Bow Technologies ZZ-Eight CD player Measurements

Sidebar 2: Measurements

The Bow Technologies ZZ-Eight's analog output was absolute polarity-correct, and at 2.11V: 0.45dB higher than the CD standard of 2V RMS. Its source impedance was just over 45 ohms across the band, implying that the player will have no difficulty driving low-impedance preamps. The ZZ-Eight coped very well with damaged discs, playing without dropouts through the Pierre Verany test disc's track 32, which has 1.5mm gaps in the data spiral.

The ZZ-Eight's frequency response at full level (fig.1, top traces) was flat, with a negligible balance error. The response with de-emphasis, however, featured a maximum error of –0.7dB at 4kHz (fig.1, bottom trace), which will be audible on the small number of pre-emphasized discs as a slight lack of presence. Crosstalk (not shown) was below –100dB across the band in the L–R direction, but about 5dB worse in the other direction. Both of these are excellent figures.


Fig.1 Bow Technologies ZZ-Eight, frequency response at 0dBFS (top) and de-emphasis response (bottom) (right channel dashed, 0.5dB/vertical div.).

Fig.2 shows a 1/3-octave spectral analysis of the ZZ-Eight's output while it decodes data representing a dithered 1kHz tone at –90dBFS. Other than a very small amount of second-harmonic distortion and some low levels of the 120Hz power-supply component, the noise floor is very low and free from spurious garbage. Extending the measurement bandwidth to 200kHz and driving the player with "digital black" data gave the spectrum shown in fig.3. Again, some very-low-level power-supply components can be seen, as can some slight noise peaks well above the audio band. But even the latter are at or below –100dBFS.


Fig.2 Bow Technologies ZZ-Eight, spectrum of dithered 1kHz tone at –90.31dBFS, with noise and spuriae (16-bit data, right channel dashed).


Fig.3 Bow Technologies ZZ-Eight, spectrum of digital silence, with noise and spuriae (16-bit data, 1/3-octave analysis, right channel dashed).

The ZZ-Eight's left-channel linearity error is shown in fig.4 (the right channel was identical). Any amplitude error is negligible down to well below –100dBFS, below which the effects of noise make their presence known. This is superb performance, and the waveform of an undithered 1kHz tone at exactly –90.31dBFS (fig.5) features three easily identifiable, equally spaced voltage levels, with the Gibbs Phenomenon "ringing" visible at each level transition. One thing did bother me: this stairstep waveform could be made out—even on full-scale sinewaves—to an extent I have not seen before. I have no idea what the subjective efect of this would be; as the frequency content of the "steps" is well above the audible range, I assume it is benign.


Fig.4 Bow Technologies ZZ-Eight, left-channel departure from linearity (2dB/vertical div.).


Fig.5 Bow Technologies ZZ-Eight, waveform of undithered 1kHz sinewave at –90.31dBFS (16-bit data).

Analog-domain harmonic distortion was extremely low in level. Fig.6 shows the spectrum with the player reproducing a 61Hz sinewave. Odd-order harmonics predominate, if that verb is appropriate considering that even the highest level, the fifth, is well below 90dB down from the level of the fundamental. Intermodulation distortion was higher: when the player reproduced a full-scale mix of 19kHz and 20kHz tones (fig.7) the 1kHz difference component just crossed above the –80dB line. There were also a couple of strange enharmonic products visible above and below 12kHz.


Fig.6 Bow Technologies ZZ-Eight, spectrum, DC–1kHz, 61Hz at 0dBFS (linear frequency scale, 20dB/vertical div.).


Fig.7 Bow Technologies ZZ-Eight, HF intermodulation spectrum, DC–22kHz, 19+20kHz at 0dBFS (linear frequency scale, 20dB/vertical div.).

Finally, I measured the ZZ-Eight's jitter with the Miller Audio Research jitter analyzer. The spectrum of the jitter is shown in fig.8. The absolute clock error was low at +23ppm and the jitter level was also very low, at just 147.6 picoseconds peak–peak. What peaks are present are indicated with red numerical markers; these are related to the 229Hz data frequency in the special test signal, but are all very low. Interestingly, MF's sample was very much better than the earlier sample of the player measured by Paul Miller for the English magazine Hi-Fi News & Record Review (grayed-out spectrum in fig.8), which had a very high jitter level of 996ps. This was almost all data-related, and appears to have been significantly reduced by Bow Technologies' subsequent use of the I2S interface.—John Atkinson


Fig.8 Bow Technologies ZZ-Eight, high-resolution jitter spectrum of analog output signal (11kHz at –10dBFS with LSB toggled at 229Hz). Center frequency of trace, 11kHz; frequency range, !X3.5kHz. (Grayed-out trace is that of Paul Miller sample.)

Bow Technologies
Durob Audio BV
PO Box 109
5250 AC Vlijmen, The Netherlands

tonykaz's picture

"I'd buy it and be done with it, it's that good"

I expect and even demand honesty from reviewers. Reviewers at Stereophile have ( or should have ) a fiduciary responsibility to readership, shouldn't they?

It seems blatantly obvious that you have a disdain for all things 16/44, so why make an obviously dishonest attribution ?

I have you as a person whose nervous system is intentionally tuned to all things 33.3. I also had that synapse tuning arrangement, back in the day. I lately changed my synapse tuning to 16/44 ( it's like changing from Vodka to Scotch from the Islays, it's no big deal that rewards with vastly improved utility ) .

I would enjoy your observations if I felt a consistent honesty.

Tony in Venice

Ortofan's picture

... an analog disc fanboy?

Cut the poor fellow some slack.
At the time of the review, it's been 10 years since CDs started outselling LPs and it will be another decade before the vinyl revival begins in earnest.

If you want to complain, then note that MF is comparing playback from a $7K CD player with that from a turntable/tonearm/cartridge/phono stage setup with a combined cost of $15-20K. Is that in any way equitable?

Likewise, where are the comparisons with some other CD players in the same price range? A comparison with a $300 DVD player seems rather pointless.

JHL's picture

...need less projecting and moralizing and more letting go and perspective. I tend to think that the kindly reviewer, column given here for free, isn't an elected or ordained official of vast and ponderous truths.

He's a *reviewer* and this is, for now anyway, a free market.

This is entertainment, not dialysis. -N. Pass.

tonykaz's picture


JHL's picture

...what that means, but if you were a dealer, your first obligation by your own rules and usual customer expectation, was to assess and report on these same wares. Maybe some helplessness overtook the stocking, auditioning dealership that it could neither advise or counter in the face of a magazine brought in off the street.

Which leaves intact the question of badgering an ancient column for the writer's purported want of professionalism or acuity, if that's what you're alluding.

Jim Austin's picture

It almost seems like you want a slap-down. Well, I hope this will suffice.

This reviewer's statement probably mis-led but it makes sense if the review is actually a Presenting & Promotion. ( Jim Austin will give me a slap-down for accusing this )

I can't quite parse what you've written here, so I'm not sure if it's offensive or not. Maybe I should just point out that this review was published in 1998, and the company that made the product is long gone. I find it a little strange to get all personal and indignant about something written 22 years ago. But never mind.

Otherwise, I'll just say that while no one writes for Stereophile who isn't willing to call it like he [edit: or she] hears it, Michael Fremer is probably the most outspoken and plainspoken of all of us--and has been for as long as I can remember.

Times are tough--I know I could use a vacation. You?

Jim Austin, Editor

MatthewT's picture

Thanks very much.

tonykaz's picture

Thanks for writing.

I have many things in common with 33.3 and Mr.MF.

Reviewers have been ( since the days of Stereo Review & the English Mags of the 1980s ) closing with positive comments, despite not seeming to like or appreciate the reviewed devices. It almost seems a mandatory inclusion.

Some reviewers never use an apologagetic endorsement i.e. Jim Austin, J Gordon Holt, HR, Kal R., Steve G and of course the original JA1 ( true his entire life of reviewing ) . The closest JA1 ever came was to give the Adcom GFA555 a Class C recommendation after Anthony Cordesman looooooved it, after Holt sort of loved it and after reviewing the amp himself.

I feel that reviewers are "higher authorities" but they still need juried supervision in their choice of phrases. ( the measurement guy has been consistently brilliant )

Tony in Venice

ps. your new lady reviewer seems gifted

ps.2. Tyll was outstanding as are a few others that I should mention like our Canadian Stereophile Robert.

Michael Fremer's picture

I concur!

Michael Fremer's picture

For the same reason. Perhaps you didn't notice the date I wrote that review. I did not make a dishonest attribution. Not sure why you think that. It's funny because when the importer came to pick up the unit they made me an offer for purchase that had I accepted would have been dishonest. But I didn't take it because I am honest. Yes, I don't like 16/44 now though it's surely gotten better and I certainly didn't like it then but my likes and dislikes are not really the story. I do still prefer records. It's not even close for me but I did buy a dCS Vivaldi One and I do like playing my SACDs and streaming high resolution on Qobuz and Tidal. Reading this review for the first time in decades I rather enjoyed it and think it proves me prescient. You think otherwise. That's fine. Enjoy your 16/44. But please add the .1.

Anton's picture

I may be asked to turn in my audiophile card, but....

I like rocking to Radar Love in my VW.

I like listening to Louis and Ella and my now vintage Oppo UDP-205. (Insane tangential drift in this parenthetical, I just checked the model number to make sure I got it right and saw the secondary market prices, yow!)

I like CD, SACD, analog, cassette, reel to reel (even vintage commercial reels. Check out the old commercial release of Bridge Over Troubled Water and marvel!)

It's important, if we really do claim to be in it for the music, that we don't act as if we can only enjoy music "without pops and clicks," or if it is pure AAA analog...I get that an essential part of our recreation is identifying or creating differences between gear, but doesn't the joy hit you just as well when LCD Soundsytem starts singing about Daft Punk playing at his house during your commute? Or when Muse's "Madness" pops up on Sirius at the office?

If music only satisfies via a specific Hi Fi format on a 'qualifying' system, then we are really just gear fetishists.

End of rant.

rschryer's picture

...until you had to mention cassette.

Turn in your Audiophile card, sir. Right now! Do not make this any more difficult than it has to be.

tonykaz's picture

Can I have my Card Back?

I don't even remember getting it.

Did you scoop it up before they got around to mailing ?

Tony in Venice

ps. when are y'all gonna float down to my little "incubator for old people" in Venice?

I'll take you Kayak Fishing and let you enjoy the associations of all the other Canadians ( Montreal & Quebecers & Ontarios & Yellow Knife folks )

But, we replaced Hockey with shuffleboard and wacky-tobaccy

Tony in Venice

rschryer's picture

...for old people" in Venice?

When I get old. :-)

Ortofan's picture

... any of the pre-recorded cassette tapes from Telarc?

tonykaz's picture

It feels that we are now sailing into the uncharted waters of the 21st Century.

Audio Journalism, coming to my Mailbox, probably has less editorial content than the Audiophiliac YouTube operation of Steve G.

Format wise: I visited my nephew working on the Kevin Costner Montana TV series. I got to see part of the editing and sound gear. They maintain outstanding sound quality ( of course, digital ) . They are constantly improving their gear. Stereophile's Mr.Kal R would probably be staggered by what these Pro Audio folks work with on a daily basis and the performance results of their output.

Where are 'we' little, personal audio people, going to be in 5 years?

I was amazed at 2011 RMAF gear and digital's change to 24bit ( which I still haven't embraced now that my hearing is drooping at both ends of the audible range but corrected yet still dubious )

The iPhone designers have conquered.

Y'all Analog Planet people seem more Curators than Fortune Tellers but I hope that you will work to accurately forecast the next brief future reveals.

Bring us insights, pa-leeeeeeze.

Tony in Venice

ps. I keep forgetting that .1, old age is get'n me. ( I wonder if I can actually hear it ? )

canyelles's picture

Maybe your idea of audio bliss is listening to the equivalent of computing with an early analog computer, but it's not mine.

DWOOD's picture

Bow Technology may be finished but Lars Moltke, their CTO is still servicing hardware and also has a new DAC available for the ZZ-8. I have a Wizard which had it installed last year.

Here’s a link to the Facebook page. If you scroll down a bit you can see my player being upgraded.

Here’s a link to his site where he describes the upgrade and occasionally has things for sale