Aleph-3 Questions

hi david, not having directly heard this amp, i can't offer any direct experience, but i *do* have a couple comments - how efficient are your speakers? i know that the aleph 3 is supposed to be more powerful than its watts, but it is still only 25wpc. also, what's its input impedance? ewe have a rogue 99 preamp, right? my experience w/that preamp was not as positive as i'd hoped, partly, i think, due to an impedance mismatch - if the aleph's input impedence is 25k-ohms or less, that mite be affecting the dynamics. doug

rogue sez their 99 preamps' output impedence is 100 ohms, but this *can't* be correct, as my experiments w/crossing the outputs w/resistors indicates an output impedence in the 2k-2.4k range. fwiw... doug

david, ya mite wanna contact me about a conversation i had w/another mfr about the output impedence of the rogue 99. his feelings were that it would be hard to design a mu-follower-type preamp that *didn't* have an output impedence of 2k-2.4k ohms. the test i did comprised of placing resistors across the outputs, and listening for the reduction in volume. generally, 3db is the smallest perceived volume difference that can casually be noticed by people. (and, the output impedence rating indicates what input impedence will cause a 3db drop in volume). well, when crossing the outputs w/a 2.2k-ohm resistor, there was an easily audible drop in volume, when connected to my 25k-ohm input impedence system. a 1k-ohm resister *really* reduced the volume level w/the rogue preamp. when i tried the cary slp98 linestage, the 2.2k-ohm resistor had absolutely *no* affect on the volume level, i had to go down to a 1k-ohm resistor to get the same reduction in volume as w/the 2.2k-ohm resistoe on the rogue. the cary's output impedence is ~800 ohms, btw... hope this helps, doug

rogue audio doesn't put the output impedence spec in their 99 preamp manual. at least it wasn't in the manual that came w/*my* 99... which is why i tried crossing the 99's outputs w/differing resistors. as i previously said, a 2.2k-ohm resistor audibly reduced the volume of my rig, when the rogue was hooked up to my 25k-ohm impedence crossover. *no* drop in volume w/the 2.2k-ohm resistor crossing the cary preamp's outputs, which is rated at 800 ohms output impedence. this is why i believe that the rogue 99's output impedence is at least 2k-ohms. i've asked pass labs for input on a 2k-2.4k-ohm preamp driving their aleph-3, & haven't gotten a definitive answer; i'll post it when i receive it.

nelson pass sez that the aleph-3's input impedence is 23k-ohms, not 10k-ohms. he sez it's their balanced amps that have 10k-ohms impedence. so, using a preamp w/2k-2.4k-ohms seems it's right on the edge of what may or may not work. (mr pass *did* say he thought a preamp w/2k-2.4k-ohms output impedence would not be a problem w/the aleph-3). my rogue 99 didn't synergize in my system, w/its 25k-ohm input impedence, your results may vary. regards, doug