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Old 13 October 2016, 21:44   #54
pandy71
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Join Date: Jun 2010
Location: PL
Posts: 1,546
Quote:
Originally Posted by meynaf View Post
My point was just about adding several channels together to get sounds that can't be made in theory.
It can be made and it is used in real life circuits - i already provided you multiple examples like PCM63 where there are two 19 bit DAC connected in a way to allow them process 20 bit samples (and you think that Burr Brown guys was so stupid that they use two 19 bit converters i.e. 28 bits to convert only 20? why they not used two 10 bit converters stacked as you propose?)

Quote:
Originally Posted by meynaf View Post
It's clear you don't have a clue on what calibration does
That's why i asked you as experienced software coder for explanation, i can understand if you don't know or if you not wish to share such knowledge but then say this openly.

Quote:
Originally Posted by meynaf View Post
But do we really have problems in analog path ?
IMHO this depends from you - as you don't care too much about facts if they not fit to your opinion.

Quote:
Originally Posted by meynaf View Post
But you do agree that the calibrated output must lead to less than 16384 different values, and this can be verified.
This is quite obvious as in combined two 8 bit Paula DAC's at best we may have 16384 different values and if DAC is not perfect then it means that less than 16384 values can be available.

Quote:
Originally Posted by meynaf View Post
It does not introduce "6 bit attenuation", just reduces the signal by 64. $40 with a volume of 1 is NOT the same as $01 with a volume of 64.
Please correct me but HRM provide this kind of values -36dB is exactly 6 bits.

Quote:
Originally Posted by meynaf View Post
Sure, but you didn't do the experiment.
As i said - i've tried long time ago 14 bit on Amiga and IMHO it was not 80dB+ SNR but less - i would locate his somewhere around 60 - 70dB.

Quote:
Originally Posted by meynaf View Post
It's not an opinion. It's a fact that can be checked.
Something can be fact for you and opinion for someone else.
If you write 'checked' you refereeing to subjective or objective method?

Quote:
Originally Posted by meynaf View Post
Apparently yes, else you wouldn't talk about -36dB coming out of the paula chip.
Well this almost direct value from HRM.

Quote:
Originally Posted by meynaf View Post
This has nothing to do with "correcting 2 bits". It's about combining two 8-bit signals to get 14 bit.
So somehow splitting 16 bit on upper and lower part leading us to 14 bit sample resolution... why not 10, 12 or 16 but 14? And why this is 2 bit difference?


Quote:
Originally Posted by meynaf View Post
Why wanting external sources ? It's an experience anyone here can do.
Try playing 14 bit on any PC (uncalibrated 14 bit running on an emulator should suffice), and compare with an Amiga running software such as Play16.
Nope as common audio DAC in PC has usually 16 bit and additionally it is usually single bit converter.
If you run calibration on emulated in PC Amiga what you expect to get?

Quote:
Originally Posted by meynaf View Post
You don't know, but according to what you said, it should be less than 16384.
I can do that measurement anytime, but first you have to be clear on what to expect. If, say, it's 17000, there's something wrong somewhere, don't you think ?
I expect to see measurement results not 15500 or 18000.
And yes i will be surprised to see for example SNR like 98dB but trust me if this will be for example 82dB (as this is very close to 14 bit) it will be more then very good for such circuitry like in Amiga and i will be very happy.


Quote:
Originally Posted by meynaf View Post
As said, i don't care about all that DAC theoretical stuff. What matters is the final output quality, and i know for having heard it that it's certainly not just 10 bit.
Did you ever have opportunity to hear 10 bit DAC?


Quote:
Originally Posted by meynaf View Post
As i already said, the component that provides the 14 bit accuracy isn't Paula.
At the end the trick is exactly the same as if we were using 8-bit video D/A and do +1 half the time - at the end we get 9 bit (if we're fast enough).
It is not clear to me - are referring to temporal dithering?


Quote:
Originally Posted by meynaf View Post
The top 8 bits aren't used directly. That would be too easy
Well - if they are not used directly then it means that DAC resolution suffer and overall SNR will be worse.

Quote:
Originally Posted by meynaf View Post
But in real life a PC (16 bit DAC) won't play a 8 bit sample better than an Amiga (8 bit DAC), at least not without some upsampling.
This is a fact anyone can check.
You refereeing to subjective or objective method?

If in real life you will feed analog signal from 8 bit DAC with 8 bit accuracy (assumption decent +-0.5LSB) then same samples played by 16 bit DAC with same accuracy (i.e. +-0.5LSB) will be objectively better - not sure if this can be hear but this is subjective area and everyone may have own opinion.


Quote:
Originally Posted by meynaf View Post
Again, just theory.
The one you didn't care...


Quote:
Originally Posted by meynaf View Post
Perhaps it's better to just wait until you have the Amiga...
If you need a program able to play any wave file, ask me (if you're not locked to old 68000).
As i said, waiting for V500 then i need to find player capable to play 14 bit with and without calibration from HDD.
And I have many Amiga computers and that's why i know that CDTV was worse than CD32 in terms of audio quality.

Quote:
Originally Posted by meynaf View Post
I don't want a formalized discussion, you trying to bring me to your land, huh ? It doesn't work this way.
I've realized - you don't care about objective data.

Quote:
Originally Posted by meynaf View Post
You're not exactly answering the question...
Well... not sure - what do you mean?

Quote:
Originally Posted by meynaf View Post
So i will ask it again, in a different way.
Let's say we load a calibration file, then build the table giving the 65536 values. How many unique value pairs do you expect to find in the table ? (this can easily be verified ; if you don't know you can at least estimate a reasonable range)
Well if LUT has 65356 entries and they need to be mapped to 16384 16 bit words then i expect at best 16384 unique values (i assume that LUT is to deal with slow processing capabilities of Amiga - sample value is address for LUT and value read from LUT is feed to DAC's)
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