Counterpoint DA-10 digital processor Measurements

Sidebar 2: Measurements

The DA-10's unique ability to accept different DACs made measuring it more interesting and challenging. On one hand, it took nearly three times longer to measure. On the other, it was possible to look at the performance of different DACs with the same input receiver, filter, and output stage. Because presenting all the measurements on each DAC would consume too much space, I'll show the measurements with the AD1862 (the DAC most likely to be installed in the DA-10), and comment on the performance of the other DAC cards when of interest.

The DA-10's maximum output voltage when decoding a full-scale, 1kHz sinewave was 2.15V with the AD1862, 1.31V with the CS4328, and 3.39V with the UltraAnalog. Referenced to the standard 2V output, these levels are +0.63dB, –3.7dB, and +4.6dB respectively—a very large variance. When comparing the DAC cards, be sure to match levels with a voltmeter.

Output impedance—which is determined by the analog output stage, not the DAC—measured a low 109 ohms across the audio band. I measured very low levels of DC at the analog outputs: 300µV at the left channel, 400µV at the right. The DA-10 doesn't invert absolute polarity with any of the three DAC cards tested. It also had no trouble locking to the three standard sampling frequencies.

Frequency response (fig.1) was predictably flat, but the DA-10's de-emphasis error was unusual in that it changed when the I/V converter stage, which is used only with the AD1862 DAC card, was switched into the circuit. The middle pair of traces is the DA-10's de-emphasis error with the AD1862 card; the lower pair of traces is the de-emphasis error with the CS4328 card. With the UltraAnalog DAC, this error was identical to that measured with the CS4328, leading me to speculate that the I/V converter was somehow involved in this anomaly. I repeated these measurements several times on separate occasions, always obtaining identical results. The small positive error seen in the middle trace will cause a brighter, more forward presentation when playing pre-emphasized CDs. Although the error is small (less than half a dB), it spans more than three octaves of bandwidth—enough to be heard. The large negative de-emphasis error shown in the bottom traces will be much more audible: the rolloff is greater than 1dB at 10kHz, and 1.5dB at 20kHz. This will cause a slight loss of air and openness when playing pre-emphasized discs, perhaps accompanied by a reduction in immediacy. (Very few CDs are pre-emphasized, however (footnote 1).

666CPDA10fig01.jpg

Fig.1 Counterpoint DA-10, frequency response with AD1862 DAC (top); de-emphasis error with the AD1862 DAC (middle); de-emphasis error with the CS4328 DAC (bottom) (right channel dashed, 0.5dB/vertical div.).

Interchannel crosstalk was low, the DA-10's separation measuring 110dB at 1kHz, decreasing to 93dB at 20kHz. The crosstalk plot (fig.2) is dominated by power-supply noise at low frequencies. The peaks at 120Hz and 180Hz are power-supply noise intruding on the crosstalk measurement.

666CPDA10fig02.jpg

Fig.2 Counterpoint DA-10 with AD1862 DAC, crosstalk (right–left dashed, 10dB/vertical div.).

When I performed a spectral analysis on the DA-10's output when decoding a –90dB, 1kHz dithered sinewave, I saw a huge (15dB) linearity error in one channel. Trimming the MSB with the front-panel control reduced this error to 12dB, still a severe error. Because the AD1862 DAC card also has MSB trimmers next to the DACs (which are not intended to be user-adjustable), I trimmed the bad channel for no error at –90dB. This produced a spectral analysis that looked better, but didn't correct a fundamental problem with the DAC card. When I measured the DA-10's linearity, it indeed had no error at –90dB, but did have what looked like missing code transitions (seen in the linearity plot of fig.3). Notice that at –90dB (the level at which I set the internal MSB trimmer) there's no error, but clearly the right-channel DAC is severely misbehaving. No amount of MSB adjustment could correct this problem.

666CPDA10fig03.jpg

Fig.3 Counterpoint DA-10 with AD1862 DAC, first sample, departure from linearity (right channel dashed, 2dB/vertical div.).

Counterpoint sent me a new AD1862 DAC card. Its linearity is shown in the bottom pair of traces in fig.4. The right channel's linearity is excellent, but the left channel has nearly 4dB of positive error at 90dB—hardly good performance. This linearity problem can't be corrected with the single front-panel MSB trimmer: if you set the left channel correctly, the right will be wrong. I then adjusted the left channel's internal MSB trimmer on the AD1862 DAC card so it matched the right channel, producing the top pair of traces in fig.4. Note that the top traces have been offset by +4dB, and the lower traces by –6dB, so I could show them on the same graph.

666CPDA10fig04.jpg

Fig.4 Counterpoint DA-10 with AD1862 DAC, second sample, departure from linearity before trimming (bottom); after trimming (top) (right channel dashed, 2dB/vertical div.).

In short, the AD1862 DAC card, as shipped, didn't have its linearity matched between channels. Now we know that Counterpoint doesn't cherry-pick review samples. Two minutes on an Audio Precision System 1—JA tells me that Counterpoint does use a large number of Audio Precision systems for its production-line QA and setup—could have adjusted the internal MSB trimmers so that the DACs would have behaved identically. The failure of two samples in a row to perform optimally—samples sent for review and measurement—raises questions about Counterpoint's quality control which I assume they will address in their "Manufacturer's Comment."

Incidentally, don't try to adjust the internal MSB trimmers without proper test equipment; the range of the pot is so wide that severe misadjustment could easily occur. The front-panel MSB trimmer has a much smaller range; even if it's set incorrectly, the absolute linearity error won't be large.

Linearity measurements on the CS4328 and UltraAnalog DAC (not shown) indicated that these DACs' low-level performances were swamped by noise. The positive error at low levels suggested that the implementation of these DACs in the DA-10 was perhaps less ideal than that of the AD1862. Both the Crystal CS4328 and UltraAnalog D20400 have intrinsically better linearity and are quieter than I measured in the DA-10.

Fig.5 is the spectral analysis of a –90dB, dithered 1kHz sinewave with the AD1862 DAC card (after I set the internal MSB trimmer). The DACs are now well-behaved, although there's still a disturbing amount of power-supply noise intruding on the audio signal. This noise was there regardless of the DAC card installed, and remained even with different grounding arrangements.

666CPDA10fig05.jpg

Fig.5 Counterpoint DA-10 with AD1862 DAC, second sample after trimming, spectrum of dithered 1kHz tone at –90.31dBFS, with noise and spuriae (1/3-octave analysis, right channel dashed).

The DA-10's reproduction of a –90dB, undithered 1kHz sinewave is shown in fig.6 from the AD1862 DAC, and in fig.7 from the UltraAnalog DAC. Note the much better wave shape and symmetry from the UltraAnalog DAC. The three transitions at this level (+1, 0, –1) are more clearly delineated in fig.7. Note how the power-supply noise seen earlier shifts the zero crossing point above and below the DC line. In effect, the 1kHz sinewave is riding on the low-frequency noise component.

666CPDA10fig06.jpg

Fig.6 Counterpoint DA-10 with AD1862 DAC, waveform of undithered 1kHz sinewave at –90.31dBFS.

666CPDA10fig07.jpg

Fig.7 Counterpoint DA-10 with UltraAnalog DAC, waveform of undithered 1kHz sinewave at –90.31dBFS.

Fig.8 shows the DA-10's excellent noise-modulation performance: the traces are tightly grouped, the noise level fairly low. This measurement was made on the best channel of the second sample, which I hand-trimmed with the Audio Precision.

666CPDA10fig08.jpg

Fig.8 Counterpoint DA-10 with AD1862 DAC, noise modulation, –60 to –100dBFS (10dB/vertical div.).

The DA-10 intermodulation spectrum is shown in fig.9 with the AD1862, and in fig.10 with the UltraAnalog DAC. Although both spectra are quite clean and free from intermodulation components, the 1kHz difference component is completely nonexistent with the UltraAnalog DAC, but sticks up to –95dB with the AD1862. There are also IM components at multiples of 1kHz in the AD1862 FFT. The noise floor is also higher with the UltraAnalog DAC, even though it has a higher intrinsic signal/noise ratio than the AD1862. This further supports my assumption made earlier that this particular implementation of the UltraAnalog DAC degrades its noise performance, and that the DA-10's circuit works best with the AD1862.

666CPDA10fig09.jpg

Fig.9 Counterpoint DA-10 with AD1862 DAC, HF intermodulation spectrum, DC–22kHz, 19+20kHz at 0dBFS (linear frequency scale, 20dB/vertical div.).

666CPDA10fig10.jpg

Fig.10 Counterpoint DA-10 with UltraAnalog DAC, HF intermodulation spectrum, DC–22kHz, 19+20kHz at 0dBFS (linear frequency scale, 20dB/vertical div.).

Fig.11 is the 8x (352.8kHz) word-clock jitter when the DA-10 was driven by a full-scale, 1kHz sinewave. The signal-related jitter components are clearly apparent as spikes at odd multiples of 1kHz. The RMS level was a rather high 510 picoseconds, measured over a 400Hz–22kHz bandwidth. With a –90dB, 1kHz sinewave input, the jitter spectrum was much cleaner (fig.12), and the RMS level dropped to 450ps. Most processors have more, and higher-amplitude, signal-correlated jitter components at low signal levels. At –70dB (not shown), the spectrum looked very much like the full-scale spectrum shown in fig.11. To look at how well the DA-10 attenuates (or passes) higher-frequency jitter, I drove it with a full-scale, 10kHz sinewave. The spectrum, shown in fig.13, shows a large spike of jitter energy at 10kHz. Overall, the DA-10's jitter performance was less good than I have found to be possible with the CS8412 input receiver. (For comparison, see my measurements of the PS Audio Reference Link's jitter in Vol.16 No.10, p.206.)

666CPDA10fig11.jpg

Fig.11 Counterpoint DA-10 with AD1862 DAC, word-clock jitter spectrum, DC–20kHz, when processing 1kHz sinewave at 0dBFS (linear frequency scale, 10dB/vertical div., 0dB = 1ns).

666CPDA10fig12.jpg

Fig.12 Counterpoint DA-10 with AD1862 DAC, word-clock jitter spectrum, DC–20kHz, when processing 1kHz sinewave at –90dBFS (linear frequency scale, 10dB/vertical div., 0dB = 1ns).

666CPDA10fig13.jpg

Fig.13 Counterpoint DA-10 with AD1862 DAC, word-clock jitter spectrum, DC–20kHz, when processing 10kHz sinewave at 0dBFS (linear frequency scale, 10dB/vertical div., 0dB = 1ns).

Overall, the DA-10 was somewhat disappointing on the test bench. I've come to expect better technical performance from digital processors in this price range. Moreover, after receiving two misbehaving AD1862 DAC cards, I'm concerned about Counterpoint's quality control.—Robert Harley


Footnote 1: CD pre-emphasis is a high-frequency boost applied during recording or CD premastering. Pre-emphasized CDs carry a flag (in the Q-channel subcode) that tells the CD player or digital processor to switch in the de-emphasis circuit that attenuates the treble and restores flat response. If the de-emphasis circuit's attenuation characteristics don't match the pre-emphasis characteristics, de-emphasis error results. De-emphasis error can be thought of as a frequency-response error whenever the processor is decoding pre-emphasized discs.

Emphasis was designed to improve the CD's S/N ratio. By attenuating the treble after the DAC, DAC noise and artifacts are also attenuated. Very few discs have been pre-emphasized, particularly recently manufactured CDs, because engineers don't like the reduction in headroom it leads to. Although emphasis can subject the signal to more electronics (on both the recording and playback sides), it can theoretically improve CD performance if properly implemented.

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ARTICLE CONTENTS

COMMENTS
smargo's picture

reviews of digital from 1995 are so prehistoric.

your kidding me - that this was written now

John Atkinson's picture
smargo wrote:
reviews of digital from 1995 are so prehistoric.

your kidding me - that this was written now

Published in 1995, as it says in the heading, but posted now as part of our project to have every review published in Stereophile since the magazine's founding in 1962 available in our free on-line archives.

I'd offer to refund your money but as our archives are free access, I won't. :-)

John Atkinson
Editor, Stereophile

RH's picture

Hi John,

It's always intriguing (to me at least) to read the old reviews posted on this site, so please keep them coming.

Having visited the measurement section for the Counterpoint DAC it had me wondering: In your experience measuring these for so many years, could you sum up some of the areas of measurable improvements you see in the best modern DACs vs 90's (and earlier) era DACs like the Counterpoint?

smargo's picture

John: I have been reading stereophile for 25 years - Im not looking for a refund - im just saying id rather read about where companies and the people that ran them - are now - in this day and age

signalbeach's picture

A Counterpont DAC from 1995 ? Really ? This review is so old it's not relevant today; and not a very interesting piece either. I've been an audiophile since the early 70's and am very interested in reading reviews of seminal equipment from the past. Republishing old Audio Research, Krell, Levinson, McIntosh, etc reviews would be great.

BradleyP's picture

I'll bet that this DAC sounds just fine today for 44.1/16. I am the original owner of a storied JVC 1050 CD player from 1993, which also sounds just fine. Using it as a transport and feeding a more recent DAC with it yields only slight sonic improvements.

stereophilereader's picture

i wonder if anyone is still using this unit today ?

rschryer's picture

— a well-respected company that had at its core a gifted and innovative audio designer in Michael Elliott. In 1996, a year after this article was published, the company filed for bankruptcy, but not because its stuff didn't sound good. It just ran out of money.

stereophilereader's picture

but build and reliability were not the best.

tonykaz's picture

I ran out of money and customers in the middle 1980s. Geez, Counterpoint held out till 1996 ?, that's say'n sump'n !

I'm thinking the Customers are back now and bringing their pals, because the Recorded Music is wonderful, better than ever and improving. Phew!!

Of course there's plenty of Competition from 4K OLED TVs but that stuff is sooooooo computer generated ( not real and hard on the eyes ).

Simple music seems real and easy on the nervous system, it lets everyday life proceeds as normal and doesn't try to barge in on our "attention".

Nice recorded music ( like Lang Lang playing ) seems like going "off the grid" in your own home.

This is a very good time to be starting out as a recorded Music lover and consumer.

Too bad about Counterpoint and Michael Elliott, where is he now ?

Tony in Michigan

ps. I've never owned or even touched one single piece of Counterpoint Gear. Hmm....

rschryer's picture

...he was still posting back-page ads in audio magazines, Stereophile included, offering to repair/mod Counterpoint gear.

And I agree with you about these being unprecedented times in terms of access to recorded music. Tidal, bRadio, LPs, CDs... so much to enjoy, in so many different ways. I thank my lucky stars for it every day!

tonykaz's picture

Today,

Paul McGowan delivers a incredible summary about Audio's developments, to date.

Steve G talks logic concerning SubWoofers.

Brilliant stuff being released from Colorado & NY on the YouTube Channels.

Audiophile TV is where it's at.

Tony in Michigan

ps. listening while I work

rschryer's picture

...but probably not the "audiophile TV is where it's at" thing, which sounds to me dangerously close to being an oxymoron.

But that's only because TV sound doesn't interest me much. I am, however, interested in any potential technology that can accustom more people (read: regular folk) to good audio, and make them more resistant to not-good audio.

Good sound a bad thing? Never!

tonykaz's picture

Silly boy, Audiophile TV is Paul McGowan and Steve Gutenberg ( our people ) doing Audio Reviewing.

It isn't a TV thing it's a YouTube Channel specifically for us types.

Tony

rschryer's picture

Oops. I guess I should listen to music less and watch YouTube more (hehehe, as Herb would say). But I will check it out, Tony. Thanks for the heads up. (And, hey, nobody told me!)

tonykaz's picture

I'm nobody ?

Geez, you don't treat your pals very well, do ya?

So, I'm tell'n ya.

Anyway, Paul and Steve are the Competition, who would tell you?

The whole thing wouldn't matter except that these two are FiveStar Philosophers with tons of real experience, they're better than Harry Pierson & Pals at TAS!

Tony in Michigan

rschryer's picture

I will surely drop in to YouTube to check out Paul and Steve. You're right, these guys do know a ton of stuff about the audio biz. Should be interesting...

tonykaz's picture

It will be interesting and informative.

Mr.Carson's Lab and Blueglow Electronics are two more ( kinda at the grass roots level ) both are informative and insightful about how gear is built, breaks, is repaired and performs.

YouTube has become a wonderful adventure place.

Tony in Michigan

volvic's picture

Always wanted to own Counterpoint products in the 80's and 90's, but as a struggling poor student I could never afford them. This DAC was enthusiastically reviewed by a magazine that I love and respect north of the border, the reviewers loved it so much they used it as their reference. If I recall the authors thought the bitstream cards wasn't the way to go but with the HDCD card it was a killer. Pity such great companies; Counterpoint, Sonic Frontiers and Hovland are no longer around. Thanks for sharing, such great memories living in Montreal, spending endless hours at a local hifi store that I supported, which sadly is no longer around, and which always had an open door policy with me.

rschryer's picture

...Counterpoint was one of the first audiophile companies to properly implement HDCD capability in its DAC, the DA-10. That unit could make digital playback sound musical!

I do wonder if the demise of some of the well-known audiophile companies of the day wasn't partly due to bad customer service. Over the years, I've dealt with some talented, widely revered designers whose people skills could best be described as hostile and antithetical to repeat business.

I hope you've found an audio shop oasis in your neighborhood where you can feel at home, Volvic. If not, at least you live in a city replete with live music venues.

volvic's picture

I do live in a city that has great live music, thank god for the top tier at the Met and the subscription to JLCO. But sadly here, there are no local hifi dealers I can hang my hat, like I used to in Mtl. It was great listening and being introduced to great gear growing up at my then local audio store. After it shuttered, I gravitated towards another one which only recently closed, on the east side of Mtl. Great service and great guys. That personal touch I feel is lost, especially in a larger city like NYC. Keep the postings down memory lane coming JA, love these old reviews.

Ortofan's picture
volvic's picture

That's when Sony was a great company. Good times!

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