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3e Audio SY-DAP2002 Review (DSP Amplifier)

amirm

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#1
This is a review and detailed measurements of the 3e Audio SY-DAP2002 stereo desktop DSP amplifier with Bluetooth. It was kindly purchased new by a member and drop shipped to me. I will also do a teardown and test with upgraded op-amps. I went to look up the price just now and it says no longer available! I think it was US 116.

The enclosure is heftier than is typical for the class:

DAP2002 Review DSP Stereo Amplifier.jpg


A cute set of white LEDs rotate around the volume control when first turned on and then indicate volume level. An unusual twist for this class of amplifier is inclusion of mains power supply:
DAP2002 Review DSP Stereo Bluetooth Amplifier.jpg


No figure-8 power cord was included however so I have to supply my own. As you see, there is a little fan to help with cooling but it never came on during my testing. I had the top open and touching the heatsinks showed that they were pretty cool which explains the fan staying off.

Note that while there is a DSP subsystem, I did not test it. It is based on "Sigma" ADAU1701 platform which I already reviewed.

Amplification is provided using the ST Micro TPA3255 chip.

SY-DAP2002 Measurements
I started my testing using stock configuration:
DAP2002 Measurements Stereo Amplifier.png


Distortion is quite low at -95 dB however SINAD is way worse at just 72 dB indicating noise as the limiting factor (SINAD is sum of noise+distortion relative to signal). Don't be confused by the -100 dB noise floor in FFT. That is after some 35 dB of "FFT gain."

The owner had warned me about the noise and indeed had gone ahead and purchased the recommended upgrade opamps, the LM 4562. I took the top off and swapped both and performance indeed improved:

DAP2002 Measurements with LM4562 Upgrade Stereo Amplifier.png


Noise still dominates though so performance continues to be average:

Best budget stereo amplifier review.png


You can see the effect of noise in SNR tests:

DAP2002 Measurements SNR  with LM4562 Upgrade Stereo Amplifier.png


Here is the comparison of noise with no input signal with or without the op-amp upgrade:
DAP2002 Measurements Noise Stereo Amplifier.png


Frequency response is limited based on digitization and load dependency:
DAP2002 Measurements Frequency Response with LM4562 Upgrade Stereo Amplifier.png


Crosstalk was generally good but somewhat variable:
DAP2002 Measurements crosstalk with LM4562 Upgrade Stereo Amplifier.png


Multitone test shows how low the distortion is, alas with high noise floor:

DAP2002 Measurements Multitone with LM4562 Upgrade Stereo Amplifier.png


Healthy amount of power is available before shut down:
DAP2002 Measurements power into 4 ohm with LM4562 Upgrade Stereo Amplifier.png


Because of aggressive protection circuit, I could not get to 1% THD to measure max or peak power.

Good bit of power is available at 8 ohm indicating that the 4 ohm performance above is current limited:
DAP2002 Measurements power into 8 ohm with LM4562 Upgrade Stereo Amplifier.png


Transfer function is quite good for a switching amplifier:

DAP2002 Measurements Power vs Frequency vs Distortion with LM4562 Upgrade Stereo Amplifier.png


SY-DAP2002 Teardown
Overall construction seems reasonably clean:
DAP2002 stereo amplifier teardown ADAU11701.jpg



Top row is the switching power supply which naturally has high-voltage rectified mains in it. As such, I would have liked to see a routed slot in addition to existing isolation that exists on the PCB. That would reduce the chances of arcing from high voltage side to the low voltage amplifier.

Capacitors are lower grade as usual but at least all the ones I looked at are higher grade 105 degree C.

The heatsink is quite beefy for its size and seemed to do its job keeping the TPA3255 chip amp cool in my testing. I am not sure the fan will do any good since it likely pushes air in but there are no vents to push air out. High static pressure then reduces its effectiveness although likely it is better than nothing (if noise is not a problem).

I did not like the Bluetooth antenna lead travelling from the front of the board to the mains side. The noise from switching power supply may reduce Bluetooth range and at any rate, it is not a safe place for it should the lead come off and touch the high-voltage areas of the power supply. The RCA cables could have been moved a bit up (in the picture) and made room available for that in the low voltage section.

I see no regulatory and safety certifications which is not good in mains powered gear.

Overall, this is not nearly as bad as it could be.

Conclusions
Getting a DSP platform and top-flight chip amp and power supply in a small box takes good bit of effort. Overall, this is not a bad platform but compromises are there with performance dropping below what the chip amp can do. Personally I use DSP upstream so have no use for it in the amp in this configuration so the performance hit (if due to that) is not good in my book. But you can decide otherwise.

I could have recommended the amp but seeing how I had to upgrade the op-amp to get good performance, I am going to pass.

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

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amirm

amirm

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Thread Starter #3
Not sure how one can use the DSP interface, via Bluetooth?
There is a header marked "USBi" close to front panel. You plug in their special adapter and use the Sigma software to program it.
 

Vini darko

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#6
Thanks for the review amirm. Pardon my ignorance , how does dsp work with this? Don't see any controls or computer inputs to control it.
 

maverickronin

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#7
Thanks for the review amirm. Pardon my ignorance , how does dsp work with this? Don't see any controls or computer inputs to control it.
There is a header marked "USBi" close to front panel. You plug in their special adapter and use the Sigma software to program it.
 

gvl

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#10
This is the first example where I've seen an upgraded opamp improve performance significantly. 7dB increase in SINAD for a few dollars (according to Mouser) seems like a no brainer, even with the low price of $116.
Sounds like they designed for the "recommended" upgraded opamps but included a cheaper version to lower the bill of materials.
 
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#11
I used the same Op-amps in mine, but then also added the capacitors that were missing in my unit. I've also got the 8Ω one and would be willing to send it in if you wanted to test that, and see if there was a difference with the caps installed.
 

m8o

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#12
This is the first example where I've seen an upgraded opamp improve performance significantly. 7dB increase in SINAD for a few dollars (according to Mouser) seems like a no brainer, even with the low price of $116.
Ya, I thought that too. But also like Amir says, I apply dsp upstream if/when necessary. That said having it in the amp is ideal if I'm making a turn-key system, usually bi or tri amped. And the price of entry here makes that cheaply attainable. An interesting amp. I would give one or more a try.
 

respice finem

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#14
Sorry for the probably "borderline offtopic" remark, but it seems to me that many modern amps, including this one, might measure better (and not need a fan) if they were designed less "dense". The more compact the form factor, the higher the risk of interferences etc. Small is beautiful, but packed may bee too small... or am I thinking too "oldschool"?
 
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#15
Interesting platform. Does ADAU1701 support channel matrix mixing? add eARC, bitstream decoding and some decent upmixing algorithm (Logic 7 or ProLogic 2) and you have an all-in-one HT & music solution. Not quite NC252MP level performance, but the price level should reflect that.
 

abdo123

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#18
$116 for all that? Good deal. Get 3 and you're all set for a reasonable 3-way active speaker setup.
How would you control the volume? Individually use all 3 volume knobs and hope that the potentiometer/digital rotary encoder matches the volume between all 3?

Thanks, I'll pass.

The multichannel market is honestly a mess.
 

gvl

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#19
How would you control the volume? Individually use all 3 volume knobs and hope that the potentiometer/digital rotary encoder matches the volume between all 3?

Thanks, I'll pass.

The multichannel market is honestly a mess.
Upstream, DAC, preamp, etc.
 

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