Hi seanheis1, amplifier designers modifying class D modules is largely an urban legend.... One of the few amp designers who has done this is Bruno Putzeys, who has made some minor modifications to his own Hypex NCore NC1200 for integration into the Mola Mola Kaluga amplifier that he has also designed.
Rather, Designers who utilize class D amplifier use an incremental design approach to their amp implementations.
For some entry level implementations, it is often possible to limit oneself to housing the power conversion module in a chassis and wiring it to output terminals.... If the module is of very high quality, such as the NC1200, or its NC600 younger brother, the results can still be remarkably good.
Some other manufacturers, such as Merrill Audio, do a thorough "passive" component design around the modules... They implement highly dampened chassis, highest quality internal wiring (e.g. Cardas), and I/O connectors: see for example the Merrill Audio Veritas monos that I have reviewed for PFO a couple years ago. In some cases, like in the entry level Merril Teranis stereo amp, they design custom input stages.
Finally, some manufacturers, like Rowland, utilize the Hypex NCore NC1200 models as component parts of sophisticated amps, where all but the power conversion module is a custom-designed component.... In the M925 monoblock, the power supply is a 2500W DC multi-regulated SMPS unit fed by a power factor corrected rectifier (PFC) where the generated DC is further "whashed" through Jensen 4-pole capacitors to eliminate any residual ripples. The inputs are coupled to very large Lundahl transformers to maximize common mode noise wrejection.... There is a lot more to the technology of the Rowland M925 amps in my own system, but I do not pretend to know all technical details.
Suffice to say that the resulting sound and music are too die for.... The amps are as quiet as can be, and the output is harmonically articulate, with no trace of grain, and certainly without any treble intermodulation that I would otherwise easily detect as harshness in split high string and high brass parts.
Granted, in general NCore amps, the higher end Pascal amps, and also the better ICEpower implementations are not likely to fit the requirements of the lover of triode designs who prefers a slight bloom in the midrange, a warm mid bass, and a gently tapered off treble.
Rather, these amps, once they are well broken in, tend to yield what I like to call a "goldielockian" musicality. In other words, a sonic environment that yields an even harmonic treatement to the entire audible spectrum.... I love it, but admittedly not everyone does.
Regards, Guido
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