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miniDSP SHD w/Dirac: -10 dB ouput level setting cuts resolution 90%?

YouCanCallMeGeorge

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#1
From the miniDSP SHD Series User Manual:
If audio playback is distorted, you may have too much gain internal to the DSP. Dirac Live can apply up to 10 dB of gain, so the output level should be kept lower than -10 dB to guarantee that there is no distortion with a full-scale input signal. This issue typically occurs when volume control is being done downstream of the SHD Series processor. If so, set the SHD Series processor at -10 dB, and then use the downstream equipment to control volume.
If I've done the calculation correctly, -10 dB means the output is one tenth the input. I interpret this to mean that the signal coming into the DSP will be multiplied by 0.1 before any work is done by Dirac.

Seems like the result would be loss of 90% of the resolution in the original signal.

Separately, I don't understand what the downstream volume control has to do with the problem of avoiding clipping internal to the DSP. If DL applies a maximum gain of N (multiplier, not dB), then the incoming signal must be multiplied by 1/N prior to feeding into DL to avoid clipping.
 
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#2
SHD operates in 32 bit floating point and therefore has plenty of headroom to handle boosts internally without clipping. However, if the output level ever exceeds 0 dB you will clip the analog output. The volume control is one way to reduce the analog output level and is implemented after the DSP, not before. If you are not using the internal volume control then you will need to attenuate the SHD output by the maximum boost you have implemented to avoid clipping. You can measure this value exactly and do not need to rely on a blanket -10 dB cut.

The recent updated SHD review discusses this issues in more detail.

https://www.audiosciencereview.com/...sp-shd-review-updated-dsp-dac-streamer.18681/

Michael
 
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YouCanCallMeGeorge

YouCanCallMeGeorge

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Thread Starter #3
SHD operates in 32 bit floating point and therefore has plenty of headroom to handle boosts internally without clipping. However, if the output level ever exceeds 0 dB you will clip the analog output. The volume control is one way to reduce the analog output level and is implemented after the DSP, not before. If you are not using the internal volume control then you will need to attenuate the SHD output by the maximum boost you have implemented to avoid clipping. You can measure this value exactly and do not need to rely on a blanket -10 dB cut.

The recent updated SHD review discusses this issues in more detail.

https://www.audiosciencereview.com/...sp-shd-review-updated-dsp-dac-streamer.18681/

Michael
That all makes sense. I made it halfway through the comments on the SHD review; that's where I heard about the -10 dB offset. I'll go back and read about the maximum boost value. Hopefully that info is also in the DL user manual, as I ordered an SHD an hour ago.
 
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