Hi the mods are as follows:
"The CD23 is essentially made up of two PCBs, the main power supply & digital PCB, then the audio circuitry PCB is fixed to an aluminium plate and held upside down on top of the main PCB. Phase 1 of the modifications upgrades the main PCB digital & analogue power supplies, employing Black Gate NX for the analogue power supply. Regulator bypass & local digital de-coupling capacitors are also replaced for Rubycon ZA types.
The OEM master clock is a single transistor discrete design, evidently better than the poor quality CMOS inverter based clocks seen in other CD players regardless of price. We were keen to hear how the Superclock 4 (SC4) would perform in the CD23 and made this upgrade in isolation and listened.
We were keen to hear how the Superclock 4 (SC4) would perform in the CD23 and made this upgrade in isolation and listened. We can report that this new clock improves significantly upon OEM oscillator. Most notable is the increase in sound-stage depth and projection, a more flowing, organic, relaxing sense of the music. There's more detail, truth of pitch & timbre, bass delineation.
Tonally the CD23 looses that degree of hardness, leanness heard in the OEM player, with SC4 the tonal balance has a natural warmth and organic flow which makes listening for longer periods fatigue free. Bass is more sure footed, with added energy and power to ensure that the lower registers are more convincing.
Next we turned our hands to the audio board; regulator bypass & de-coupling bulk electrolytic capacitors are replaced with Black Gate FK & N types. Selected polyester film capacitors in the post DAC analogue stage are replaced with Black Gate NX Hi-Q. The OEM selected op-amps for filter are OP275 and the buffer uses the Burr Brown OPA2134, a 7 year old op-amp designed specifically for audio. The OPA2134 offers mediocre performance, with a laid back, lacklustre sound which tends to soften and veil the sound.
In this final part of the Phase 1 modification we replace the buffer op-amps with the new LM4562 from National Semiconductor. The LM4562 is op-amp to love, if reading spec sheets gets you going then check the excellent 120db PSRR or the vanishing low 0.00003% THD, the 4562 is the closest to no op-amp we have heard in a long time."
I have a CD72 at the moment, not a CD23, and like the big weighty sound, but cant get away from the lean mid - high bass. I note that you have also have a DAC - do you use the CD72 for transport only or also as a stand alone player...?