soongsc said:
thanks soongsc
you can take a look at the datasheet of ucd and ice
or anyother class-d amp.
and take a look at the noise floor or THD+N at lowest power output.
perhaps you can get more about the smps+class-d
rg
fumac
fumac!
No, and I think he didn't calculate dynamic range either! He calculated exactly what he wrote: difference of the highest and lowest level at wich you specified your amp. Obviously this is not the full dynamic range.
This is from there too:
I agree with this. That part is a complete mess. In logaritmic scale dinamic range is difference, in linear scale it's ratio. The 2 method is equivalent, but not allowed to mix them.
soongsc!
Measurements of what? If noise is much lower than signal (eg. -49 dB), then distortion is unchanged, but if noise is higher then harmonics (eg. -120 dB), then THD+n will be obviously higher!
No, there is no connection between efficiency and PSRR.
But it is dominating. 0,01 % THD+n at 200 mV (5mW@8ohm) means 20 uV "error". Do you think output noise is much less then 20 uV?
No, and I think he didn't calculate dynamic range either! He calculated exactly what he wrote: difference of the highest and lowest level at wich you specified your amp. Obviously this is not the full dynamic range.
This is from there too:
I agree with this. That part is a complete mess. In logaritmic scale dinamic range is difference, in linear scale it's ratio. The 2 method is equivalent, but not allowed to mix them.
soongsc!
Measurements of what? If noise is much lower than signal (eg. -49 dB), then distortion is unchanged, but if noise is higher then harmonics (eg. -120 dB), then THD+n will be obviously higher!
No, there is no connection between efficiency and PSRR.
But it is dominating. 0,01 % THD+n at 200 mV (5mW@8ohm) means 20 uV "error". Do you think output noise is much less then 20 uV?
fumac said:
I have tested ClassA amps, and they have PSRR from 0 dB to 100 dB.
Really? Then why did you say it is low?
Yes, 120 dB from the positive rail, but continue reading! 105 dB from negative rail, at DC! PSRR at DC??? Who cares? It's only war of numbers, without any importance. Compare them at full audio band! UcD have uniform PSRR, while LM3886 starts to fall at 50 Hz. What about yours?
I guess I should have done the numbers before I spoke.😀 So it seems like we really have to try and measure through the noise.Pafi said:
Pafi said:
to me , large than 80db is good ,
please check here, Mr Bgt have test his MCD amp
and he is using a singal supply to drive his mcd-255
http://www.diyaudio.com/forums/showthread.php?s=&threadid=116053
Bgt said:
rg
fumac
Nihao fumac, you know, 71db PSRR and loop gain "10", whatever db or 10:1, it's mutually exclusive things, there something wrong, and rather your amp has much bigger loop gain, than you like to think. 😉
IVX said:
i just told you the gain of mcd is about 10x
this is gain of our amp.
it just means input a 1v, you can get 10v at output.
have i told you about our open loop gain?
and have i told you that we have Decay at the input of power stage?
we have talked about at the phone,
because you are doing a job at china now , and not so far away from me , so perhaps we can make friends at real life,
but now , i don't think so.
because no one like others to post his personal talking at the Public .
so i will never talk with you again, and please delete my phone No. that i have gave you.
there are about 10 Foreign guys have gone to my lab when they was visiting or working at china,
we know each other at diyaudio, and make friends at real life.
or do biz at real life.
sometimes i drive them to club to have happy hours,
my English is better and better because i can talk with them at real life, this help me great.
most of them are very well know here.
but i have never post the personal MSG at here or another website.
because i know the Privacy right , i will not post their any MSG at public.
rg
fumac
to now the lowest THD+N of our project.
THD+N=0.00132%(still no test filter 🙂 )
THD+N=0.00132%(still no test filter 🙂 )
An externally hosted image should be here but it was not working when we last tested it.
What do you mean with that ? Setting up so the diagram shows output power ? I think Fumac like to display the input signal with the THD+N curves.
darkfenriz said:
when power down the amp, AP system also testing,
and sometimes , test the amp at power off (forget to power on)
so the max THD+N will perhaps up to 200%
🙂
rg
fumac
hi fumac
Can you add picture of audio output.for example 1Khz sin wave.I want to see the low amplitude sin wave.
thanks.
Can you add picture of audio output.for example 1Khz sin wave.I want to see the low amplitude sin wave.
thanks.
darkfenriz said:
It might depend to what you refer as 100%.
If 100% is the entire output signal, then you cannot exceed 100%.
If 100% is the fundamental, then you can exceed 100%.
What I would like to see is the carrier residual with no input signal and 10A DC load to one of the supply rails... 😉
Eva said:
yeah, and scope band >100mhz
fumac, so what about loop gain, how much?? And please, "very low" isn't answer, ok?
BTW, THD RMS or AVG? A-weighted? BW 22khz? Can you show FFT?- Status
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