Produced 1985-1987, the Philips CD150 is basically a cost-reduced version of the original CD100. While the CD mechanism and chassis are cheaper, the DAC section remains the same. The digital audio data from the CD is oversampled 4x by the SAA7030 chip before a pair of TDA1540P chips (one for each channel) perform the D/A conversion. This is a 14-bit switched current source converter with current output. The analogue circuitry consists of two LM833N opamps for I/V conversion and low-pass filter followed by a DC-blocking capacitor.
The unit tested here was purchased used on eBay for a few quid. Cleaning (it was filthy inside) and replacing electrolytic capacitors brought it back to fully working order. Date codes on parts inside suggest it was manufactured in late 1985 or early 1986.
A 1 kHz tone at 0 dBFS yields this spectrum at the output:
Lots of harmonics interspersed with other distortion products make for a rather ugly picture. THD up to 20 kHz is -85.4 dB (0.0054%), close enough to the specified figure of 0.005%. THD+N (20 kHz, unweighted) is -84.1 dB (0.0062%). This places the CD150 on similar footing to the Totaldac d1.
Looking at one cycle of the waveform, we see something that isn't quite smooth:
Lowering the signal level to -60 dBFS gives a surprising result:
The spectrum at this level is normally clean, yet here we have harmonics approaching -40 dB below the signal resulting in a THD figure of -36.4 dB (1.52%).
On the bright side, this player is capable of reproducing a -120 dBFS tone cleanly:
Moving on to the frequency response, the unit remains unimpressive with a stopband attenuation barely exceeding 50 dB. Still better than the Totaldac, though.
A closer look at the passband:
Those are some serious ripples, but at least there's none of that slow roll-off nonsense.
For completeness, the transition band looks like this:
To finish, we look at the jitter performance. There's some skirting and a few side tones, but nothing too bad:
In conclusion, this 35-year-old low-cost device landing above a good few devices in the chart is saying something. What it's saying is about those other devices, and it isn't something nice. I would only recommend it if the only other option is a Totaldac (or worse).
The unit tested here was purchased used on eBay for a few quid. Cleaning (it was filthy inside) and replacing electrolytic capacitors brought it back to fully working order. Date codes on parts inside suggest it was manufactured in late 1985 or early 1986.
A 1 kHz tone at 0 dBFS yields this spectrum at the output:
Lots of harmonics interspersed with other distortion products make for a rather ugly picture. THD up to 20 kHz is -85.4 dB (0.0054%), close enough to the specified figure of 0.005%. THD+N (20 kHz, unweighted) is -84.1 dB (0.0062%). This places the CD150 on similar footing to the Totaldac d1.
Looking at one cycle of the waveform, we see something that isn't quite smooth:
Lowering the signal level to -60 dBFS gives a surprising result:
The spectrum at this level is normally clean, yet here we have harmonics approaching -40 dB below the signal resulting in a THD figure of -36.4 dB (1.52%).
On the bright side, this player is capable of reproducing a -120 dBFS tone cleanly:
Moving on to the frequency response, the unit remains unimpressive with a stopband attenuation barely exceeding 50 dB. Still better than the Totaldac, though.
A closer look at the passband:
Those are some serious ripples, but at least there's none of that slow roll-off nonsense.
For completeness, the transition band looks like this:
To finish, we look at the jitter performance. There's some skirting and a few side tones, but nothing too bad:
In conclusion, this 35-year-old low-cost device landing above a good few devices in the chart is saying something. What it's saying is about those other devices, and it isn't something nice. I would only recommend it if the only other option is a Totaldac (or worse).
