This is a review and detailed measurements of the Minidsp DDRC-88A balanced 8 channel in, 8 channel out, Dirac and manual EQ DSP system. It is on kind loan from a member and costs US $999. The connectivity as you see is with phoenix connectors and if you order a set of cables to XLR for that, it would add another $60. A remote is included as I think a Dirac 3.0 license plus manual configuration software.
The front is business like and doesn't give you much control over the unit other than changing configs and volume:
Back panel shows the rich connectivity of both unbalanced (RCA) and aforementioned balanced:
Due to some mix up, I did not get the external adapter and had to use my lab power supply. It drew 750 milliamps at 12 volts.
To be clear, the DDRC-88A digitizes all the inputs, processes them using a DSP and then converts them back to analog. Stated sample rate is said to be 48 kHz at 24 bits.
The USB connection is sadly for control only but there, the provided software worked beautifully in configuring the unit, changing DSP, levels, etc. All my testing was doing using the balanced inputs and outputs.
DSP Audio Measurements
I ran my testing as if the DDRC-88A is an analog preamp since that is the connectivity it provides. All effects unless said otherwise were disabled. Here is our dashboard then:
There is a default -8 dBFS of headroom which makes sense based on what I have heard the requirement from Dirac to be. At that default value, the gain is negative causing 4 volt input to produce 2 volts out. That can be adjusted of course and that is what I did to get the performance relative to output level:
Unlike many AV processors with EQ, as you see the DDRC-88A is fine producing output in excess of input to the tune of 4.7 volts before clipping.
Back to the dashboard, I turned on crossover processing and it did not impact the performance whatsoever. As it is, we have 15 bits of distortion-free range (90 dB of SINAD).
Dynamic range is just good enough to not impact the distortion-rating which dominates:
Frequency response is droops a bit at 20 kHz:
It seems that the sample rate is 44.1, not 48 kHz. But maybe there is a setting for that?
Intermodulation and noise are well above state-of-the-art analog preamps:
THD+N sweep versus frequency shows some low frequency perturbations:
The overall level is high also. My sense was that this was due to noise shaping and indeed it was:
Quantization noise in the audible band is pushed into ultrasonics. Since THD+N vs frequency has a wide, 90 kHz bandwidth, it takes in all the ultrasonic noise and penalizes the device with it. In reality worst case distortion spike is still at -90 dB.
DSP Performance
As a quick test, I dialed in an 80 Hz crossover for say, a subwoofer and used the default 48 dB/octave:
Looks clean and nice to me.
Conclusions
The performance of Minidsp DDRC-88A is just good enough to say it is not broken. It is significantly better than recently tested DSPeaker Anti-mode 2.0 Dual Core. With a SINAD of 90 dB, you are good using it on an amp having a SINAD of 80 dB. If the amp is any better than that, then the minidsp degrades its performance.
Based on measurements alone, I was borderline on recommending the DDRC-88A. But the software pushed me over the line, making it a joy to program the thing to build a discrete 7.1 system or two active speakers. Sadly, you can't do better than a good AVR or AV Processor although it does give you Dirac EQ and very nice set of programmable EQ.
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As always, questions, comments, recommendations, etc. are welcome.
I must stay, my commentary regarding our garden has not gotten me much donations. Maybe people think if I am getting produce form our garden I don't need money??? I am not a vegetarian folks. Need money for meat, fish, etc. So please donate what you can using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The front is business like and doesn't give you much control over the unit other than changing configs and volume:
Back panel shows the rich connectivity of both unbalanced (RCA) and aforementioned balanced:
Due to some mix up, I did not get the external adapter and had to use my lab power supply. It drew 750 milliamps at 12 volts.
To be clear, the DDRC-88A digitizes all the inputs, processes them using a DSP and then converts them back to analog. Stated sample rate is said to be 48 kHz at 24 bits.
The USB connection is sadly for control only but there, the provided software worked beautifully in configuring the unit, changing DSP, levels, etc. All my testing was doing using the balanced inputs and outputs.
DSP Audio Measurements
I ran my testing as if the DDRC-88A is an analog preamp since that is the connectivity it provides. All effects unless said otherwise were disabled. Here is our dashboard then:
There is a default -8 dBFS of headroom which makes sense based on what I have heard the requirement from Dirac to be. At that default value, the gain is negative causing 4 volt input to produce 2 volts out. That can be adjusted of course and that is what I did to get the performance relative to output level:
Unlike many AV processors with EQ, as you see the DDRC-88A is fine producing output in excess of input to the tune of 4.7 volts before clipping.
Back to the dashboard, I turned on crossover processing and it did not impact the performance whatsoever. As it is, we have 15 bits of distortion-free range (90 dB of SINAD).
Dynamic range is just good enough to not impact the distortion-rating which dominates:
Frequency response is droops a bit at 20 kHz:
It seems that the sample rate is 44.1, not 48 kHz. But maybe there is a setting for that?
Intermodulation and noise are well above state-of-the-art analog preamps:
THD+N sweep versus frequency shows some low frequency perturbations:
The overall level is high also. My sense was that this was due to noise shaping and indeed it was:
Quantization noise in the audible band is pushed into ultrasonics. Since THD+N vs frequency has a wide, 90 kHz bandwidth, it takes in all the ultrasonic noise and penalizes the device with it. In reality worst case distortion spike is still at -90 dB.
DSP Performance
As a quick test, I dialed in an 80 Hz crossover for say, a subwoofer and used the default 48 dB/octave:
Looks clean and nice to me.
Conclusions
The performance of Minidsp DDRC-88A is just good enough to say it is not broken. It is significantly better than recently tested DSPeaker Anti-mode 2.0 Dual Core. With a SINAD of 90 dB, you are good using it on an amp having a SINAD of 80 dB. If the amp is any better than that, then the minidsp degrades its performance.
Based on measurements alone, I was borderline on recommending the DDRC-88A. But the software pushed me over the line, making it a joy to program the thing to build a discrete 7.1 system or two active speakers. Sadly, you can't do better than a good AVR or AV Processor although it does give you Dirac EQ and very nice set of programmable EQ.
-----------
As always, questions, comments, recommendations, etc. are welcome.
I must stay, my commentary regarding our garden has not gotten me much donations. Maybe people think if I am getting produce form our garden I don't need money??? I am not a vegetarian folks. Need money for meat, fish, etc. So please donate what you can using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/