Philips CDR880 CD-R/RW CD recorder Measurements

Sidebar 4: Measurements

I performed a full set of measurements on the CDR880 as a CD player, followed by a selection of recorder tests, from both analog and digital inputs. The CDR880's maximum output was 1.9V RMS, almost 0.5dB below the standard 2V, sourced from a low output impedance of 200 ohms in the midrange and treble. Below 20Hz the source impedance rose to 622 ohms, which is still low. The output polarity was absolute-phase correct.

The CDR880 featured superb error-correction/concealment, playing through all the standard missing-data tracks on the Pierre Verany test CD without muting. It stumbled only on track 46, which features two successive 0.5mm data gaps. The only clue that the player was working hard on the tracks with a large gap in the data spiral was a slight increase in the measured distortion figure with more than 1mm of missing data.

The top trace in fig.1 is the replay-only frequency response at 0dBFS. The low frequencies start to roll off below 30Hz, reaching –0.4dB at 10Hz, and there is a very slight lift (0.2dB) at 20kHz. Neither should be audible. Below that response is the record/replay (analog in to analog out) response at –1dBFS; it has less top-octave rise but a greater LF rolloff, reaching –0.8dB at 10Hz. The bottom traces in fig.1 are the responses with de-emphasis, which show a maximum –0.65dB error at 4kHz. The replay-only crosstalk is shown in fig.2. It is very low, reaching –100dB at 1kHz and rising to just below –90dB at 20kHz.

Fig. 1 Philips CDR880, replay frequency response at 0dBFS (top), record/replay frequency response at –1dBFS (middle), and de-emphasis response (bottom). (Right channel dashed, 0.5dB/vertical div.)

Fig.2 Philips CDR880, crosstalk (10dB/vertical div.).

Fig.3 shows the audioband spectrum of a dithered 1kHz tone played back at –90dBFS. There is a very slight negative-level error and a trace of second-harmonic distortion, but the plot is otherwise clean at high frequencies. Note, however, the peaks at low frequencies, due to the 60Hz AC line frequency and its harmonics. The CDR880 did seem quite fussy over how it was grounded to the Audio Precision System One test setup, and this and the other spectral analyses were taken with the grounding that gave the lowest level of power-supply noise. These artifacts are too low to be heard as hum, however.

Fig.3 Philips CDR880, replay spectrum of dithered 1kHz tone at –90.31dBFS, with noise and spuriae (16-bit data, right channel dashed).

Extending the measurement bandwidth to 200kHz and driving the player with data representing digital silence gave the spectrum shown in fig.4. The power-supply harmonics can again be seen, and there is an increase in noise apparent above the 20kHz edge of the previous graph. This is due to the noise-shaping algorithm used by the Bitstream D/A converter.

Fig.4 Philips CDR880, replay spectrum of digital silence, with noise and spuriae (16-bit data, 1/3-octave analysis, right channel dashed).

With its record-level control all the way up, the Philips CDR880's analog input clips (1% THD+noise) at 850mV at 1kHz. The meter's "0dB" lights were flickering at this level, though the "Over" lights remained dark. Backing off the level to 825mV dropped the distortion to 0.07%, meaning that the recorder's A/D converters overload quite abruptly. Dropping the input level by 1.2dB, to 740mV, turned off the "0dB" lights, leaving the "–3dB" lights illuminated. (I would have preferred more resolution at the top of the meter's dynamic range window.) I then fed the CDR880 with an analog 1kHz tone at 82.5µV (–80dB ref. the overload level). The resultant playback spectrum, again measured with a wide 200kHz bandwidth, is shown in fig.5. The power-supply components can be seen, as can the ultrasonic noise, but the trace is basically free from distortion products.

Fig.5 Philips CDR880, record/replay spectrum of 1kHz tone at –80dBFS, with noise and spuriae (16-bit data, right channel dashed).

Fig.6 shows the CDR880's replay-level error plotted against absolute level. The DAC is obviously very linear down to well below –100dBFS. Spot-checking the level error for tones fed to the analog inputs revealed that the A/D converters also offered good linearity. Fig.7 shows the waveform of an undithered 1kHz tone at –90.31dBFS. The expected three distinct voltage levels can be easily made out, but note that there is some low-frequency noise present that makes the graph slope from right to left. This is the 60Hz-supply noise noted earlier. There is also a very small DC offset noticeable in this graph.

Fig.6 Philips CDR880, right-channel departure from replay linearity (2dB/vertical div.).

Fig.7 Philips CDR880, replay waveform of undithered 1kHz sinewave at –90.31dBFS (16-bit data).

As far as steady-state distortion is concerned, the CDR880's analog stages were very linear. Fig.8 shows the spectrum of a maximum-level low-frequency tone, 61Hz, played back from the CBS Test CD. The distortion components are all very low in level, with the highest in level—the second and third harmonics—both more than 90dB down from peak level. Recording a 61Hz tone from the analog input at –1dBFS gave an identical spectrum, suggesting that the '880's ADCs do not add significant distortion.

Fig.8 Philips CDR880, replay spectrum, DC–1kHz, 61Hz at 0dBFS (linear frequency scale, 20dB/vertical div.).

Intermodulation was also very low. Fig.9 shows a spectral analysis of the '880s' analog output while it replayed data representing 19kHz and 20kHz tones, each at –6dBFS. There is no appreciable 1kHz difference component visible, while the second-order components are all at or below –85dB. This is excellent performance.

Fig.9 Philips CDR880, replay HF intermodulation spectrum, DC–22kHz, 19+20kHz at 0dBFS (linear frequency scale, 20dB/vertical div.).

I used the Miller Audio Research jitter analyzer to analyze jitter on both the Test CD-R provided by MAR, and on a digital clone of that disc made at 44.1kHz on the Philips. One peculiarity of the jitter tests was that the results were more variable/less repeatable than is usually the case. I also did not get any statistically significant differences in jitter from the original disc, or from a clone made with the CDR880.

But a typical result is shown in fig.10. The absolute jitter level was 1130 picoseconds peak–peak, which is quite high. (The grayed-out trace in fig.10 is the Meridian 508.24's jitter, measured on the same basis, which is a very low 144.2ps.) Though a large number of higher-frequency sidebands can be seen, these are realtively low in level; most of the CDR880's jitter is present in the form of low-frequency sidebands, which can be seen clustered around the center tone and are marked with purple numerical indicators. Note also the strongly asymmetric sidebands, marked with a purple "30." These are all unknown in origin, but the low-frequency components may well contribute to the quality of the bass noted by WP in his auditioning, and which I heard in my own listening sessions.

Fig.10 Philips CDR880, high-resolution jitter spectrum of analog output signal (11kHz at –10dBFS with LSB toggled at 229Hz). Center frequency of trace, 11kHz; frequency range, ±3.5kHz. Grayed-out spectrum is that of the Meridian 508.24.

Finally, the conjecture in the UK press that the earlier CDR870's sample-rate converter gave rise to audible problems led me to check out the '880's behavior when fed the same data but with different sample rates. I used the Audio Precision System One to generate a low-distortion 11kHz sinewave which I digitized with a dCS 902 professional A/D converter set to 16-bit resolution. The peak level was –6dBFS, the average level the same –10dBFS as the Miller test signal. I fed the dCS's digital output to the CDR880's coaxial digital input and recorded a couple of minutes of data with the dCS first set to a 48kHz sample rate, then to a 44.1kHz sample rate. For the former, the '880's sample-rate converter is in circuit, rewriting the data at the CD's standard 44.1kHz rate; for the latter, it is switched out, the recorded data being bit-for-bit identical with the original. Using the Miller analyzer to perform a narrow-band, high-resolution analysis of the player's noise floor around the tone's fundamental while the '880 played back both versions of the 11kHz tone, I generated the traces shown in fig.11. (Thirty two readings, each with a 32,768-point FFT size, were averaged for each spectrum to reduce the contribution of random noise.)

Fig.11 Philips CDR880, high-resolution noise-floor spectral analysis of analog output signal with 11kHz sinewave at –10dBFS, cloned from 44.1kHz sample-rate original via coaxial digital input. Grayed-out spectrum is of identical signal cloned from 48kHz sample-rate original via coaxial digital input.

The foreground spectrum is with the 44.1kHz sampled data cloned directly. The same low-frequency sidebands can be seen as in fig.10; these have a fundamental frequency of 22.5Hz—to what this is related, I have no idea. The central peak also has "skirts" added by the presence of low-frequency, noiselike jitter. The grayed-out spectrum in the background is of the same tone but sample-rate converted from 48kHz to 44.1kHz by the CDR880. The noise level is basically the same, but note how the skirts have spread either side of the central peak, covering the lowest-frequency sidebands. According to Paul Miller, such spreading tends to be perceived subjectively as a smearing of stereo images, and possibly as a "slowing" of the bass. Certainly, the switching out of the sample-rate converter for 44.1kHz-sampled clones appears to be a step in the right direction, measurement-wise.—John Atkinson

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COMMENTS
Lofty's picture

Why, oh why, do we get a vintage review of a cd recorder/player. These machines are obsolete. Don't get me wrong, I have a component cd recorder and use it occassionally. 

To add to further irrelevance, the keepers of this website deem it important that we should read of a late 80's FM tuner. Don't get me wrong but I have three tuners and use them every day. Thank God for public/college radio in the NYC area.

OK, editors of Stereophile, what is the criteria for determining what vintage equipment reviews to publish on-line. For instance, I would rather put up a Music Reference MR9 amplifier (reviewed by DO) or a tuner, more important than the Marantz, like the Onyko T-9090 MkII.

So, to make a short story short, what is Stereophile's criteria  on listing equipment reviews on this website? 

As JA might say, "color me (un)impressed".

John Atkinson's picture

Quote:
OK, editors of Stereophile, what is the criteria for determining what vintage equipment reviews to publish on-line

One: requests from readers, as in the case of the Marantz tuner to which you object.

Two: filling in gaps in our archived reviews, which are almost complete going back to 1994, with many more going back to the magazine's founding in the early 1960s. (My goal is have every review Stereophile has ever published available on this website.) The 1998 Philips CD-R recorder review falls into this category, as it is one the few remaining reviews by Wes Phillips that had not yet been posted.

Three: personal interest on my part. Again, this was the case in the Philips recorder review, as it shone a light into an era where recordable CDs had not devolved into a commodity with no intrinsic value and where the concerns of the record industry were still affecting the performance of the hardware.

Four: from the page view statistics, these reviews appear to be as popular as anything else we post on-line.

And I fail to understand your objection. We are not forcing you to pay to read these vintage reviews. They also don't replace anything. You object to seeing them on-line, turn the page.

John Atkinson

Editor, Stereophile

mrplankton2u's picture

Arghh....another whiny post about vintage reviews:

 

"why, oh why do we get a vintage review..."

 

Considering all the other e-zines that offer nothing but advertising and cheesy subjective reviews for non subscribers and subscribers alike, it would probably be smarter to refrain from looking a gift horse in the mouth - unless you represent a competing ezine. That would certainly explain the sour, demanding, and petty attitude.  Not very shocking though as the above commenter calls him/herself "Lofty". Perhaps LoftyWhiner would be more suitable. If you would prefer more "cheese" with your whine, there are several other ezine websites available to choose from. They're very good at serving up hyped, subjective, propaganda...ahem... I mean "reviews" - for the companies that advertise with them and you won't have to endure the posting of vintage reviews. You'll only get advertising hype....ahem... I mean "reviews" - of currently produced and advertised product.

smittyman's picture

There are a couple of valid questions being asked in Lofty's post.  I've wondered about the vintage reviews myself and I think JA has done a good job of explaining the rationale for the decisions.  I've always applauded Stereophile for making so much content available for free; I had no idea that JA's goal was to get every review  ever published on to the site and I think that is great.

I usually skip the reviews of older equipment - especially stuff that is no longer in production and I wondred why these reviews were posted.  I would find them a lot more valuable if they perhaps referenced current used prices and or compared the equipment to its present day equivalant - but I realize that would be a huge amount of work and might not even be possible in some cases.

Stephen Mejias's picture

I usually skip the reviews of older equipment - especially stuff that is no longer in production and I wondred why these reviews were posted.  I would find them a lot more valuable if they perhaps referenced current used prices and or compared the equipment to its present day equivalant - but I realize that would be a huge amount of work and might not even be possible in some cases.

For me (and I bet I'm not the only one who feels this way), the simple historic value is enough. I wasn't aware of this stuff the first time it came around, so it's great for me to have the opportunity to learn about the past and tie it with what we're seeing today.

A time when CD-RWs sold for $30 each?! Unthinkable today. 

Plus, this is just really fine writing from Wes.

volvic's picture

As someone who buys vintage gear these reviews are a "trip down memory lane".  Besides some of this gear still holds its own even today and are great bargains and have such character.  Nope, keep em coming, I love reading them.  

Nick  

IgAK's picture

This is useful to used equipment buyers, just not titillating to dry-salivating perusers of stratospheric equipment those Walter mitty-esque folks generally can't afford to buy anyway. You know, used equipment...what happens to new equipment that the more well heeled sell after it isn't this year's latest and greatest.

FWIW, nowadays you can also buy used pro machines like the HHB 850, which ignore scams...I mean SCAMS...and also have excellent sound quality both as players and recorders...if you can find ones that aren't misbehaving. These are pro versions of the Pioneer PDR555RW, which SCAMS you into submission. While I don't know if the Pioneer consumer version has the same problem, I see no reason to buy a "scammed" burner on the used market, then have to fuss with all the restirictions. The problem? The HHB's have a 1F memory backup "supercap" that leaks ands destroys the triple-layered main board irreparably, which costs about as much to buy as the whole used unit, and installation under multiple boards in the way above this main board isn't quick or easy. But if you find a unit that isn't acting up yet, you can simply replace that cap for under $10 at worst price possible, and it can even be done (carefully) without removing any boards to do so - if you or someone you know is skillful enough. Just don't figure on repairing one that has already gone bad and acting up already - too late by then, that board is already rotting away from the caustic exudate form the cap! Then you have a fantastic unit for cheap, and no one is going to tell you what you can copy or not...oh, not that anyone would actually ignore the industry-profit serving legalities...of course (eyeroll)...right? We should respect laws rammed through with lobby money, never mind where on us they rammed them, of course...right? 

;>)

 

Audio Asylum Bruce from DC's picture

You never know what you learn on this site!  I happen to own an HHB 850 (working) which I have had for a number of years.  I don't use it to make copies of CDs, but I do use it to make digital versions of analog recordings.  So, for example, I can have my vinyl records "playing" in my car.

Never knew about the 1F cap failure.  So, I'll pull the sucker out and have a look.  TIA, as they say.

While we're at it, using the balanced outputs, the HHB is an inferior-sounding CD player to my Sony XA-777ES, which has only unbalanced outputs.   But CD dupes it makes of my records are surprisingly good.  Also, a couple of years ago we discovered a vinyl record of my late mother-in-law (who had a trained, operatic voice) singing Christmas carols, probably recorded in th e1950s.  The record was a mess, but using the HHB to make a digital copy that I could work with on my PC, we cleaned it up surprisingly well . .  . and gave CD's of the cleaned up version to all of her descendants who greatly apprceiated the gift.

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