THD is excellent, however THD+N is quite poor in comparison. What is the reason, amplifier noise or measuring system noise?
OK, thank you. Did you measure amplifier output noise with shorted input? It is as important as low THD.
Noise measurements
Cosmos ADC unbalanced noise (input 50R) = 2.111uV or -113.5dBV
FukAMPv4 voltage amplification = 35.9x or 31.2dB
Simulated noise bw 20kHz = 26uV or -91.7dBV (ideal power supply)
Measured noise bw 20kHz (input 50R) = 29.8uV or -90.5dBV (SSR3 included)
Cosmos ADC unbalanced noise (input 50R) = 2.111uV or -113.5dBV
FukAMPv4 voltage amplification = 35.9x or 31.2dB
Simulated noise bw 20kHz = 26uV or -91.7dBV (ideal power supply)
Measured noise bw 20kHz (input 50R) = 29.8uV or -90.5dBV (SSR3 included)
Attachments
I reduced the gain from 36 to 29, the residual noise is 25uV (-92dBV) unweighted BW20kHz ref@1Vrms (SSR3 is not part of the output)
WELL DONE
WELL DONE
Attachments
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This is PCB v4.0, v4.1 is slightly modified (rc filter added to the 3ef driver/pre-driver power supply line)
Square wave test.
4Vpp 10kHz, load 2R parallel 47n,100n,680n,2u2.
Measured after the output coil. (just 0.1uH)
Fantastic, completely tamed 3 pole TMC compensated VFA at 3MHz ULGF.
4Vpp 10kHz, load 2R parallel 47n,100n,680n,2u2.
Measured after the output coil. (just 0.1uH)
Fantastic, completely tamed 3 pole TMC compensated VFA at 3MHz ULGF.
Attachments
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Comparison of linear and switched power supply.
Linear power supply -> 2x3x10000uF/63V
The smps has two 150uF/400V input caps, later I plan to try 2x330uF/400V.
https://www.audiophonics.fr/en/smps-power-supply/smps500r-power-supply-module-500w-55v-p-6458.html
Linear power supply -> 2x3x10000uF/63V
The smps has two 150uF/400V input caps, later I plan to try 2x330uF/400V.
https://www.audiophonics.fr/en/smps-power-supply/smps500r-power-supply-module-500w-55v-p-6458.html
Did you try to level down the noise just use a RC filter...XRK did this afaik at the VSQA (quasi) amp.
e.g. 0,33R 3W ...not able to handle 100W into 4R but..
chris
e.g. 0,33R 3W ...not able to handle 100W into 4R but..
chris
-120dBc mains ripple level is not bad, the HF level is even better (in conjunction with my amplifier)
IMHO, that smps is quite good (at that price level), it has regulated output
IMHO, that smps is quite good (at that price level), it has regulated output
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For low-cost projects, why not? In a quality hifi amplifier I wouldn't even consider it, ...
The parts in SMPS speak for themselves, ...
The parts in SMPS speak for themselves, ...
Doubling the capacity of the HV rectifier (300uF/400V -> 600uF/400V) => mains related noise decreases by 10dB
For those of us who like to see the zero's... -121.6 dB THD is 0.00008% -100w 4r measured! Very impressive.
Personally, I don't care if the amplifier has a distortion of 0.001% or 0.00008%, the sound performance is more important. I would also buy Fukamp boards, but there are 3 things that bother me.
1, Absence of quality polypropylene at the input
2, Wago terminal at the output, into which you can put a maximum of 1.5mm2, even with problems, ... (I prefer Faston)
3, Missing choke at the output, which you replace with a 30cm wire...
1, Absence of quality polypropylene at the input
2, Wago terminal at the output, into which you can put a maximum of 1.5mm2, even with problems, ... (I prefer Faston)
3, Missing choke at the output, which you replace with a 30cm wire...