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miniDSP 2x4 HD Sweetspot-audio Mod Review

Rate this DSP Mod:

  • 1. Poor (headless panther)

    Votes: 191 88.0%
  • 2. Not terrible (postman panther)

    Votes: 16 7.4%
  • 3. Fine (happy panther)

    Votes: 2 0.9%
  • 4. Great (golfing panther)

    Votes: 8 3.7%

  • Total voters
    217

amirm

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This is a review and detailed measurements of the miniDSP 2x4 HD as is, and as modified by German company sweetspot-audio. Later version was kindly provided by a member and costs US $191 (EUR 175) on top of the cost of the 2x4 HD ($225).
miniDSP 2x4 HD Toslink In DSP DAC sweetspot-audio mod review.jpg

As you see, the main indication that the 2x4HD has been modified is their sticker. This is what the company says they modified:

Scope of modification:
  • Improvement 12v DC input voltage
  • Improvement entrance level
  • Improvement output stage
  • Replacement of all operational amplifiers
  • RFI measures
  • Reducing the noise floor
  • Distortion Reduction (THD)

Total changes: 21

The 2x4 HD was one of the earliest measurements I had made with my older analyzer. So let's first update that with a handful of new measurements.

miniDSP 2x4 HD Measurements
We start with our dashboard:
miniDSP 2x4 HD Toslink In DSP DAC Measurement.png

We are just there as far as performance (all tests use Toslink input), clearing the 16-bit audio hurdle by a hair. Such is the case with dynamic range as well:
miniDSP 2x4 HD Toslink In DSP DAC DNR Measurement.png


Jitter test shows some harmless interference:
miniDSP 2x4 HD Toslink In DSP DAC Jitter Measurement.png


IMD sweep shows that noise floor could be lower:
miniDSP 2x4 HD Toslink In DSP DAC IMD Measurement.png


Wideband THD+N vs frequency shows rather poor performance:
miniDSP 2x4 HD Toslink In DSP DAC THD vs frequency Measurement.png

It could be due to filtering (did not measure).

miniDSP 2x4 HD with sweetspot-audio mod Measurements
Note:
I used the US power supply that my minidsp came with. The one supplied has the same rating but has European plug. I don't think this is something that is upgraded.

Let's go back to our dashboard:
miniDSP 2x4 HD Toslink In DSP DAC sweetspot-audio mod dashboard Measurement.png

Well, this is not good. We lost 6 dB of SINAD performance which we could ill afford. The cause is increased noise:
miniDSP 2x4 HD Toslink In DSP DAC DNR Measurement.jpg


Same story continues through the rest of measurements:
miniDSP 2x4 HD Toslink In DSP DAC sweetspot-audio IMD mod Measurement.png

miniDSP 2x4 HD Toslink In DSP DAC sweetspot-audio mod Measurement.png


Clearly there is no reduction in noise or distortion as company claims.

Edit: additional tests for analog in/out

Analog In/Analog Out Measurements
As requested, here are the tests with analog input and output. Let's start with the dashboard of the stock unit:
miniDSP 2x4 HD Toslink In DSP DAC Analog Measurement.png


Now the modded version:
miniDSP 2x4 HD Toslink In DSP DAC Analog Sweetspot-audio dashboard Measurement.png


The mod once again degrades performance especially in noise department:
miniDSP 2x4 HD Toslink In DSP DAC Analog Sweetspot-audio Measurement.png


You are losing a full bit of dynamic range you can ill afford. Fortunately frequency response is intact:
miniDSP 2x4 HD Toslink In DSP DAC Analog Sweetspot-audio frequency response Measurement.png


The degradation is across the full input/output levels:
miniDSP 2x4 HD Toslink In DSP DAC Analog Sweetspot-audio THd vs Level Measurement.png


Conclusions
Focusing on sweetspot-audio modifications, seems like you are paying a lot of money (almost the cost of 2x4 HD) only to get worse performance! Owner has indicated that he measures. If so, very strange to get the results we are seeing.

The 2x4 HD seems to have just good enough performance. Company makes higher end products with much better performance so if that is what you want, getting one of those would be a better bet than going with the above mod.

Needless to say, I can't recommend the sweetspot-audio modifications for miniDSP 2x4 HD.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
Last edited:

Sokel

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Seems like the PSU is also updated as they say "improved 12 DC input voltage" but I wouldn't expect to make a difference.
I think both the original and the updated need an update by the company.

Thanks Amir!
 

pogo

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Clearly there is no reduction in noise or distortion as company claims.
Could it be that the improvements are only achievable with the original power supply unit in the European power system?
 

dogmamann

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May be he measures to make sure they are “different “ from the original hence an audible difference in sound. So as the sound isn’t identical to the stock, depending on your preference, you may end up thinking it’s an upgrade. Fidelity aside, had liked old audio gear with hiss over something clean at some point becomes it was relaxing for me ! Even when completely informed, it’s not necessary that everyone would prefer the ones with the best measurements. There can be just few wrong things which would be someone’s preferences and if they choose to live their life with their choices we don’t have to argue that they have to be changed.
 

ReDFoX

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For $191 they could easily add multichannel dac and even upgrade ADC. 2x4 HD has I2S bus literally exposed... You can just solder wires and use your own DACs
Curious about what's inside this "upgraded" unit
 
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amirm

amirm

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Seems like the PSU is also updated as they say "improved 12 DC input voltage" but I wouldn't expect to make a difference.
I read that as internal post regulator. The supplied PS is a chinese stock adapter. Just looks a bit different than the one I have.
 
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amirm

amirm

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Could it be that the improvements are only achievable with the original power supply unit in the European power system?
I don't see how. The thing operates on DC, not AC. I can simulate 50 Hz 240v but I think it will be waste of time.
 
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amirm

amirm

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wwenze

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Seems like the PSU is also updated as they say "improved 12 DC input voltage" but I wouldn't expect to make a difference.
I think both the original and the updated need an update by the company.

Thanks Amir!
In their provided images the capacitor for DC power is upgraded to something a bit bigger. Not necessarily automatically meaning better performance even if it is now a Panasonic FM. (Or is it FC, I always mix up the two)

tKllr3Y.jpg
 

Sokel

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Replacing opamps without caring about PSRR and input impedances, as well as changing the gain structure can do that.
What's strange in the original version is it's THD+N vs Freq measurement which is consistently in the 65-70db SINAD area except in the region between 1-2Khz.
And ok,higher freqs get the big hit from the extended bandwidth of the measurement but is the same everywhere!
A suspicious one would say that is tailored.
 

MCH

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@amirm can you tell if the stock unit you measured was the older or newer version? Someone posted a few days ago measurements of the newest version of the 2x4HD that show slightly better results (Sinad >100db iirc) it would be good to have a side by side comparison or that the OP ( @wbenjin ) post his results here as well.
PS: thanks for revisiting this classic. They should give one to every student in audio enthusiasts schools :)


edit: here it is:
Thread 'miniDSP 2x4 HD (DDRC-24) V2 simple measurement and teardown pictures' https://audiosciencereview.com/foru...mple-measurement-and-teardown-pictures.50900/
 
Last edited:

poxymoron

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Thanks Amir. What a complete waste of money and effort this thing is. Not the first time we've seen that.
Or maybe not, if you build it they will come.
 
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