Tips and tricks

Omid

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May 28, 2017
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44
I thought I’d share some thoughts here some might find helpful:
  • If your Dac has an adjustable output voltage (my Motu has a trim that varies output from -4 to + 20 dBu), you should adjust it to match your amp’s input sensitivity. Too low and you won’t get as loud as you could, or conversely too high, your amp will clip.
  • The higher the dBu output of your DAC, the better signal to noise ratio.
  • Audio signals can exceed 0 dBFS due to intersample overs. This becomes more obvious when you upsample your 44.1 kHz source. Programs like Roon, and DACs like benchmarkmedia have headroom management to get around that.
  • Audiolense attenuates your signal depending on the configuration settings you choose (often people pick 6-10 dB, I’ve presently set mine to 0 dB). If your amp doesn’t have enough gain, or your speakers are not sensitive, you might not be able to play as loud as you’d like.
So from all the above info, it follows that if your DAC can potentially be set to have a much higher dBU output than your amp can handle, you should take advantage of that. Set your Dac to Max output, and use the excess voltage as headroom management, and Audiolense correction room, while improving your DACs SNR, and also playing music as loud as your system can.

To illustrate: my amplifier, a benchmark AHB2 can be set to have an input sensitivity of 22 dBu, or 14.2 dBu, or 8.2 dBu.

If I select 22 dBu, my DAC, can only output a maximum of 20 dBu. I lose 2 dBu which is not great.

So I have chosen the second option, 14.2dBu. I set my DAC to an output of 20 dBu. My Audiolense correction at the present time is set to 0 dB, so I have dialed 5.8 dB attenuation for headroom in Roon.

This ensures that the effective output from my DAC is 20-5.8= 14.2dBu. This improves my signal-to-noise ratio, and gives an exact match for my amplifier’s input. It also prevents any intersample overs, i.e. no clipping.

If I chose 8.2 dBu, I would have even more room to play (say 4 dB headroom in Roon for intersample overs, 8 dB for Audiolense correction). The downside is my amp’s SNR would be a bit worse.

This might be self evident to some, but I thought it might help some people (esp if you have an adjustable DAC output like a MOTU or Lynx Hilo, and/or adjustable amp input sensitivity).
 
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