The Mini-Disc Portable Kit:

In late 2002 I decided I needed something more portable to take to Trinidad for the upcoming Steelband Music Festival.  Several manufacturers were selling Mini-Disc recorders, extremely compact and not very expensive.  The downside was that they recorded "compressed bit-rate" recordings in a Sony format called ATRAK, similar to MP3's.  They were applying psycho-acoustics and leaving out "inaudible" sounds in order to achieve reasonable recording times on the small mini-discs.  I was not happy to make this compromise, but listening tests of the highest bit-rate, least compressed recordings compared favorably with CD's.  I purchased a recorder made by Sharp that had good reviews.  One other negative was that there was no way to transfer the complete recording digitally into my computer to edit.  I had to play the disc in real time, recording in analog on the computer connected to the line/headphone output of the Minidisc.  Tests showed that there was no audible degradation doing this. (More recently I have acquired, at no cost, a professional Mini-Disc recorder with digital inputs and outputs. It came from a radio station that was about to send it to electronic recycling. I have re-transferred some of my early Mini-Disc recordings, now completely in the digital domain. I notice little difference from the original analog transfers.)

For microphones, I decided to try a pair of DPA 4061 lavalier microphones (the type you see news anchors wearing) that I already owned.  These are omnidirectional mikes (they pick up sound from all directions essentially equally).  The specifications on these mikes are very good, the frequency response is essentially flat from well below to well above the range of human hearing, with a slight "presence bump" in the upper midrange that typically adds a little "sparkle" to recordings.  Their only weaknesses are that they have somewhat high "self noise", hiss that will be totally inaudible in any live recording situation; and the cables are somewhat fragile, more of an issue when worn by performers than when on a fixed stand.

DPA has now come out with improved models, with even less distortion at high sound levels and an option that uses much stronger cables, not likely to be broken in use. I have purchased a pair of the improved model which I now use regularly. I also have purchased a pair of much improved windscreens, which have the additional benefit of being mostly rainproof.

To do orchestral recordings I used a technique used since the earliest days of stereo in the 1930's, called "spaced omnis".  The microphones are placed anywhere from a few inches to some number of feet apart, depending on the width of the "orchestra" you are recording and how wide you want the stereo image to be in the recordings.  The advantages for me were:

• it allowed me to use the very small and light lavaliers.
  
  
• Omnidirectional mikes typically have very good bass response, better than most Cardioids (mikes that pick up from the front only.)
  
  
• The setup is simple and can be easily varied to suit the needs of the venue. 
  The  disadvantages of spaced omnis are that the recording may not be very "monophonic compatible" (not an issue today unless you plan to broadcast it on AM radio), and that being omnidirectional, the microphones may pick up undesired sound, such as noise in the audience, spill from a PA system, etc.  To me, given my goals, the advantages outweighed the disadvantages.

One remaining issue was powering the microphones.  Electret microphones, such as these lavaliers, require a source of voltage to work.  The Minidisc microphone inputs provided voltage to work with consumer headset microphones.  While it would have worked with the DPA mikes, the voltage was less that that recommended by DPA and would have degraded the sound of the microphones. I could have bought a pair of battery packs from DPA for about $150. each, but I designed my own, built with a few dollars worth of parts from Radio Shack.  I did purchase some extension mike cables from DPA. 

So I was in business.  I tried this setup and was quite pleased with the results.  I used this setup for several years before upgrading.