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Minidsp Flex Review (Audio DSP)

Rate this product:

  • 1. Poor (headless panther)

    Votes: 2 0.5%
  • 2. Not terrible (postman panther)

    Votes: 8 2.0%
  • 3. Fine (happy panther)

    Votes: 85 21.0%
  • 4. Great (golfing panther)

    Votes: 309 76.5%

  • Total voters
    404

amirm

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This is a review and detailed measurement of the Minidsp Flex audio signal processor. It was sent to me by the company and costs US $475 for unbalanced and $550 for balanced that I tested.

Minidsp Flex Review Analog In Crosstalk DSP Audio Processor Balanced.jpg

Flex borrows the interface from SHD and puts it in a compact package. Seeing how I really liked that interface with nice volume control, this is a very good move.

Back panel shows why this product is so useful:

Minidsp Flex Review Back Panel Power Supply DSP Audio Processor Balanced.jpg


Not only do you have a suite of digital input but also analog. More importantly, you can rote any input to any output and apply crossover, parametric EQ filters and compression. The software interface is mostly intuitive except for channel routing which required a bit of looking around.

The supplied remote control allows you to eliminate any need for a preamplifier and drive a power amp directly.

Minidsp Flex DAC Measurements
I alternated between Coax S/PDIF input and USB although performance is the same in both. Here is our dashboard:
Minidsp Flex Measurements DSP Audio Processor Balanced.png


OK, I was not ready for this. A multifunction device with DSP that has a SINAD (relative sum of distortion and noise) to rival and outperform many dedicated DACs?


best audio dsp review.png


Among its own category which is a mix of DSP and AV receivers and processors it sets a new high bar:


Best AV processor review.png


First of its kind to land in the blue "excellent" category!

Above was with the volume at -0.5 dB. There is a bit more performance if you set it to 0:

Minidsp Flex Measurements THD+N vs Level DSP Audio Processor Balanced.png


Dynamic range is very respectable for this class:

Minidsp Flex Measurements Dynamic Range DSP Audio Processor Balanced.png


There is something holding IMD distortion back though:

Minidsp Flex Measurements IMD DSP Audio Processor Balanced.png


This causes the same limiting in multitone:

Minidsp Flex Measurements Multitone DSP Audio Processor Balanced.png


JItter test shows some interference but they are at such ridiculously low level that bother the eye far more than any ear could ever detect them:

Minidsp Flex Measurements Jitter DSP Audio Processor Balanced.png


DAC filter is the typical default "lazy" ones in DAC chips:

Minidsp Flex Measurements DAC Filter DSP Audio Processor Balanced.png


This hurts THD+N versus frequency a bit but the outcome is still good:
Minidsp Flex Measurements THD+N vs frequency DSP Audio Processor Balanced.png


Linearity is excellent:
Minidsp Flex Measurements Linearity DSP Audio Processor Balanced.png


Minidsp Flex Analog Input Measurements
Some people have an analog only path (e.g. for turntables) and would still want to implement active speakers and/or equalization for room modes. Let's see how we do here:


Minidsp Flex Measurements Analog In DSP Audio Processor Balanced.png


I am amazed once again! End to end performance this good? Remember this is the performance of ADC and DAC combined. And we still manage to have distortion at < -110 dB (18+ bits).

Dynamic range suffers a bit naturally but still, quite good:

Minidsp Flex Measurements Analog In SNR DSP Audio Processor Balanced.png


I was relieved to see wide and flat response:

Minidsp Flex Measurements Analog In Frequency Response DSP Audio Processor Balanced.png


So unlike many AV products that resample everything to 48 kHz, here we have end to end sample rate of 96 kHz (my guess). Bandwidth is in excess of 35 kHz.

Crosstalk was superb:
Minidsp Flex Measurements Analog In Crosstalk DSP Audio Processor Balanced.png


This is better than countless stand-alone preamps!

THD+N vs frequency again shows no frequency dependence:

Minidsp Flex Measurements Analog In THD+N vs frequency DSP Audio Processor Balanced.png


IMD performance is again limited by DAC performance:
Minidsp Flex Measurements Analog In IMD DSP Audio Processor Balanced.png


EDIT: Post review question was raised about performance of channels 3 and 4. Here is that dashboard:

Minidsp Flex Measurements Channels 3 and 4 DSP Audio Processor Balanced.png


As you see, performance is just as excellent as channels 1 and 2.

Another question was performance drop when using RCA input to TRS balanced adapter:

Minidsp Flex Measurements Analog In RCA to TRS DSP Audio Processor Balanced.png


This is definitely the case. That said, highest distortion component is at -96 dB which is the same as 16 bit audio dynamic range. This is well above what analog sources such as LP can achieve. So I would not worry about it if this is the configuration.

Conclusions
What a nice combination of functionality, usability and performance! As with many DAC companies, it is clearly Minidsp has put strong focus on chasing away sources of noise and distortion. Yes, there is some work left to do with intermodulation distortion but other than that, measurement after measurement put a smile on my face. All AV processor and receiver companies lose any excuses they have for not providing this level of performance seeing how the Flex also implements various signal processing modules.

It is my pleasure to highly recommend Minidsp Flex audio signal processor, DAC and ADC. You made my day!
 
Last edited:

Neddy

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Thank you, esp for the analog in/out measurements. Will be ordering as soon as I can, to replace the Venu 360.
 

voodooless

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Why is this thing cathegorized as AV processor? It’s just a DAC+DSP.

Did you also test the second output? People seem to have meassured significantly worse performance.

Since it only brings 16 bit performance, I voted “fine”.
 

Tangband

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This is a review and detailed measurement of the Minidsp Flex audio signal processor. It was sent to me by the company and costs US $475.

View attachment 185804
Flex borrows the interface from SHD and puts it in a compact package. Seeing how I really liked that interface with nice volume control, this is a very good move.

Back panel shows why this product is so useful:

View attachment 185805

Not only do you have a suite of digital input but also analog. More importantly, you can rote any input to any output and apply crossover, parametric EQ filters and compression. The software interface is mostly intuitive except for channel routing which required a bit of looking around.

The supplied remote control allows you to eliminate any need for a preamplifier and drive a power amp directly.

Minidsp Flex DAC Measurements
I alternated between Coax S/PDIF input and USB although performance is the same in both. Here is our dashboard:
View attachment 185806

OK, I was not ready for this. A multifunction device with DSP that has a SINAD (relative sum of distortion and noise) to rival and outperform many dedicated DACs?


View attachment 185807

Among its own category which is a mix of DSP and AV receivers and processors it sets a new high bar:


View attachment 185808

First of its kind to land in the blue "excellent" category!

Above was with the volume at -0.5 dB. There is a bit more performance if you set it to 0:

View attachment 185809

Dynamic range is very respectable for this class:

View attachment 185810

There is something holding IMD distortion back though:

View attachment 185811

This causes the same limiting in multitone:

View attachment 185812

JItter test shows some interference but they are at such ridiculously low level that bother the eye far more than any ear could ever detect them:

View attachment 185813

DAC filter is the typical default "lazy" ones in DAC chips:

View attachment 185814

This hurts THD+N versus frequency a bit but the outcome is still good:
View attachment 185815

Linearity is excellent:
View attachment 185816

Minidsp Flex Analog Input Measurements
Some people have an analog only path (e.g. for turntables) and would still want to implement active speakers and/or equalization for room modes. Let's see how we do here:


View attachment 185817

I am amazed once again! End to end performance this good? Remember this is the performance of ADC and DAC combined. And we still manage to have distortion at < -110 dB (18+ bits).

Dynamic range suffers a bit naturally but still, quite good:

View attachment 185818

I was relieved to see wide and flat response:

View attachment 185819

So unlike many AV products that resample everything to 48 kHz, here we have end to end sample rate of 96 kHz (my guess). Bandwidth is in excess of 35 kHz.

Crosstalk was superb:
View attachment 185820

This is better than countless stand-alone preamps!

THD+N vs frequency again shows no frequency dependence:

View attachment 185821

IMD performance is again limited by DAC performance:
View attachment 185822

Conclusions
What a nice combination of functionality, usability and performance! As with many DAC companies, it is clearly Minidsp has put strong focus on chasing away sources of noise and distortion. Yes, there is some work left to do with intermodulation distortion but other than that, measurement after measurement put a smile on my face. All AV processor and receiver companies lose any excuses they have for not providing this level of performance seeing how the Flex also implements various signal processing modules.

It is my pleasure to highly recommend Minidsp Flex audio signal processor, DAC and ADC. You made my day!
Wow ! Finally a highend measuring dsp-crossover at a very good price for the DIY:er . :)
Combine this with tpa 3251/3255 modules inside the loudspeakers, you can build really good ones for not much money.
 
Last edited:

respice finem

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SOTA product at a relatively low price.

One thing I don't understand: DIRAC is an option, but while the USB will be for the PC interface, where to connect the measurement mic? To the PC itself, probably?
 

Tangband

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Why is this thing cathegorized as AV processor? It’s just a DAC+DSP.

Did you also test the second output? People seem to have meassured significantly worse performance.

Since it only brings 16 bit performance, I voted “fine”.
No, its much more than a dac - its a dsp two-way digital crossover as well, and you can aparently use USB digital input from a computer as sound source . This unit uses a XMOS at the USB input. The future for highend performance at normal prices looks good.:)

  • Processor: 32-bit floating-point 400MHz Analog Devices SHARC DSP
  • Multi-Core USB Audio processor (XMOS)
  • Bluetooth streaming: LDAC™/aptX™ HD/aptX™/AAC/SBC
  • Optional upgrade to Dirac Live® 3.x Digital Room Correction, Full Range Room Correction (20~20kHz)
  • Audiophile performance (SINAD
  • Inputs: Stereo digital (USB Audio/SPDIF/Optical/Bluetooth), stereo analog (Unbalanced RCA)
  • Flexible Output versions: Unbalanced (RCA), Balanced (TRS), Digital (Future)
  • USB audio recording feature (4xCH processed output via USB audio to record inputs, e.g. Vinyl)
  • White/Black OLED front panel controller with IR control
 

Blew

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So unlike many AV products that resample everything to 48 kHz, here we have end to end sample rate of 96 kHz (my guess). Bandwidth is in excess of 35 kHz.
The manual and specs state 96KHz without Dirac, but 48KHz with Dirac.

1644563666440.png
 

BoredErica

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Let's see, how does this compare to Motu UL5?
Well, UL5 has more inputs/outputs + ADC. It has less distortions overall and higher output level for special amps. Flex has no ESS IMD hump and 3.5db higher sinad at 2v? It has a remote. Extra charge for balanced Flex + $25 shipping but no tax for me. Totals to $71.8 cheaper than UL5 but still on the hook for ADC. (Flex is in stock, UL5 still MIA.)

Flex has Bluetooth streaming still while UL5 does not. If you're buying DSP there's not much difference and Flex is just another dac. If not then there's another difference.

Hmm. At this point I'd be very hard pressed to hear a difference between this or UL5 even in pretty extreme circumstances but if I had to pick noise vs distortion I think I'm still going to go with less noise? That $72 cheaper price tag is really actually higher than Motu for me since I still need ADC (and extra devices in my room) but that remote is cool.

Potential customs fee at the door for minidsp?

Am I missing something?
 
Last edited:

voodooless

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No, its much more than a dac - its a dsp two-way digital crossover as well, and you can aparently use USB digital input from a computer as sound source . This unit uses a XMOS at the USB input. The future for highend performance at normal prices looks good.:)

  • Processor: 32-bit floating-point 400MHz Analog Devices SHARC DSP
  • Multi-Core USB Audio processor (XMOS)
  • Bluetooth streaming: LDAC™/aptX™ HD/aptX™/AAC/SBC
  • Optional upgrade to Dirac Live® 3.x Digital Room Correction, Full Range Room Correction (20~20kHz)
  • Audiophile performance (SINAD
  • Inputs: Stereo digital (USB Audio/SPDIF/Optical/Bluetooth), stereo analog (Unbalanced RCA)
  • Flexible Output versions: Unbalanced (RCA), Balanced (TRS), Digital (Future)
  • USB audio recording feature (4xCH processed output via USB audio to record inputs, e.g. Vinyl)
  • White/Black OLED front panel controller with IR control
Yeah, like I said, it’s a DAC + DSP.. sure it also has analog inputs. But this thing is not an replacement for an AV processor as the grouping would indicate.

By the same reasoning the $20 adau1701 DSP board should be in the list as well.
 
Last edited:

Robbo99999

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My take on this product is that it's a useful high end way of applying DSP/EQ "in hardware" rather than those that prefer or are able to implement it in software at the playback source - the usefulness of that is debateable depending on use case and personal preference, but as a poster pointed out earlier it's not really a replacement for an AV home theatre product.
 

martijn86

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This was the one I've been waiting for since the announcement! Thanks for reviewing it this fast. The result is even better than expected, this is a brilliant piece of kit!

Whoooo. Hyped, hyped, hyped.


Edit: I have one question before I pre-order. I don't use long cable runs. Is there any advantage to the higher output voltage of the balanced version? Otherwise I see no reason not to get the RCA version for home use.
 
Last edited:

Newman

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No USB input? Can't be used as a USB DAC with extras?
 
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