Minidsp Flex Review (Audio DSP)

[JiiPee]

Not to turn this thread to politics and kudos for MiniDSP for developing a good product, but I really wish a European company would offer something similar in 1K€ - 2 K€ price bracket. (Due to different cost structure, expecting matching prices is not realistic, and yes, I do know that some of the components would probably have to be Chinese manufactured anyway).

 

[feynman]

So, it sound like there is really no downside to upgrading to the TRS version ($75US) and using a TRS (balanced) to RCA (single ended) adapter on the input and output side of this processor? In that case it seems like the TRS version would be the best route for people wanting to 'future proof' their purchase if they only have single ended components now but might upgrade to 'balanced' components in the future. If I'm misunderstanding something here please correct me. Thanks!

It tends to be confusing...in some (most?) cases it would be better to buy the unbalanced version if you are using unbalanced inputs, then connect the unbalanced output to the balanced input on the amp/monitors via properly terminated cables. This is frequently misunderstood (most often by me)...there is no real downside feeding the unbalanced output to the balanced amp input.

Doing the conversion on the input side can be more problematic (though of course, not always).

MiniDSP recommends purchasing the unbalanced model for mixed use cases like this.

---

 

[m8o]

Don't really need it but want it. I wonder if the ADC portion uses the same chip Ivan speaks so highly about he used in his Cosmos (easy enough to discover I imagine; just hadn't looked for it yet)

 

[Draki]

ADC chip: TI PCM4202 https://www.ti.com/lit/ds/symlink/pcm4202.pdf

DAC chip(s): TI PCM1795 https://www.ti.com/lit/ds/symlink/pcm1795.pdf

 

[Holmz]

Yes. Dirac is automated. You can do similar work manually with the filters in this box. In addition, you can also route low frequency to subs. Or implement an active speaker system.

OK does this mean that I can shove the FIR tap into the unit?
(I want to do an active XO, and then replicate it to a second or third unit.)

i.e. using rePhase or something else…

…
Dirac room correction is something one can implement later .
…

Is that how it works?
I have always thought of Dirac more like speaker correction and the PEQ stuff as room correction.
where one only is doing the direct path using Dirac. The reflections also get Dirac.

Or the phase part is the Dirac, and then it is whether wants the amplitude to be a flat speaker frequency response in an anechoic sense…
The amplitude could be done in the DIrac or in PEQ, but for 1k of FIR taps, there is not a lot of resolution in the subwoofer region (???).

Yes, this is basically a pre-amp with 1 analog input and 4 digital inputs (Bluetooth, USB, TOS, & Coax), plus Dirac room correction if you add it, and fully customizable DSP and crossovers on every output channel.

So for a 2 way, there are two schemes that could be used:

Scheme A (Horizontal Flex):

• Run right and left in, and get right low and high out along with left low and hi.
• And then a second Flex unit for the subwoofer band.
  (but as mentioned above the Dirac part does not seem to have many taps that would facilitate the ability to do a lot for group delay compensation.)

Scheme B (Vertical Flex):

• Run right ORleft into 1 channel, and output low, high, and two subwoofer outputs.
  • or a three way may be:
    • Sub
    • Woofer,
    • MR
    • Tweeter
• And then maybe a R/L in to a second Flex unit for the subwoofer band.
  (but as mentioned above the Dirac part does not seem to have many taps that would facilitate the ability to do a lot for group delay compensation.)

I could use some help here…

1. Are there 4x 1k FIR banks?
2. Or 2x 2k FIR banks?
3. or 2x 4K FIR banks?
4. … and then the IIR stuff get implemented after those?

If so, then a “horizontal” scheme seems to perhaps be a better choice?

 

[TheBatsEar]

Excellent device but why so small? I can’t imagine it staying in place when most connectors are plugged in.

Some use Ikea door stoppers to keep lighter devices in place.

Ok, but you cant do dsp crossover the way you use your behringer, with digital out to a dac.

There is a MiniDSP Flex coming with digital out, End of Q1 2022.

Hi, apologies if this is obvious - I'm new to this sort of tech (I'm a straightforward stereo audio guy). Would this work as a pre-amp, allowing me to route the turntable (analogue in) and streamer (digital into the DAC) and output to a power amp, and to add Room EQ or Speaker EQ? Is there a better way of doing that (for the money)? Cheers

You would need a preamp to get a proper line level signal for your turntable, but yes, it's a preamp, one analog in (which you can extend with a passive switch of course), 3x digital in (SPIDF, Toslink, USB). For the money it's hard to beat.

My current preamp becomes an input switch for all my old analog stuff and a phono preamp, and this unit becomes the EQ and volume control.
And I can channel a couple of digital sources directly to it, if I want.
Do I have that right?

You have.

Not to turn this thread to politics and kudos for MiniDSP for developing a good product, but I really wish a European company would offer something similar in 1K€ - 2 K€ price bracket. (Due to different cost structure, expecting matching prices is not realistic, and yes, I do know that some of the components would probably have to be Chinese manufactured anyway).

You can buy this device for 900€ from a European company, if you add Dirac you'll crack the 1k barrier .

 

[73hadd]

I really want this but hesitating because:

-IMD "issue". Is there any chance that minidsp can fix this in software and patch later? Has anyone opened a "ticket" with them to see if they are aware? Maybe more importantly, is this measurement only bad in comparison to the overall performance, or is it worse than "average" for any normal DAC?
-Does the IMD issue go away/improve or get worse when using at volume "0" (full volume)? I assume this would be the setting for using this only as a Crossover where the volume control is upstream?
-This comment about "2nd output measuring much worse". Is this verified or a one-off? Has anyone asked minidsp and/or do they respond to those types of questions?

I really like the Motu products but I do not want to do the DSP on a PC.

 

[mdsimon2]

@amirm can you test using a TRS to RCA cable as that seems like a common configuration for folks that have at least one amplifier that is unbalanced? Curious how much distortion increases in this configuration (if at all)?

Michael

 

[Grotti]

Not to turn this thread to politics and kudos for MiniDSP for developing a good product, but I really wish a European company would offer something similar in 1K€ - 2 K€ price bracket. (Due to different cost structure, expecting matching prices is not realistic, and yes, I do know that some of the components would probably have to be Chinese manufactured anyway).

I am looking at you, RME

 

[ROOSKIE]

Excellent device but why so small? I can’t imagine it staying in place when most connectors are plugged in.

Bluetac or similar.
Velcro.
Strong two sided tape. (I use some that is so strong it is unbelievable)

But yah, this is an issue.

 

[rvsixer]

You would need a preamp to get a proper line level signal for your turntable, but yes, it's a preamp, one analog in (which you can extend with a passive switch of course), 3x digital in (SPIDF, Toslink, USB). For the money it's hard to beat.

@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.

 

[Madjalapeno]

Some use Ikea door stoppers to keep lighter devices in place.

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

 

[Sam Ash]

The Flex seems to be a nice product. If one had a library of music on a USB3 storage device (SSD / USB Stick), any recommendations on a WiFi enabled device that can access music from a USB drive and be controlled via a simple smart phone app? The Bluesound Node and Sonos Port are nice solutions but a bit overkill for those that want to access local content only.

 

[Sean Ku]

So, it sound like there is really no downside to upgrading to the TRS version ($75US) and using a TRS (balanced) to RCA (single ended) adapter on the input and output side of this processor? In that case it seems like the TRS version would be the best route for people wanting to 'future proof' their purchase if they only have single ended components now but might upgrade to 'balanced' components in the future. If I'm misunderstanding something here please correct me. Thanks!

My thoughts on this are similar to the response you got from Feynman.
Full scale input and output on the RCA version is 2.0 Vrms
Full scale input and output on the Balanced version is 4.0 Vrms.

Consider the output levels of your legacy RCA equipment and to what extent of full scale they are able to drive the analog inputs of the Flex.
For example, the Zone 2 output of my Yamaha AVR drives at 200 mV. Hooking them up directly, I'm going to be throwing away a lot of SNR / ADC bits and won't be getting a lot of volume out of my amp. I haven't tried it yet, but suspect I will need to find a gain stage to put in between. It would be better to attenuate balanced outputs into RCA inputs in my opinion.

 

[anotherhobby]

Here is a real world example of using Dirac on the Flex in my 2.2 system (I also posted this info in the other Flex thread).

Setup: This system is in a small 115 sq/ft office that is also treated with several carefully placed (and measurement confirmed) 2.5" OC701 absorption panels. The Flex is being fed a digital input from a computer, and then outputs 2 channels with an 80 Hz high-pass to a Topping PA5 with Revel M105s and 2 channels with an 80 Hz low-pass to a Crown XLS 1500 feeding 2 custom 8" subs I built.

The graph below compares the automated and untouched Dirac only correction vs the raw uncorrected response. Both sweeps had the 80 Hz crossovers applied. No EQ filters were used in addition to Dirac in this comparison. The sound improvement from this alone is fantastic.

Also worth mentioning, in my testing I tried EQing the subs individually before running Dirac (since Dirac does not have direct control over the subs). The Dirac correction was nearly identical, and I could not tell the difference between the two corrections in listening tests.

 

[LightninBoy]

I'm seriously considering this for my hobby studio as a more convenient way to apply room/speaker EQ correction. Today I have to put an EQ plugin into the master channel of the DAW, but that causes issues when rendering, switching to headphones for monitoring, etc.

My one concern is latency, since it would be used for monitoring during instrument tracking. Has anyone measured latency on both the digital and analog inputs?

 

[rdenney]

The Flex seems to be a nice product. If one had a library of music on a USB3 storage device (SSD / USB Stick), any recommendations on a WiFi enabled device that can access music from a USB drive and be controlled via a simple smart phone app? The Bluesound Node and Sonos Port are nice solutions but a bit overkill for those that want to access local content only.

I just use a cheap laptop--some HP plastic cheapie that I bought on sale at Best Buy. I was about to abandon it, because the fan started getting noisy. But I found a replacement fan on Amazon for $8 and it only took ten minutes to replace it, and blow out all the cat hair that was making it noisy in the first place. It's silent again. I think I'll buy several of those fans for the future--by the time I use them up, I'll have to replace the thing anyway. It connects to my home network via WiFi, and the Music Bee player software I use can access the library on my home server. I suppose it could also access the online streaming service.

The good news is that I can also run Vinyl Studio on it for making needledrops, and it works fine running REW, Audacity, and Presonus DAW software, at least for the simple things I do.

With a device like this, I can still use my Benchmark ADC (which has superb front-panel indications and controls) for making needledrops, and use this as the input for other devices.

Rick "cheaper than many streamers, even with the price of the DAC" Denney

 

[anotherhobby]

One aspect of the Flex that I've found to be massively awesome that I was not anticipating are the config presets. There are 4 config slots, each with a direct preset button on the remote, and each one can be a completely different configuration (routing matrix, DSP, levels, Dirac calibration, etc). Shortly after setting it up it occurred to me that I can have custom calibrations for each listening position in my office. So far I am using these three:

1. motorized desk in seated position
2. motorized desk in standing position
3. comfy chair in the corner

Likewise you could have calibrations that have less of a correction for a wider number of seats in a room, but then one that's the ultimate tight sweet spot for when it's just you in your favorite chair. This is a very powerful concept that I quickly fell in love with.

 

[rdenney]

I'm seriously considering this for my hobby studio as a more convenient way to apply room/speaker EQ correction. Today I have to put an EQ plugin into the master channel of the DAW, but that causes issues when rendering, switching to headphones for monitoring, etc.

My one concern is latency, since it would be used for monitoring during instrument tracking. Has anyone measured latency on both the digital and analog inputs?

I've decided that for recording my own playing, I'm going to a setup that is completely separate from my playback system. For that, I have a Presonus Studio 24C interface, which came with the excellent Presonus DAW software (but Audacity works, too). The Studio 24C has acceptable mic preamps for two channels, which is all I need (at least at one time). It also has its own headphone amp, which allows me to hear accurately time-aligned playback of other tracks. That head amp is not powerful, so efficient headphones are necessary, but that's the only weakness. I can apply al the recording EQ and mixing levels I need in the DAW.

Rick "finding it too much hassle to reconfigure the mains system for recordings" Denney

 

[rdenney]

One aspect of the Flex that I've found to be massively awesome that I was not anticipating are the config presets. There are 4 config slots, each with a direct preset button on the remote, and each one can be a completely different configuration (routing matrix, DSP, levels, Dirac calibration, etc). Shortly after setting it up it occurred to me that I can have custom calibrations for each listening position in my office. So far I am using these three:

1. motorized desk in seated position
2. motorized desk in standing position
3. comfy chair in the corner

Likewise you could have calibrations that have less of a correction for a wider number of seats in a room, but then one that's the ultimate tight sweet spot for when it's just you in your favorite chair. This is a very powerful concept that I quickly fell in love with.

Oh, that is awesome--I was wondering about that. My Yamaha PEQ has 40 memories, of which I've needed...4 (one for correcting a phono cartridge plus room EQ, one for room EQ alone from line-level sources, and those two for a headphone destination). I might have needed more than two for a headphone destination, but I'm finding I'm just not that sensitive to making my headphones all sound alike. Computer playback has its own EQ capability, though I've never needed it.

Rick "saving pennies" Denney