hi guys...before to go completely crazy it's better if i ask you...
after the idea of speakers, ampli, crossover, volume control...i'm starting to think about a dac...not too much complicated...so i have read everything for a week, noting that most of the people say that it's better a non os dac(like tda1541) than an os dac, and the main problem is the jitter introduced from os type...
BUT:
tda1541 has a THD of about 0.05%
versus new type OS that have 0.0005%!!!
how is possible that it sounds better??is it really true??
i'd like to know it before to start my project...
every comment is welcome!!!
after the idea of speakers, ampli, crossover, volume control...i'm starting to think about a dac...not too much complicated...so i have read everything for a week, noting that most of the people say that it's better a non os dac(like tda1541) than an os dac, and the main problem is the jitter introduced from os type...
BUT:
tda1541 has a THD of about 0.05%
versus new type OS that have 0.0005%!!!
how is possible that it sounds better??is it really true??
i'd like to know it before to start my project...
every comment is welcome!!!
raikkonen said:
tda1541 has a THD of about 0.05%
versus new type OS that have 0.0005%!!!
how is possible that it sounds better??is it really true??
i'd like to know it before to start my project...
every comment is welcome!!!
Do not trust the numbers, use your ears, worse specs always sound better
Most manufacturers' application notes ignore the jitter produced by oversampling filters. And since so many "designs" are simply rehashes of manufacturers' application notes, oversampling DACs get a bad name.
Your more serious concern is whether you want to use a multibit DAC or a noise-shaping 1 bit DAC. The TDA1541 is a multibit whereas most modern DACs are 1 bit with noise-shaping. If you choose a multibit, you can still use oversampling to avoid the need for serious filtering. Alternatively, you can take the modern audiophile SEP* approach and ignore the fact that a multibit DAC spews out a load of ultrasonic rubbish that can't be removed by a simple capacitor (as is done by 1 bit DACs).
* Someone Else's Problem
Your more serious concern is whether you want to use a multibit DAC or a noise-shaping 1 bit DAC. The TDA1541 is a multibit whereas most modern DACs are 1 bit with noise-shaping. If you choose a multibit, you can still use oversampling to avoid the need for serious filtering. Alternatively, you can take the modern audiophile SEP* approach and ignore the fact that a multibit DAC spews out a load of ultrasonic rubbish that can't be removed by a simple capacitor (as is done by 1 bit DACs).
* Someone Else's Problem
There seems to be a very strong relationship I've observed: The less one understands oversampling, the worse it sounds.
I am convinced that the ultrasonic rubbish, what EC8010 talks about and more, intermodulates to create audible spectra, and this rubbish is subsequently labeled as "detail".
I am convinced that the ultrasonic rubbish, what EC8010 talks about and more, intermodulates to create audible spectra, and this rubbish is subsequently labeled as "detail".
Ah, well there are some reasonable arguments in favour of multibit DACs like the 1541. The two extremes of DACs are multibit and 1 bit. A multibit receives the entire data word and changes state just once with each wordclock to produce the correct voltage. Conversely, a 1 bit DAC can only produce a 1 or a 0, and none of the intermediate levels. So what you do is you slice the time between wordclock edges into the number of levels you require, then switch the DAC to a 1 for the right number of levels, and a 0 for the remaining levels. When you low-pass filter it, you get the same answer as you would if you'd had a multibit DAC. And because it's easy to measure time, you get very low distortion. However... 44.1kHz x 2^16 = 2.89GHz, and clocking that fast is expensive.
What practical 1 bit DACs do is to run at a much lower clock frequency, then treat errors as noise and manipulate them so that the noise is supersonic. That's not quite enough to get acceptable performance, so the next wheeze is to manipulate the in-band noise spectrum so that it isn't so perceptible to the human ear. Look carefully, and you will always find modern DACs have their S/N ratio given "A" weighted...
A good multibit DAC can produce a genuinely good S/N ratio, and that, I think, is why the 1541 is popular.
What practical 1 bit DACs do is to run at a much lower clock frequency, then treat errors as noise and manipulate them so that the noise is supersonic. That's not quite enough to get acceptable performance, so the next wheeze is to manipulate the in-band noise spectrum so that it isn't so perceptible to the human ear. Look carefully, and you will always find modern DACs have their S/N ratio given "A" weighted...
A good multibit DAC can produce a genuinely good S/N ratio, and that, I think, is why the 1541 is popular.
so, tell me if i've understand...
the problem is that 1bit dacs have a lot of noise in the inaudible range, but people don't want them because they simply know that there is still that noise, even if they can't hear it?
this don't seem to be a logical reason...especially if you think that the ampli cuts after 20K...
so???
the problem is that 1bit dacs have a lot of noise in the inaudible range, but people don't want them because they simply know that there is still that noise, even if they can't hear it?
this don't seem to be a logical reason...especially if you think that the ampli cuts after 20K...
so???
I'm a non-os guy. But I don't believe non-os is better than os, or vice versa. I see them as two different approaches to the same problem. Non-os cannot reproduce an accurate sine wave, for example. On the other hand, the filters used in os DACs cause ringing. All filters do.
Non-os DACs may have higher distortion, but aren't as susceptible to jitter. The maximum acceptable jitter in a non-os DAC is 173ps and 1.35psec in an 8X os, 20 bit DAC, according to Kusunoki Ryõhei.
Pick your poison.
Non-os DACs may have higher distortion, but aren't as susceptible to jitter. The maximum acceptable jitter in a non-os DAC is 173ps and 1.35psec in an 8X os, 20 bit DAC, according to Kusunoki Ryõhei.
Pick your poison.
raikkonen said:
No idea if it is a problem with all os filters, but SAA7220A and B together with 1541A produce different sound and different distortion spectra. So almost one of them must be wrong.
Also one and the same PCM56 chip behaves different with different os filters and different os rates such as Yamaha 8x filter and NPC 4 x filter.
Bernhard said:
Would that be because the SAA7220A has a deliberately rising response designed to compensate for the in-band attenuation caused by the 3rd order analogue filter expected at the output of the DAC? Together, they give a flat response in-band, but if you use a different analogue filter, this scheme wouldn't work correctly. The source of this information? An Analog Devices data sheet!
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