TW #66 — Sound Recording (Cowboy)

An engineering student's (NDSU, mechanical engineering with EE and CS; built his own speakers and sub) answer to "what is the best method of recording" for a tracker: the signal chain from source to sample, measured with a scope where he could.

Key claims#

• The source matters most. An A/D conversion never improves on what went in (his "second law of thermodynamics" analogy), so set the source's output level optimally first, then check the connectors: clean (he wipes them with a rag and a little WD-40), correctly plugged, shielded 3-conductor cable (he makes his own), short (under 3 feet, so impedance balancing is no issue). "Oxygen free copper is a myth."
• Direct digital CD recording (in fasttracker-2 "or some other direct CD recorder"; OS/2 has it built in) "is the way to go".
• Never route the CD-ROM's analog audio cable through the case to the sound card: "The inside of your computer case has more RF crap than any other source in your home" — his scope test (200 Hz–20 kHz) found as much as −40 dB of pickup on a loop line through the case. If you must, wrap the wire in foil and insulate it, or run a cable from the drive's outside plug to the card's line-in, outside the case.
• EQ / synth / mixer in between: use active, not passive, filtering; a bass/treble/bass-boost box can be built for under $25 (Radio Shack books, Radio Electronics back issues).
• Sound cards: on his Fluke scope the GUS had the least THD in playback and recording, S/N 72 dB at 50 Hz to 81 dB at 8.5 kHz; the AWE32 "a CLOSE second" at 70 dB at 45 Hz to 79 dB at 7 kHz (worst and best figures within 40 Hz–18 kHz). A foil-and-cardboard shield around the card, one layer grounded to the case, might help — he could not verify it.
• Sample formats: as he states it, IFF is 8 kHz mono only; WAV goes to 44.1 kHz stereo but most players cannot sustain that throughput, so keep samples under about 2 MB; avoid AU and SND except for special effects.
• Recording a mixdown: ordinary hi-bias cassettes. In a lab test of ten waveforms, an expensive metal tape had more noise than a $1.50 tape, though it helped below 200 Hz; CrO2 was only ±2 dB better between 200 Hz and 10 kHz. No cheap analog cassette holds up above 16 kHz or below 200 Hz — reel-to-reel if you must; DAT would be nice but few cards do 48 kHz or digital out. He uses Goldwave and Cubic Player.

Practical takeaways#

• Level and cabling before anything else; keep cables short and clean.
• Record CDs digitally; keep analog runs out of the PC case.
• Active EQ if you insert one; GUS or AWE32 for the cleanest converters of 1996.
• Keep samples under 2 MB; 44.1 kHz stereo WAVs are fine for the editor, not for playback on 1996 machines.

Notable quotes#

• "The inside of your computer case has more RF crap than any other source in your home."
• "Oxygen free copper is a myth. Save your money unless that is what you believe."

Relevance#

The only source so far on the recording end of sampling; basis of recording-samples and a hardware note for fasttracker-2 (direct CD sampling).

Pages touched#

recording-samples, multisampling, fasttracker-2, instrument-design, levels-and-headroom.