Queries on AGA Copper and 14-bit Audio

[vulture]

@pandy71

They're active studio monitors, as I said, dead silent, volume at max. Transcend CF 32gb internal, 1gb sandisk on pcmcia, simple chinese cf2ide adapter. Motherboard rev is 2b with the usual capacitor fix for compatibility, but no recapping or anything else. PSU is from an A500, rca cables are of the simplest/cheapest type.

[pandy71]

Originally Posted by vulture

@pandy71

They're active studio monitors, as I said, dead silent, volume at max. Transcend CF 32gb internal, 1gb sandisk on pcmcia, simple chinese cf2ide adapter. Motherboard rev is 2b with the usual capacitor fix for compatibility, but no recapping or anything else. PSU is from an A500, rca cables are of the simplest/cheapest type.

Once again FDD/HDD not CF where current consumption at worst case is approximately 10 times lower than on best case scenario for FDD/HDD .
As Meynaf pointed earlier - FDD/HDD are mechanical and they use significantly more power than SSD/CF/SD etc - as such current ripple is way higher and this current ripple will propagate also to Paula and as final effect to audio output.
Hope you see difference between 100mA and 1.0A - formally such thing is called PSRR http://www.analog.com/static/importe...als/MT-043.pdf - in Amiga voltage reference for DAC is taken directly from power lines trough very minimalistic low pass filter - in decent audio equipment you have at least dedicated low noise voltage regulator (as people complain for noisy voltage regulators such as LM317) to improve PSRR.

http://tech.juaneda.com/en/articles/lm317.html
http://www.tnt-audio.com/clinica/reg..._noise2_e.html
http://www.diyaudio.com/forums/power...egulators.html
https://hifiduino.wordpress.com/2011...se-regulators/

Somehow you trying to convince me that noisy power supply with low quality power distribution, with variable load between 25 and 30% (in peaks) of maximum power supply capabilities and very simplistic circuit used to feed voltage reference source have no impact on audio quality.

[meynaf]

But are they on the same power line input ?
Don't mechanical parts take 12V where paula uses 5V ?

[vulture]

@pandy71

I'll try loading a floppy game tonight and see how it goes. And I'm not trying to convince anyone about anything, it's what happens.

[pandy71]

Originally Posted by meynaf

But are they on the same power line input ?
Don't mechanical parts take 12V where paula uses 5V ?

And? PSU has single transformer with two outputs (or more - never found Amiga PSU's schematics) - usually highest voltage is used as feedback voltage - any changes in 12V are injected to 5V lines also...
Side to this Amiga audio path using both lines ( i.e. 5V, 12V also -12V is used) - Vcc (5V) is used to supply Paula (digital and analog part share same voltage pin), Vref is created in resistor divider from Vcc, there is separate analog ground, OPAMP are directly powered from +12/-12V lines - there is only few capacitors and resistors working together as very simplistic filters. This is not bad but definitely not the most optimal way - however it is justified for computer where cost of production was sensitive - just enough but not 14 or more bit - if you really wish to have HQ audio then all those problems need to be addressed properly, audio supply and ground need to be clean, proper PCB layout etc.

[Stratosplat]

Originally Posted by pandy71

...if you really wish to have HQ audio then all those problems need to be addressed properly, audio supply and ground need to be clean, proper PCB layout etc.

+1.

It's passably OK for the intended job, but it could have been so much better at the minor expense of dedicated audio stage voltage regulation and correct signal ground referencing. Also, setting up a guard band around the audio stages would have been very easy and quite effective at keeping radiated digital noise away from the audio signals. All of this was standard practice at the time on high quality audio equipment.

Show the schematics and PCB layout to any competent electronics design engineer and they'll tell you exactly the same thing. I suspect that penny-pinching is partly responsible as doing it properly can be very cheap, but not quite free.

I'm happy to accept it for what it is as I don't use the Amiga for any serious audio work, but I certainly wouldn't attempt doing so without at least a partial circuit redesign.

I re-capped my 2B A1200 at the weekend, so I know they're not responsible in my case. The incoming supply rails are as clean as can be expected from the fairly crude (by modern standards) external PSU design, so I'm happy that nothing is broken per-se.

Please note: I am not moaning. This is exactly what I'd expect to see from the hardware that's sitting in front of me. I'm under no illusions that high quality audio will be delivered or should be expected.

[meynaf]

Well, it appears we have some folks here who talk about schematics, voltage, noise, audio theories, etc, and try to explain why our miggy's sound is so damn piss poor (in their opinion), while not having actually listened to the real result.

[Stratosplat]

Originally Posted by meynaf

Well, it appears we have some folks here who talk about schematics, voltage, noise, audio theories, etc, and try to explain why our miggy's sound is so damn piss poor (in their opinion), while not having actually listened to the real result.

What makes you think that myself and pandy71 haven't listened to it? I certainly have and it's OK-ish for reproducing 8-bit audio, and nowhere near good enough for reproducing 14-bit audio. It's very obvious to an experienced electronics design engineer why this is the case when examining the schematics and PCB layout. As is nearly always the case, there is a direct correlation between cause and effect.

It makes perfect sense to listen first (as your ears tell you everything you need to know about what you actually hear) then investigate after if you feel the need, so that's precisely what I've done. It's exactly what I'd expect based on my own independent listening tests and backed up by 35 years knowledge and experience of digital and analogue electronic circuit design.

Sounding good to certain individuals doesn't negate the fact that it's actually very poor in terms of circuit design and implementation, hence the fact that it does sound fairly awful to certain others with good enough equipment and ears to notice. Another contemporary example is MP3 where a high quality encoding may sound identical compared to the source to one person, yet very different to another. There is no 'black and white' when it comes to what different people can hear and find audibly acceptable.

Please show me where I said that the Amiga's sound is "so damn piss poor", or is that in reference to someone else's reply that I've missed?

I have no problem with others being perfectly happy with it, so why do you have a problem with others who aren't so impressed? Chill.

[meynaf]

Originally Posted by Stratosplat

What makes you think that myself and pandy71 haven't listened to it?

If you have listened to something, it's certainly not the same thing as i have.

Originally Posted by Stratosplat

I certainly have and it's OK-ish for reproducing 8-bit audio, not good enough for 14-bit audio, and nowhere near what's required for 16-bit audio. It's blindingly obvious to an experienced electronics design engineer why this is the case when examining the schematics and PCB layout.

It makes perfect sense to listen first (as your ears tell you everything you need to know about what you personally actually hear) then investigate after if you feel the need, so that's precisely what I've done. It's exactly what I'd expect based on my own independent listening tests and backed up by 35 years knowledge and experience of digital and analogue electronic circuit design.

Too bad we can't just do a blind experiment to verify your assertions.

Originally Posted by Stratosplat

Sounding good to certain individuals doesn't negate the fact that it's actually very poor in terms of circuit design and implementation, hence the fact that is does sound fairly awful to certain others with good enough equipment and ears to notice.

I have the slight impression we're not talking about the same thing and/or not living in the same world.

Originally Posted by Stratosplat

Please show me where I said that the Amiga's sound is "so damn piss poor", or is that in reference to someone else's reply that I've missed?

Aside of what's in bold above, see below.

Originally Posted by Stratosplat

On that basis, upgrading the opamp is probably a complete waste of time as the distortion and noise it creates is most likely already at least an order of magnitude below what's present in the input signal.

Translation : that thing produces lots of noise.
Problem : i never actually heard that noise.

Originally Posted by Stratosplat

The entire audio circuitry is incredibly poorly implemented. It would be hard to have made it any worse on purpose let alone by accident.

So you didn't write "so damn piss poor" but it looks quite the same !

Originally Posted by Stratosplat

I have no problem with others being perfectly happy with it, so why do you have a problem with others who aren't so impressed? Chill.

Yeah, continue spitting on it if you want.
But please plug an Atari ST on a hifi equipment and listen. Then you will know what 'noise' and 'incredibly poorly implemented' really mean.

[Stratosplat]

I'm quite obviously saying the complete opposite of what you're claiming I'm saying in at least one of the above quotes, plus you seem to be denying that psychoacoustics which differs between individuals determines what a person does or doesn't hear.

You're clearly putting your own spin on my words for some reason that I don't understand. On that basis, I shall take no further part in this conversation.

[pandy71]

Originally Posted by meynaf

Well, it appears we have some folks here who talk about schematics, voltage, noise, audio theories, etc, and try to explain why our miggy's sound is so damn piss poor (in their opinion), while not having actually listened to the real result.

Why you constantly misleading everything?
Honestly - I don't trust your ears and i have limited trust to mine. Why not using something not so subjective?
And as i can't listen your Amiga (used by you as reference to justify your claim) then perhaps you can record sound from your Amiga (for example using samples provided in this topic) for example on PC with Line In input?
Will be nice if you can place those samples in uncompressed or compressed losslessly (FLAC?) somewhere where i can download them and i can hear your Amiga same as you (then i will be able to hear same signal as you with proper Amiga and proper software).
For today as i can't hear your Amiga I can tell only one thing 68 or 72dB is not 14 bit as electric current is not simple arithmetic in 68k registers and assumption that you feeding 16 or 14 bit to two 8 bit DAC's where one of them has introduced -36dB doesn't mean that they behave like 14 or 16 bit DAC and all this without even involving other problems related to audio circuits design.
If you reject this opportunity to answer questions then i have proposal to stop talking what you or i can hear (or not) until i will be able to measure in objective way Amiga audio output (of course after all you can be a real audiophile and reject scientific approach claiming that theory is meaningless).

[meynaf]

Originally Posted by Stratosplat

I'm quite obviously saying the complete opposite of what you're claiming I'm saying in at least one of the above quotes, plus you seem to be denying that psychoacoustics which differs between individuals determines what a person does or doesn't hear.

I'm not claiming you saying anything you didn't say. I just copy-pasted your text. The fact you might have changed said text by editing later, doesn't change that.

Originally Posted by Stratosplat

You're clearly putting your own spin on my words for some reason that I don't understand. On that basis, I shall take no further part in this conversation.

Originally Posted by pandy71

Why you constantly misleading everything?

I will ignore this - looks too much like personal attack.

Originally Posted by pandy71

Honestly - I don't trust your ears and i have limited trust to mine. Why not using something not so subjective?

Considering what you wrote, the difference should be obvious to the ear.
If the ear, either yours or mine, can't perceive it, then it's just too subtle and not worth talking about in depreciating terms such as those that were written.

If you want some not subjective way, just make it heard by enough people. Sound quality can't really be measured - you can only measure accuracy but accuracy isn't equal to quality.

Originally Posted by pandy71

And as i can't listen your Amiga (used by you as reference to justify your claim) then perhaps you can record sound from your Amiga (for example using samples provided in this topic) for example on PC with Line In input?

Oh yeah, on PC input. Just the best way to add PC noise to some sound.

Originally Posted by pandy71

Will be nice if you can place those samples in uncompressed or compressed losslessly (FLAC?) somewhere where i can download them and i can hear your Amiga same as you (then i will be able to hear same signal as you with proper Amiga and proper software).

It would be better if you get an accelerator for your A500 then use proper replay software.

Originally Posted by pandy71

For today as i can't hear your Amiga I can tell only one thing 68 or 72dB is not 14 bit as electric current is not simple arithmetic in 68k registers and assumption that you feeding 16 or 14 bit to two 8 bit DAC's where one of them has introduced -36dB doesn't mean that they behave like 14 or 16 bit DAC and all this without even involving other problems related to audio circuits design.

Seems that, once again, you just isolate the DAC.
(and forget what calibrated output is all about)

Originally Posted by pandy71

If you reject this opportunity to answer questions then i have proposal to stop talking what you or i can hear (or not) until i will be able to measure in objective way Amiga audio output (of course after all you can be a real audiophile and reject scientific approach claiming that theory is meaningless).

You can stop talking with me if you want. All this electronic stuff is off-topic there anyway.

[Stratosplat]

@pandy71: Reading back through this thread again, it would appear as though meynaf is picking fights with almost everyone on the basis that he is right and they are wrong no matter what they say. Don't let him wind you up.

[meynaf]

Originally Posted by Stratosplat

@pandy71: Reading back through this thread again, it would appear as though meynaf is picking fights with almost everyone on the basis that he is right and they are wrong no matter what they say. Don't let him wind you up.

Here is a very nice example of personal attack.
(appears some really do not like being proven wrong...)

[pandy71]

Originally Posted by meynaf

I will ignore this - looks too much like personal attack.

This completely not true - this is simple conclusion after your last comments. I never wrote about poor Amiga audio quality and it was not me suggesting that i never hear Amiga.
I'm vaccinated and immune to FUD.

Originally Posted by meynaf

Considering what you wrote, the difference should be obvious to the ear.
If the ear, either yours or mine, can't perceive it, then it's just too subtle and not worth talking about in depreciating terms such as those that were written.

Not sure if your ears are different than average human however human auditory system constantly changing and depends even from current weather... lot of factors affecting our perception and as such there is no reference hearing as such it is quite important to me to find which approach to play HQ audio samples is better for Amiga - or oversampled 8 bit with dithering and aggressive noiseshaping or 14 bit quasi-uniformly distributed PCM like current audio.

Originally Posted by meynaf

If you want some not subjective way, just make it heard by enough people. Sound quality can't really be measured - you can only measure accuracy but accuracy isn't equal to quality.

OK let assume that you are right and sound quality can't be measured (not true) but audio circuits used for sound reproduction can be measured.
I hope you not suggesting that bad audio circuit with poor measurement results will provide good sound quality - however if you think it is true i will be glad of some examples for such situation.
Accuracy can be measured and indirectly can be used to quality assessment. I hope you not trying to suggest that Amiga is somehow high end audiophile source.

Once again i highly recommend http://www.harman.com/sites/default/...dioScience.pdf -
He (Floyd E. Toole, Ph.D.
Vice President Acoustical Engineering, Harman International Industries, Inc) cover some of things you wrote about measure, science, theory - there is no electronics there but rather sound quality remarks and how subjective testing is complementary to objective, it is nice paper written with simple and understandable language - you may find it interesting.

Originally Posted by meynaf

Oh yeah, on PC input. Just the best way to add PC noise to some sound.

Modern PC very frequently outperform even theoretical 14 bit Amiga quality. You can subtract PC input noise, just use well defined high quality source like CD player or DVD (media player) - i can provide you samples with any resolution and sample rate you wish. By simple comparison it will be possible to at least assess if Amiga is worse/same/better than other known source. As a audiophile you probably have plenty high quality sources to use. I would say this rather problem of a good will than technical.

Originally Posted by meynaf

It would be better if you get an accelerator for your A500 then use proper replay software.

There is no affordable accelerator for A500 i can buy. Software - do you have any proposal? (i have some hope that your software to avoid any doubts that i'm unfair and trying bias result by my point of view will be used).

Originally Posted by meynaf

Seems that, once again, you just isolate the DAC.
(and forget what calibrated output is all about)

Nope and that's what i've wrote about misleading - my point is that every part of circuitry even not directly related with audio will affect audio signal quality, you constantly says that you feed 16 bit samples, and after shifting there is 14 bits (calibrated) of signal and as such from my perspective this translate (your words about 14 bits) to somewhere around 86dB SNR and comparable IMD/THD.

Originally Posted by meynaf

You can stop talking with me if you want. All this electronic stuff is off-topic there anyway.

Why i should stop talking with you? I assume you are mature (you 43 me 45) to have sane discussion where we are able to present different point of view, where there is a place for exchanging arguments and where at some point we can discuss some objective data and as a programmer you (i hope) appreciate that 2+2 will give you 4.

[vulture]

ok, so I'm formatting a floppy disk and I can still hear no noise/static/hiss from the speakers.

[meynaf]

Originally Posted by pandy71

This completely not true - this is simple conclusion after your last comments. I never wrote about poor Amiga audio quality and it was not me suggesting that i never hear Amiga.
I'm vaccinated and immune to FUD.

So you never write about poor Amiga audio quality. But you still wrote that it just can't do 14 bit, that it's closer to 10. You say there is noise, which not only me but several other ppl here don't hear (even when formatting floppies, lol). And you didn't disagree with anyone saying it was crap (my bold quotes).
However if you're vaccinated then why not just stopping here and try to discuss something more interesting.

Originally Posted by pandy71

Not sure if your ears are different than average human however human auditory system constantly changing and depends even from current weather... lot of factors affecting our perception and as such there is no reference hearing as such it is quite important to me to find which approach to play HQ audio samples is better for Amiga - or oversampled 8 bit with dithering and aggressive noiseshaping or 14 bit quasi-uniformly distributed PCM like current audio.

Of course ears differ about perception of small details. But big noise is big noise for everyone, isn't it ?
If you want to experiment oversampled 8 bit with dithering and aggressive noiseshaping, you can tell me exactly what computations have to be made on the signal, and i can try coding it. I have the code (somewhere) to play audio by cpu poking AUDxDAT.

Originally Posted by pandy71

OK let assume that you are right and sound quality can't be measured (not true) but audio circuits used for sound reproduction can be measured.
I hope you not suggesting that bad audio circuit with poor measurement results will provide good sound quality - however if you think it is true i will be glad of some examples for such situation.
Accuracy can be measured and indirectly can be used to quality assessment. I hope you not trying to suggest that Amiga is somehow high end audiophile source.

Ok so you want to measure sound quality. But, perfect accuracy in comparison to the digital signal, wouldn't lead to quality. The replay frequency itself (and preferably its harmonics as well) must be removed from the sound (aka anti-aliasing), so it won't be 'accurate'. I doubt any output in the world do exactly what the numbers say : if the samples say f.e. 1,3,5, values 2 and 4 should and will be observed in the output.
So with all this, what do you want to do ?

Originally Posted by pandy71

Once again i highly recommend http://www.harman.com/sites/default/...dioScience.pdf -
He (Floyd E. Toole, Ph.D.
Vice President Acoustical Engineering, Harman International Industries, Inc) cover some of things you wrote about measure, science, theory - there is no electronics there but rather sound quality remarks and how subjective testing is complementary to objective, it is nice paper written with simple and understandable language - you may find it interesting.

Didn't i read that already ? Oh well, i'll take the time to check that again.

Originally Posted by pandy71

Modern PC very frequently outperform even theoretical 14 bit Amiga quality. You can subtract PC input noise, just use well defined high quality source like CD player or DVD (media player) - i can provide you samples with any resolution and sample rate you wish. By simple comparison it will be possible to at least assess if Amiga is worse/same/better than other known source. As a audiophile you probably have plenty high quality sources to use. I would say this rather problem of a good will than technical.

Well, looking again, it seems my PC has no RCA input. And even though it can perhaps outperform 14 bit, it's still just 16. Input A/D may filter or otherwise damage the signal. Rather than a PC, an oscilloscope may give better results - with samples tuned for that use - but i am not equiped.

Originally Posted by pandy71

There is no affordable accelerator for A500 i can buy. Software - do you have any proposal? (i have some hope that your software to avoid any doubts that i'm unfair and trying bias result by my point of view will be used).

I have written a program that can play wav, aiff, and flac (and mp3, and even ogg if i enable them). Custom versions can be made for different output comparisons. However you won't be able to use it on A500 and i'm not sure tests made on an emulator can be meaningful.

Originally Posted by pandy71

Nope and that's what i've wrote about misleading - my point is that every part of circuitry even not directly related with audio will affect audio signal quality, you constantly says that you feed 16 bit samples, and after shifting there is 14 bits (calibrated) of signal and as such from my perspective this translate (your words about 14 bits) to somewhere around 86dB SNR and comparable IMD/THD.

I'm not saying every part of circuitry can't affect audio signal. I know they can.
But having plugged it into some big amp where normal music with volume knob set to 8 would have been enough to make the neighbors come, i set it to 40 and still got only silence. Let's be honest : i was very surprised to hear nothing !

Maybe you're right and it's not good by todays standard. Yet it sounds good in everyday life.
If you play 24-bit samples on super accurate 24-bit D/A, will you hear the difference with regular 16-bit ? Where's the point in which it starts to count ?
If 14-bit doesn't sound different than 12-bit then maybe we only have 12-bit dynamics while playing 14. But then whether we have 12,14,16 or more, doesn't matter (at least for me).

Originally Posted by pandy71

Why i should stop talking with you? I assume you are mature (you 43 me 45) to have sane discussion where we are able to present different point of view, where there is a place for exchanging arguments and where at some point we can discuss some objective data and as a programmer you (i hope) appreciate that 2+2 will give you 4.

Weren't you the one with the proposal to stop talking ?

Anyway, we have to remember that we communicate in english, which i don't regard as a very good tool, especially when neither is a native speaker.
So many misunderstandings can occur.

[pandy71]

Originally Posted by meynaf

So you never write about poor Amiga audio quality. But you still wrote that it just can't do 14 bit, that it's closer to 10. You say there is noise, which not only me but several other ppl here don't hear (even when formatting floppies, lol). And you didn't disagree with anyone saying it was crap (my bold quotes).
However if you're vaccinated then why not just stopping here and try to discuss something more interesting.

I never said crap also i can't take responsibility for things said by others but i can understand sometimes their reaction - from time to time it is very difficult to not realize that you behave in a condescending way - some people not dealing with this gently.
From my perspective this very amusing part of science applicable as in theory you can imagine such software approach (you should like this - there is no hardware but pure software) to beat limitations of hardware - for example deliver audio quality beyond Amiga designers imagination.
List thing more interesting than breaking old HW limits - i think this is important especially for you as a software guy - i have own ideas about improving HW but it is real art to not change main HW architecture yet bend limit beyond imagination only by using clever software.

Originally Posted by meynaf

Of course ears differ about perception of small details. But big noise is big noise for everyone, isn't it ?
If you want to experiment oversampled 8 bit with dithering and aggressive noiseshaping, you can tell me exactly what computations have to be made on the signal, and i can try coding it. I have the code (somewhere) to play audio by cpu poking AUDxDAT.

Yes and no - it depends from many things, side to this our auditory system can adapt and begin to ignore some distortions (noise like mild hiss can be one of them).
Computation you can check for example SoX or ffmpeg code (ffmpeg use SoX part but they added coefficients for some common sub-Nyquist sample rates - disputable if they improve or not perceived quality but they exist).
Someone provided code for using Copper (as my assumption is that Copper will provide jitter free sampling) but even using HW DMA and sample rate like 56kHz with proper signal processing i think Amiga can easily match dynamic of the 16 bit system (with respect to Gerzon-Craven theorem).

Originally Posted by meynaf

Ok so you want to measure sound quality. But, perfect accuracy in comparison to the digital signal, wouldn't lead to quality. The replay frequency itself (and preferably its harmonics as well) must be removed from the sound (aka anti-aliasing), so it won't be 'accurate'. I doubt any output in the world do exactly what the numbers say : if the samples say f.e. 1,3,5, values 2 and 4 should and will be observed in the output.
So with all this, what do you want to do ?

Nope - anti-aliasing is a problem of AD conversion and later can't be removed from signal - DAC doesn't require anti-aliasing filter - DAC require reconstruction filter (sometimes it must be also anti-imaging filter).
There are some techniques to deal with problems, temporal averaging to remove uncorrelated with signal noise is one of them. And also we note measuring particular sample values (albeit it possible and it is used with some DAC calibration techniques).

Originally Posted by meynaf

Didn't i read that already ? Oh well, i'll take the time to check that again.

Obviously not as you arguing using arguments common for some audiophiles - once again i never heard on equipment that has bad objective (measurements) results but anyway has amazing sound - behind good sound reproduction there is lot of scientific knowledge.
Wise people not say f**k theory - i live long enough to experience situation when good theory perfectly match real life.

Originally Posted by meynaf

Well, looking again, it seems my PC has no RCA input. And even though it can perhaps outperform 14 bit, it's still just 16. Input A/D may filter or otherwise damage the signal. Rather than a PC, an oscilloscope may give better results - with samples tuned for that use - but i am not equiped.

Nope, practically all audio PC cards using delta sigma AD converters - they are free from aliasing problem also AA filter is not a limitation as due way how DS works those filter are quite gentle and they are stable in phase domain.
Oscilloscope will be highly unsuitable for this as very limited dynamics present in typical oscilloscope - they usually use not more than 8 bit AD converters and with typical sample rates around 100MHz efficient number of bits is usually somewhere around 6 or less - definitely very bad for 14 bit audio.

Originally Posted by meynaf

I have written a program that can play wav, aiff, and flac (and mp3, and even ogg if i enable them). Custom versions can be made for different output comparisons. However you won't be able to use it on A500 and i'm not sure tests made on an emulator can be meaningful.

Nope - emulator is not interesting as we testing idealistic not real system that functionally is close to Amiga but completely different.

I have A1200 and A3000 (CPU capable to run 68020 code) - in 3 -4 weeks i should e able to use A1200 (need to buy IDE>SD adapter and restore system disk), A3000 is slightly more challenging as i need to rework some problems on MB and buy a keyboard - as you can imagine it is impossible to buy A3000 keyboard nowadays.

Originally Posted by meynaf

I'm not saying every part of circuitry can't affect audio signal. I know they can.
But having plugged it into some big amp where normal music with volume knob set to 8 would have been enough to make the neighbors come, i set it to 40 and still got only silence. Let's be honest : i was very surprised to hear nothing !

We not talking about high fancy amp - i know what I've heard on some Amiga's mentioned A600 is disaster not only due leaking caps.

Originally Posted by meynaf

Maybe you're right and it's not good by todays standard. Yet it sounds good in everyday life.
If you play 24-bit samples on super accurate 24-bit D/A, will you hear the difference with regular 16-bit ? Where's the point in which it starts to count ?
If 14-bit doesn't sound different than 12-bit then maybe we only have 12-bit dynamics while playing 14. But then whether we have 12,14,16 or more, doesn't matter (at least for me).

But this was never my goal to match Amiga with modern digital audio - it will be unfair as Amiga is 8 bit, it is designed in particular way and it was compromise between cost and other aspect of computer - this is same as watching movie at Atari ST or Amiga - it is not about cinema experience more it is how much of things we can squeeze from those machines having present knowledge - i remember when played with DSP and samples on Amiga and i know how moronic was almost everything from this time yet thanks to this times i evolved to current state.
And from beginning quite clearly stating that my listening experience telling me that Amiga is somewhere between 60 and 70dB which is not bad and i will be very positively surprised to see better numbers.

Originally Posted by meynaf

Weren't you the one with the proposal to stop talking ?

Anyway, we have to remember that we communicate in english, which i don't regard as a very good tool, especially when neither is a native speaker.
So many misunderstandings can occur.

Yes but then side discussion was triggered about analog circuitry around Paula - i've expressed my point of view on current hype that every company currently trying to create impression having fancy audiophile equipment only due of fact that you can replace OPAMP in socket.
And there is large group of people seriously deliberating on superiority of Analog Devices AD8597 over AD797 - referring to Amiga - there is no magic - simple OPAMP replacing will not magically change sound - many thing need to be addressed to improve sound - this is another interesting topic for Amiga - after checking what is better - 14 bit or 8 bit with oversampling and NS there will be time for some improvement on Amiga to even improve audio more.
And i agree on language (my English is really self learned - i know that my vocabulary and grammar are poor), i agree on stopping discussion to the point where some objective data will be known so i t will be easier to see some picture and discuss something more real than our impressions.
Once again - i respect you even if sometimes it is not easy to discuss with you.

[meynaf]

Originally Posted by pandy71

Nope - anti-aliasing is a problem of AD conversion and later can't be removed from signal - DAC doesn't require anti-aliasing filter - DAC require reconstruction filter (sometimes it must be also anti-imaging filter).
There are some techniques to deal with problems, temporal averaging to remove uncorrelated with signal noise is one of them. And also we note measuring particular sample values (albeit it possible and it is used with some DAC calibration techniques).

Whatever you call it, there is still some kind of filtering that will make the output level differ from the numeric input.

Originally Posted by pandy71

Obviously not as you arguing using arguments common for some audiophiles - once again i never heard on equipment that has bad objective (measurements) results but anyway has amazing sound - behind good sound reproduction there is lot of scientific knowledge.
Wise people not say f**k theory - i live long enough to experience situation when good theory perfectly match real life.

A theory is only valid when all of the data it needs is known...

Originally Posted by pandy71

Nope, practically all audio PC cards using delta sigma AD converters - they are free from aliasing problem also AA filter is not a limitation as due way how DS works those filter are quite gentle and they are stable in phase domain.
Oscilloscope will be highly unsuitable for this as very limited dynamics present in typical oscilloscope - they usually use not more than 8 bit AD converters and with typical sample rates around 100MHz efficient number of bits is usually somewhere around 6 or less - definitely very bad for 14 bit audio.

Ok but there is probably better hardware than mere pc to do that kind of measurement.

Originally Posted by pandy71

Nope - emulator is not interesting as we testing idealistic not real system that functionally is close to Amiga but completely different.

I have A1200 and A3000 (CPU capable to run 68020 code) - in 3 -4 weeks i should e able to use A1200 (need to buy IDE>SD adapter and restore system disk), A3000 is slightly more challenging as i need to rework some problems on MB and buy a keyboard - as you can imagine it is impossible to buy A3000 keyboard nowadays.

The A1200 seems to be the best bet.

Originally Posted by pandy71

We not talking about high fancy amp - i know what I've heard on some Amiga's mentioned A600 is disaster not only due leaking caps.

The machine i tried was internally labeled A300, but i don't remember other details.
I had two A1200 and none made any hearable noise.
I could, however, hear a significant quality loss when using the calibration file of one machine on the other.

[roondar]

@audio discussion:
Is it really that relevant wether or not an Amiga can compete with modern PC audio hardware which is 25 years newer and leans heavily on technologies which where either not available at all or not available for any reasonable cost back in 1985?

Of course we have better audio these days. And no, that is not at all relevant when looking at the Amiga audio out quality. It'd be much more interesting to know how it compares to audio produced back in the day by PC's and such and much less in current day high end studio performance.

The Amiga is not a high end audio device. Then again, neither was a PC back in the 90's (I'm pretty sure Soundblasters where actually quite a bit worse in the actually produced signal to noise ratio department until the AWE32*), so again why is this relevant at all?
*) as opposed to the stats on the box, which never held to any serious scrutiny.



If we're going to compare DAC performance, it should be done fairly - compare it to other DAC's from the 1980's, available for similar prices as Paula (i.e. a few dollars max). Comparing the Amiga against high end audio stuff is hardly fair (and outright silly when doing so against stuff from 2016!) and doing so does make it seem like the goal is to make the Amiga look bad (IMHO anyway).