About a year ago, I reviewed another Classé Audio integrated amplifier and CD player (the CAP-100 and CDP.5; Audio, July 1997). The CAP-80 and CDP.3 reviewed here are about 30% less expensive.
Even so, the CAP-80 has at least one feature not found on the CAP- 100, an input selector that can be operated by the re mote. The CAP-80’s front panel includes a two-button input selector that cycles both ways through the five unbalanced (“Reg 1” through “Reg 5”) and one balanced (“Bal 1”) inputs. Three more pushbuttons turn on power, the tape monitor, and muting. Volume is controlled by the sole knob on the front panel, and relative volume level is indicated on an adjacent display in 121 steps. There is no balance control. The sup plied remote control has separate push buttons for selecting each signal input and for power, muting, up/down volume adjustment, and display brightness (adjustable in three steps). On the rear panel are the connectors for the unbalanced and balanced inputs, the tape and preamp outputs, five- way binding posts for speaker connections, and an IEC power-cord connector.
The CDP.3, like the CDP.5, has a simple, elegant, and attractive front panel that bears the usual drawer, display, and trans port controls. A red LED to the right of the display window glows when an HDCD disc is being played and decoded. The player’s supplied remote, larger and shaped differently from the CAP-80’s, has additional control functions, such as a button to switch the display from track elapsed time to total remaining time or elapsed time from the beginning of the disc.
Measurements
The CAP-80 integrated amplifier’s two channels performed almost identically on many of my tests, so I’m mainly showing data for only one channel, the left. Test signals were applied to an unbalanced line in put unless otherwise noted.
The CAP-80’s frequency response does not change much with loading, whether you’re looking at the power-amplifier or preamp output. In both cases, the small change in output when the load is changed demonstrates that the impedance is quite low at either output.
The effect of changing the amplifier section’s load is more noticeable above the audio range (Fig. 1A). This is typical of most amplifiers; it is caused by reduced negative feedback at high frequencies and by the resistor-inductor output-buffering network, whose series impedance rises with frequency.
--- SPECS ----
AMPLIFIER
Rated Power: 100 watts/channel with 8-ohm loads; 150 watts/channel with 4-ohm loads.
Dimensions: 19 in. W x 4¼ in. H x 14¼ in. D (48.3 cm x 11.1 cm x 36.2 cm). Weight: 25 lbs. (11.3 kg).
Price: $1,395.
CD PLAYER
Dimensions: 19 in. W x 3¾ in. H x 12 in. D (48.3 cm x 8.6 cm x 32.7 cm). Weight: 20 lbs. (9.1 kg).
Price: $1,395.
Company Address: 5070 François Cusson, Lachine, Que. H8T 1B3, Canada; 514/636-6384.
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The preamp section’s frequency response (Fig. 1B) also shows more loading effect at higher frequencies, but not much, even on the expanded vertical scale used here. As can be seen, the bandwidth of the preamp section is considerably greater than that of the CAP-80’s power amplifier section. Results were essentially the same using the balanced input. The impedance of the pre amp output was low, about 105 ohms, which explains why the output signal was little affected by the capacitance in the IHF load. The impedance at the tape outputs was about 500 ohms. For the unbalanced inputs, impedance was a high 300 kilohms; for the balanced input, it was 21 kilohms.
The power-amp section’s bandwidth dominated the rise and fall times and the square-wave response. The former were 5.2 microseconds for an output of ±5 volts into 8 ohms (rise and fall times at the preamp output were a fast 400 nanoseconds at ±1 volt out). As to the latter, a 10-kHz square wave had a perfect exponential shape into an 8-ohm load. When 2 microfarads of capacitance were added to the load, ringing was very low, about 8% overshoot that damped out in one cycle. A 20-Hz square wave had just noticeable tilt.
From Fig. 2’s curves of the CAP-80’s power versus total harmonic distortion plus noise (THD + N) at 1 kHz and SMPTE IM distortion, it appears that this amp meets its 8- and 4-ohm power output specs. But above 1 kHz, THD + N into 4-ohm loads is higher (Fig. 3); with 8-ohm loading, the distortion was somewhat lower, reaching a maximum of 0.14% at 12.5 kHz. A harmonic-distortion spectrum for a 1-kHz, 10- watt signal into 8 ohms is plotted in Fig. 4. The harmonic spectrum is rather complex, consisting principally of odd harmonics ex tending out to 20 kHz and beyond, but these harmonics are reasonably low in amplitude. For these distortion tests, the volume control was set at around 32, close to the midpoint of its numerical range.
Digitally controlled electronic volume controls such as the Crystal CS3310 used in the CAP-80 will overload at some input level, regardless of the volume setting. This control circuit’s overload levels can be read from Figs. 5A (for unbalanced input) and 5B (for balanced output), which show how the pre amp section’s distortion changes with input level and frequency. (These tests were run with the volume reduced to 18.5, keeping over all gain low enough to ensure that the power-amp output would not clip when this input overload occurred.) As is most often the case, distortion increases at the highest frequencies, but here overall distortion is quite low and the preamp’s ability to withstand input overload is more than adequate for any nor mal signal source.
Plots of THD + N versus level for analog circuits traditionally ex press the THD + N as a percentage of the signal level rather than a percentage of some fixed value. Distortion typically varies with signal level, while a circuit’s noise level is fixed. As the signal level drops, this noise level becomes a larger and larger percentage of the total and then eventually dominates the readings. Once that point is reached, THD + N rises at 6 dB per octave as the level keeps dropping. So the straight-line portion at the left of these curves represents noise, not distortion. Only where the curves deviate from this 6-dB/ octave slope does actual distortion dominate the reading. This hap pens at about 1 to 2 volts in Fig. 5A and at about 2 to 4 volts in Fig. 5B. The results were essentially the same with instrument or IHF loading on the preamp output. (For digital circuits, we measure THD + N in dB relative to full- scale output, or dBFS, so this potential mis understanding does not arise.)
Fig. 1—Frequency response B of CAP-80, measured at amplifier output (A)
and preamp output (B).
Fig. 2—Amplifier THD + N and SMPTE IM vs. output
Fig. 3—Amplifier THD + N vs. frequency, 4-ohm load..
Fig. 4—Amplifier distortion residue for 10 wafts into 8 ohms at 1 kHz.
Fig. 5—Preamp distortion vs. input level for balanced inputs (A) and unbalanced inputs (B).
Fig. 6—Frequency response of CDP.3 CD player.
The preamp section’s IHF S/N ratios via the unbalanced inputs were 104.3 dB for the left channel and 104.5 dB for the right. For balanced inputs, the ratios were 96.2 and 92 dB. For the amp as a whole, the differences between unbalanced and balanced inputs were smaller. The S/N via unbalanced inputs was 89.8 dB for the left channel, 90.2 dB for the right; with balanced inputs, the ratios were 89.4 and 87.2 dB. The CAP-80’s interchannel crosstalk measured a little better than —70dB over most of the audio range. At 20 kHz, it increased to about —64 dB from left to right and —68 dB from right to left.
As mentioned earlier, the output impedance of the CAP-80’s power- amp section is very low. Consequently, the damping factor was quite high, measuring greater than 500 at frequencies up to about 600 Hz and decreasing smoothly to about 41 at 20 kHz.
The CAP-80’s dynamic power into 8-ohm loads was 156 watts at the beginning of the 10-millisecond IHF tone-burst signal and 138 watts at its end; with 4-ohm loads, the beginning and end powers were 253 and 210 watts. Using the values at the beginning of the burst, the dynamic headroom figures work out to 1.9 dB for 8-ohm loads and 2.3 dB for 4 ohms. Clipping power at 1 kHz (measured at the visual onset of clipping, about 0.8%) was 118 watts with 8-ohm loads and 168 watts into 4 ohms, for clipping- headroom figures of 0.7 and 0.5 dB, respectively.
When the CAP-80 is powered on, the volume indicator counts down from 20 to 0, at which time the “Reg 1” input is selected and the muting light comes on. The AC line current drawn is about 380 milliamperes after warmup. Sensitivity measurements for the CAP-80 are listed in Table I.
Turning to the CAP.3 CD player, output at digital full-scale (0 dBFS) into instrument loads was just over 2.01 volts for the unbalanced outputs and about 4.025 volts for the balanced outputs. IHF loading reduced the unbalanced output level by a mere 0.04 dB and the balanced output by 0.08 dB. The unbalanced output’s impedance was 45 ohms, and the balanced out put’s was 90 ohms.
The CD player’s frequency response with unbalanced output and instrument loading (Fig. 6) was no different from its balanced output’s response, and IHF loading didn’t alter the response shape for either output. Frequency response with de-emphasis engaged was essentially the same, too, indicating a negligible de-emphasis error. Square- wave output had the usual linear phase characteristic, i.e., symmetrical ringing about the vertical center line of each half cycle of the wave. The ringing on a 1 -kHz, 0-dBFS (full-scale) square wave was not clipped off, which is characteristic of the Pacific Microsonics HDCD decoding/digital filter chip used in the CDP.3. The polarity of both unbalanced and balanced out puts was correct.
Figure 7 shows the CDP.3’s THD + N versus frequency at 0 dBFS for two measurement bandwidths. The data plotted is for unbalanced output and instrument loading; results for balanced output and IHF loading were about the same. Commendably, high-frequency distortion does not rise much with the wider measurement bandwidth; this is frequently not the case. In Fig. 8, THD + N is plotted as a function of level for a 400-Hz tone, with an IHF load on the unbalanced output.
Fig. 7—CD player THD + N vs. frequency, for narrow and wide measurement
bandwidths.
Fig. 8—CD player THD + N vs. level.
Fig. 9—Deviation from linearity.
Fig. 10—CD player noise spectra.
Fig. 11—Jitter spectrum.
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TABLE 1—Input sensitivity, CAP-80 amp, for 500 mV into 10 kilohms + 1,000 pF or I watt into 8 ohms.
Sensitivity
LEFT---RIGHT
Unbalanced In to Preamp Out---41.1 mV 40.5 mV
Balanced Into Preamp Out---80.4 mV 81.2 mV
Unbalanced In to Tape Out---529.6 mV 528.4 mV
Balanced In to Tape out---1.0641 V 1.0641 V
Unbalanced In to Power Amp Out---7.66 mV 7.74 mV
Balanced Into Power Amp Out---15.3 mV 15.5 mV
Preamp Out to Power Amp Out---96.4 mV 96.6 mV
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Equipment used in the listening tests for this review consisted of:
CD Equipment: PS Audio Lambda Two Special and modified Sonic Frontiers SFT- 1 CD transports and Sony CDP-• 707ESD CD player, Genesis Technologies Digital Lens anti-jitter device, and Classé Audio DAC-1 and Sonic Frontiers Processor 3 D/A converters
Phono Equipment: Kenwood KD-500 turntable, Infinity Black Widow arm, Win Research SMC-l0 moving-coil cartridge, and Vendetta Research SCP2-C phono preamp
Additional Signal Sources: Nakamichi ST-7 FM tuner, Nakamichi 1000 cassette deck, and Technics 1500 open- reel recorder
Preamplifiers: Sonic Frontiers Line-3, Dynaco PAS-2, and First Sound II passive
Amplifiers: Arnoux Seven-B stereo switching amplifier, Quicksilver Audio M-135 mono tube amps, and Audio-Note Conqueror single-ended stereo tube amp
Loudspeakers: B&W 801 Matrix Series 3 speakers used as subwoofers with Dunlavy Audio Labs SC-Ill speakers, and Lowther PM5A drivers in modified Lowther Club Medallion II speaker cabinets
Cables: Digital interconnects, Illuminati DX-50 (AES/EBU balanced); analog interconnects, Tara Labs Master and Music and Sound (unbalanced); speaker cables, Transparent Cable MusicWave Reference, Jena Labs Speakeasy Twin Three, and Madrigal Audio Laboratories HF2.5C
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The CDP.3 s deviation from linearity when playing a 500-Hz tone (Fig. 9) is greater in the right channel than in the left below about —80 dBFS; this characteristic will affect some of the measurements to come. In Fig. 10, for example, a third-octave sweep of the audio range with a —80 dBFS, 1-kHz signal, the right channel’s greater deviation from linearity manifests it self as greater harmonic distortion (especially the third harmonic, at 3 kHz). But the complete absence of 60-Hz hum components is notable.
Interchannel crosstalk was very low, measuring less than —100 dB from 125 Hz to 16 kHz from right to left and about —90 dB from left to right. Several other readings were better in the left channel: Dynamic range measured 99 dB in the left channel and 95.1 dB in the right; quantization noise was 93.6 dB in the left channel and 89.6 dB in the right; and S/N (re 0 dBFS with the transport in pause) was 84.7 dB wideband and 106.7 dB A- weighted for the left channel versus 84.2 and 102.4 dB for the right.
The jitter spectrum in Fig. 11 was measured, with the transport in pause, at the latch-enable pin of one of the CDP.3’s DAC chips. In multibit DACs like the ones used in this player, it is said to be primarily the jitter at this pin that affects the reconstructed audio signal. On this plot, 0 dB represents a jitter of 10 nanoseconds peak to peak or, assuming a sinusoidal jitter wave form, 3.54 nanoseconds rms. An individual spectral component down, say, 60 dB would be 3.54 picoseconds rms. The rms sum of all the jitter components above 70 Hz in frequency and —70 dB in amplitude is about 6.7 picoseconds, which is quite good.
Use and Listening Tests
I used the CAP-80 as my system amplifier for a considerable time, along with the CDP.3 CD player. Most of my listening was with the Dunlavy Audio Labs SC-III speakers, which I sometimes augmented by using B&W 801 Matrix Series 3s as subwoofers. I found that the speaker cables I used made a noticeable difference in the sound; I settled on the Madrigal Audio Laboratories HF2.5C wire as giving the best, fullest, smoothest sound.
+++++++++ TECHNICAL HIGHLIGHTS++++++++++++
The Classé CAP-80’s circuitry is distributed among four boards. The board carrying the line-level inputs and outputs, signal selection, and preamp circuitry is mounted at the rear of the enclosure. A smaller board, also at the rear, is an auxiliary power supply that keeps the amp’s control microprocessor powered up so that it can respond to control inputs from the front panel or remote. The microprocessor itself is on a board behind the front panel, which also connects to the front-panel controls and display. The power amplifier board and generously sized toroidal power trans former occupy the rest of the interior.
The preamp and signal-selector circuits are always powered by the auxiliary supply. When the front-panel power switch is turned on, a relay on the auxiliary supply switches AC power to the toroidal transformer that feeds the power amplifier section.
Preamplifier gain and volume are handled by a Crystal CS3310 chip on the signal-selector and preamp board. (It and the op-amps in the CAP-80 are powered by a ±5-volt supply.) This chip, a reasonably good-sounding device, can vary level from —95.5 to +3 1.5 dB in 0.5- dB steps, but the CAP-80 uses only 97.5 dB of this range. From full volume (shown as “60” on the display) down to an indicated level of “7,” volume changes in 0.5-dB steps; below that, the steps grow larger until there’s a 12-dB level difference between steps “1” and “0.5,” and the last step mutes the signal completely. Solid-state switches handle signal selection. Burr-Brown OPA2134 dual op-amps take care of signal buffering and convert differential, balanced in put signals to unbalanced ones.
The CAP-80 has no power-amp input, and no way to break the link between its preamp and power-amp sections, yet there is a preamp output.
The power-amplifier circuitry uses only discrete parts. Each channel has its own rectifiers and filter capacitors. These capacitors are 4,700-microfarad, 63-volt filter capacitors, two paralleled per supply polarity for each channel. The supply for the preamp section has its own transformer winding, rectifier, and filter capacitors. Driver and output transistors are mounted on the heat sink, their leads soldered to the p.c. board. One pair of output transistors is used in each channel.
The CDP.3 CD player’s transport mechanism is decoupled from the chassis with elegant little rubber isolators. An internal metal enclosure shields the transport electronics. A p.c. board at the rear of the unit handles digital filtering, HDCD decoding, and D/A conversion. The filtering and HDCD decoding are done with the Pacific Microsonics PMD 100 chip; the DAC chips are Burr-Brown PCM 1702s, and Burr-Brown OPA604 and OPA2604 op-amps handle analog filtering and convert unbalanced signals to feed the balanced outputs. A number of three-terminal regulators pro vide various voltages for the digital and analog circuitry on this board. A toroidal power transformer sits behind the CD transport. Another board, which is behind the front panel, inter connects the front panel’s pushbuttons and display window with the player’s control microprocessor.
Both of these units are very nicely made with high-quality parts. B.H.K.
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The CAP-80 amp proved highly listenable. When I cranked it up on recordings with heavy bass, it easily drove the SC-Ills to very loud levels. The bass was tight arid defined, midrange and highs were smooth, and imaging and sense of space were very good. It did, however, tend to sound etched and a little thin in the lower midrange. When I used the CAP-80 to drive the Lowther speakers, which have unusually high sensitivity (about 102 dB), the amp’s turn-off thump displaced the drivers to a worrisome degree, nearly ½ inch. This thump should not be a problem with drivers of normal sensitivity, however.
I found the CDP.3 musically satisfying with most of my CDs. The sound was high Iv detailed, though through the CAP-80 it seemed to lack a little weight in the lower midrange relative to my other (much costlier) CD sources. When I used the Classes with the Lowther speakers, the sound was quite detailed, though occasionally some what bright and edgy.
Both components’ remote controls worked well. I was particularly impressed with the taper of the CAP-80’s volume control, which made the degree of volume change seem unusually well matched to the degree of control rotation. It did feel odd, though, that volume did not change unless I rotated the knob at some minimum rate; this was no problem in normal use but mildly annoying when I was trying to set precise levels for my lab tests. I also would have preferred the CDP.3’s drawer to extend about a quarter of an inch further outward, so it would be less easy to scrape CDs on the front panel when loading and unloading. And I felt the player was a bit slow getting from track to track and beginning play.
But those are only minor reservations. Overall, the Classé CAP-80 and CDP.3 performed very well and should provide good musical satisfaction in systems appropriate to their price range.
Adapted from 1998 Audio magazine article. Classic Audio and Audio Engineering magazine issues are available for free download at the Internet Archive (archive.org, aka The Wayback Machine)