Ack, thank you. My knowledge of Spectral's designs is limited to what I've read at their website and in reviews. You may find the comments by me, Atmasphere, and a number of others in this thread to be of interest, if you haven't seen it already.
An excerpt from one of my posts in that thread dated 2-6-15:
Designs having ultra-wide bandwidth have their potential downsides, however, certainly in terms of additional challenges that have to be faced in the design process. And perhaps also in terms of additional challenges that might have to be faced by the user, to the extent that there may be increases in sensitivity to RFI, speaker cable capacitance, AC power quality, etc.
The potential benefits of their ultra-wide bandwidth approach seem to me to be mainly applicable to power amps, though. I'm not sure what the benefits of ultra-wide bandwidth might be for preamps or phono stages (as opposed to bandwidths of say 200 kHz or thereabouts, that being a factor of 10 greater than the supposed upper limit of human hearing, and therefore arguably high enough to eliminate the possibility of audibly significant phase shifts). But I don't doubt that with sufficiently good engineering excellent results can be obtained for those kinds of components with their approach, while also being obtainable with other approaches.
Regards,
-- Al
An excerpt from one of my posts in that thread dated 2-6-15:
... slew rate, risetime, and bandwidth will in the case of many designs extend well beyond the point of being overkill with respect to effects that may have DIRECT audible significance. The Spectral amplifiers being extreme examples in that respect. As I'll get into in a moment, though, that does not necessarily mean that the only benefit is to those who write marketing literature....In the case of their power amplifiers, my speculation would be that the main contributor to the subjective perception of speed that is generally attributed to them is the avoidance or minimization of TIM (transient intermodulation) distortion that might otherwise be a consequence of the use of negative feedback. Rather than the perceived speed being a consequence of the ultra-wide bandwidth in itself. Reduced TIM means "cleaner" transients, and it would seem expectable for that to correlate with subjectively "faster" performance.
So why have I put the word directly in caps? Well, I would presume the designers feel that by designing ultra-fast circuitry they can avoid or minimize effects which may be audibly significant. For example, they may be able to realize the benefits of increased amounts of negative feedback while avoiding or minimizing what would normally be its adverse effects, such as transient intermodulation distortion. Or the higher speed circuitry might help to minimize crossover distortion, or the effects of unwanted energy storage in devices, etc.
So what can be said about that? Well, its an approach, and a philosophy. As is usual in audio, how good or bad the results are will depend on quality of implementation, system matching, and listener preference.
Designs having ultra-wide bandwidth have their potential downsides, however, certainly in terms of additional challenges that have to be faced in the design process. And perhaps also in terms of additional challenges that might have to be faced by the user, to the extent that there may be increases in sensitivity to RFI, speaker cable capacitance, AC power quality, etc.
The potential benefits of their ultra-wide bandwidth approach seem to me to be mainly applicable to power amps, though. I'm not sure what the benefits of ultra-wide bandwidth might be for preamps or phono stages (as opposed to bandwidths of say 200 kHz or thereabouts, that being a factor of 10 greater than the supposed upper limit of human hearing, and therefore arguably high enough to eliminate the possibility of audibly significant phase shifts). But I don't doubt that with sufficiently good engineering excellent results can be obtained for those kinds of components with their approach, while also being obtainable with other approaches.
Regards,
-- Al