Marantz CD 50n Streaming CD Player Measurements

Link: reviewed by Dennis Burger on SoundStage! Simplifi on April 1, 2024

General Information

All measurements were conducted using an Audio Precision APx555 B Series analyzer.

The CD 50n was evaluated as a fixed-output DAC and conditioned for 30 minutes at 0dBFS (2.3Vrms out) into 100k ohms before any measurements were taken.

The CD 50n offers three digital inputs: one coaxial S/PDIF (RCA), one optical S/PDIF (TosLink), and one USB. There are two sets of unbalanced (RCA) line-level outputs (fixed and variable) and one headphone output (1/4″ TRS). There is an analog volume control for the headphone output.

The CD 50n offers a few features and settings. The following are the default settings used for the coaxial input, unbalanced line-level outputs, using a 0dBFS input, unless otherwise specified:

• Line Out Level: Fixed
• Lock Range: Wide (Medium and Narrow also available)
• Filter: Filter 1 (Filter 2 also available)
• H/P Amplifier Gain: High (Mid and Low also available)

The analyzer’s input bandwidth filter was set to 10Hz–22.4kHz for all measurements, except for frequency response (DC to 1 MHz), FFTs (10Hz to 90kHz). and THD vs. Frequency (10Hz to 90kHz), with the latter to capture the second and third harmonics of the 20kHz output signal.

The CD 50n analog volume control for the headphone outputs appears to be a potentiometer. Channel-to-channel deviation proved typical for this type of volume control implementation.

Volume-control accuracy (measured at the headphone output): left-right channel tracking

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Marantz for the CD 50n compared directly against our own. The published specifications are sourced from Marantz’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth as set at its maximum (DC to 1MHz), assume, unless otherwise stated, assume a fixed 2.34Vrms output (RCA) into 100k ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the coaxial input and the single-ended line-level outputs (unless specified, assume a 1kHz sinewave at 0dBFS, 100k ohms loading, 10Hz to 22.4kHz bandwidth):

Our primary measurements revealed the following using the coaxial input and the headphone output (unless specified, assume a 1kHz sinewave at 0dBFS, 300 ohms loading, 10Hz to 22.4kHz bandwidth, gain set to High):

Frequency response vs. sample rate (16/44.1, 24/96, 24/192, Filter 1)

The plot above shows the CD 50n’s frequency response as a function of sample rate. The blue/red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz, the purple/green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and finally orange/pink represents 24/192 from 5Hz to 96kHz. The behavior at low frequencies is the same for the digital input—perfectly flat down to 5Hz. The behavior at high frequencies for all three digital sample rates is that of a shallow reconstruction filter (Filter 2 offers brickwall-type filtering). The -3dB point for each sample rate is roughly 17.5, 36.6, and 64.5kHz, respectively. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue, purple, or orange trace) is performing identically to the right channel (red, green, or pink trace), and so they perfectly overlap, indicating that the two channels are ideally matched.

Frequency response vs. filter setting (16/44.1)

The plots above show frequency response for a 0dBFS input signal sampled at 44.1kHz for Filter 1 (blue) and Filter 2 (red), into a 100k-ohm load for the left channel only. The graph is zoomed in from 1kHz to 22kHz to highlight the various responses of the filters. We can see that Filter 1 offers soft attenuation around the corner frequency, likely minimizing phase shift, with a -3dB point at 17.5 kHz, while Filter 2 is a brickwall-type filter, with a -3dB point at 20.9kHz. It’s worth pointing out that Filter 1 (the default filter) may be discernible with 16/44.1 content when compared to DACs with ruler-flat frequency responses using brickwall filters, depending on one’s age and high-frequency hearing acuity. The -1dB point is at roughly 12.5kHz.

Phase response (8-ohm loading, line-level input)

Above are the phase-response plots from 20Hz to 20kHz for the coaxial input, measured across at the unbalanced output, using both Filter 1 (blue) and Filter 2 (red) for a 16/44.1 input. We can see that the CD 50n does not invert polarity, with a worst-case phase shift of -80 degrees at 20kHz for Filter 2 (the brickwall filter). What Filter 1 loses in high-frequency response, it gains with zero phase shift in the audioband.

Digital linearity (16/44.1 and 24/96 data)

The graph above shows the results of a linearity test for the coaxial digital input (the optical input performed identically) for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the unbalanced line-level output of the CD 50n. The digital input is swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output is analyzed by the APx555. The ideal response is a straight flat line at 0dB (i.e., the amplitude of the digital input perfectly matches the amplitude of the measured analog output). The 24/96 input data is essentially perfect down to -120dBFS, while the 16/44.1 input data performed well, only overresponding by 2.5/2dB (left/right) at -120dBFS. The 24/96 data yielded such superb results that we extended the sweep down to . . .

-140dBFS. Above we see that even at -140dBFS, the CD 50n is only overshooting by 1dB with a 24/96 signal (right channel, the left is still at 0dB). This is an exemplary linearity test result.

Impulse response (24/44.1 data, Filter 1 and Filter 2)

The graph above shows the impulse responses for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s), for one sample period then back to digital silence, fed to the coaxial digital input, measured at the unbalanced outputs into a 100k-ohm load for the left channel only. Filter 1 is blue and Filter 2 is red. We can see that Filter 1 is a simple filter with virtually no pre/post ringing. Filter 2 shows almost no pre-ringing, but significant post-ringing.

J-Test (coaxial, Lock Range Wide)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output of the CD 50n, using the Wide Lock Range setting. J-Test was developed by Julian Dunn in the 1990s. It is a test signal—specifically, a -3dBFS undithered 12kHz squarewave sampled (in this case) at 48kHz (24 bits). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz squarewave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sinewave (the main peak). In addition, an undithered 250Hz squarewave at -144dBFS is mixed with the signal. This test file causes the 22 least significant bits to constantly toggle, which produces strong jitter spectral components at the 250Hz rate and its odd harmonics. The test file shows how susceptible the DAC and delivery interface are to jitter, which would manifest as peaks above the noise floor at 500Hz intervals (e.g., 250Hz, 750Hz, 1250Hz, etc.). Note that the alternating peaks are in the test file itself, but at levels of -144dBrA (fundamental at 250Hz) down to -170dBrA for the odd harmonics.  The test file can also be used in conjunction with artificially injected sinewave jitter by the Audio Precision, to also show how well the DAC rejects jitter.

The coaxial input shows a good J-Test result, with two peaks at the -130dBrA level clearly flanking the 12kHz primary peak. This is an indication that the CD 50n may have good jitter immunity with the Wide setting.

J-Test (coaxial, Lock Range Wide, 100ns)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz without perfect jitter immunity. The results show visible sidebands at 10kHz and 14kHz, but at a very low -130dBrA. This is further evidence of the CD 50n’s strong jitter immunity using the Wide Lock Range setting.

J-Test (coaxial, Lock Range Narrow)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output of the CD 50n using the Narrow Lock Range setting. The result is identical to the Wide Lock Range setting.

J-Test (coaxial, Lock Range Narrow, 100ns)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz, without perfect jitter immunity. The result is very poor, with a significant increase in the noise floor. The Narrow Lock Range setting should not be used with sources that may be prone to jitter.

J-Test (coaxial, Lock Range Medium)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output of the CD 50n using the Medium Lock Range setting. The result is identical to the Wide and Narrow Lock Range settings.

J-Test (coaxial, Lock Range Medium, 100ns)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz, without perfect jitter immunity. The results show visible sidebands at 10kHz and 14kHz, but at an extremely low -145dBrA. This is evidence of the CD 50n’s very strong jitter immunity using the Medium Lock Range setting.

J-Test (optical, Lock Range Wide)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output of the CD 50n. The optical input is clearly worse than the coaxial input using the Wide Lock Range setting, with peaks as high as -105dBrA flanking the 12kHz fundamental.

J-Test (optical, Lock Range Wide, 100ns)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz without perfect jitter immunity. The results show visible sidebands at 10kHz and 14kHz, at a significant -80dBrA. This shows that the Wide Lock Range setting on the CD 50n should not be used with the optical input if the source is prone to jitter.

J-Test (optical, Lock Range Narrow)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output of the CD 50n using the Narrow Lock Range setting. The result is identical to the Wide Lock Range setting for the coax input.

J-Test (optical, Lock Range Narrow, 100ns)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz without perfect jitter immunity. The result is very poor, with a significant increase in the noise floor. As with the coaxial input, the Narrow Lock Range setting should not be used with sources that may be prone to jitter.

J-Test (optical, Lock Range Medium)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output of the CD 50n using the Medium Lock Range setting. The result is identical to the wide Lock Range setting for the coax input.

J-Test (optical, Lock Range Medium, 100ns)

The plot above shows the results of the J-Test test for the optical digital input measured at the unbalanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz without perfect jitter immunity. The results show visible sidebands at 10kHz and 14kHz, but at an extremely low -145dBrA. This is evidence of the CD 50n’s very strong jitter immunity using the Medium Lock Range setting. For the optical input, this should be the preferred setting for sources that are prone to jitter.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Filter 1)

The plot above shows a fast Fourier transform (FFT) of the CD 50n’s unbalanced-line level output with white noise at -4 dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1 (purple/green), using the Filter 1 filter. There is a soft roll-off above 20kHz as the white-noise spectrum shows. There are low-level aliasing artifacts in the audioband at -120dBrA at 6 and 13kHz. The primary aliasing signal at 25kHz is barely suppressed at -10dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Filter 2)

The plot above shows a fast Fourier transform (FFT) of the CD 50n’s unbalanced line-level output with white noise at -4 dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1 (purple/green), using the Filter 2 filter. There is a steep roll-off above 20kHz in the white-noise spectrum due to the brick-wall filter. There are absolutely no imaged aliasing artifacts in the audioband above the -135dBrA noise floor. The primary aliasing signal at 25kHz is at -80dBrA.

THD ratio (unweighted) vs. frequency vs. load (24/96)

The chart above shows THD ratios at the unbalanced line-level output into 100k ohms (blue/red) and 600 ohms (purple/green) as a function of frequency for a 24/96 dithered 1kHz signal at the coaxial input. The 100k and 600 ohms data are very close throughout the audioband, with only a 5dB increase in THD at 20kHz into the 600-ohm load. The right channel outperformed the left channel by roughly 5dB throughout. THD ratios into 100k ohms (right channel) ranged from 0.0003% from 20Hz to 5kHz, then up to 0.0005% at 20kHz.

THD ratio (unweighted) vs. frequency vs. sample rate (16/44.1, 24/96)

The chart above shows THD ratios at the unbalanced line-level output into 100k ohms as a function of frequency for a 16/44.1 (blue/red) and a 24/96 (purple/green) dithered 1kHz signal at the coaxial input. THD ratios are roughly equivalent between the 16/44.1 and 24/96 data, roughly between 0.0003 and 0.0005%,  with the same 5dB increase in THD between right and left channels seen in the previous graph.

THD ratio (unweighted) vs. output (16/44.1, 24/96)

The chart above shows THD ratios measured at the unbalanced output as a function of output voltage for the coaxial input into 100k ohms from -90dBFS to 0dBFS at 16/44.1 (blue/red) and 24/96 (purple/green). The 24/96 outperformed the 16/44.1 data at lower levels due to the increased noise floor with the lower 16-bit depth data (the analyzer cannot assign a THD ratio for peaks that do not manifest above the measured noise floor). For the 16/44.1 data, THD ratios ranged from 2% at 200uVrms, down to just below 0.0005% at the maximum output voltage of 2.34Vrms. The 24/96 THD ratios ranged from 0.1% at 200uVrms, down to the same 0.0005% at the maximum output voltage.

THD+N ratio (unweighted) vs. output (16/44.1, 24/96)

The chart above shows THD+N ratios measured at the unbalanced output as a function of output voltage for the coaxial input into 100k ohms from -90dBFS to 0dBFS at 16/44.1 (blue/red) and 24/96 (purple/green). The 24/96 outperformed the 16/44.1 data due to the increase noise floor with the lower 16-bit depth data. For the 16/44.1 data, THD+N ratios ranged from 20% at 200 uVrms, down to just 0.002% at the maximum output voltage of 2.34Vrms. The 24/96 THD+N ratios ranged from 1% at 200uVrms, down to 0.0005% at the maximum output voltage.

Intermodulation distortion vs. generator level (SMPTE, 60Hz:4kHz, 4:1, 16/44.1, 24/96)

The chart above shows intermodulation distortion (IMD) ratios measured at unbalanced output for 16/44.1 (blue/red) and 24/96 input data (purple/green), from -60dBFS to 0dBFS, for the coaxial input. Here, the SMPTE IMD method was used, where the primary frequency (F1 = 60Hz) and the secondary frequency (F2 = 7kHz) are mixed at a ratio of 4:1. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 16/44.1 data yields IMD ratios from 2% down to 0.002% at 0dBFS. The 24/96 data yields IMD ratios from 0.1% down to 0.0005% from -10 to -5dBFS, then up to 0.001% at 0dBFS.

FFT spectrum – 1kHz, 16/44.1 at 0dBFS

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the unbalanced output into 100k ohms for the coaxial digital input, sampled at 16/44.1. We see signal harmonics dominate at the second (2kHz) and third (3kHz) position at roughly -110dBrA, or 0.0003%, but also visible at lower levels up to and beyond 20kHz. There is only one small power-supply noise peak—the left channel at 120Hz at -130dBFS, or 0.00003%.

FFT spectrum – 1kHz, 24/96 at 0dBFS

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the unbalanced output into 100k ohm for the coaxial digital input, sampled at 24/96. Due to the increased bit depth, the noise floor is much lower compared to the 16/44.1 FFT at a very low -150 to -160dBrA. We see signal harmonics ranging from -110dBrA to -150dBrA, or 0.0003% to 0.000003%, all the way to 20kHz (and beyond). Here again, the second (2kHz) and third (3kHz) signal harmonics dominate at roughly -110dBrA. We find power-supply-related noise peaks at the second (120Hz), fourth (240Hz), and eighth (480Hz) harmonics, at -130dBrA to -140dBrA, or 0.00003% to 0.00001%.

FFT spectrum – 1kHz, 16/44.1 at -90dBFS

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the unbalanced output into 100k ohm for the coaxial digital input, sampled at 16/44.1 at -90dBFS. We see the signal peak at the correct amplitude, and no signal harmonics above the noise floor within the audioband.

FFT spectrum – 1kHz, 24/96 at -90dBFS

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the unbalanced output into 200k ohm for the coaxial digital input, sampled at 24/961 at -90dBFS. We see the signal peak at the correct amplitude, no signal harmonics, and the same power-supply-related noise peaks as seen in the 24/96 0dBFS FFT above.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, 16/44.1)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the unbalanced output into 100k ohms for the coaxial input at 16/44.1. The input dBFS values are set at -6.02dBFS so that, if summed for a mean frequency of 18.5kHz, would yield 2.34Vrms (0dBrA) at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -125dBrA, or 0.00006%, and the third-order modulation products, at 17kHz and 20kHz, are at -130dBrA, or 0.00003%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, 24/96)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the unbalanced output into 100k ohms for the coaxial input at 24/96. The input dBFS values are set at -6.02dBFS so that, if summed for a mean frequency of 18.5kHz, would yield 2.34Vrms (0dBrA) at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz), is at -120dBrA, or 0.0001%, and the third-order modulation products, at 17kHz and 20kHz, are at -125dBrA, or 0.00006%.

Intermodulation distortion FFT (coaxial input, APx 32 tone, 24/96)

Shown above is the FFT of the unbalanced line-level output of the CD 50n with the APx 32-tone signal applied to the input. The combined amplitude of the 32 tones is the 0dBFS reference, and corresponds to 2.34Vrms into 100k ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and below the -140dBrA, or 0.00001%, level. This is a very clean IMD result.

Diego Estan
Electronics Measurement Specialist