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blgentry:
--- Quote from: pschelbert on August 01, 2016, 02:20:45 pm ---If you upsample a CD, the antialiasfilter must cut off to lets say -100dB to -130dB above 22050Hz.
--- End quote ---
As far as I know, this is incorrect. Increasing the sampling frequency, by doing Sample Rate Conversion, increases the aliasing frequency to 1/2 of the new sampling frequency. So if you upsample (oversample, SRC) 44.1kHz audio to 352.8 kHz, the aliasing frequency is now 352.8/2 = 176.4 kHz. Not 22.05kHz. Notice that I said "sample rate conversion". This is not the same as simply inserting zeros.
If I'm incorrect, please provide a reference to back up your claim.
Brian.
pschelbert:
In order to do your sample rate conversion, first you need to antialias at 22050Hz. The resulting upsampled spectra has then the alias at 96kHz for example if your samplerate is 192kHz.
here:
https://www.google.ch/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiAzZyrpKHOAhXFC8AKHZnZAaMQFgguMAE&url=http%3A%2F%2Fwww.cppsim.com%2FBasicCommLectures%2Flec10.pdf&usg=AFQjCNGj64cXeo1Db4AnuTU7lo8d9xMwHg
or here:
http://melodi.ee.washington.edu/courses/ee518/notes/lec9.pdf
or here:
http://src.infinitewave.ca/help.html
Peter
flac.rules:
--- Quote from: kstuart on August 01, 2016, 03:51:31 pm ---That would be fine if we listened to words, but in listening to music in 2016, there is more of a difference between DACs than any other part of the audio chain. (And this difference is no longer a matter of pricing.)
The chips are fine as far as they go, the implementation can make a significant difference.
People seem to have a blind trust that someone selling a device has a wide and deep knowledge of electronics and also has not cut any corners in order to increase profit margin (cf Bay Bridge bolts, Challenger o-rings, etc.).
--- End quote ---
I am not sure what you mean? Your posts are words, my posts are words, It seems like everyone here is talking about perceivable differences in music reproduction. That fact does't change because we use words to communicate. Anyway, its is hard to find any scientific backing for such a claim, differences between reasonable DAC designes are pretty small, especially when compared to things like loudspeakers, which clearly are a more important part of the chain. But this might be drifting a bit of topic, so I will concentrate on the technical aspects the digital domain and DA-conversion, as I see that as the threads main topic.
pschelbert:
--- Quote from: Elvis133 on August 01, 2016, 05:54:50 pm ---I am not sure what you mean? Your posts are words, my posts are words, It seems like everyone here is talking about perceivable differences in music reproduction. That fact does't change because we use words to communicate. Anyway, its is hard to find any scientific backing for such a claim, differences between reasonable DAC designes are pretty small, especially when compared to things like loudspeakers, which clearly are a more important part of the chain.
--- End quote ---
Hi
I made some listening test with several users in a german forum. Two tests actually. Now I am doing a third test. Result up to now:
Difference to be heard is very difficult, even in a mediocre ultra cheap DAC (around USD50). Measurements are not really good of that DAC, however obvioulsy HighEnd users cannot distinguish!
A third test is going on with really high priced DAC. Lets see.
Conclusion up to now: buy a professional DAC, one which is used in studios, like RME, Lynx, Focusrite, Motu, Apogee etc.
Or go with one of the Japanese brands for reasonable price, which know how to do electronics (Yamaha, Sony, Teac, Marantz, Denon etc.)
Invest your money otherwise in Loudspeakers and headphones of high quality (not costly ones but good ones!): Stax, Sennheiser, Beyer, AKG
I agree, the difference in sound reproduction is significant in loudspeakers and headphones, while DAC does a minimal change, as far as you have a good, even rather cheap DAC.
Driver is key: ASIO works great in Windows (Mac probably kernel is okay)
There are some strange tube DAC out there, highly priced, yet bad performance, so beware...
Get the datasheet with frequency response, THD, IMD, SPDR etc. if you get it... if not stay away
Peter
blgentry:
--- Quote from: pschelbert on August 01, 2016, 05:47:47 pm ---In order to do your sample rate conversion, first you need to antialias at 22050Hz.
--- End quote ---
Hmm, OK. That makes some sense I suppose.
The links you provided are kind of hard to follow, but let's set that aside.
All of your writing about this, is all about the digital lowpass filter that's applied before sample rate conversion then. But any DAC that upsamples (which all modern ones do) is doing the same thing. So all of your discussion is about filter parameters of an alternative low pass filter implemented in software as part of SRC.
I'm kinda scratching my head as to why you think this matters. Particularly when you go on to say that in your tests people can't tell the difference between DACs. You seem to be arguing two sides: One that says all DACs are the same and another that says that minor changes in a filter (that would normally be inside the DAC) are audible.
Well, if nothing else, I think I learned something. Though I'm still confused by absolute details of SRC when upsampling. I thought new samples were calculated by successive approximation. At least one of the links talks about inserting zeros and then low pass filtering the result. Which seems all kinds of wrong.
EDIT: I take it back. Anti-alias filtering before Sample Rate Conversion (up) makes no sense. Why in the world would DAC manufacturers have implemented SRC in a DAC if it *still* had to have a steep filter in the audible band? Why not just use the digital brick wall filter at 22.05 and be done with it? There would be no reason to upsample in the first place. I stand by my statement until further proof is presented.
Brian.
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