Slew-rate refers to a rate-of-change limit. This limit is set by bandwidth and/or output impedance. For example, if an amp uses feedback and has a narrow open-loop bandwidth (i.e., before feedback is applied) then this amp will probably have a poor slew-rate. Also, if the amp contains stages that cannot supply current at high frequencies (due to high output impedance) then that stage will slew-rate limit. Slewing means distortion on high-slope signals (i.e., signals that are both high in level AND high in frequency). If you want a faster sound, I would look for an amp that is dead flat to 20kHz (i.e., not more than 0.1dB-0.2dB down at 20kHz). After that, I would look for a higher slew rate, which is less critical at normal listening levels and with typical program material. Rather than ultra-high slew-rate, I would look for a direct-coupled amp, which will sound faster (as a rule) than cap-coupled amps. Finally, I would look for an amp with a regulated power supply, as these are most often the fastest in terms of pumping current around the audio circuit.
what is Slew Rate ?
I am not a audio specialist so I would like your suport: I have a Jeff rowland model 1 amplifier and i'd like to know what it's specifications mean: most things I understand, but what is the "slew rate"? It's specified in the manual: 70 volts per microsecond. is this what technically determines how quickly the amplifier amplifies a siganl from the pre-amp? In that case, is a smaller value better? How can this be described from an empirical viewpoint? Is this what audiophiles describe by "speed", as in a "fast" amplifier; my stereo sounds good to me, but in real life music sounds better. ...Of course it does! Actually, vinil sounds much more realistic than CD's, but still I notice a lack fullness and "fastness" of music coming out of my speakers. I would like to somehow improve this sound area of my stereo. Does the slew rate relate to these sound qualities or do I need to look elsewhere? I wish I could just audition different equipment and choose the one I like best, but living in Chicago, I have access to only those brands that my local shop provides. I need some criteria to narrow down my search. Great site! yours, Herman