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What makes a DAC better than another - Page 2

post #16 of 22
Quote:
Originally Posted by regal View Post




Every heard of phase distortion?   If you see a DAC with a razor flat frequency response odds are good that it has a lot of phase distortion in the treble.     


We are aiui typically rather insensitive to phase distortion and you do not get that much anyway from a DAC, you are talking about delays of some ns whereas we tend not to notice it till it gets to several microseconds.(Lipshitz) and at higher frequencies the ear is much less sensitive anyway.

 

Quote:Dr Floyd Toole
 It turns out that, within very generous tolerances, humans are insensitive to phase shifts. Under carefully contrived circumstances, special signals auditioned in anechoic conditions, or through headphones, people have heard slight differences. However, even these limited results have failed to provide clear evidence of a 'preference' for a lack of phase shift. When auditioned in real rooms, these differences disappear.."(The piano note demo shows that if you accept a broad definition of "contrived" you can get more than a "slight" difference).

 

 

If you look at Stereophile's DAC measurements there are many expensive products with flat FR, viz deviating by no more than say 0.25db from 20 - 20K - perhaps we have different definitions of flat, sorry if that is so, certainly a .25db drop off at 20k would seem trivial to me as it is in an area of very poor sensitivity.

 

 

post #17 of 22

 

Originally Posted by nick_charles View Post


We are aiui typically rather insensitive to phase distortion 


We're on a headphones forum, and headphones distort it like hell to project their headstage anyway.

post #18 of 22
Quote:
Originally Posted by leeperry View Post

 


We're on a headphones forum, and headphones distort it like hell to project their headstage anyway.


The discussion *here* is DACs which tend to be rather better behaved  than speakers or headphones

post #19 of 22

 

Originally Posted by nick_charles View Post


The discussion *here* is DACs which tend to be rather better behaved  than speakers or headphones


My point was that considering we're primarily using headphones, there's no need to lose sleep over a non-linear phase response...That's what messing w/ professional EQ plugins has taught me.

 

And we're not in the science forum, so I guess anyone can say whatever what he fancies w/o showing hard proofs...like saying that a flat FR on a DAC means a fubar'ed phase response, hehe.

post #20 of 22
Quote:
Originally Posted by leeperry View Post

 


My point was that considering we're primarily using headphones, there's no need to lose sleep over a non-linear phase response...That's what messing w/ professional EQ plugins has taught me.

 

Ah, okay

 

And we're not in the science forum, so I guess anyone can say whatever what he fancies w/o showing hard proofs...like saying that a flat FR on a DAC means a fubar'ed phase response, hehe.

 

I can make myself invisible and fly and my urine cures leprosy

 


 

post #21 of 22


If phase response were not important then why do the old CDP's with a perfect frequency sweep but a brickwall filter at 20khz sound so bad that we had to engineer oversampling?
 

Quote:
Originally Posted by nick_charles View Post


We are aiui typically rather insensitive to phase distortion and you do not get that much anyway from a DAC, you are talking about delays of some ns whereas we tend not to notice it till it gets to several microseconds.(Lipshitz) and at higher frequencies the ear is much less sensitive anyway.

 

 

post #22 of 22
Quote:
Originally Posted by nick_charles View Post



 

 

Better is a loaded term, but here is my take on it.


The job that a DAC has to do is to accurately reconstruct a continuous waveform (changing voltage) from discrete samples. If a DAC can do that with negligible added noise/distortion and with no added phase difference between channels (perceived as wider soundstage)  it is a good DAC whether it costs $50 or $25,000 - if it cannot do that it is flawed. It it adds it's own character to the sound it is flawed, if it rolls off before 20K it is flawed, basically if it is not razor flat from 20 - 20K it is flawed, IMHO of course. If two DACs are very different, to the point of audibility then at least one of them is faulty, IMO.

 

Of course rigorous testing of audible differences is rarely performed here, mostly we have (IMO) unhelpful, poorly controlled sighted tests which are open to all forms of cognitive bias. 

 

The biggest single difference you will ever find betwen two "good" (i.e flat) DACs is volume pure and simple, the line outs on different DACs can vary by several db , my own Entech is a good 0.7db hotter than my Marantz, this is a difference easily detectable and often mistaken as greater dynamics and so on.

 

Once you adjust for level many times the differences between good DACs become very very hard to detect.

 

As for audibility of other differences between good DACs, well normally unless you are talking about NOS jobbies then distortion/noise are so low as to be undetectable in normal listening, jitter has never been sufficiently proven by any rigorous testing to be an audible issue, so you can forget that.

 

What is left ?

 

Hear, hear.

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