Minidsp Flex Review (Audio DSP)

[antcollinet]

I was looking for something like this, but didn't find anything I felt I could trust on U.S. ebay. Any chance that this device is available from a U.S. source or dealer? I've had "interesting" results shipping stuff from the other side of the pond lately, and even this is promising shipping of a month and more.

I have not seen any finished devices that offer the specifications this one is claiming. I want it to be at least as good as my analog preamp. I'd probably install it inside my preamp and get power from its internal supply, which I think provides +/- 12V rails. But small 12VDC supplies are not exactly challenging.

Rick "definitely put it on the watch list" Denney

I believe sparkfun is US based

SparkFun THAT 1646 OutSmarts Breakout - BOB-14003 - SparkFun Electronics

The THAT 1646 OutSmarts Breakout Board offers an easy solution to adding a balanced audio output to your circuits. The THAT OutSmarts technology has been d

www.sparkfun.com

(obviously need two of these though)

 

[Holmz]

If someone wanted to use this to drive a Benchmark amp, they would not be able to use it in low gain, even if they still wanted to use their nice DAC going through this device. The AHB2 in low gain has a sensitivity of 9VRMS as I recall.

^It^ is probably better worded as 9V full scale.

The low gain setting is 9.2dB
17 dB for medium and
22 dB for high gain

Benchmark AHB2 Power Amplifier

Benchmark's new AHB2 Power Amplifier - "The Quietest, Cleanest Audio Amplifier on the Planet"

benchmarkmedia.com

Why would we worry about not having enough gain on gthe low setting, when one can go to the medium or high setting?

Rick "thinking not looking active analog preamps typically produce around 10 VRMS--10dB of gain when standard line level was 1VRMS unbalanced” Denney

I thought most RCA pre-amps were at 1 or 2 v?
(And most XLR are ~4v ?)

XLR vs RCA - The Chord Company

XLR vs RCA – which is best? It’s very easy to assume that if your equipment has both XLR and RCA connections, that XLR connections are going to be the better sounding connection. It’s not always the case. The XLR connection carries a balanced signal. The hot pin carries the signal, the cold...

chord.co.uk

 

[rdenney]

I believe sparkfun is US based

SparkFun THAT 1646 OutSmarts Breakout - BOB-14003 - SparkFun Electronics

The THAT 1646 OutSmarts Breakout Board offers an easy solution to adding a balanced audio output to your circuits. The THAT OutSmarts technology has been d

www.sparkfun.com

(obviously need two of these though)

Someone had posted these earlier, but I had lost track of it. These may be the real solution--looking into it more.

Rick "appreciative" Denney

 

[rdenney]

I thought most RCA pre-amps were at 1 or 2 v?
(And most XLR are ~4v ?)

XLR vs RCA - The Chord Company

XLR vs RCA – which is best? It’s very easy to assume that if your equipment has both XLR and RCA connections, that XLR connections are going to be the better sounding connection. It’s not always the case. The XLR connection carries a balanced signal. The hot pin carries the signal, the cold...

chord.co.uk

Look at the maximum output (NOT peak output). Most of my active preamps put out 8-12 VRMS unbalanced at max. Their "rated" output is at line level. MiniDSP uses the word "maximum" for its 2VRMS output.

I've known people who have installed attenuators in their active preamps to knock down the amplification so they have more range on the volume knob.

Note that most integrated amps, which have preamps and power amps combined, have gain of 40+ dB.

Rick "who asked a similar question when wanting to know what it would take to drive the Buckeye amp to full power" Denney

 

[luft262]

No, its much more than a dac - its a dsp two-way digital crossover as well, and you can aparently use USB digital input from a computer as sound source . This unit uses a XMOS at the USB input. The future for highend performance at normal prices looks good.

• Processor: 32-bit floating-point 400MHz Analog Devices SHARC DSP
• Multi-Core USB Audio processor (XMOS)
• Bluetooth streaming: LDAC™/aptX™ HD/aptX™/AAC/SBC
• Optional upgrade to Dirac Live® 3.x Digital Room Correction, Full Range Room Correction (20~20kHz)
• Audiophile performance (SINAD
• Inputs: Stereo digital (USB Audio/SPDIF/Optical/Bluetooth), stereo analog (Unbalanced RCA)
• Flexible Output versions: Unbalanced (RCA), Balanced (TRS), Digital (Future)
• USB audio recording feature (4xCH processed output via USB audio to record inputs, e.g. Vinyl)
• White/Black OLED front panel controller with IR control

I agree that it's more than a DAC, but it's not really an AVR either. It can't process or passthrough video for one. IMHO this would be used for a different purpose than an AVR and is in a different category. I would put it under a separate category of DSP controllers, but that's just me. Most people will probably use this with seperates in an audio only system or with an AVR to have more control over their subs' EQ.

But that doesn't change the fact that it's a great product and an awesome review!

 

[Holmz]

Look at the maximum output (NOT peak output). Most of my active preamps put out 8-12 VRMS unbalanced at max. Their "rated" output is at line level. MiniDSP uses the word "maximum" for its 2VRMS output.

I've known people who have installed attenuators in their active preamps to knock down the amplification so they have more range on the volume knob.

Note that most integrated amps, which have preamps and power amps combined, have gain of 40+ dB.

Rick "who asked a similar question when wanting to know what it would take to drive the Buckeye amp to full power" Denney

Much do what I have seen you write is very sensible.
So I am thinking I may have missed some nuance here.

 

[rodtor]

I contacted MiniDSP to clarify a statement in their 'Flex Balanced connection' user note about whether degradation of SINAD could be expected on the output side as well as the input side when using balanced-to-unbalanced cables. In their response, they confirmed that the issue only arises for inputs, and they've added the following text to the note:

"There isn't any performance drop for OUTPUTS. i.e. TRS to RCA cable for an unbalanced amplifier or subwoofer if perfectly fine. To clarify again, this limitation is for INPUTS. i.e. RCA source to TRS input of the Flex."

 

[redjr]

Not in my book. Stereo can still be fine.

Codec support and HDMI would be prerequisite in my book.

Stereo purists will scoff, but well done 5.1 channel music can sound spectacular. Talk about immersion. And Atmos just raises the bar IMHO.

 

[rdenney]

Much do what I have seen you write is very sensible.
So I am thinking I may have missed some nuance here.

The specifications for "maximum output" of a few vintage active preamps of my acquaintance:

B&K MC-101 Sonata: 14 VRMS (as specified)
Apt Holman: 9.1 VRMS (as measured by Ken Rockwell at 0.1% THD; Amir didn't measure it)
Adcom GFP-565: 10 VRMS (as reported by S'phile), ("rated" output: 2 VRMS)
SAE P102: 7.2 VRMS (specified also at 0.1% THD), ("rated" output: 1 VRMS)

So, when you crank them up, they add quite a bit of gain above unity. These are peak values, meaning the highest RMS average waveform voltage without clipping. Distortion is higher, of course, but still reasonable (often under 0.1%). Any of these (except--barely--the SAE) can run that Benchmark amp in low gain to full power. Whether one would want to do that rather than use the extra input amps in the Benchmark is a whole other thing--the preamps in the Benchmark are likely much better than in any vintage external preamp.

When I press the switch on my B&K to defeat the line amp, I the voltage going out becomes identical to the voltage coming in from the source. And the volume drops substantially. That is essentially the output level provided by the miniDSP, because it apparently provides no analog amplification. But, as I understand it, it also can't take more than 2 VRMS (unbalanced) coming into the analog inputs without clipping (4 volts for the balanced model served by balanced sources), because that produces 0 dBFS in the digital realm and digitally clips above that. There's nothing wrong with that for amps that have enough gain.

I've ordered a couple of those Sparkfun Outsmarts balanced-out differential amplifiers that use the THAT 1647 custom differential op-amp. It's noise and distortion is well below my preamp, and it provides 6 dB of gain (because it is doubling the single-ended voltage to a true differential balanced output). That means the 2-volt sources will produce 4-volt balanced outs, which will drive both the miniDSP and my amp comfortably. My preamp seems to have the necessary +/- 15VDC needed to accept and deliver enough voltage to sit in the output of the preamp even when the line amp is active. That sounds like a fun project to me whether or not I buy the miniDSP when the balanced version is again available.

Rick "there's line level and then there's line level" Denney

 

[Ultrasonic]

Much do what I have seen you write is very sensible.
So I am thinking I may have missed some nuance here.

What specifically were you referring to here?

 

[Hayabusa]

I contacted MiniDSP to clarify a statement in their 'Flex Balanced connection' user note about whether degradation of SINAD could be expected on the output side as well as the input side when using balanced-to-unbalanced cables. In their response, they confirmed that the issue only arises for inputs, and they've added the following text to the note:

"There isn't any performance drop for OUTPUTS. i.e. TRS to RCA cable for an unbalanced amplifier or subwoofer if perfectly fine. To clarify again, this limitation is for INPUTS. i.e. RCA source to TRS input of the Flex."

There is difference for optimal wiring balanced <-> unbalanced depending on signal direction.

from https://www.ranecommercial.com/kb_article.php?article=2107

Could it be the 15db SINAD loss was caused by using the wrong cable?

 

[amper42]

Ordered Flex Feb 11. MiniDSP waited 5 days to tell me it's out of stock. The next batch is expected at the end of March 2022. I would think they could have notified customers sooner? Maybe they are too busy? At least they cancelled the order promptly. That's better than having to challenge it with the credit card company.

I don't need the Flex bad enough to get in line for months while they hold my money.
Amir's review seems to have filled the order desk.

 

[Glasvegas]

I contacted MiniDSP to clarify a statement in their 'Flex Balanced connection' user note about whether degradation of SINAD could be expected on the output side as well as the input side when using balanced-to-unbalanced cables. In their response, they confirmed that the issue only arises for inputs, and they've added the following text to the note:

"There isn't any performance drop for OUTPUTS. i.e. TRS to RCA cable for an unbalanced amplifier or subwoofer if perfectly fine. To clarify again, this limitation is for INPUTS. i.e. RCA source to TRS input of the Flex."

Thanks for getting that changed.

It would be even better if they removed the statement “We've noticed a performance drop on outputs (15dB SINAD drop)”

Anyway, at least ASR members now have clarification.

 

[rvsixer]

There is difference for optimal wiring balanced <-> unbalanced depending on signal direction.

from https://www.ranecommercial.com/kb_article.php?article=2107

View attachment 187135View attachment 187136
View attachment 187139

Could it be the 15db SINAD loss was caused by using the wrong cable?

I have been thinking this as well, as most converter cables I have found tie black & shield together on the balanced end. Rane config 18 should work, but I personally would tie black & shield together on the unbalanced end also (which is the unbalanced to balanced cable config Hypex recommends see https://www.hypex.nl/img/upload/doc/an_wp/AN_Legacy_pin_1_problems.pdf).

 

[eardiggler]

Ordered Flex Feb 11. MiniDSP waited 5 days to tell me it's out of stock. The next batch is expected at the end of March 2022. I would think they could have notified customers sooner? Maybe they are too busy? At least they cancelled the order promptly. That's better than having to challenge it with the credit card company.

I don't need the Flex bad enough to get in line for months while they hold my money.
Amir's review seems to have filled the order desk.

I cancelled before they shipped mine out and they charged me a small re-stoking fee. Some may not know this but miniDSP does not accept returns. All sales are final. Make sure you order the correct one!

 

[rodtor]

It would be even better if they removed the statement “We've noticed a performance drop on outputs (15dB SINAD drop)”

I agree. They presumably mean 'output from the balanced DAC, when the signal originated from an unbalanced source', but they don't say that.

In response to @Hayabusa's query: "Could it be the 15db SINAD loss was caused by using the wrong cable?": Note that @amirm also found a 10 db drop when he measured an unbalanced signal in this way.

 

[anotherhobby]

I cancelled before they shipped mine out and they charged me a small re-stoking fee. Some may not know this but miniDSP does not accept returns. All sales are final. Make sure you order the correct one!

I just ordered a miniDSP 2x4 last night for a new project, and I accidentally ordered the wrong one. I emailed them immediately and they were able to update my order, so if you do make a mistake when ordering just make sure you respond very quickly to them.

 

[rvsixer]

In response to @Hayabusa's query: "Could it be the 15db SINAD loss was caused by using the wrong cable?": Note that @amirm also found a 10 db drop when he measured an unbalanced signal in this way.

...and we also don't know how Amir's unbalanced to balanced cable was wired (unless I missed that somewhere in the thread).

MiniDSP's cable is fine balanced to unbalanced, but possibly "incorrect" for unbalanced to balanced (per Rane and Hypex anyway). I think what @Hayabusa and I are driving at, is to see the same test with Rane/Hypex cable configs.

 

[Hipster Doofus]

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

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

Thank you , last question …(.this room currently has wifi and I only stream Tidal).

can I accomplish Parametric EQ with ….

just roon ( on laptop in other room) an IPad as my interface and of course a dac.

I do,have access to RTA and a mic, and even a minidsp with REW (but a novice)

thanks
joe from port townsend

 

[spartan922]

I’m hoping to use the flex as a preamp in my TV setup with the following audio chain:

Apple TV/Nintendo switch -> LG B7 (optical out) -> miniDSP flex -> Sony TA-N77ES amplifier -> Buchardt S400s (2.0 speakers)

Turntable -> Lounge Audio LCR MKIII phono preamp (RCA out) -> miniDSP flex -> Amplifier

Would it make any sense to get the balanced version since I will likely update my amplifier to one with balanced inputs in the future? Would the unbalanced version get loud enough (2V vs 4V)?

Is there any significant latency that would cause lip syncing issues with video?

Also, would the Apple TV remote volume control work on the flex? It would be nice to just use one remote. Thanks for the help!