Music is like "DC" to these caps, especially in the bass region. Their support here is more for the mid range dynamics, so having 2200uF or 3300uF makes no difference at bass. To really have some "support" at the low end you'd need like 0.2F or 200.000uF, thats why it's is better to increase primary capacity. If the loop bw of the SMPS is high enough, bass is supported by the SMPS regulation. Remember, this is a switching power supply at high frequency not a 50/100Hz Toroid supply where huge secondary bulk capacitance is the key. To much secondary capacity in a smps lowers loop bw and, worst case, can lead into fail of rectifier diodes due to to high dI/dT and amplifier ic fail due to overshoot events.
Can you please check what series the green Nichicons are? This should be noted on the sleeves somewhere, are they really PM series? Just curious, as PM is normally in a brown sleeve, not green/gold.
Can you please check what series the green Nichicons are? This should be noted on the sleeves somewhere, are they really PM series? Just curious, as PM is normally in a brown sleeve, not green/gold.
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I can't clear you ideas above, all the soldered board pass ultrasonic cleaning,so the board clean .
attach one short video of the board cleaning.
link：http://pan.baidu.com/s/1jIAnaj8 SN：kels
PM(M) seiries, customized type, from Nichicon China factory, lower ESR and 105oC type
There should no problems for the capacitors capacity, if apply this module in 110Vac area, SMPS stage bigger EC should good.
I compared the two amplifiers 50 Hz square wave. 8 Ω
I.AM.D V200
and SINEWAVE TPA3251
our engineers retest the module and get some photos and video ten minutes ago, it seem all good, no problems, 26V@8ohm,THD+N <10%, support long time continous runing.
accurately, all the value pass our lab test with APx525 days ago, all the curve compare to the TI datasheet values,no problems indeed.only PSRR data have not found in the datasheet, without compare now.
we ordered TPA3251 EVM from TI last month, we test all the values, I think our design have similar performance to the EVM board.
In order to facilitate customer apply, SMPS and class D stage all in one board.our China customers have applied this module to some area, like audio broadcast and 100Khz sonar transducer driver
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~1-2 watt. Peak to peak ~ 6V
Yes
No. OK. I understood you. V200 input USB. TPA3251 - analogue. I can measure input meander only in the evening.
take more photos just now with 50Hz sinewave signal.
9Vrms@8ohm 50Hz sinewave
24Vrms@8ohm 50Hz sinwave
in the datsheet, without TPA3251 SLEW RATE value . so we can not compare this value indeed. OPA1632dr as input buffer,it have 50V/us slew rate value.
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Measuring 50 Hz square wave indirectly shows the lower frequency limit. If the square wave is flat, then the amplifier may sound ideally from 0 hz. If the square wave is not flat, then the problem is with the power supply or there is insufficient capacity or the coupling capacitor.
I have subjective a lack feelings of low frequencies.
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6.74V@8ohm 50Hz square wave
we found TPA3251 PSRR performance should not good, this mean that default feedback in the chip a bit small, this is the reason why this chip have wide frequency range response(100Khz)
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Ideally it would be nice if the power supply has been synchronized with the PWM frame rate.