Essential differences

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Essential differences

Yesterday we waxed on about microphone preamplifiers and how important they are to the recording chain. 

A couple of folks asked me what brands we have that are solid state and they are Grace, and Forsell. Both are excellent preamplifiers that sound wonderful, though as mentioned, my go-to preamplifiers are the vacuum tube Manleys.

How do microphone preamplifiers different from, say, a BHK Signature preamplifier?

Let's have a look.

An audio preamplifier like the BHK has the following at its core:

  • Multiple inputs
  • High impedance direct coupled inputs (47kΩ typical)
  • Gain of no more than 20dB
  • Volume, balance, and input select and remote for controls
  • Low output impedance 

A microphone preamplifier has at its core the following:

  • 1 balanced dedicated input
  • Low impedance transformer coupled inputs (1kΩ typical)
  • Gain typically 50dB to 60dB
  • VU metering
  • Volume control for input
  • 48V phantom DC power supply to feed internal microphone preamplifiers
  • Low output impedance

So, basically microphone preamplifiers are low impedance in and out with high gain, low noise, and loads of headroom.

Audio preamplifiers are high input impedance, low gain, low noise, low output impedance.

The "same" in that they amplifiy a small signal into a big signal and provide a means of changing level. In all other respects they are very different beasts.

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Paul McGowan

Founder & CEO

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