Teus de Jong;411013 Wrote: > Ok, I'm asking again: what would be the difference between using passive > attenuation using a passive preamp stage and the same attenuation using > in-line attenuators? In his posts, cliveb is the only one who > consequently speaks about avoiding *active* preamps: here I can see the > argument. But why should the same apply to passive ones? These should > act just like variable attenuators I thought? In principle a purely passive preamp should behave pretty much the same as fixed passive attenuation. Possible differences I can think of that might (or might not) be important:
1. Some passive preamps will use potentiometers. No potentiometer can track 100% accurately. Using selected resistors in a fixed or stepped attenuator will be more accuate. 2. As you adjust the volume setting of a passive preamp (or stepped attenuator), its input and output impedances vary. It may be that at your preferred listening level these impedances go sufficiently far outside the optimal range that they affect the frequency response. A fixed attenuator can select suitable resistances so as to avoid that possibility. I have to stress that the above are just possibilities that occur to me. I have no actual evidence that either theoretical disadvantage of a passive preamp would be an issue in practice. The only genuinely obvious advantage I can see for fixed attenuation is that it's cheaper - especially if you do it yourself (when it costs pennies). -- cliveb Transporter -> ATC SCM100A ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=61821 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
