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Running analog in - Flex vs 2x4HD 2 months 1 week ago #60336

  • vvume
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Distortion is most likely to be due to digital signal clipping I'd have thought. If your analogue input peak level is close to the maximum that the DDRC-24 can accept then boosts applied by Dirac Live can cause this. The solution is to apply up to 10 dB attenuation on your miniDSP to avoid this, which can be as simple as setting the master volume to -10 dB. You could of course be overloading the input of the miniDSP too. 

The signal itself is not clipping because if I increase the XO to 100Hz (or higher) then I don't hear any distortion through my subwoofer. There is distortion even if use R200 standalone without a XO/sub. The key here is DIRAC is turned on. I did a simple 2 channel in/out without XO or Dirac on the miniDSP and used Equalizer APO in windows to do EQ using REW's measurements (PC->Equalizer APO->USB->DAC->miniDSP(A2A)->Amp/Sub) and the output is clean with corrections (so ADC/DAC alone in miniDSP is not causing the issue).

The R200 on its own goes down as low as 38Hz in my room and so I was hoping to set the XO between 38-52 Hz but this clearly results in distortion. My SA LS3/5a and Emotiva are XO at 70Hz with no distortion for the same input signal and output levels.

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Running analog in - Flex vs 2x4HD 2 months 1 week ago #60337

  • Ultrasonic
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Distortion is most likely to be due to digital signal clipping I'd have thought. If your analogue input peak level is close to the maximum that the DDRC-24 can accept then boosts applied by Dirac Live can cause this. The solution is to apply up to 10 dB attenuation on your miniDSP to avoid this, which can be as simple as setting the master volume to -10 dB. You could of course be overloading the input of the miniDSP too. 

The signal itself is not clipping because if I increase the XO to 100Hz (or higher) then I don't hear any distortion through my subwoofer. There is distortion even if use R200 standalone without a XO/sub. The key here is DIRAC is turned on. I did a simple 2 channel in/out without XO or Dirac on the miniDSP and used Equalizer APO in windows to do EQ using REW's measurements (PC->Equalizer APO->USB->DAC->miniDSP(A2A)->Amp/Sub) and the output is clean with corrections (so ADC/DAC alone in miniDSP is not causing the issue).

The R200 on its own goes down as low as 38Hz in my room and so I was hoping to set the XO between 38-52 Hz but this clearly results in distortion. My SA LS3/5a and Emotiva are XO at 70Hz with no distortion for the same input signal and output levels.

That could easily point to the digital clipping I mentioned above, noting that the Dirac filters will be different for main speaker and subwoofer when one or the other is in the pass-band and the relevant frequency. Experiment with the attenuation I suggested above.

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Running analog in - Flex vs 2x4HD 2 months 1 week ago #60338

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Distortion is most likely to be due to digital signal clipping I'd have thought. If your analogue input peak level is close to the maximum that the DDRC-24 can accept then boosts applied by Dirac Live can cause this. The solution is to apply up to 10 dB attenuation on your miniDSP to avoid this, which can be as simple as setting the master volume to -10 dB. You could of course be overloading the input of the miniDSP too. 

The signal itself is not clipping because if I increase the XO to 100Hz (or higher) then I don't hear any distortion through my subwoofer. There is distortion even if use R200 standalone without a XO/sub. The key here is DIRAC is turned on. I did a simple 2 channel in/out without XO or Dirac on the miniDSP and used Equalizer APO in windows to do EQ using REW's measurements (PC->Equalizer APO->USB->DAC->miniDSP(A2A)->Amp/Sub) and the output is clean with corrections (so ADC/DAC alone in miniDSP is not causing the issue).

The R200 on its own goes down as low as 38Hz in my room and so I was hoping to set the XO between 38-52 Hz but this clearly results in distortion. My SA LS3/5a and Emotiva are XO at 70Hz with no distortion for the same input signal and output levels.

That could easily point to the digital clipping I mentioned above, noting that the Dirac filters will be different for main speaker and subwoofer when one or the other is in the pass-band and the relevant frequency. Experiment with the attenuation I suggested above.
 

Thanks for the tip - I'll do more experimentation with the attenuation and see if that solves my particular problem.

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Running analog in - Flex vs 2x4HD 1 month 1 week ago #60751

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@ultrasonic is exactly right, I also think it could be overloaded analog ins 

i just installed a ddrc24 in a car for a gal and I used the 4v input jumper and exactly on the button 4v it started saturation and overloading the inputs 

I had to bust out my scope because my rms meter said 3.8v and it was actually a tad over 4v scoped 

so…… I would say they do exactly what they say they’ll do and not a inch more 

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