Minidsp Flex Review (Audio DSP)

[Blew]

The manual and specs state 96KHz without Dirac, but 48KHz with Dirac.

View attachment 185823

So there's not been much discussion about the fact that the Minidsp Flex only processes audio at 48KHz when using Dirac. Even without Dirac it only operates at 96KHz. So that means all your hi-res music (anything above 48KHz) will be downsampled when using Dirac, and anything above 96KHz will be downsampled when not using Dirac. Even worse, all 44.1KHz CD content (which I'd assume is the majority of our library for most people) will be upsampled to a non-integer scale. So with that in mind, I have a few questions.

1. Should we be concerned about the reconstruction filter in the Flex's DAC producing the same artefacts that plague digital audio that's encoded at just over the Nyquist frequency bound of 22-24KHz? Eg ringing, time smearing.
2. Should we be concerned by the detrimental effects to audio quality caused by the aliasing produced by upsampling 44.1KHz audio to a non-integer scale, be it 48KHz or 96KHz? Anti-aliasing would help but isn't ideal.
3. Is there any point in playing hi-res media through this DAC when using Dirac at 48KHz?
4. Does the fact that it processes the audio in 32-bit help alleviate these issues? If so, by how much?
5. Does the overall increase in audio quality to the listener as a result of using PEQ DSP in the Flex, either through using Dirac or configuring manually, outweigh the potential loss in audio quality from the above?
6. Would it be a better solution to first process PEQ DSP on a more powerful computer in 192KHz or above before streaming to a DAC? Eg Roon, Dirac Live on a PC. An advantage of this would be retaining MQA support in some cases, eg Roon.

Thanks!

 

[voodooless]

Should we be concerned about the reconstruction filter in the Flex's DAC producing the same artefacts that plague digital audio that's encoded at just over the Nyquist frequency bound of 22-24KHz? Eg ringing, time smearing.

Probably not.

Should we be concerned by the detrimental effects to audio quality caused by the aliasing produced by upsampling 44.1KHz audio to a non-integer scale, be it 48KHz or 96KHz? Anti-aliasing would help but isn't ideal.

Nope

Is there any point in playing hi-res media through this DAC when using Dirac at 48KHz?

Is there any point in high-res media, period? No.. how are your ears doing above 20 kHz nowadays?

Does the fact that it processes the audio in 32-bit help alleviate these issues? If so, by how much?

The ASRC’s in the DSP are generally quite good. See the multitone test @abdo123 did.

Does the overall increase in audio quality to the listener as a result of using PEQ DSP in the Flex, either through using Dirac or configuring manually, outweigh the potential loss in audio quality from the above?

Hell yes!

Would it be a better solution to first process PEQ DSP on a more powerful computer in 192KHz or above before streaming to a DAC? Eg Roon, Dirac Live on a PC.

Objectively: yes. Practically: no.

An advantage of this would be retaining MQA support in some cases, eg Roon.

MQA is never an advantage. Looking at your questions, it seems you drank a lot of their kool aid.

 

[Ultrasonic]

1. Does the overall increase in audio quality to the listener as a result of using PEQ DSP in the Flex, either through using Dirac or configuring manually, outweigh the potential loss in audio quality from the above?

You pose an interesting series of questions but I'll just respond to this one. It will depend on a person's room but for me the benefits of a miniDSP 2x4 HD to integrate a subwoofer and apply EQ to manage low-bass room resonances made such a HUGE improvement to my system that any other trade-offs were negligible by comparison. The measured performance of the Flex shared in this thread is better.

I'll add that the 48 kHz sample rate on a Dirac enabled Flex would seem to be the standout performance difference to the SHD series models, which run at 96 kHz. (Other differences are streaming functionality and connectivity differences.)

 

[Blew]

Probably not.

Why not?

Nope

How so?

Is there any point in high-res media, period? No.. how are your ears doing above 20 kHz nowadays?

Yes, it alleviates the artefacts produced by the reconstruction filters in DACs such as ringing and time smearing which I've already mentioned. Have you ever compared decent hi-res to CD quality on a decent DAC? You might want to try it!

The ASRC’s in the DSP are generally quite good. See the multitone test @abdo123 did.

Correct me if I'm wrong but I believe that wasn't using Dirac, so was 96KHz not 48KHz.

MQA is never an advantage. Looking at your questions, it seems you drank a lot of their kool aid.

MQA is definitely an advantage for 44.1KHz content as far as I can hear, and although I'm still on the fence about its advantage in hi-res I feel it has a slight advantage there too. Judging by your comment it seems you've never listened to it on a good DAC that supports it

 

[anotherhobby]

^ I agree with everything voodoo and Ultrasonic just said. I can't really tell much difference above CD quality, but Dirac and the miniDSP completely transforms my system. Even if I could tell the difference in "hi-res" audio, it would take something massive to outweigh the dramatic improvements made by this device. And I certainly wouldn't give up the benefits based on some sort of principled stance based on what I thought was happening, but that wasn't really making much audible difference in reality.

 

[JeremyFife]

@JeremyFife phono use case was already covered in Amirm's first post...but just to clarify you would need a phono-preamp prior to the Flex ADC input (for cartridge matching, RIAA equalization in addition to line level output). This is no different from any other analog turntable fed into any other analog line-in preamp.

Thanks. I was lazy with my question, my bad. Yes, phono-preamp into the analogy inputs. Sounds intriguing.

 

[anotherhobby]

Potentially, but I've tried comparing all known masters of a number of albums that are only available in CD quality and the MQA version definitely sounds the best when played on a DAC that supports it. When played on a DAC that doesn't support it then it's a different story. So, regardless of whether they are MQA specific masters or not, they're the best version available and thus I'd rather have MQA support than not.

I'm not sure what that is but if that's the case then MQA appears to rectify it.

Yes I've tried many different filters across three different MQA enabled DACs, including apodizing filters. Not blind though. I started out being very skeptical of it though, so if anything was cognitively biased against it, but the difference is undeniable. At least to my ears.

I should note that I've always had very sensitive hearing, particularly in higher frequencies. Hearing tests have always come back as excellent for my age, so perhaps I can hear differences that most people can't.

This post has zero place on this thread about the miniDSP Flex.

EDIT: glad to see moderators took care of it!

 

[AdamG]

This post has zero place on this thread about the miniDSP Flex.

Thread Ban handed out. More posts deleted. Warnings and Bans are next. Stay on topic please!!!

 

[Holmz]

Thanks. I was lazy with my question, my bad. Yes, phono-preamp into the analogy inputs. Sounds intriguing.

I have never heard of vinyl being referred to as an analogy, but that is a pretty good spell-check joke.

 

[testp]

Btw for people concerned about multi-tone distortion performance, I usually keep my master volume some where between -40 to -20 dBFS. With 0dBFS being 105dBSPL.

At this range like the graph shows you would be noise dominated, so the distortion would completely inaudible.

Sure not SOTA SOTA performance but the noise is already inaudible to me on 90+ dB sensitive speakers so ….

@voodooless all 4 channels measured the same btw with my Interface.

but if no way to measure, which ones are safer bet to use?

 

[testp]

Let's not forget this is four channels of Dirac (optional), xlr or rca, 2 x 4 electronic crossover, and peq, AND they have promised an all digital version (usb in, spdif out), so if there's an issue with IMD, just wait. A clear hole in one.

what do you mean? are u saying digital version would not produce that IMD anomaly?

 

[testp]

So Darko was right? Does it improve the tone though?

View attachment 185923

[IMG alt="1231rq32r1qw32r"]https://www.audiosciencereview.com/forum/data/avatars/s/31/31077.jpg?1619356453[/IMG]
Doorstoppers always improve things!!!

 

[TheBatsEar]

Excuse my ontopic-ness, but:

Would it be possible to create a 3 channel + sub signal with this device?

channel 1: stereo left
channel 2: stereo right
channel 3: center (left minus right)
channel 4: subwoofer

 

[Madjalapeno]

Thread Ban handed out. More posts deleted. Warnings and Bans are next. Stay on topic please!!!

I think we're all just too excited to see the Flex scoring well. There has been a lot of excitement waiting for this review.

Are MiniDSP on here?

 

[rockyb]

I have a newbe question: Since this has a ADC and a USB connection to a PC, can I use this to first digitize a source like a tape deck, then correct it in the frequency domain to remove distortion, then save the digitized file on the PC that is connected via USB?

 

[anotherhobby]

Excuse my ontopic-ness, but:

Would it be possible to create a 3 channel + sub signal with this device?

channel 1: stereo left
channel 2: stereo right
channel 3: center (left minus right)
channel 4: subwoofer

You can distribute 2 input channels (digital or analog) as you see fit into 4 output channels. Any output channel can carry either input channel or both input channels combined (i.e. for subs).

 

[tomchris]

The MiniDSP Flex looks like a nice packaged ADC/DAC/DSP preamp replacement possibility. Specs are great with 32-bit floating point SHARC and the Dirac option. However, the 2:4 limit leaves us with 3-way speakers some channels short when it comes to utilizing the Xover option

 

[Madjalapeno]

Excuse my ontopic-ness, but:

Would it be possible to create a 3 channel + sub signal with this device?

channel 1: stereo left
channel 2: stereo right
channel 3: center (left minus right)
channel 4: subwoofer

I'm sure someone more knowledgeable will chime in, but the MiniDSP 2x4HD software looks like this. Should be similar.

You can route audio from any input to any output, and perform processes on them there:

Hope that helps.

 

[TheBatsEar]

I'm sure someone more knowledgeable will chime in, but the MiniDSP 2x4HD software looks like this. Should be similar.

You can route audio from any input to any output, and perform processes on them there:

View attachment 185991View attachment 185992

Hope that helps.

Cheers. I have the 2x4 HD, i recognize your picture and have tried to get a proper center. Not possible.
Sad.

 

[anotherhobby]

I'm sure someone more knowledgeable will chime in, but the MiniDSP 2x4HD software looks like this. Should be similar.

You can route audio from any input to any output, and perform processes on them there:

View attachment 185991View attachment 185992

Hope that helps.

It's the similar in DDRC-24 (the Dirac version of the 2x4HD software), except when you use Dirac it disables the controls over the inputs (including the PEQ on the inputs) because that's what Dirac does. The outputs panel in the DDRC-24 app is also similar, except FIR gets removed when you use Dirac.

You don't get those features back by turning Dirac off in the panel. You need to actually switch the miniDSP to use the 2x4HD software instead.