what is the clocks? and what would be a good replacement ?
Correction: AD8516 not AD8556 (which has nothing to do with audio op amps lol)
I replaced the Dual crystal oscillator with two NDK NZ2520SD in the DSD Pro. I am not sure what frequency are in the T1 yet.
I will also replace the microprocessors in the DAC that control the high frequencies and PWM which I will do again.
The best way I can describe it’s effect on audio in my own words is, have you felt some parts speed up while others are slowed down. That's what it feels like. When you ”fix” it the audio sounds like a metronome that musicians use to keep time but it’s not “clicking” the meter instead it’s keeping time. Some people don’t like it and feel it’s to clinical, “cold” “analytic”. I don’t however.
There’s are especially two PWM versions for audio one being the Class D amplifier and the other SACD encoder which the Zishan DAC are designed using.
“A new class of audio amplifiers based on the PWM principle is becoming popular. Called class-D amplifiers, they produce a PWM equivalent of the analog input signal which is fed to the loudspeaker via a suitable filter network to block the carrier and recover the original audio. These amplifiers are characterized by very good efficiency figures (≥ 90%) and compact size/light weight for large power outputs. For a few decades, industrial and military PWM amplifiers have been in common use, often for driving servo motors. Field-gradient coils in MRI machines are driven by relatively high-power PWM amplifiers.
Historically, a crude form of PWM has been used to play back PCM digital sound on the PC speaker, which is driven by only two voltage levels, typically 0 V and 5 V. By carefully timing the duration of the pulses, and by relying on the speaker's physical filtering properties (limited frequency response, self-inductance, etc.) it was possible to obtain an approximate playback of mono PCM samples, although at a very low quality, and with greatly varying results between implementations.
In more recent times, the Direct Stream Digital sound encoding method was introduced, which uses a generalized form of pulse-width modulation called pulse density modulation, at a high enough sampling rate (typically in the order of MHz) to cover the whole acoustic frequencies range with sufficient fidelity. This method is used in the SACD format, and reproduction of the encoded audio signal is essentially similar to the method used in class-D amplifiers.”
