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
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 

The border patrol is the best sounding dac I’ve heard. I found it very transparent and almost 
life like. I’ve not compared it to 10k plus dacs but some have said it’s the r2r arrangement. I’ve heard the denefrips dacs come close at twice the cost. Would like to hear the terminator. 
@mickeyb

I found it very transparent

Hmm, Stereophile’s measurements show it has some slightly audible distortion, and I was just in conversation with someone who owns one and says he likes that it adds a slight tube sound, and that while not as transparent as his Parasound ZDAC, he preferred it in some instances. It has piss-poor volume (bit-depth) linearity, which likely contributes to what this person described as tube like, as if we use a 0.1dB threshold like Amir from ASR likes to use (though he sometimes uses 0.5dB), the BorderPatrol technically has the resolution of 10Bit, whereas even the $80 Grace SDAC has 19Bit.

EDIT: Oh, and the Stereophile review (done by actually listening to it)  also states it’s not as detailed as say the Benchmark (rolled off highs and softer bass), and is more for those wanting a more intimate, smooth sound, rather than every detail exposed.