Minidsp Flex Review (Audio DSP)

[antcollinet]

From what I can tell, CamillaDSP potentially has advantages here due to not being constrained by the hardware limitations of the Flex, eg when run on a Pi4. It doesn't support Dirac though, but I'd personally prefer to try room correction manually using REW anyway.

In this case the Marantz amp that's doing the crossover is doing it in the analogue realm. So I assume filter rolloff doesn't apply there. I don't know how it measures for frequency response, but if I kept this setup I'd look to replace it with something like the Denon X3700H that we know measures well.

According to Amir, we shouldn't be concerned with phase when listening to music in a room. Thoughts?

So then, given the above, and assuming the DSP software is equally capable, it sounds like there's little to no disadvantage in doing DSP in a streamer/player via a stereo DAC and multichannel amp which performs the bass crossover in Pure Direct when compared to doing DSP in a Flex. Or is there anything else the Flex can do better given that it's outputting the separate analogue channels directly? Just want to make sure that I'm not missing anything here.

Phase only matters with sub integration when balancing out nulls. (Phase and delay are sort of the same thing). You want to avoid base from the mains, and bass from the subs arriving out of phase at the listening position, since this causes a null. Personally I'd want to do sub integration with Flex rather than a passive filter in an amp. It has much more capable adjustments. I've no idea what Camilla can do here.

 

[TheBatsEar]

A quick update on the problems I've been having with my new Flex Digital. Looks like the problem is not with the Flex but with my Edifier speakers. I've now tried toslink and coaxial connections from my Flex to both my Edifier S1000db and my Edifier S3000pro speakers and neither type of connection will work with either set of speakers. I forgot I had an unused Evolve soundbar stored away so I dug it out and hooked it up to my Philips TV and the Flex works as it should do with the soundbar using the toslink connection. So the Flex is working, or at least the toslink on the Flex is working, I presume the coaxial works too but I've nothing else with a coaxial input to do a test. Edifier say the speakers only accept PCM format. Does anybody know if the Flex outputs PCM? I can't find anything on this in the Flex manual. I would have thought that it did. Tomorrow I'll swap out the soundbar for the Edifiers and try the toslink connections on both sets of speakers just to confirm that they do work. Next step is to get a Topping E30 DAC and try again. All a bit odd I think.

There are two kind of data streams that are sent using SPDIF protocoll (Sony/Phillips Digital Interface), either via coaxial RCA or Toslink (Toshiba optical link, optical fiber):

• Stereo-PCM audio: 2 data channels, this is what MiniDSP, Edifier and your soundbar use.
• Encoded bitstream for multichannel audio (5.1 or 7.1 channels), using Dolby or DTS encoding. To send this you'd need a Bluray player or TV and to decode it you'd need a AV processor that understands Dolby Digital or DTS or whatever is sent. MiniDSP has no device that talks this stuff.

So yes, the devices you have speak PCM.

 

[as labs]

hey guys. about to buy one of these. has anyone figured out if the IMD issue is "real" or if it's a product of some digital artifact, rate conversion or something that?

@amirm is there some other test from the dashboard that could illuminate this?

sorry if this has already been covered, i've tried searching with no luck

 

[Blew]

Phase only matters with sub integration when balancing out nulls. (Phase and delay are sort of the same thing). You want to avoid base from the mains, and bass from the subs arriving out of phase at the listening position, since this causes a null. Personally I'd want to do sub integration with Flex rather than a passive filter in an amp. It has much more capable adjustments. I've no idea what Camilla can do here.

That's interesting, thanks. Does that still apply if the amp is doing a proper LPF crossover where it filters the lower frequencies from the mains and only outputs those frequencies via the subs, and vice versa for the frequencies above the crossover? Is it the frequencies around the crossover filter (eg 80Hz) that you're referring to here?

 

[antcollinet]

That's interesting, thanks. Does that still apply if the amp is doing a proper LPF crossover where it filters the lower frequencies from the mains and only outputs those frequencies via the subs, and vice versa for the frequencies above the crossover? Is it the frequencies around the crossover filter (eg 80Hz) that you're referring to here?

Yes - in the case where both LPF and HPFiltering is done, it can be an issue around the crossover frequency. Or when using multiple subs, at any (bass) frequency.

 

[MrSoul4470]

I got my Minidsp Flex today. Super fast shipping to Germany within 3 days. BUT: I must say that I am really underwhelmed so far. It's a pretty ugly little box that looks way cheaper than it is. Very thin sheet metal, a wobbly decoder button that is almost scary to use, a front panel that has little spots on it like leftovers from a protection foil and a ugly OLED display with very low resolution that is way to bright for my taste. Operation with the decoder button seems complicated for me, but fortunately most things can be done with the remote control. What I really don't like is that is upsamples everything to 96kHz. Okay, I knew that before I got it, but I can't help but think that this alters the sound even if no EQing or anything else is done. Upsampling, and that has been my experience through the past years, makes the bass sound thin. Don't try to convince me that it does not. I'm listening in nearfield around 2 feet from the speakers (Genelec 8331) and the people that try to convince me that upsampling does not harm the sound usually sit 9 feet away from their speaker, so no wonder they cannot hear the difference (because most of what they listen to is the crap that the room adds to the signal). I will give it a try, but so far I'm not delighted. I also tried Bluetooth with LDAC and I must say that my cheap 120 Euro Lavaudio Bluetooth Receiver just sounds better/cleaner to my ears. BTW, I got the digital output version, because I want to keep my Topping DAC. So there is a not so little chance that there will be a Minidsp Flex available second hand soon here in Germany.

 

[as labs]

That's interesting, thanks. Does that still apply if the amp is doing a proper LPF crossover where it filters the lower frequencies from the mains and only outputs those frequencies via the subs, and vice versa for the frequencies above the crossover? Is it the frequencies around the crossover filter (eg 80Hz) that you're referring to here?

phase matters in any crossover. crossovers work best when frequency and phase response are relatively linear around the crossover point.

I got my Minidsp Flex today. Super fast shipping to Germany within 3 days. BUT: I must say that I am really underwhelmed so far. It's a pretty ugly little box that looks way cheaper than it is. Very thin sheet metal, a wobbly decoder button that is almost scary to use, a front panel that has little spots on it like leftovers from a protection foil and a ugly OLED display with very low resolution that is way to bright for my taste. Operation with the decoder button seems complicated for me, but fortunately most things can be done with the remote control. What I really don't like is that is upsamples everything to 96kHz. Okay, I knew that before I got it, but I can't help but think that this alters the sound even if no EQing or anything else is done. Upsampling, and that has been my experience through the past years, makes the bass sound thin. Don't try to convince me that it does not. I'm listening in nearfield around 2 feet from the speakers (Genelec 8331) and the people that try to convince me that upsampling does not harm the sound usually sit 9 feet away from their speaker, so no wonder they cannot hear the difference (because most of what they listen to is the crap that the room adds to the signal). I will give it a try, but so far I'm not delighted. I also tried Bluetooth with LDAC and I must say that my cheap 120 Euro Lavaudio Bluetooth Receiver just sounds better/cleaner to my ears. BTW, I got the digital output version, because I want to keep my Topping DAC. So there is a not so little chance that there will be a Minidsp Flex available second hand soon here in Germany.

interesting... i can get past the lights and the fiddly dial, but if it does not work well as a "close enough" state of the art USB DAC it is of no interest to me. Are you underwhelmed by the sound?

 

[as labs]

hey guys. about to buy one of these. has anyone figured out if the IMD issue is "real" or if it's a product of some digital artifact, rate conversion or something that?

@amirm is there some other test from the dashboard that could illuminate this?

sorry if this has already been covered, i've tried searching with no luck

could the IMD issue have anything to do with the processor upsampling? i have no clue..

has there been any follow up to the IMD issue?

 

[TimW]

Upsampling, and that has been my experience through the past years, makes the bass sound thin. Don't try to convince me that it does not.

Hey man... upsampling doesn't make bass sound thin.

 

[MrSoul4470]

interesting... i can get past the lights and the fiddly dial, but if it does not work well as a "close enough" state of the art USB DAC it is of no interest to me. Are you underwhelmed by the sound?

I always feel that upsampling degrades bass precision. I wish it was possible to choose the output sample rate and I wonder if it's possible to use the Dirac version firmware without a Dirac license. Then the output sample rate is 48 kHz. Does anyone know? And is it possible to go back to the non-Dirac firmware? With the 2x4hd that I previously owned you could go back and forth between the different firmwares.

 

[MrSoul4470]

Hey man... upsampling doesn't make bass sound thin.

Yes it does. I let my wife switch between my topping DAC and minidsp flex feeding the topping DAC digitally (using a toslink switch) and most of the times I could clearly hear when upsampling was done. Those boxes obviously use very primitive upsampling algorithms. It is much harder to notice when I do the upsampling with a good software resampler on my music server.

 

[antcollinet]

What I really don't like is that is upsamples everything to 96kHz. Okay, I knew that before I got it, but I can't help but think that this alters the sound even if no EQing or anything else is done. Upsampling, and that has been my experience through the past years, makes the bass sound thin. Don't try to convince me that it does not.

Well I won't try to convince you, but it doesn't.

However, if you are so convinced of that, but you knew it did it before you bought it WT h F did you buy it? It just sounds like you're looking for an excuse to send it back.

 

[mdsimon2]

I got my Minidsp Flex today. Super fast shipping to Germany within 3 days. BUT: I must say that I am really underwhelmed so far. It's a pretty ugly little box that looks way cheaper than it is. Very thin sheet metal, a wobbly decoder button that is almost scary to use, a front panel that has little spots on it like leftovers from a protection foil and a ugly OLED display with very low resolution that is way to bright for my taste. Operation with the decoder button seems complicated for me, but fortunately most things can be done with the remote control. What I really don't like is that is upsamples everything to 96kHz. Okay, I knew that before I got it, but I can't help but think that this alters the sound even if no EQing or anything else is done. Upsampling, and that has been my experience through the past years, makes the bass sound thin. Don't try to convince me that it does not. I'm listening in nearfield around 2 feet from the speakers (Genelec 8331) and the people that try to convince me that upsampling does not harm the sound usually sit 9 feet away from their speaker, so no wonder they cannot hear the difference (because most of what they listen to is the crap that the room adds to the signal). I will give it a try, but so far I'm not delighted. I also tried Bluetooth with LDAC and I must say that my cheap 120 Euro Lavaudio Bluetooth Receiver just sounds better/cleaner to my ears. BTW, I got the digital output version, because I want to keep my Topping DAC. So there is a not so little chance that there will be a Minidsp Flex available second hand soon here in Germany.

lol

Michael

 

[mike70]

It's a never ending thought in my head: mini PC with REW / Dirac or Minidsp Flex?

With the PC you can have it all, in the way you want ... but ... remote control? mini screen?
The Minidsp is much more convenient ... but ... more expensive and i agree with the "fragile" aspect / support from Hong Kong

This hobby should be to enjoy our stuff

 

[antcollinet]

It's a never ending thought in my head: mini PC with REW / Dirac or Minidsp Flex?

With the PC you can have it all, in the way you want ... but ... remote control? mini screen?
The Minidsp is much more convenient ... but ... more expensive and i agree with the "fragile" aspect / support from Hong Kong

This hobby should be to enjoy our stuff

What does a Direc license for PC cost?

 

[mike70]

What does a Direc license for PC cost?

350 USD

https://www.dirac.com/online-store/dirac-live-room-correction-suite/

 

[antcollinet]

350 USD

https://www.dirac.com/online-store/dirac-live-room-correction-suite/

Add the cost of PC and Dac, and you are probably exceeding the cost of the Dirac flex. OTOH if you already have the PC and DAC...

 

[testp]

Yes it does. I let my wife switch between my topping DAC and minidsp flex feeding the topping DAC digitally (using a toslink switch) and most of the times I could clearly hear when upsampling was done. Those boxes obviously use very primitive upsampling algorithms. It is much harder to notice when I do the upsampling with a good software resampler on my music server.

if i were you, i would send minidsp 96khz to pc, downgrade to 48 khz and see does it sound like original 48Khz..
i did some 44.1 to 192 khz conversions in computer miles ago, and i did think it sounded hollow for some reason (bascally not the same as original 44.1), but that was so long ago it might of been just bias, dont know (close range listening..) i think its rather bias, especially if analizying the signal afterwords does not show any changes

however 96khz is the best option for minidsp and i would take it like that, rather than 44.1/48

 

[mike70]

Add the cost of PC and Dac, and you are probably exceeding the cost of the Dirac flex. OTOH if you already have the PC and DAC...

well, yes .. even i have the DAC and i like an external DAC ... more future proof

 

[asrUser]

What I really don't like is that is upsamples everything to 96kHz.

Can't you just choose the sample rate in settings?

from the manual