So its an analog to digital converter that uses sampling and quantization? I understand all of that but it sounds to me like it would change the outputted sound. How exactly is this performed?

The reason I ask is because I'm looking at these two near identical preamps

AD MPA II with A/D conversion


So the first one is digital and it does this conversion that way? The second does it the old way aka analog? Whats the difference besides price?

1 Answer 1


The difference between those two products is that one includes an analog to digital converter and a digital output, in addition to the analog outputs. You might want the digital output if you have a mac (most modern macs have digital input) but no outboard audio interface. Or if you have other gear with S/PDIF digital input.

Don't trust me (really). Check out the owners manual on the artpro website. There is a signal flow diagram on page 2 that shows you exactly where the A/D conversion occurs. Compare with the analog-only version.

An analog to digital converter measures the voltage of an input signal at a fixed frequency, and converts the voltage to a binary value. Modern ADCs typically support at least 16 bits of resolution at a 44.1 KHz sample rate (CD quality), many support 24 bits at 96 KHz.

It is typical for digital effects boxes to have Analog to Digital Converters (ADC) on the inputs, digital processing in the middle, and Digital to Analog Converters (DAC) on the output. This is because the effects are operating in the digital domain. Preamps are generally analog devices, so any conversion to digital would typically be saved for the output side. You want to do your amplification in the analog domain.

  • Ah thanks for the clarification. I have Akai EIE Pro as my outboard audio interface, so I wouldn't need the one with the ADC would I?
    – Travis Dtfsu Crum
    Oct 2, 2012 at 18:52
  • 2
    I'm not sure you need that ART preamp at all - the Akai has four inputs that can handle mics and provides phantom power and gain. If you need more gain or like the way that the ART colors your mic signal, then go for it. Otherwise, the ART and Akai seem to have a lot of overlap. Oct 2, 2012 at 18:56
  • I like the color of the ART and the preamp inside of my EIE isn't cutting it for me. Especially with my Shure SM7B. Every recording just seems to be lacking that extra omph and have annoyingly low gain levels. At least with vocals which is mainly what I'm recording.
    – Travis Dtfsu Crum
    Oct 2, 2012 at 19:11
  • also adds a bit of noise when gain levels are raised which I do not like at all
    – Travis Dtfsu Crum
    Oct 2, 2012 at 19:13
  • 1
    Almost everything wants analog. The only FX box that I'm aware of that requires digital input is the Space Station SST-206, which appears to be out of production. Everything else will have analog inputs. Oct 2, 2012 at 21:00

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