The Border Patrol DAC - Maybe linearity in a DAC is bad ... Spitballing


Hi Everyone,
I've been thinking about a few things related to DAC's and how they behave and how we hear. Also thinking about a couple of audiophile comparisons I've heard and how we interpret what we hear.

Let's talk about this simple measurement called linearity.

In a DAC what we mean is that as the magnitude changes the output changes the same amount. That is, if the signal says "3 dB softer" you want to get exactly 3 dB softer output on the jacks.

And with modern, top tier DACs this is usually really good until around -90 dB where noise becomes the limiting factor.

For a long time I felt that a DAC which allowed me to hear the decay of a note, so that it fades instead of stops suddenly was the mark of a truly excellent sounding DAC.

I'm wondering if what I'm actually hearing is compression? Lack of linearity.

The reason I bring this up is that I was reading a long article about the complexities of reviewing a DAC from Border Patrol. One of the main failings, from measurements, is that it is really not linear at all. Sounds don't get softer fast enough. And ... low and behold, Herb Reichert actually makes many comments about how much more he can hear with this DAC than with others.

I'm going to link to a critique of the "scandal" so you all can get a better look:


https://parttimeaudiophile.com/2019/01/06/border-patrol-dac-revisited-audio-fur/


Also, take a look at the linearity charts in the original review. Honestly, awful. Not up to what we expect in state of the art DACs today, but ....


https://www.stereophile.com/content/borderpatrol-digital-analogue-converter-se-measurements

What do you all think? Do we need a compression feature in DACs so we can hear more details? That would make more sense to me than a lot of the current fad in having multiple filter types.

Best,
E

erik_squires
I agree a lot with whart. I am not any kind of a measurements guy. But I do not think we can measure what Herb R. says is 'human sounding musical pleasures'. In a live event that is what it is like,  'human sounding musical pleasures'.  And also there is something about the physical feeling to a live event, I like to have much of that in my listening experience at home. And for me that does not mean listening to my music loud or bass heavy. Just that feel of being in the presence of a real musical production. That is when it becomes more real to me. I don't think you can measure that. And I don't need the detail to hear flies bumping into each other on the recording. Only just enough detail to make things real. I certainly pay attention to measurements initially to see if components are somewhat compatible, but after that I don't make use of them. So I appreciate the measurements and specs a whole lot to get started but not for a lot of my musical pleasure, there I appreciate my ears.
But I do not think we can measure what Herb R. says is 'human sounding musical pleasures'.


In this case, I actually genuinely think we can. My hypothesis is that he is enjoying the compression at the bottom of the dynamic range.

I'm going to see if I can prove this. :)

Stay tuned.

E

That would be nice if it could be correlated to what we perceive as 'human sounding musical pleasure'. Then it could be designed into our components. But so many, by my wild approximation of 250, systems I have heard most have a very small measure of that sound. Interesting topic Erik. I think it('human sounding musical pleasure')for me is a kind of core importance.
The most common use of a compressor in music production is to reduce overall dynamic range by some combination of lowering the peaks and increasing the soft passages.  If uses judiciously it will bring out low level detail in a track.  It's a basic and widely used recording technique.
If the Border Patrol is manipulating the output signal to mimic a compressor, than it is not surprising that many listeners would like the effect.  An analogy would be upping the contrast slightly in a video signal.  There's no magic involved.
That is a a pretty natural sounding dac ,the New Audio Mirror
is very similar and uses Vacuum tubes currently $1200 Outstanding ,Audio Analog Multibit dac which yourarely see anymore the Burr Brown 1704  dac chipsetcomes to mind.
way to expensive to make ,greatchipsets of the past