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Minidsp SHD Power Amplifier Review

amirm

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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:

Minidsp SHD Power Review.jpg


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;
Minidsp SHD Power back panel XLR AES.jpg


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:

Minidsp SHD Power DAC Measurements.png


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:

best DSP amplifier review.png


And among AVRs and AV Processors, it ties for the best there is:
Best AVR Processor DAC Measurements.png


Sweeping the output level we see the issue above 1.7 volts:
Minidsp SHD Power DAC THD+N vs output level Measurements.png


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:

Minidsp SHD Power DAC Filter Measurements.png


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:
Minidsp SHD Power DAC IMD Measurements.png


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:


Minidsp SHD Power DAC Multitone Measurements.png


Linearity is near perfect:

Minidsp SHD Power DAC Linearity Measurements.png


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:

Minidsp SHD Power DAC Jitter Measurements.png


Notice how both inputs are clean.

This last test was a puzzle:

Minidsp SHD Power DAC THD+N vs Frequency Measurements.png


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

Minidsp SHD Power DAC FFT Measurements.png


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:

Minidsp SHD Power Measurements.png


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

Best AVR DSP Review.png


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

Best Dirac Amplifier Review.png


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

Minidsp SHD Power Measurements Crosstalk.png


Frequency response had early roll off but easily fixable by turning on the DSP:
Minidsp SHD Power Measurements Frequency Response.png


Noise performance is very good though missing my mark for excellence at 5 watts:
Minidsp SHD Power Measurements Dynamic Range.png


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

Minidsp SHD Power Measurements Power into 4 ohm.png


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:

Minidsp SHD Power Measurements Power into 8 ohm.png


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:

Minidsp SHD Power Measurements Powervs Frequency  into 4 ohm.png


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.

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

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mrkc

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The price certainly doesn't reflect its overall performance when the Loxjie earlier perform just slightly worse in Amp
 
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amirm

amirm

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The price certainly doesn't reflect its overall performance when the Loxjie earlier perform just slightly worse in Amp
This has four times more power though.
 

LTig

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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.
I must be blind. The only analog RCA out I see is named Sub Out (Out 1 and Out 2). Do they carry the full range signal?
 

oohlou

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I must be blind. The only analog RCA out I see is named Sub Out (Out 1 and Out 2). Do they carry the full range signal?
It is configurable. To Amir's point in the conclusion you can do pretty much anything you want with respect to how inputs are routed and processed.
 
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amirm

amirm

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I must be blind. The only analog RCA out I see is named Sub Out (Out 1 and Out 2). Do they carry the full range signal?
Yes. You program the DSP however you like. I got confused too at first seeing those sub labels and hence, did not test the DAC originally. Got to the end of the amp measurements and only then realized they are just normal outputs.
 

waynel

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this thing deserves a better amp. SHD + Hypex 250W into 4 ohm amp is only $200 more.
 

dwkdnvr

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A bit disappointing given how good the basic SHD idea is, but not exactly bad. I agree with Wayne above - for the minor increment in price I'd probably be more inclined to go with a standalone SHD plus a Hypex 252 - better performance, more flexibility and only slightly more $$$.
 

Xyrium

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Very surprised they didn't go icepower like their other stuff. Neat package, DAC, amp, Dirac...
 

win

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I don't have any issues streaming 24 bit to my shd studio via Roon.

i think I had to configure the initial setup but yea it should be supported, all but officially.
 

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Worth Davis

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volumio need like one or two clicks and it will light up as a Roon endpoint
 

mrkc

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This has four times more power though.
Oh that is true indeed. Though I still don't think the price is justified (roughly 7times I think)
I think it will be interesting to see MiniDSP perhaps collab with one of the good amp manufacturers to improve the amp performance
 

o2so

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I could not see any Roon end point exposed.
From September 2020 Roon has started to not recognize endpoints that are not officially Roon certified, such as all the SHD units. Those who added an SHD as an endpoint to their Roon core before September 2020 are still able to use it, but if they remove the end point, or re-install Roon, they won't be able to add the SHD back. This is what MiniDSP told me. Apparently, they are working to get full Roon certification but it is a bit tricky, they say.
 
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