Minidsp Flex Review (Audio DSP)

[Carlton80@0]

For those that are considering the purchase of the Flex. Partsexpress is currently offering $75.00 off on all orders over $500 with free shipping. This would be applied to the SE and BAL versions. This deal ends at midnight. Currently showing the SE on back order and the BAL stock of 4.

 

[JW001]

For those that are considering the purchase of the Flex. Partsexpress is currently offering $75.00 off on all orders over $500 with free shipping. This would be applied to the SE and BAL versions. This deal ends at midnight. Currently showing the SE on back order and the BAL stock of 4.

I ordered it on minidsp.com site on Monday and DHL delivered it on Thursday. Just 3 days from HK to New Jersey. The total shipping $30, no customs fee nor tax.

 

[greyscale]

From a miniDSP Flex DL. When the criptic message appears, the Flex must be powered off/on to regain control.
Guess the PRC is running out of translators?.

 

[jrmr]

On the input I use a simple RCA to TS for a turntable. It works fine, and performance will exceed the levels vinyl is capable of.

So this kind of cable will also work with a bluray-player as cd transport without the drop in db? I am asking because i ordered the flex balanced version. After i read here about the warning about the analog in with unbalanced to balanced, i tried to cancel my order but it was too late. It´s already on the way and i will give it a try. After all the informations i got here i guess it will work. I already have such cable thanks to my audio-interface.

So just the right cable is the solution..(?) The manufacturer should be better in informing. On the german site of MinisDSP i only found the manual from 2021, here they say about the flex balanced:

"Analog inputs. Connect an analog source here. The input jacks are balanced TRS (1/4” tip-ring-sleeve)
connectors, so typically XLR to TRS adapter cables would be used. Alternatively, RCA to TRS adapter cables
can also be used. Typically, the left channel is connected to input 1 and the right channel is connected to
input 2. See Specifications for maximum input voltages."

The later version from 2022 i found later at another place:
"Balanced analog inputs. Connect an analog source here. The input jacks are balanced TRS (1/4" tip-ring-sleeve) connectors, so XLR to TRS adapter can be used to connect to equpiment with XLR outputs. Typically, the left channel is connected to input 1 and the right channel to input 2. The maximum voltage is 4.0 v rms."

Here they could have tell some words about the issue.. and i will tell about my experience after i received the device.

My first post here. I really like this forum!

 

[antcollinet]

So this kind of cable will also work with a bluray-player as cd transport without the drop in db? I am asking because i ordered the flex balanced version. After i read here about the warning about the analog in with unbalanced to balanced, i tried to cancel my order but it was too late. It´s already on the way and i will give it a try. After all the informations i got here i guess it will work. I already have such cable thanks to my audio-interface.

So just the right cable is the solution..(?) The manufacturer should be better in informing. On the german site of MinisDSP i only found the manual from 2021, here they say about the flex balanced:

"Analog inputs. Connect an analog source here. The input jacks are balanced TRS (1/4” tip-ring-sleeve)
connectors, so typically XLR to TRS adapter cables would be used. Alternatively, RCA to TRS adapter cables
can also be used. Typically, the left channel is connected to input 1 and the right channel is connected to
input 2. See Specifications for maximum input voltages."

The later version from 2022 i found later at another place:
"Balanced analog inputs. Connect an analog source here. The input jacks are balanced TRS (1/4" tip-ring-sleeve) connectors, so XLR to TRS adapter can be used to connect to equpiment with XLR outputs. Typically, the left channel is connected to input 1 and the right channel to input 2. The maximum voltage is 4.0 v rms."

Here they could have tell some words about the issue.. and i will tell about my experience after i received the device.

My first post here. I really like this forum!

Really don't worry about it. There is a small drop in SINAD for using RCA to TRS (or TS) on the input. But the resultant SINAD is still way better than the performance of any vinyl playback system.

Even if you are putting a CD into the analogue input the performance only drops to about the same level as CD - and in any case is inaudible in practically all real world listening situations. I have the balanced version, and only connect unbalanced analogue sources to it.

 

[mike70]

Really don't worry about it. There is a small drop in SINAD for using RCA to TRS (or TS) on the input. But the resultant SINAD is still way better than the performance of any vinyl playback system.

Even if you are putting a CD into the analogue input the performance only drops to about the same level as CD - and in any case is inaudible in practically all real world listening situations. I have the balanced version, and only connect unbalanced analogue sources to it.

I have the balanced flex with a single ended phono preamp and the difference with the direct phono preamp is ... hands down better with the flex.
why?

1) i can't find any sound difference using the Flex in a "flat" configuration (without EQ, with same crossovers / gain, etc etc)
2) the difference with the right room EQ is waaaayyyy better than the direct preamp

So, to anyone using the Flex, forget about it and enjoy your analog source.
At some time i'll change the actual phono preamp to other preamp with balanced output, not to "improve" the SQ, but the extra passive gain from balanced gives you a better volume ratio compared with digital sources.

 

[jrmr]

@antcollinet @mike70

thanks to you both, i am reassured

 

[gitesh]

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.

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

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

View attachment 186032

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:

View attachment 186033

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!

Hello . I recently brought B & W 706 s2 speakers but I find them bright for listening to streaming music on my stereo setup comprising of harman kardon 3380 stereo receiver , speakers and iPad . They are causing me ear fatigue though rest of the family is fine !!

I use my iPad directly connected to my Harman kardon 3380 stereo receiver to run the speakers . On the iPad I stream Amazon music .

I was thinking about some solution for brightness and I read about mini dsp flex . My question is that can I use it's equaliser for reducing the brightness in my stereo set up ?

 

[Elder]

Hello . I recently brought B & W 706 s2 speakers but I find them bright for listening to streaming music on my stereo setup comprising of harman kardon 3380 stereo receiver , speakers and iPad . They are causing me ear fatigue though rest of the family is fine !!

I use my iPad directly connected to my Harman kardon 3380 stereo receiver to run the speakers . On the iPad I stream Amazon music .

I was thinking about some solution for brightness and I read about mini dsp flex . My question is that can I use it's equaliser for reducing the brightness in my stereo set up ?

The Flex would be perfect, although maybe a little overkill.

Have you tried lowering the treble on your HK reciever using the tone controls on the front?

 

[Doodski]

Hello . I recently brought B & W 706 s2 speakers but I find them bright for listening to streaming music on my stereo setup comprising of harman kardon 3380 stereo receiver , speakers and iPad . They are causing me ear fatigue though rest of the family is fine !!

I use my iPad directly connected to my Harman kardon 3380 stereo receiver to run the speakers . On the iPad I stream Amazon music .

I was thinking about some solution for brightness and I read about mini dsp flex . My question is that can I use it's equaliser for reducing the brightness in my stereo set up ?

I operate the EQ/PEQ thread here @ ASR and there are softwares available for EQ/PEQ there if you want to try them. PEQ is a solution for you that I think you should try.
iOS/iPadOS:>>>

EQ Software for Windows, Linux, macOS, iOS/iPadOS and Android.

Any suggestions are welcome. Post suggestions here. I will gather the details and add them. Thanks. :D This will be organized as results come in. @sweetchaos made a guide for PEQ filter data input and operation. For crossover software go here. Windows: AutoEQ four easy steps to make your...

www.audiosciencereview.com

Alternatively if you want to transition to a Mac PC then these PEQ softwares will solve your listening problems very well.

eqMac - System Audio Equalizer and App Volume Mixer for macOS

System Audio Equalizer for Apple macOS (OS X) System. Professional grade Parametric EQ with Unlimited Bands, Volume Mixer (per Application volume control), Spatial Audio (Reverb effect). The last and only tool you will need for your Mac.

eqmac.app

SoundSource - A Superior Sound Control

Access your Mac's audio devices, control per-app audio, and much more, all from the menu bar.

rogueamoeba.com

 

[antcollinet]

Hello . I recently brought B & W 706 s2 speakers but I find them bright for listening to streaming music on my stereo setup comprising of harman kardon 3380 stereo receiver , speakers and iPad . They are causing me ear fatigue though rest of the family is fine !!

I use my iPad directly connected to my Harman kardon 3380 stereo receiver to run the speakers . On the iPad I stream Amazon music .

I was thinking about some solution for brightness and I read about mini dsp flex . My question is that can I use it's equaliser for reducing the brightness in my stereo set up ?

If you are using apple music, then also look at the graphic equaliser options in. your ipad to reduce the brightness a little.

If you are using another app, check if it has tone controls or equaliser functionality. If it doesn't, can you replace it with one that does.

This page should help with where to make adjustments for fatigue.
audio-frequency-range

 

[mike70]

Try to position the tweeter not facing directly at you ... I mean, position the tweeter facing behind you (less "toe-in").

 

[gitesh]

The Flex would be perfect, although maybe a little overkill.

Have you tried lowering the treble on your HK reciever using the tone controls on the front?

Tried it helps a bit but not able to solve the problem totally

 

[Strobilus]

Tried it helps a bit but not able to solve the problem totally

Started using minidsp (DDRC now Flex) and Dirac for this reason with my system (KEF ls50 a tad bit too bright) and tinnitus. As others are saying using treble control is a first step and if possible other PEQ software to see if room correction with house curve is suitable. With Dirac I have different curves and I find that it results in less fatigue.

I would say that investing and testing with a measurement mic can also show if there is something odd with the speakers or room (mine had faulty tweeters, resulting in additional brightness which I realised after measuring them).

If you see a point in having the flex as the central unit in your system it would be valuable.

 

[gitesh]

Started using minidsp (DDRC now Flex) and Dirac for this reason with my system (KEF ls50 a tad bit too bright) and tinnitus. As others are saying using treble control is a first step and if possible other PEQ software to see if room correction with house curve is suitable. With Dirac I have different curves and I find that it results in less fatigue.

I would say that investing and testing with a measurement mic can also show if there is something odd with the speakers or room (mine had faulty tweeters, resulting in additional brightness which I realised after measuring them).

If you see a point in having the flex as the central unit in your system it would be valuable.

How did u measure to check whether tweeters are Allright. ?

 

[anotherhobby]

Tried it helps a bit but not able to solve the problem totally

Is returning the B&Ws an option? If so you can get a speaker that you like the sound of rather than trying to fix something you don't like to begin with? That's what I did a few years ago when I tired some B&W bookshelf speakers that also sounded overly bright and harsh. Returned them in less than a week and went and got a pair of Revel M105 and never looked back.

 

[mike70]

Is returning the B&Ws an option? If so you can get a speaker that you like the sound of rather than trying to fix something you don't like to begin with? That's what I did a few years ago when I tired some B&W bookshelf speakers that also sounded overly bright and harsh. Returned them in less than a week and went and got a pair of Revel M105 and never looked back.

that happens normally with "detailed" speakers ... "detailed" in audiophile terms usually means more energy in HF.
brands like B&W / Monitor Audio / Focal generally have that "great detail" (it works great in the 20 mins demo, but not with 2 hours in your home )
In the same level of B&W 700s i bought the Kef R3 and no regrets at all.

 

[jrmr]

Today i received the new amplifier from Audiophonic AP300-S250NC and connected the Flex balanced. Since two days before i tinkered a bit with the Flex on my Mac to check all the functions and get used to it. I guess the Flex is faulty because no Bluetooth pairing with phone or mac. I already asked the support but no solution. The Pairing mode appears for just three seconds and then BT (NC Not connected). Also there is no output when on USB with my Mac. All settings are ok, audio-midi-setup is showing the Flex but still no output. I will go for this tomorrow.

My first and urgent question for now is: Is it normal to crank up the volume almost to 0dB? Depending on the source the volume i set is between -30--15dB when listening to music but the TV is so silent that i could almost go to 0dB when listening to News for instance. The TV is on S/PDIF. There is also AppleTV and a Sony Blu-Ray-player connected and the audio out for all is the TV-connection to the flex with S/PDIF. The volume there is different but still i have to go at least to -35dB. At -20/-15 it is loud then. I know, "loud" is subjective but i mean i don´t need more. On Toslink it´s the same, maybe a bit louder.

Maybe my speakers are so hungry for power? Dynaudio X34 with 8ohm/86dB. They are so called amplifier-friendly but my old amp sounded distorted already at 12 o'clock with 85w at 8ohm.

Now it´s really strange for me to pull up the volume on the flex so high, it´s like 3 o´clock at an integrated amp. I guess the situation is different because of pre-amplifying but still it takes getting used to- or is something wrong? Can i adjust something in gain? I wonder also because all the dBs less than-40dB (down to -127) are completely useless because i hear just nothing there...

I did not connect anything to analog-in yet, for today it was enough. Thanks a lot for ideas!

edit: just connected again my Mac and USB is working suddenly. Volume at -30db by night...

 

[staticV3]

Today i received the new amplifier from Audiophonic AP300-S250NC and connected the Flex balanced. Since two days before i tinkered a bit with the Flex on my Mac to check all the functions and get used to it. I guess the Flex is faulty because no Bluetooth pairing with phone or mac. I already asked the support but no solution. The Pairing mode appears for just three seconds and then BT (NC Not connected). Also there is no output when on USB with my Mac. All settings are ok, audio-midi-setup is showing the Flex but still no output. I will go for this tomorrow.

My first and urgent question for now is: Is it normal to crank up the volume almost to 0dB? Depending on the source the volume i set is between -30--15dB when listening to music but the TV is so silent that i could almost go to 0dB when listening to News for instance. The TV is on S/PDIF. There is also AppleTV and a Sony Blu-Ray-player connected and the audio out for all is the TV-connection to the flex with S/PDIF. The volume there is different but still i have to go at least to -35dB. At -20/-15 it is loud then. I know, "loud" is subjective but i mean i don´t need more. On Toslink it´s the same, maybe a bit louder.

Maybe my speakers are so hungry for power? Dynaudio X34 with 8ohm/86dB. They are so called amplifier-friendly but my old amp sounded distorted already at 12 o'clock with 85w at 8ohm.

Now it´s really strange for me to pull up the volume on the flex so high, it´s like 3 o´clock at an integrated amp. I guess the situation is different because of pre-amplifying but still it takes getting used to- or is something wrong? Can i adjust something in gain? I wonder also because all the dBs less than-40dB (down to -127) are completely useless because i hear just nothing there...

I did not connect anything to analog-in yet, for today it was enough. Thanks a lot for ideas!

edit: just connected again my Mac and USB is working suddenly. Volume at -30db by night...

For volume, use a multimeter and 60Hz test tone (attached below) to make sure that you're getting the full 4.0Vrms

For this, disable any EQ, plug the XLR cables out of your Amp, then play the test tone via the Apple TV, BD Player, the TV itself, the Mac, and check the output voltage at 100% volume (XLR Pin 2&3):

 

[antcollinet]

Today i received the new amplifier from Audiophonic AP300-S250NC and connected the Flex balanced. Since two days before i tinkered a bit with the Flex on my Mac to check all the functions and get used to it. I guess the Flex is faulty because no Bluetooth pairing with phone or mac. I already asked the support but no solution. The Pairing mode appears for just three seconds and then BT (NC Not connected). Also there is no output when on USB with my Mac. All settings are ok, audio-midi-setup is showing the Flex but still no output. I will go for this tomorrow.

My first and urgent question for now is: Is it normal to crank up the volume almost to 0dB? Depending on the source the volume i set is between -30--15dB when listening to music but the TV is so silent that i could almost go to 0dB when listening to News for instance. The TV is on S/PDIF. There is also AppleTV and a Sony Blu-Ray-player connected and the audio out for all is the TV-connection to the flex with S/PDIF. The volume there is different but still i have to go at least to -35dB. At -20/-15 it is loud then. I know, "loud" is subjective but i mean i don´t need more. On Toslink it´s the same, maybe a bit louder.

Maybe my speakers are so hungry for power? Dynaudio X34 with 8ohm/86dB. They are so called amplifier-friendly but my old amp sounded distorted already at 12 o'clock with 85w at 8ohm.

Now it´s really strange for me to pull up the volume on the flex so high, it´s like 3 o´clock at an integrated amp. I guess the situation is different because of pre-amplifying but still it takes getting used to- or is something wrong? Can i adjust something in gain? I wonder also because all the dBs less than-40dB (down to -127) are completely useless because i hear just nothing there...

I did not connect anything to analog-in yet, for today it was enough. Thanks a lot for ideas!

edit: just connected again my Mac and USB is working suddenly. Volume at -30db by night...

Bear in mind the flex only attenuates (reduces) whatever volume is provided by the source. So if the source is already providing a level needed for listening, it is absolutely normal for the flex to by at maximum.

For the TV check it is not already setting the volume over the SPDFI. If it is, make sure the TV volume is set to maximum.

Regarding USB from the mac check:
1 - the flex is set to USB input.
2 - The mac is set to output to the flex