Minidsp SHD Power Amplifier Review

[Bruce Morgen]

Great review as always. BTW, it seems using TPA3255 can possibly build solid yet budget amps. Is there any well designed power/integ amp based on TPA3255 in the market yet?

The dirt-cheap Aiyima A07 -- a tiny power amp with a handy gain control -- is remarkably good if you team it with an adequate power supply. I use two of them in my system and subjectively they vastly outperform the highly acclaimed, Nelson Pass designed Adcom GFA-535 I swore by back in the day. Too bad I can't spare one of mine for Amir to test -- and of course he may well find measurable flaws that I can't hear if/when he gets his hands on one. I also understand that Allo has a TPA3255-based amp in the works, and given that those folks did such a good job with the much older, far less capable TPA3116 chip -- check out Amir's review -- I'm looking forward to what they come up with.

 

[somebodyelse]

Great review as always. BTW, it seems using TPA3255 can possibly build solid yet budget amps. Is there any well designed power/integ amp based on TPA3255 in the market yet?

There are a few of threads about them, but the complete amps (as opposed to boards) lack detailed measurements. A couple of manufacturers (@3eaudio and @AIYIMA) have started posting in response, but I don't think either have sent amps in for testing yet. Their amps have been getting most attention - 3E's includes DSP but you'll need to use SigmaDSP and a programming dongle to use it, while Aiyima's A04 and A07 seem to have plenty of satisfied customers.

 

[McFly]

I believe “Aiyima” have said on this forum they have sent a TPA3255 to amir for testing, be interesting to see what this chip can do stand alone.

 

[Bruce Morgen]

I believe “Aiyima” have said on this forum they have sent a TPA3255 to amir for testing, be interesting to see what this chip can do stand alone.

That's good -- now I don't have to feel guilty about not sending Amir one of mine.

 

[Lorenzo74]

This is a review and detailed measurements of the multifunction Minidsp SHD Power amplifier with Dirac Room EQ and general signal processing. It was kindly sent to me by a member and costs US $1499 including a measurement microphone.

The SHD Power has a muscular look and feel to it:

View attachment 94015

I like the large display and size of the big knob. Then again, for a right handed person I like to see the knob on the right, not left! Sensitivity of the rotary encoder is good for volume changes but not for selection of inputs. It is not predictable how much you need to turn it to change inputs. It also has many functions overloaded into its single click making it hard to use. I understand a remote comes with but I did not have it so don't know to what extent it remedies these issues.

The back panel shows unique set of inputs and outputs;
View attachment 94017

As you see from the dual XLR outputs, the SHD Power supports four (4) channels of processing and digital output. If you want to use analog out to an external amplifier, you only have RCA outputs. A good suite of digital inputs are provided from USB to streaming via network. I was unhappy to see that streaming is limited to Airplay only as that doesn't support anything above 16 bits and its conversion from 24 bits to 16 is quite awful. Minidsp should get Roon support for it.

In use, only the bottom of the unit got warm and not that much. So make sure you don't put it on anything hot. Amplification is class D of course but not through any Hypex or ICE modules. Instead, I have read that it uses a TI chip amp (TPA3255).

Minidsp SHD Power Measurement: DAC
Let's start with the DAC performance as seen through the RCA outputs. Spec says that it can only reach 1.7 volts and that is true. Severe clipping occurs above that:

View attachment 94019

But look at that excellent SINAD score! This is a very competent DAC implementation in a multifunction amplifier with DSP. It holds its own against standalone DACs:

View attachment 94020

And among AVRs and AV Processors, it ties for the best there is:
View attachment 94022

Sweeping the output level we see the issue above 1.7 volts:
View attachment 94023

Fortunately vast majority amplifiers out there should be able to reach their maximum power at 1.7 volts.

I like the high attenuation of the DAC filter:

View attachment 94024

Which indicates very noise floor in the DAC (sorry, forgot to run dynamic range test).

The DAC in use must be ESS as we see a hint of increasing IMD distortion in mid levels:
View attachment 94025

My multitone test runs at 192 kHz. Documentation says SHD Power runs at 96 kHz internally. That may be the reason this test result is not as good as it could be:


View attachment 94026

Linearity is near perfect:

View attachment 94027

Jitter shows a lot of random spikes but some of that is due to low noise floor and at any rate, they are utterly inaudible:

View attachment 94028

Notice how both inputs are clean.

This last test was a puzzle:

View attachment 94029

Something else other than distortion is dominating this wide bandwidth test. So let's look at that spectrum:

View attachment 94030

We see a common technique called "noise shaping" where noise in audible band is pushed out into ultrasonics. That is there regardless of the distortion in the device so heavily degrades the previous measurement. Since we don't hear the ultrasonic noise, it is fine although I do like newer approaches that keep this spectrum clean.

Minidsp SHD Power Measurements: Amplifier
We could have guessed the good performance of the DAC subsystem based on our previous review of Minidsp SHD. Question then is how good the amplifier is. Let's get into that using digital input which is the only option we have:

View attachment 94031

This is well above average performance but alas, not what many of us were hoping:

View attachment 94032

That expectation aside, performance is pretty good, especially for a chip amp:

View attachment 94033

Crosstalk is excellent although the path here is digital so not fair to analog input amplifiers:

View attachment 94034

Frequency response had early roll off but easily fixable by turning on the DSP:
View attachment 94035

Noise performance is very good though missing my mark for excellence at 5 watts:
View attachment 94036

The amp doesn't seem too happy driving 4 ohm load:

View attachment 94037

It shut itself down before clipping (sadly with no indicator on the display). Power available though is much more than specification to the tune of 167 watts. Strangely the spec shows the same power for 8 ohm but that is not what I got:

View attachment 94038

Notice the cleaner results now, easily beating our "high-end" Arcam AVR10. We have a nearly 10 dB advantage in noise department.

I could not run my peak and max power test due to the chip amp aggressive protection mechanisms. This is good for reliability but not for this type of testing or hoping for burst peaks.

I set a lower limit to run power curves for different frequencies:

View attachment 94039

At or below 1 kHz response is very clean. Above that it gets erratic. Fortunately audibility of distortion gets lower at higher frequencies so consequences are much lower.

Conclusions
To paraphrase a saying, expectation is enemy of good. Such is the case here. The Minidsp SHD delivers the best performance in the DAC department for amplifiers with equalization. Certainly going above and beyond even high-end AV Processors. Alas, such is not matched by its amplifier implementation, wasting much of the performance of the DAC on it.

I should note that the Minidsp Windows App is a delight to use to program the SHD Power to do what you want across four channels. You can easily convert this unit to make an excellent powered stereo 2-way speaker. Or go crazy and build a 4-way one in mono with ease. Automatic EQ is also available courtesy of Dirac but manual ability is excellent as well. Likely the amp here is more powerful and lower distortion and noise than you find in all but the highest rated powered speakers.

My wish for minidsp is simple: offer a second unit with a Purifi amplifier module in it. And add Roon streaming.

For now, I am still going to recommend the Minidsp SHD Power. It is a good attempt at excellence in a field where such is very hard to find.

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As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

that's a great review on a fantastic 1.5k$ all in one device that includes:
state of the art DAC, Pre-amp, Room Correction and excellent (for the price) amplifier plus up to 48db/octave LR digital crossover for two way crossover less setup.
it mirror what I'm using since 2018,
- minidsp DDRC 2x4HD
- TPA3255 DIY (up to 2 months ago generic chinese, now 3E Audio)
I'm still believer my floorstander speakers + Subwoofer + asymmetric Room "screw up the" the THD+N ratio of my reproduction chain even if I upgrade with SHD minidsp or with a Purifi/Benchmark amplifier... open to debate with more expert than me on this.

however @anyminidsp silent account (I'm sure that they are reading... ) when the "second unit with a Purifi amplifier module in it. And add Roon streaming" will be available I'm going to purchase it alongside with 2 Purifi 6.5inch 4Ohm woofer+ 2 Bliesma or viawave waveguided Tweeters for a "fabulous" 2 way fully digital XXI century proof, DIY speaker and ship to @hardisj for his gold medal...

 

[Davelemi]

Ah, then they should send it preconfigured this way. One of the reasons to buy a packaged product is to not deal with the Pi software yourself.

As good as MiniDSP's products are, their software is terrible. I wonder how many buyers give up and send their purchase back?

 

[Helicopter]

Maybe better call them "international", as one of their co-founders is French. Maybe someone can shed some more light on their history.

I take it back, they are HQ-ed in Hong Kong, so they have to be official "Chinese".

Definitely a global product. Swedish software is one of its most important features, though not tied to everything under the brand umbrella. Likewise TI chips.

For the right speakers, maybe sub, and room, with the right source, this thing really could be a slam dunk. It really depends most on whether there is enough clean power to get you the sound pressure you need at the listening position.

For me, their all digital and digital in / line out DSP products make the most sense, because then I can use an Amazon streamer and pick my amp.

It is exciting to anticipate what Topping, Loxjie/SMSL, maybe even Schiit bring to the table in the coming years with DSP and powerful class D amps. What are the next generations of chip amps going to do? Will someone make great amps or modules in the Hypex/Purifi league? Why are there no amps from these firms using exising modules? Who will put PEQ, Dirac, and or other room correction suites in an inexpensive DAC or other product? It is fun to think about.

 

[hardisj]

As good as MiniDSP's products are, their software is terrible. I wonder how many buyers give up and send their purchase back?

Guys in the car audio community love their products. I personally know quite a few (personal friends of mine). And I know a lot through the internet. I can't name anyone who has complained about the GUI enough to send it back. Maybe they've had complaints about feature sets (on some of the lower end models with more limited EQ bands).

I run their C-DSP 8X12DL. Not the best GUI I've used. But not the worst.

 

[Koeitje]

My hope is that one day MiniDSP releases a surround processor and shows all these kids how its done. Too bad HDMI, DTS and Dolby licensing is a bitch.

 

[Ron Texas]

Another great review @amirm. I would probably spend a bit more for the SHD DAC and a Hypex or Purifi amp.

 

[stunta]

My wish for minidsp is simple: offer a second unit with a Purifi amplifier module in it. And add Roon streaming.

Bingo! That would be a killer unit. I would consider it even with the NCore modules. This type of device has the potential to be a SOTA single-box solution perfect for a small standmounts + sub setup.

Love how these reviews capture the performance of the DACs independent of the amps. If hope the manufacturers read reviews like these and get inspirations for future versions.

 

[win]

Who will put PEQ, Dirac, and or other room correction suites in an inexpensive DAC or other product? It is fun to think about.

this has to be the ripest low hanging fruit out there.

 

[tw99]

...

To me, the big drawback of the miniDSP units is poor ergonomics. Assuming it's like the plain SHD, the network connection is used for streaming ONLY. To upload firmware and software requires a bunch of downloads, then hooking the thing to a PC via the USB port, which may mean disconnecting your sources and so on. Then, try to find the directions! It's all rather tweaky and irritating to use compared to other products I've owned. However, IMO the SHD line offers a lot of features and good sound quality at a price lower than those easier-to-use products.

I agree - the software installation is a mess. First you need to set up a MiniDSP login; then find and download the software archive; separately install the MiniDSP s/w; the windows driver; Dirac; find the calibration details for your Umik-1 etc... It could certainly be made a lot simpler.

Once that's done, the software does give a lot of flexibility, but I'd say that it's definitely NOT for the novice or non-techie type of user.

I moved from a Dspeaker Antimode to an SHD recently, and while the SHD is ultimately more flexible and offers a couple of features that I wanted, the Dspeaker has nicer build quality and is SO MUCH EASIER to set up to do basic room correction!

 

[airs]

Another great review @amirm. I would probably spend a bit more for the SHD DAC and a Hypex or Purifi amp.

This is the setup I have now - Hypex DIY NC400 monoblocks + SHD. It was a bit time consuming to setup -

Setup a computer connected to the SHD
MiniDSP login to get the Windows software and firmware update
Dirac download, install
Connect UMIK-1, get the calibration file
Go through Dirac measurements
Load the Dirac result into the SHD

In the end, I feel that it is 100% worth it though. I'm able to stream over LAN (WiFi is also included) with Roon (via the Volumio plugin), use the preouts from my AVR into the analog inputs on the SHD (no more speaker cable swapping!), and get room correction with subwoofer output/support all in one package.

The most frustrating part of the purchase is the lack of Roon Ready. Up until September, this worked just fine in Roon - albeit with a warning that the SHD was uncertified. Then RoonLabs made the decision to no longer allow uncertified devices to work at all. MiniDSP has promised a firmware update "soon" that will make the SHD certified. Here's the 414 response thread about the tug of war: https://community.roonlabs.com/t/a-fix-for-uncertified-roon-ready-devices/120426

 

[levimax]

Great review as always. BTW, it seems using TPA3255 can possibly build solid yet budget amps. Is there any well designed power/integ amp based on TPA3255 in the market yet?

25 pages that try to answer https://www.audiosciencereview.com/forum/index.php?threads/which-tpa3255-amp-do-you-recommend.9148/

 

[McFly]

The Connectivity for my miniDSP SHD Studio makes me want to tear my laptop in half. The PEQ/Xover/Comp. DSP software is okay, but the USB connection to the unit only works 1 in 10 connects, and the Dirac Live constantly fails to connect to it also (has gotten better with revisions of Dirac to be fair, but still bad). I wonder if the USB receiver in them was a lemon?

 

[Worth Davis]

mcfly - update everything - especially DIRAC - one of the previous versions of Dirac live really did not like to connect over USB - I havent had a single issue in about a year on my SHD.

 

[amirm]

USB connection worked reliably for me too. But yes, getting the software is a pain. I had no trouble using it though.

 

[Dj7675]

As good as MiniDSP's products are, their software is terrible. I wonder how many buyers give up and send their purchase back?

I wouldn't say terrible but I would say completely different than a traditional receiver, preamp, etc. There is a learning curve but it isn't too bad and documentation is actually pretty good. What you loose in simplicity, you gain in flexibiity. This is still a nice product although most here were hoping for hypex/purify amp performance. Power seems a bit low in 8ohm to me. Not a lot of Dirac choices in this type of product, so still a nice unit, but just not for everyone.

 

[TimW]

USB connection worked reliably for me too. But yes, getting the software is a pain. I had no trouble using it though.

BTW Amir, in the miniDSP plugin you can change a setting for the amplifier from 4 ohm mode to 8 ohm mode. This setting may be what caused your 8 ohm power output to be low.