Minidsp DDRC-88A Dirac Multichannel DSP Review

[PeteL]

Well, looking at the SINAD, it won't measure better. The recent Denon's are 6 tot 10dB better than this.

I believe Denon don't do Dirac, maybe Odyssey is good too but Martin was talking about "The recent crop of Dirac receivers"

 

[voodooless]

I believe Denon don't do Dirac, maybe Odyssey is good too but Martin was talking about "The recent crop of Dirac receivers"

Ah yes, true that.. Well, in that case it's shamefully close.. I'm not sure who should be more ashamed though..

 

[Martin]

I believe Denon don't do Dirac, maybe Odyssey is good too but Martin was talking about "The recent crop of Dirac receivers"

Beat me to it.

 

[PeteL]

If you can't invest the money, you can always invest some more time and learn how to do it yourself using freeware tools.. there is more than enough out there.

Is there? I believe that FIRs/Mixed Phase, with impulse response correction is quite a unique package, Sonarworks seems to have interesting features too, all options are fairly expensive, I really only have a stereo setup that I'm kinda happy with at the moment, but I don't even know if any software only version could work, I mainly use BlueOs for Music, and VLC + streaming sites for movies. I'd invest some time, and I have all the technical background needed, but I am really not sure that "there's more than enough out there" What do you recommend?

 

[voodooless]

Is there? I believe that FIRs/Mixed Phase, with impulse response correction is quite a unique package, Sonarworks seems to have interesting features too, all options are fairly expensive, I really only have a stereo setup that I'm kinda happy with at the moment, but I don't even know if any software only version could work, I mainly use BlueOs for Music, and VLC + streaming sites for movies. I'd invest some time, and I have all the technical background needed, but I am really not sure that "there's more than enough out there" What do you recommend?

Rephase should do the trick I think. And if you actually invest some time, you can also do everything on your own using Mathlab or Octave

 

[ehabheikal]

Dirac on PC is expensive. Multichannel version is $500.

I thought dirac on pc was discontinued?

 

[digicidal]

I thought dirac on pc was discontinued?

Nope, but it's painfully hard to find (or at least it was... better now). It's available as a plugin solution which can be used with a DAW or JRiver, etc.

 

[PeteL]

Rephase should do the trick I think. And if you actually invest some time, you can also do everything on your own using Mathlab or Octave

Not very familiar with Octave, but Mathlab, altough an extraordinary tool, is far from cheap... Having said that, Yes I could create all the filter necessary, but I don't think I could run this after a player that is network based, can't think of a way to do this, Would still need an external processor, I believe that Mini Dsp open DRC platform fit the bills. I'll look up rephase.

 

[TNT]

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:
View attachment 82281

Back panel shows the rich connectivity of both unbalanced (RCA) and aforementioned balanced:
View attachment 82283

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:

View attachment 82285

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:

View attachment 82286

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:
View attachment 82287

Frequency response is droops a bit at 20 kHz:
View attachment 82288

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:
View attachment 82289

THD+N sweep versus frequency shows some low frequency perturbations:

View attachment 82290

The overall level is high also. My sense was that this was due to noise shaping and indeed it was:

View attachment 82291

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:

View attachment 82292

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/

 

[TNT]

It would be nice to see what the filter function does to it's perfromance i.e.:

- make a 2 way filter (as here)
- sum the two channels and run all measurements (FR, IM, SINAD etc) again.

//

 

[TNT]

Dirac on PC is expensive. Multichannel version is $500.

There is a new kid on the block... Camilla.

https://github.com/HEnquist/camilladsp#introduction

Free for Linux, MacOS and Wind... with a GUI... and as many channels as you like... whats not to like ;-)

//

 

[SirMaster]

For about the same price you can grab the Okto and implement software version of DSP, yeh ends up a little more expensive but you get pristine measurements with your chosen DAC.

I think people need to get over hardware based DSP when software is more versatile and allows you to choose the best equipment to implement it with.

It's not like your getting a range of Dolby, or other decoders for surround plus Dirac and top of the line measurements.

But how do we get Atmos and DTS:X decoding?

 

[snackiac]

But in typical miniDSP fashion, they would not think they have done their job unless they have selected combination of features and connectors that always have people scratching their heads on how to use/connect to 90% use cases requiring all kinds of adapters and dongles.

Only the SHD series avoids this quirkiness.

This smells of engineer driven design, probably fixated on particular use cases they have themselves. With the SHD series looks like they actually hired some product managers

 

[SirMaster]

There is a new kid on the block... Camilla.

https://github.com/HEnquist/camilladsp#introduction

Free for Linux, MacOS and Wind... with a GUI... and as many channels as you like... whats not to like ;-)

//

Where is the GUI?

 

[ElNino]

There is a new kid on the block... Camilla.

https://github.com/HEnquist/camilladsp#introduction

Free for Linux, MacOS and Wind... with a GUI... and as many channels as you like... whats not to like ;-)

//

Thank you for that link! I hadn't seen that -- it looks like a good project.

The architecture they chose is a little unfortunate though... it's using a push-based model rather than a pull/event-based architecture, suggesting that the author isn't particularly experienced with writing low-level real-time audio processors. The model he chose works with ALSA because there's a feedback mechanism, but unless you're working with a single clock domain on Windows or OS X (i.e., a hardware loopback device), you'll basically have to use the resampler.

 

[ehabheikal]

Nope, but it's painfully hard to find (or at least it was... better now). It's available as a plugin solution which can be used with a DAW or JRiver, etc.

how much for stereo?

 

[Vasr]

how much for stereo?

https://live.dirac.com/pro-audio/

All the information you need for computer use on one page.

 

[phoenixdogfan]

Nope, but it's painfully hard to find (or at least it was... better now). It's available as a plugin solution which can be used with a DAW or JRiver, etc.

I actually have it installed. Did so at middle of last month, but I've been to busy to run corrections.

 

[stunta]

Thank you @amirm. This is one review I was very eagerly waiting for.

I am a bit confused with the comments. I use the DDRC-88A with a pre-pro that does Dobly/DTS decoding for a 5.1 setup (I don't use Atmos or DTS-X). Is there a single-box solution for the same that measures better that this combo?

Regarding using a PC with some software into a device like Okto, where and how would the Dolby/DTS decoding occur? How would that play along with Dirac on the PC?

 

[phoenixdogfan]

Dirac on PC is expensive. Multichannel version is $500.

For me, it's a mostly sunk cost. I've owned two channel, PC based Dirac 1.0 since 2015. I will have to spend for bass management and the multichannel upgrade when they become available, but the upgrade to 3.0 was free.