Aleph-3 Questions

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

Sedond,I e-maied Mark(Rogue) and he got right back to me as he is working late as they are getting ready to move to a larger facility this week.I gave him the specs.for the Aleph-3.He said the match should be fine with the 99.I told him about your comments (no name) and he said"Im not sure what he was measuring but it would be darned hard to design a mu-follower type preamp with a high output impedence of 2K-2.4K ohm." I just hope this amp pleases me when fully burned in.If not anybody want a Aleph-3 for a grand?

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

Well, I guess what it comes down to is who to have more trust in.I will have to side with Mark.He designed the 99 as well as all the other pre-amps and amps they manufacture.It would be my opinion Mark knows what he is doing and knows his designs better than anyone.All his products are getting rave reviews.He must know exactly what he is doing.If it comes down to me having to decide which piece of gear has to go it sure wont be the 99.Its staying in my system forever!

Hello David99, As stated earlier, I haven't heard the Rogue 99 ( know just from the stellar reviews posted by owners ...) , And I don't mean to suggest that it's not a good match for the Pass Aleph 3 . But, *tube* preamps in general can have one theoretical problem mating to the Aleph amps ...ie, the Output impedence of the tube pre's is usally higher than the 10 kohm Aleph input impedence would suggest ( rule of thumb : Amp Input Impedence should be At Least 10 Times as large as the Preamp Output Impedence ) . In the case of the Aleph amps, this would mean an output impedence of 1000 ohms or less ( most tube pre's are higher than 1000 ohms output impedence ) . From the Oct. Stereophile Review of the Rogue 66 ( would the 99 be similar ? ) JA measured an Output impedence of beteen 600 ohms and 3000 ohms ,...but he does go on to say 10 kohm amps should be OK . I don't have a real technical understanding of *why* this 10 to 1 ratio is significant . But , I have heard hampered sonics from pre's with this ratio violated and there were sonic consequences ( rolled at both the top and bottom, less depth, thiner/smaller sound ) ,...I've heard the Aleph amps be stunning in the right context ( with an Aleph P pre ) and I've heard them in other situations where all their weakness's were on display ( too polite mid-bass, lack dynamic kick and headroom ) without any of the amps usual strengths ( of which there are many ) . Also,...I'm guessing on the input impedence of the Aleph 3,..I know many of the Aleph amps are 10 kohms, but the Aleph 3 might not be the same ( see Pass site , probably the info is posted there ) . The Rogue 99 designer claimed 280 ohms ( or something like that ) Output impedence ? Does he mean all the way from 10 k to 20,000 khz ? This would mean it's a lot different than the 66 JA measured for Stereophile ... What ever you do ( and I'd experiment a lot ...could all work ) I agree with your notion to keep the 99 . The pre is the one component you have to interact with the most and it's important that you like *using* it . Clearly this is the case with the 99 ,..and from the many , many happy users posting all over the place , I'd have to believe it's capable of making serious Music and Enjoyment . Regards, Martin