driveby scenarios, I'll stand next to the road with microphone pointing at a 45 degree angle to the approaching car. As the car passes, I'll rotate roughly 90 degrees to follow the car, so the mic ends up pointing 45 degrees down the road. This seems to give me the most signal while still preserving some of the stereo "pan". Wind is a constant enemy, and if it's blowing more than a few miles an hour it comes through on the tape as rumble, even with the stock Sony foam windscreen. I have done my best to pull this out in post-processing with little success. There are devices that go over the mic to cut down on this, but I've been unable to find them for my microphones. The trade name for it is Rycote. Correct levels are key, and engine music can have a very wide dynamic range (i.e. really soft to really loud). I keep a constant eye on the record levels watching for the [OVER] indicator. If I see that, it's my cue to back off the levels a bit. The biggest mistake I made when I started is not recording long enough. I've missed a couple of nice fadeouts by hitting [stop] too early. It's always possible to truncate things later, but not add what you've missed. Once the sound is on the tape, I plug the D8 into an Opcode DATport (no longer available) through a 7-pin to SPDIF Core Sound cable. From the DATport, the digital signal passes into the computer through its USB port and into Audacity software. There the samples can be cropped to individual sound clips, which are then normalized. Normalization amplifies the whole clip so that its loudest part is as loud as permitted. This helps to make all the clips sound about the same volume. I then do any equalization or compression. Equalization is taking parts of the frequency range and making them louder or softer. This is one of my methods of reducing wind noise (bass rumble). Compression is very handy for the driveby samples as it raises the volume of the lead in and lead out in relation to the volume when the car is right in front of me. When I'm happy with the clip, I'll do a .5 second fade-in and a 1.5 second fade-out and save the file. The .wav file is then encoded into the MP3 format using the LAME encoding engine and posted here. The MP3 format is a way of saving audio files using a compression scheme to drastically shrink the file. While many claim that MP3 is "CD quality", it is not. Different encoding rates are used (measured in kilobits per second, or kbps), and the quality is inversely proportional to the filesize. For example, a file encoded at a rate of 128kbps may compress by a ratio of 1:9, but may have a harshness to the high frequencies. A file encoded at 192kbps will compress 1:7, but sound much better. I try to post my samples at 192kbps as this keeps the high frequencies clearer. I'd be happy to answer any questions or just chat about gear and techniques. I would especially love to hear from anyone else who is doing this sort of thing. Please E-mail me.
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