Minidsp Flex Review (Audio DSP)

[Ultrasonic]

Thanks—yes, it really seems no better than a passive volume control, and considering the amps on the market with input sensitivity higher than 2 VRMS, seems like a significant limitation.

You're right that it is a consideration for people to be aware of but I'd suggest that for most it will not be a practical limitation. Also, there are pros and cons of each type of volume control - traditional analogue pre-amps aren't flawless, or free.

Where signal level is an issue for the main speakers I suppose it would be possible to use a fixed gain pre-amp (or one made so by just not adjusting the volume knob) between the Flex output and the power amp input. I can't see this ever being an issue for an active subwoofer due to their own gain controls.

 

[Ultrasonic]

I have already proven to myself that I can make the clipping indicators flash without over driving my speakers

Just so I fully understand, is this a clipping indication on your power amp or somewhere else? And is this happening at a level you'd want to listen at?

 

[Glasvegas]

Thats unusual.. How is this 'reported'? I would expect 6dB max.

This link was provided in an earlier post by @rbachl

see TRS to RCA ”

The 15dB reduction is on the OUTPUT. They don’t actually state what the reduction would be on the INPUT.

However, they do not recommend customers use an unbalanced to balanced cable on the "input" side of the Flex.

 

[abdo123]

Thats unusual.. How is this 'reported'? I would expect 6dB max.

Amir already measured and confirmed it on the review thread.

 

[Hayabusa]

Amir already measured and confirmed it on the review thread.

Indeed, I just saw it while reading back.

Still wonder why its so far off of the expected loss....

 

[Holmz]

Yes. You can apply EQ in software in Roon with each room/DAC getting its own EQ profile.

One needs 3 flex for that?
and three cables into them?
And how do they feed the three simultaneously?

Is there a 3 way USB, optical, or ???

 

[Eetu]

One needs 3 flex for that?
and three cables into them?
And how do they feed the three simultaneously?

Is there a 3 way USB, optical, or ???

You need 3 endpoints such as 3 Roon ready streamers, Raspberry Pis running Ropiee or Chromecast Audios. You can group them in different zones and play separately or in-sync. If you apply room correction/EQ within Roon you don't need this MiniDSP at all, a regular DAC will do UNLESS you need the 4 output channels (sub integration or digital active XOs).

 

[Holmz]

You need 3 endpoints such as 3 Roon ready streamers, Raspberry Pis running Ropiee or Chromecast Audios. You can group them in different zones and play separately or in-sync. If you apply room correction/EQ within Roon you don't need this MiniDSP at all, a regular DAC will do UNLESS you need the 4 output channels (sub integration or digital active XOs).

Maybe an answer in the context of the original question?

Wonderful review…and so much fun to see the bar rise before our eyes.

.ahhh and I almost pulled the trigger as I am looking for a parametric to tame my Tekton Set speakers.

But no MQA.

And since I only stream tidal nowadays.

I was thinking of roon but this system is in the room without Ethernet. And roon makes my feeble head spin, Will roon work in all 3 of my rooms and let me equalize differently for each of my 3 sets of speakers without lots of new equipment.

thank you

I assumed that 3x flex, and eithernet into the room, is “lots of new equipment.”

 

[cyruz]

Question for the owners, the USB connection is only for audio output (like a DAC) or the digital inputs as well (audio interface style)?

 

[Hayabusa]

Question for the owners, the USB connection is only for audio output (like a DAC) or the digital inputs as well (audio interface style)?

Allready discussed, ubs output and input. But the input samples the 4 output channels

 

[feynman]

Looking at the spec sheet on the web page, I see that the unbalanced version has a “maximum” (not “rated”) output of 2 VRMS, showing unity gain with the input. Where is the preamp part? This seems insufficient to drive a Buckeye NC502MP (25.5 dB gain) to full power (input sensitivity 2.35 VRMS, balanced, assuming 4-ohm speakers). My analog preamp has a rated output about that, and a max output of a dozen or so VRMS, but that is unbalanced.

But MiniDSP recommends using the unbalanced version if the sources are single-ended, even if the amp has balanced inputs.

I must be missing some point.

Rick “would like to a version with unbalanced inputs and balanced outs, with at least some gain” Denney

I suppose my reply may not rightly belong in a review thread, but since there is a lot of discussion around your situation on the Flex…perhaps the larger SHD would better fit your needs.

 

[rdenney]

Just so I fully understand, is this a clipping indication on your power amp or somewhere else? And is this happening at a level you'd want to listen at?

Yes and yes. I bought a powerful amp because I have one use case that needs it (and many that don’t).

Rick “who thought that through out loud in ASR, too” Denney

 

[rdenney]

I suppose my reply may not rightly belong in a review thread, but since there is a lot of discussion around your situation on the Flex…perhaps the larger SHD would better fit your needs.

Possibly. I’ll save that for elsewhere.

Rick “too expensive” Denney

 

[eardiggler]

By special I mean : what analog source are you using that has SINAD better than 90dB? In that case you may want to use one of the unbalanced to balanced converters linked in my prior post.
Balanced output to the amps trumps analog in degradation.

Just out of curiosity, what sources outside of a DAC, would go above 90DB? DVD audio maybe? I noticed the best tested Phono preamp (cambridge audio duo) scored 90DB and that's messing with the gain settings to achieve the best outcome. So, it seems the loss in Sinad on the MiniFlex using an RCA to TRS adapter on the input side should have little to no consequence if using these older sources (CD, Phono, Tape, ect).

 

[cyruz]

Allready discussed, ubs output and input. But the input samples the 4 output channels

So let me understand, everything that goes on output can be processed on your PC before/after the internal DSP? Does this mean that digital inputs can be processed on a PC?

 

[mdsimon2]

So let me understand, everything that goes on output can be processed on your PC before/after the internal DSP? Does this mean that digital inputs can be processed on a PC?

You can digitally capture the processed output signal on a computer. You cannot capture it before processing and it works for any input.

Michael

 

[waynel]

Just out of curiosity, what sources outside of a DAC, would go above 90DB? DVD audio maybe? I noticed the best tested Phono preamp (cambridge audio duo) scored 90DB and that's messing with the gain settings to achieve the best outcome. So, it seems the loss in Sinad on the MiniFlex using an RCA to TRS adapter on the input side should have little to no consequence if using these older sources (CD, Phono, Tape, ect).

you are correct., only a digital source would be degraded by using the single ended source to the TRS input. It would make sense to use a digital input to the Flex avoiding the issue. The only thing I could think of is an AVR output which isn't available digitally.

 

[waynel]

This link was provided in an earlier post by @rbachl

see TRS to RCA ”

The 15dB reduction is on the OUTPUT. They don’t actually state what the reduction would be on the INPUT.

However, they do not recommend customers use an unbalanced to balanced cable on the "input" side of the Flex.

MiniDSP's wording is confusing, hopefully they clean it up. Amir measured a 15dB degradation from 105dB to 90dB when using an unbalanced source to the balanced INPUT of the flex.

 

[Ultrasonic]

Yes and yes. I bought a powerful amp because I have one use case that needs it (and many that don’t).

In that case it honestly sounds like your speakers aren't sensitive enough for what you're trying to achieve. Running an amp right up to and hitting its limits really isn't going to be optimal, as demonstrated by the measured distortion data for your particular amp. High-pass filtering the signal sent to your main speakers may increase the headroom you have though, since I'd bet it's bass notes that mostly cause you to see clipping.

As I've said, you've raised an important aspect of the Flex performance for people to be aware of but your situation is unusual and I'm confident that the vast majority of users won't have the issues that you are concerned about.

 

[Holmz]

In that case it honestly sounds like your speakers aren't sensitive enough for what you're trying to achieve.

When they are hissing like a Pentecostal revival, they are either too sensitive, or the amps have too much noise.

Running an amp right up to and hitting its limits really isn't going to be optimal, as demonstrated by the measured distortion data for your particular amp. High-pass filtering the signal sent to your main speakers may increase the headroom you have though, since I'd bet it's bass notes that mostly cause you to see clipping.

If they hiss without any signal, then that would be noise from the amp.
We can talk about THD+N, but the noise part can be distressing, and the HD part may not be too distressing on the ears.

As I've said, you've raised an important aspect of the Flex performance for people to be aware of but your situation is unusual and I'm confident that the vast majority of users won't have the issues that you are concerned about.

It is also possible, and likely, that a DAC could be plugged into a preamp.
Many preamps have gain in addition to attenuation, so if the preamp had 10dB of gain, then it seems like it all gets to be at a good level?

What other “line level” things are at the 20v that Denny described needing?