To disassembly Topping PA3s (MA12070) you need long (at least 14-15cm) thin 2mm hexagon key (front panel is screwed from the inside), use it through the rear screw holes. You can make it yourself from scraps of any small 2mm wrench by welding a long handle if it's difficult to find such size in local stores.
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Yo need to use a balanced input attenuator helper board connected to XLR input of audio interface. Make sure not to let ground shield connect to speaker output. There is a circuit I used described in the REW distortion measurement thread. For Class D amps, you also want to use a passive brick wall 100kHz filter to prevent aliasing the data in the FFT.
Filter:
Hi, somebody know, can i put this LCR filter to BRZhifi? I think this filter need be use with input PVDD filter. How it calc? Cause I have inductors 9.1uH
Also this is right script for ATtiny85, that switch MA12070 to PMP2 and than put ATtiny85 to deep sleep state, with ADC off and BOD off for minimize EMI.
You need to use special LowPower library that support ATtiny85 - this is it https://github.com/sej7278/LowPower
You need to use special LowPower library that support ATtiny85 - this is it https://github.com/sej7278/LowPower
#include<Wire.h>
#include <LowPower.h>
void setup()
{
Wire.begin();
//Change PMP from 0 (default) to 2
Wire.beginTransmission(0x20); // 0x20 = default MA12070 I2C address
Wire.write (0x1D); // 0x1D = PMP Register
Wire.write (0x02); //Set to PMP2
Wire.endTransmission();
LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF);
}
void loop(){}
If you don't bypass the opamps you will not get close to the potenial of these Boards. The way I use them they are better than the Accuphase E303 I owned. With a differential signal straight to the input pins of the Merus Chip, you get stunning performance. I never gave any sonic impression of these boards in stock form so please don't blame me for suggesting these boards if the sonic result is just mediocre.
It is planned to remove the entire preamplification part...
It's still in progress...
The multichannel dac (balanced) on the right in the photo will be connected directly to the inputs of the chip with a balanced signal ! 😉
I finally had time to modify one amp board!
The sound is really good! direct coupling to balanced DAC output, without coupling capacitor.
No breath, nothing! Despite the gain which seems high to me (no signal attenuation).
Thanks Radian!
The sound is really good! direct coupling to balanced DAC output, without coupling capacitor.
No breath, nothing! Despite the gain which seems high to me (no signal attenuation).
Thanks Radian!
If MCU is here - i think that china's guys are already set it 😉
How do these copare to TPA3255. I have a tiny version of this chipset I use for outside speakers it sounds nice and clear. Thinking of making a bigger badder version
I made first upgrade in this amp, sounds better )
IMHO but with TPA3250 in amp from Aliexpress, this MA12070 sounds much better, more musical and little bit smoothly
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Anyone tryed to add input common mode filter? I assembled and installed the recommended common mode filter 2x100μH + 100nF NP0 capacitor and got worse results. I also tried adding a 220nF film capacitor. The sound became more soapy, less clear. I test it with dell 130w PSU from liteon and this PSU have hisown common mode filter on output, and i do not meassured it. Do you have any idea?
I have 2 of these boards...symmetrical entries.
The quality of the components and assembly is exceptional!
Huge sound across the entire spectrum and surprising clarity (all the details are there), better than any TPA and ice power I've tried.....
This is huge for a 7mm x7 chip. Neutral amp, quality DAC and high resolution files required!👍