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3e Audio SY-DAP2002 Review (DSP Amplifier)

daftcombo

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#42
Thanks Amir!

If max input is 1V, what about running the dashboard again at 1V?
 

IVX

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#43
Hey, I just found how they offer to use the DSP, you have to disassemble the unit to get access to the internal USBi connector, and of course, you have to have USBi interface too i.e. buy it first ($84 for the original one). I think, for 99% of users the amp has no DSP at all.
 

AnalogSteph

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#44
They used ADAU1701 with its ****** ADC, that's why SNR just 90db, actually, $1/2 ADC today offers SNR 105db(A), and I see no reason to save money on it.
If the capacitor fix drops noise another 6 dB over what's shown, that would get us to about 98 dB(A). Seems reasonably close to what you would expect from ADAU1701 converter specs (A/D 100 dB(A) + D/A 104 dB(A), both combined = 98.5 dB(A)). Swapping the ADC for one with 105 dB(A) would improve matters by 3 dB only, no doubt very welcome (300 µV counts as mediocre) but still not exactly earth-shattering.

I still find it weird that one would have to use comparatively fancy opamps just to achieve a sub-100 dB dynamic range... this smells of gain staging issues of some kind.
 

MadMan

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#45
They used ADAU1701 with its ****** ADC, that's why SNR just 90db, actually, $1/2 ADC today offers SNR 105db(A), and I see no reason to save money on it.
From the review..."Note that while there is a DSP subsystem, I did not test it." I guess that means he didn't configure it?

Pretty sure it's only for the Bluetooth input as a DAC, although no one answered my previous post confirming that. Or maybe if it's turned on via USB configuration it also does an ADC-DAC path for the analog inputs? Otherwise it seems pretty silly to do an ADC-DAC conversion for analog inputs.
 

IVX

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#46
AnalogSteph, of course, the real bottleneck is the class D IC, and there is SNR 114db(A) as I remember, hence, the ADC with 114-120db(A) would be reasonable to me. It will push the cost up to a couple of dollars(CS5361?). Any cheapest opamp, including 10pcs/$ lm353, may outperform 90db SNR, no doubt.
 
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#47
This is not a knob, it's a rotary encoder. Volume is controlled by the STM32 micro controller.

View attachment 110783
This is not a rotary encoder. It's a potentiometer with hard stops. The STM32 doesn't control volume, it is for LED indication. Look closely at the block diagram. The potentiometer connected to the ADAU via Auxiliary ADC Input.
 

Mnyb

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#50
Why would anyone even consider using mains powered products without safety and regulatory approvals ?
Evaluation just stops there , product can not be used safely .

We can build a playlist for you .o_O

Fire starter ( prodigy )
Burning down the house ( talking heads )
We didn’t start the fire ( Billy Joel )
 

IVX

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#51
Mnyb, actually you are right, I measured on the picture the distance between 2W resistors on the HOT side and the metal case and found that 5.5mm, that's less than any UL/VDE safety standards requirements, and no matter if resistors are painted because we have to consider the worst case. However, if the manufacturer did place there .2mm mylar film, the safety limits could be passed. No idea how the PCB was fixed, if there plastic standoffs 6-7mm in length, the required air gap is there, or mylar film under the PCB required again.
 

IVX

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#52
jlesterp, for the distortions levels are actual in audio industry, THD+N and SINAD are the same thing only negative vs positive. When distortions reached tens of % SINAD will show a noticeable difference vs THD+N, that's why SINAD expression was offered to measure a huge amount of distortions for example in an SSB radio. The audio-industry uses THD+N. I would like to measure, and I usually do, the THD+N vs freqquency of the loaded to areal speaker amp, such class D amps, like IR, or Ti, NXP, ST -all use FB before an LC and the THD+N a good is only on a resistor.
 

respice finem

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#53
Why would anyone even consider using mains powered products without safety and regulatory approvals ? Evaluation just stops there , product can not be used safely...
a) this. b) For equipment not needing much power, an external "brick" PSU may be a nice solution, as long as it's not [email protected], because it keeps noise away from the internals. The problem is, many are [email protected] In the end, one gets what one has paid for (and that's the best case).
 

respice finem

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#55
From a high-powered amp, certainly, but these things are a) not really high powered and b) trying to be "all that fits in the box", and if I were building such, I would seek to root out all sources of interference, either this way or by shielding. Maybe I'm thinking too "oldschool", but there are high frequency chips etc. involved here, and thus potential for HF noise and such.
 

IVX

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#56
respice finem, all that is manageable:

1) a resonant SMPS for the minimal EMI aka HF noise
2) 4 layers PCB for an optimal layout
3) not really cheap parts
4) of course some skills are needed but actually, skills needed even to open a bottle of beer as well

I have my dusty HiFiTOY proto PCBA 120x93mm. For the moment almost abandoned project but if I'll get the app.info for the Qualcomm PWM modulator I can wake it up and finalize.
https://e1dashz.wixsite.com/index/hifitoy
 

IVX

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#58
any codecs are about the particular BT module in use +/-$2, unfortunately, all of these codecs are lossy-compressed, and "HD" just a nickname without connection to reality.
respice finem was 100% right, the most challenging thing is a high power density design with minimal EMI disturbances from SMPS to class D and to the frontend etc. One BT module to another one I think can change my 8 years old son ;)
 

respice finem

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#59
...all that is manageable...
Yes of course it's manageable, but not necessarily "on the cheap". It seems to me, nowadays the most important thing is to issue a new model before the competition, with maximum features to minimum cost. Proper construction and quality, as long as it survives the guarantee period, comes second. The end product is then often a waste of good chips. Mass market has become like junk food, "the customer is not a p!g, he'll eat anything"... On the other end of the market, there are some who think they need to "ameliorate" reference designs without enough knowledge, with similar results.
 

Mnyb

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#60
a) this. b) For equipment not needing much power, an external "brick" PSU may be a nice solution, as long as it's not [email protected], because it keeps noise away from the internals. The problem is, many are [email protected] In the end, one gets what one has paid for (and that's the best case).
This thing does not have a brick psu , that would be easier for them just buy an approved psu ?
 

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