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We're not even close

— By Paul McGowan —
We're not even close
Part of the joy and privilege of being involved in both the recording and playback chains is the chance to grow and learn: new methods in recordings of miking and capturing sound and, in the reproduction chain, new circuit topologies and silicon. Recently a fellow recording engineer working with the same basic DSD chain suggested to me that using an external microphone preamplifier before going into the A/D converter is probably a bad idea. Why? Because it is thought that the particular A/D converters we both use (from Pyramix) are better served skipping a step and going directly in. That made one heck of a lot of sense to me, and so, on a recent recording session of Octave's beautiful Steinway piano by composer and pianist, Gustaf Hoyer, I recorded it both ways: directly in and with the addition of an external microphone preamplifier. Oh my. The difference between those two methods is stark. Using the identical microphones and setup for both:
  1. Going directly into the A/D converter's built in microphone stage left me cold. Unmoved. Mechanical. Clear and crisp, yes. But without life or feeling.
  2. Inserting in the same path the Manley vacuum tube microphone preamplifiers between the microphones and A/D direct inputs. Holy sh*t! Life! Musicality. Openness. You are there. Still clear and crisp.
And here's the crazy thing. When in Pyramix you switch between microphone and line level inputs, the electronic chain remains identical. In other words all that changes is the impedance and gain of the input stage. Same circuitry with only a 20dB pad inserted. This is absolutely bizarre and makes no sense to me. It reminds me of when I used to be an advocate of the shorter path of DAC->power amplifier. Inserting the BHK preamp (DAC->BHK preamp->power amp) made magic. Other than just reporting this observation, my only thought is that my friend must not have used the same microphone preamplifiers. The good news is twofold: first, all recent Octave recordings (and many earlier ones) have used the Manley's for preamplification. Second, while we always take suggestions and are anxious to experiment, in the end, our ears tell us what works and what does not. As my hero, Mr. Spock might say, fascinating.

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