Aleph-3 Questions

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

David, Martin has owned many amps and equipment, and knows of what he speaks. Martin: I'm very glad to see that you can shed some light on this!...............I agree about the input and output impedance, and I believe that the Aleph series of power amplifiers have the lowest input impedance of any power amplifier that I've ever heard of (makes it a more difficult load for the preamp to drive it). (By contrast, the Model 88 power amp has a 100k ohm input impedance, the same as my Krell. This amount of input impedance is considered to be in the upper part of the "mid-range" of input impedances for amplifiers....20k ohms and below is considered low to very low....the little 2A3 tube amps I'm going to build have an input impedance of 200,000 ohms....I'll be racking my brain to figure out what cables work best with them, that's for sure. But they will be a tremendously easy load for the linestage/CD player to drive...Incidentally, my CD player has a specified output impedance of only 50 ohms for the RCA connection, so that's why I take offense when somebody says it can't drive a power amplifier directly!!! Not only does it, but it does so better than many linestages!) I'm sorry I didn't mention this might be a factor before, I should have been thinking about it. I guess I figured you had that part worked out already, since you had specifically wanted the Aleph 3 for quite a while. This will all work out, in any case...

Carl,I did have that part worked out.I did my home work.I talked with Rogue,Pass and my dealer to make sure the 99(came first) would mate well with an Aleph-3 should I ever actually get one.The mismatch idea has only come into play because of sedonds statements.Please read above about how I contacted Rogue about this.I am waitng for a reply from Pass also.