BorderPatrol Digital to Analogue Converter SE Measurements

Sidebar 3: Measurements

I measured the BorderPatrol DAC SE with my Audio Precision SYS2722 system (see the January 2008 "As We See It", using both the Audio Precision's S/PDIF outputs and USB data sourced from my MacBook Pro running on battery power with Pure Music 3.0 playing WAV and AIFF test-tone files. Apple's USB Prober utility identified the DAC SE as "USB2.0 High-Speed True HD Audio\000" from "C-MEDIA Inc.\000," its serial number as "0 (none)," and confirmed that its USB port operated in the optimal isochronous asynchronous mode.

BorderPatrol specifies the DAC SE as operating with data sampled at up to 96kHz. Apple's AudioMIDI utility revealed that, via USB, the BorderPatrol DAC SE accepted 16-, 24-, or 32-bit integer data sampled at all rates up to 384kHz, and that its coaxial inputs accepted PCM datastreams with sample rates up to 192kHz. However, with sample rates greater than 96kHz, the right channel was reproduced 9dB higher than the left! Do not attempt to play high-sample-rate data with this DAC. BorderPatrol also states, correctly, that the DAC SE will play Tidal Masters streams, which are sampled at 44.1 or 48kHz and are MQA encoded. However, it will not unfold the MQA encoding.

The BorderPatrol DAC SE's maximum output level at 1kHz was 1.87V, which is 0.6dB lower than the CD standard's 2V. The output impedance was very high, at 2.3k ohms at 1 and 20kHz, rising to 5.8k ohms at 20Hz. This DAC needs to be used with a preamplifier having an input impedance of 50k ohms or higher if the low frequencies are not to sound lightweight.

The outputs inverted absolute polarity, and the BorderPatrol's impulse response with 44.1kHz was a perfect inverted pulse (fig.1; ignore the tiny amounts of pre- and post-ringing, which are due to the SYS2722's anti-aliasing filter operating at a sample rate of 200kHz). As there is no digital reconstruction filter, with white noise sampled at 44.1kHz (fig.2, magenta and red traces, footnote 1) there was a slow rolloff above the audioband, disturbed by nulls at 44.1 and 88.2kHz. Consequently, the aliased image of a 19.1kHz tone at –3dBFS (cyan and blue traces) was hardly suppressed at all. I usually use a full-scale 19.1kHz tone for this test, but the BorderPatrol DAC dumped a lot of aliased image energy into the audioband with this signal, and the noise floor was higher than expected.


Fig.1 BorderPatrol DAC SE, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).


Fig.2 BorderPatrol DAC SE, wideband spectrum of white noise at –4dBFS (left channel red, right magenta) and 19.1kHz tone at –3dBFS (left blue, right cyan), with data sampled at 44.1kHz (20dB/vertical div.).

Fig.3 shows the BorderPatrol's frequency response at 44.1 and 96kHz sample rates. The output is down by 0.5dB at 12Hz and 20kHz with 44.1kHz data, and the top-octave response doesn't extend much higher in frequency with 96kHz data. The DAC SE's channel separation was disappointing, at 52dB L–R and 55dB R–L from 100Hz to 1kHz, and only slightly greater in the treble. The low-frequency noise floor was free from any power-supply–related spuriae (fig.4), but this was perhaps because the noise floor rose as the signal level approached 0dBFS (see later). This graph and the others were taken with the tube rectifier active; I repeated much of the testing with the tube bypassed using the front-panel button, but there were no significant differences.


Fig.3 BorderPatrol DAC SE, frequency response at –12dBFS into 100k ohms with data sampled at: 44.1kHz (left channel cyan, right magenta), 96kHz (left blue, right red) (1dB/vertical div.).


Fig.4 BorderPatrol DAC SE, tube rectifier, spectrum (0Hz–1kHz) of dithered 1kHz tone at 0dBFS (20dB/vertical div.).

As with other non-oversampling (NOS) DACs I've measured, the 1kHz waveform on my oscilloscope was stepped rather than smooth. A relevant problem with resistor-ladder DACs is the linearity error: Will a digital signal at, say, –80dBFS be reproduced at the outputs by an analog signal the same 80dB down from full level? When I examined the BorderPatrol's linearity, the left channel (fig.5) performed significantly differently from the right channel (fig.6). As the 1kHz tone drops below –60dBFS, the right channel has an increasingly positive amplitude error; ie, the level of the reconstructed analog signal is too high, reaching +5dB at around –90dBFS. By contrast, the left channel suffers from an increasing amount of negative amplitude error as it drops below –60dBFS.


Fig.5 BorderPatrol DAC SE, left channel, 1kHz output level vs data level in dBFS (blue, 20dB/vertical div.); linearity error (red, 2dB/vertical div.).


Fig.6 BorderPatrol DAC SE, right channel, 1kHz output level vs data level in dBFS (blue, 20dB/vertical div.); linearity error (red, 2dB/vertical div.).

I had seen this exact behavior before. A quick search of the equipment-review archive on Stereophile's website found a product that exhibited identical measurements: the HiFiMan HM-602 digital audio player, which Stephen Mejias reviewed in May 2011. It came as no surprise to see that the HiFiMan player used the same Philips TDA1543 DAC chip. The TDA1543 is a low-cost DAC that can be powered with a 5V supply—hence its use in a portable player—and has buffered outputs rather than the usual current sources, which is why BorderPatrol can use it without a separate output stage.

The TDA1543 is a 16-bit part; while increasing the bit depth from 16 to 24 with a dithered 1kHz tone at –90dBFS lowered the noise floor by 7dB or so (fig.7), the relatively high levels of odd-order harmonics in the 24-bit traces (blue and red traces) indicate that this DAC chip truncates data with a bit depth greater than 16. This graph also confirms the differences in how the two channels handle 16-bit data: the left channel (green trace) has insufficient energy at 1kHz, the right (magenta) too much. With undithered data representing a tone at exactly –90.31dBFS (fig.8), it can be seen that the DAC starts to act as a frequency doubler at low levels. It pumps energy into a tone an octave higher (hence the high level of second-harmonic distortion in fig.7) and, as it does this, reduces the level of the fundamental.


Fig.7 BorderPatrol DAC SE, spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS with: 16-bit data (left channel green, right magenta), 24-bit data (left blue, right red) (20dB/vertical div.).


Fig.8 BorderPatrol DAC SE, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit TosLink data (left channel blue, right red).

The BorderPatrol DAC SE had problems at high levels, even into the Audio Precision's benign 100k load impedance. There were high levels of distortion with a full-scale 50Hz tone (fig.9), with the third harmonic the highest in level at an audible –43dB (0.7%, footnote 3), and significant levels of many other harmonics. Dropping the level to –3dBFS into 100k ohms (fig.10) reduced the level of the third harmonic to –67dB (0.045%), and the second harmonic is now the highest in level, at –57dB (0.14%). Further reductions of the signal level preserved the levels of the second and third harmonics. This distortion might not be audible at typical levels of recorded music (footnote 2), but peak transients will be accompanied by bursts of distortion.


Fig.9 BorderPatrol DAC SE, spectrum of 50Hz sinewave, DC–1kHz, at 0dBFS into 100k ohms (left channel blue, right red; linear frequency scale).


Fig.10 BorderPatrol DAC SE, spectrum of 50Hz sinewave, DC–1kHz, at –3dBFS into 100k ohms (left channel blue, right red; linear frequency scale).

The poor ultrasonic rejection visible in fig.2 resulted in a multitude of aliased images in the audioband with a full-scale mix of 19 and 20kHz tones (fig.11), and reducing the signal level by up to 6dB (fig.12) produced only a slight change in the number of images. Fortunately, music rarely has significant energy toward the top of the audioband. Figs. 11 and 12 also indicate that actual intermodulation distortion is relatively low, the 1kHz difference product lying at –64dB (0.06%).


Fig.11 BorderPatrol DAC SE, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 0dBFS into 100k ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).


Fig.12 BorderPatrol DAC SE, HF intermodulation spectrum, DC–30kHz, 19+20kHz at –6dBFS into 100k ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

When I tested the BorderPatrol DAC SE for its rejection of word-clock jitter using undithered 16-bit J-Test data, both the noise floor and the odd-order harmonics of the low-frequency, LSB-level squarewave were much higher than they should have been (fig.13). (The correct levels are indicated by the sloping green line.) This behavior was identical when I repeated the test using the USB input. I suspect that this behavior is due in part to noise modulation: as the signal level rises toward 0dBFS, the noise floor rises also.


Fig.13 BorderPatrol DAC SE, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit S/PDIF data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

The BorderPatrol Digital to Analogue Converter SE's measured performance is dominated by its use of the underperforming TDA1543 DAC chip. Google indicates that the current price of this chip is between $4 and $6, depending on the quantity purchased; I would have expected a D/A processor costing $1850 to have used a better resistor-ladder chip. However, it is fair to note that Philips's much-better-performing TDA1541 DAC, long discontinued, currently costs around $140 each for the basic version, and up to $299 for the premium S1 Crown version—prices too high for that chip to be used in BorderPatrol's DAC SE.—John Atkinson

Footnote 1: My thanks to Jürgen Reis of MBL for suggesting this test to me.

Footnote 2: Stereophile's Test CD 2 has tracks where you can listen for yourself how audible different amounts of second, third, and seventh harmonics are. Click here for details.

BorderPatrol Audio Electronics, c/o Kaja Music Systems,
11864 Sidd Finch Street
Waldorf, MD 20602
(301) 705-7460

Bogolu Haranath's picture

"Oh No, Not Again" ............ Bill Harley :-) ...............

Bogolu Haranath's picture

"Oh No, Not Again" ............... Marky Ramone & The Intruders :-) .............

Bogolu Haranath's picture

8 to 10 bit resolution and loads and loads of 2nd harmonic distortion :-) ..........

jeffhenning's picture

...By the bucket loads.

Sorry, but the Earth is not flat and that prince from Africa is not sending you $20M.

Ortofan's picture

... pleasant versus accurate debate - except that this time it revolves around a DAC instead of an amplifier.

The challenge for the Border Patrol designer is could he design a DAC that measures as well as the Benchmark unit but still exhibit a sound quality that would appeal to the reviewer?

Bogolu Haranath's picture

The designer probably can, for a price tag of $20,000 :-) ...............

Herb Reichert's picture

"facing the pleasent versus accurate debate" . . . because no such "debate" exists - except in the minds of people who listen to numbers printed on pages. If David Chesky (HDTracks) or Kavi Alexander (Water Lily Acoustics) or Todd Garfinkel (M-A Recordings) record a solo piano -- the DAC that lets that piano sound most like the real piano is - UNDEBATEABLY - the most accurate. Is it not?

By that simple - easily-varifiable - measure, the Border Patrol is far more "accurate" than the Benchmark.

Ortofan's picture

... (or any other piece of audio equipment) with distortion measurements such as those shown in figures 9 and 10 is an accurate device? You may prefer the resultant sound quality, but it's undeniable that you're listening to significant amounts of added distortion. The performance of this DAC is barely above that available from an analog disc and is far below the requirements for CD, let alone even higher resolution recordings.

Regarding "real piano" sound, I have a real piano in my listening room as an "easily verifiable" point of reference - do you?

Part-Time Audiophile's picture

An excellent question.

The corollary being -- can he do it for under $2k and still like it enough to want to make it?

I'm reminded of an old sign at work:

1. Done Fast
2. Done Well
3. Done Affordably


The interesting point to note is that this designer did in fact make a DAC that appeals to reviewers. An embarrassing number have refused to return them, preferring instead, to send a check. There's a reason for that -- and it's not "because it's handy to have around".

mav52's picture

Get real JA. I thought it was always about the sound the listener hears not how much it the device or component cost.

johnnythunder's picture

"I am reminded of a quote by Daniel R. von Recklinghausen, Chief Engineer, H.H. Scott: "If it measures good and sounds bad—it's bad. If it measures bad and sounds good, you've measured the wrong thing."

I'm not an audio engineer but I agree. Apart from the subjective aspects of what sounds good and bad of course. Go to a Best Buy one day or even a Bang and Olufsen store - you'll hear lots of low-ish quality audio that sounds great to the people buying and who are we to tell them they are wrong for liking what they like!

geoffreyvanhouwaert's picture

Hello Mr Reichert,

I've read your reviews for the past few years now and learned a lot about writing reviews and your personal flavours. The one thing i never understood is why you have a Mytek dac in your set-up, let alone two... I have a wonderful Nos dac with the same phillips chip inside and even without the tube it sounds ten times more 'analogue' than the sabre dacs. I know bad word. The designer of my dac doesn't believe in tubes in a dac. He does make preamps with tubes...

Anyway my question: say for argument sake that the Myteks are too detailed and the Border Patrol with tube is too romantic (tempting as it is to use the tube) wouldn't the border patrol without the tube be just about right? Wouldn't a good nos dac without tubes be just about right for digital.

I know right doesn't exist in audio and i loved the last two sabre dacs i tested recently, i have nothing against the Mytek for instance. It's just a thing i've been thinking about personally because i've been very tempted in buying the border patrol because of that damn tube. But with a tube preamp for instance would it be too much on the tuby side? Hope you understand what i'm trying to say here.

Best regards
Geoff from Belgium

Herb Reichert's picture

The simple answer to your Mytek inquiry is - I listen. I am presently living an audiophile's dream. I get to use and experience a wide range of audio technologies (almost at will) but it is against my religion to assign virtue or value to equipment based on the designer's choice of technology. I deeply enjoy my Mytek DACs because, like I told Ortolan, they make piano and vocal recordings sound like real people and real pianos. Right now I use only three DACs: the Mytek Brooklyn, the Schiit Yggdrasil Analogue 2, and the Holo Audio Spring. All sound different but all are 'real' sounding -- not overly processed.

geoffreyvanhouwaert's picture


You already answered my question in your review. Only read half of the review when i posted my question. I should have known. Thanks!

tonykaz's picture

I've been reading DAC reviews since 2011, when NwAvGuy did his Benchmark comparable Odac ( that I still own ).

Back then, nobody dared dig thru DAC performance in any sort of descriptive "Attempt " !

Back then Jason Stoddard said that DACs are boring!

Back then DACs did their job and politely stayed out of the debates, leaving it all up to Amplification and Transducers to grab and keep the Spotlights.

Back then, we had Big Sound in Montana where the finest DACs were up on display and compared alongside the World's greatest Amplifiers and Headphone Transducer Systems. Hardly anyone noticed the DACs! ( including the obsolete Yggy from Schiit , hmm ).

I paid attention, I auditioned the Yggy and found it lacking, I considered the MSB Analog DAC but kinda passed because of something Jason Stoddard said.

So, all these Years we've had Bland, ho-hum, yawning reviews of DAC's near sameness.

Until NOW !!!

Now we have a wordy Loquacious Bon-Vivant who's willing to go out on that limb that all others seem to dare not go.

Are DACs gonna get described now? ( finally ), does Stereophile have a brave soul able to go where no man has dared go?

I'm wading around the murky DAC understandings craving some assist in putting these complex puzzle pieces into a coherent understanding.

Thank you

Tony in Michigan

emcdade's picture

The measurements confirm What my audition of this dac was like; not good.

Soft bass, slightly grainy and lacking air in treble region, amorphous imaging. I hate to say it but there are a number of dacs at 1/3 the price that will sound better to my ears.

I now have a T+A DAC 8 DSD being fed nothing but quad rate DSD from Roon. Now that is a product that sounds different than your standard Benchmark DAC in a very good way. It has gobs of air and three dimensionality, while still having tons of body and real flesh and blood sound. That combination is elusive, but it does it.

Part-Time Audiophile's picture

While your experience is, no doubt, valuable and insightful, your comment is rather less so.

What did you "test" with? What are your preferences? Did you follow the instructions and advice of the manufacturer or any of the reviewers that wrote about it, or did you strap it the back of an airplane, dip it in chocolate, or attempt to chokeslam the unit before use?

The point: is your judgment relevant without your argument or your assumptions?

hollowman's picture

1982: 1st gen Sony (and other Japanese) CD players
2003: Zanden intro's super-$ model 5000 DAC -- it is NOS and uses Philips '80's-era TDA1541 dac. Reviewed by Stereophile in 2006
2018: TotalDAC, BorderPatrol, Soekris , et al.
1982: 1st gen Philips CD players (4x OS used to "emulate" 16-bit performance 'cause the TDA1540 dac was only 14-bit)
1984: 3rd gen Japanese CDPs intro 2x OS. Philips cont. to use 14-bit/4x OS
1986: Philips intro's new 16-bit dac (TDA1541) and new 4x OS chip (SAA7220)
2018: Chord's latest DAC with massive OS via gazillion taps

Clarkston's picture

Thank you Jon Iverson, CACC, and Stereophile for going the extra mile to question your own conclusions, even at the expense of potential embarrassment. Great to see blind testing and a larger group participate in making real world comparisons. Great to see a wide range of music tested including tracks that would get you shamed out of a regional show or high-end store. This is the first time I've seen anyone suggest in print that most DAC's actually sound very similar. I own two pieces of equipment that measure poorly - one being the the Boarder Patrol SE DAC and the other are my speakers. I've tried alternatives and listened to countless others but my ears (and my friends ears) tell me ignorance is bliss, I guess. Does this make me a bad audiophile? Hope to see input from other local clubs creep into your reviews in the future.