AMPS- class A, AB or D?

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  • swayback
    Member
    • Feb 2010
    • 38

    AMPS- class A, AB or D?

    Any preferences on the different classes?
    Has anyone done head-to-head comparisons?
    Benefits and drawbacks?
    I love this forum and have learned so much. Thanks everyone for their respective inputs.
  • omar7631
    Member
    • Sep 2009
    • 39

    #2
    I had a pair of rotel class d rb-1091 500 watts x1 with a pair of b&w 683 and they sounded awesome. I had to sell them for financial reasons. I then got an emotiva xpa-5 and they were not louder but I noticed the xpa-5 would have a longer deeper bass tone. It also made them jump more. just my thoughts.
    B&W 804s
    B&W htm3s
    B&W dm601 s3
    Outlaw lfm-1 EX x 2
    Denon 2808ci
    Emotiva XPA-5
    Emotiva XPA-2
    Sony PS3

    Comment

    • brunsje
      Junior Member
      • Jan 2009
      • 21

      #3
      Class A vs Class A/B Questions

      This is a great thread.

      I am ignorant of the differences also.

      Krell is the only Pure Class A that I am aware, also very expensive.

      It appears most amps are Class A/B, shifting at 5 to 15 watts.

      There are some new designs in Class D that reviewers are stating sound terrific, AR and CI.

      Is Class A the way to nirvana?

      Thanks, JohnnyB

      Comment

      • wettou
        Ultra Senior Member
        • May 2006
        • 3389

        #4
        Originally posted by brunsje
        This is a great thread.

        I am ignorant of the differences also.

        Krell is the only Pure Class A that I am aware, also very expensive.

        It appears most amps are Class A/B, shifting at 5 to 15 watts. There are some new designs in Class D that reviewers are stating sound terrific, AR and CI. Is Class A the way to nirvana? Thanks, JohnnyB
        If you can afford Class A go for it Pass Labs has amazing Class A amps. Get ready to shell the green and get warm :B



        Here is a great article on the benefit of Class A



        Electrocompaniet as well has Class A
        Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

        Comment

        • jbreezy5
          Member
          • May 2009
          • 59

          #5
          Second the vote for Pass Labs. If you can't go for class A, their A/B amps are great also, and more affordable on the used market.

          Class A amps run hot (b/c of this they are either very large with heatsinks, or very low power); class A/B amps run warm; and class D run cool.

          Sonically, Class A is supposed to be the best b/c there is no crossover distortion from one operating class (A) to another (B). I think class D has a very clean sound with an emphasis on transients, but less harmonic follow-through with trailing sounds; I also detect some high-frequency harshness with class D; they are also often praised for a sense of immediacy. Class D also has a smaller bandwidth (frequency response) due to design limitations.

          Although it is subjective, some people prefer wide-bandwidth amps (typically class A or A/B); they are sometimes perceived as producing better soundstaging and imaging characteristics, although humans technically can only hear up to 20kHz. My preference is for class A/B because it is more economical than class A, and sounds more full than class D (to echo what Omar said).

          As for the different operating classes, amps by different manufacturers still sound dissimilar. For example, Krell class A doesn't sound like Pass Labs class A. Hope this helps.

          -JBreezy-

          Comment

          • audioqueso
            Super Senior Member
            • Nov 2004
            • 1930

            #6
            Originally posted by swayback
            Any preferences on the different classes?
            Has anyone done head-to-head comparisons?
            Benefits and drawbacks?
            I love this forum and have learned so much. Thanks everyone for their respective inputs.
            Last year I did a comparison of a McIntosh amp vs Nuforce's class D amp. In the end I favored the McIntosh, but to be honest, it's really subjective and a matter of personal taste.
            B&W 804S/Velodyne SPL-1000R/Anthem MRX720

            Comment

            • HDBLU
              Senior Member
              • Jul 2008
              • 311

              #7
              I would love Class A like the Musical Fidelity AMS35i but I don't have the money so I bought the M6i from Musical Fidelity Class A-B and love the sound quality truly amazing stuff. As you know Class A-B a part of time you are listing to Class A because it over laps the two sine wave when listening to Class A-B. Also I know Musical Fidelity are true Pure Class A amplifiers.
              2ch Setup
              Krix Neupohonix
              Musical Fidelity M6i
              Musical Fidelity M6CDP
              Denon DCD-1510 SACD Player

              Cables I Use
              MIT

              Comment

              • theblue
                Senior Member
                • Dec 2009
                • 116

                #8
                I would be most interested in hearing from people who have found cases where they overall preferred class D to class A without money or value being a factor.
                Marantz SR5002 (music fed by apple airport express via optical)
                rotel RB-985 THX (4 channels bipowering fronts, 1 for the center)
                B&W - 683, CDM-CNT, CDS3 (sides), DM601 (rears)
                a combo of haveflex and audioquest cables.

                Comment

                • WelshOne
                  Senior Member
                  • Jan 2009
                  • 117

                  #9
                  I prefer my Rotel 1575 to my previous Nad 218THX 2x225 Class AB, and more recently an Audionet IV Class AB which I had on loan for a few weeks.

                  In both cases the class D sounded smoother. The above amps sounded hard and edgy, but the differences were very small.

                  Never tried any others at home in my own system..........but I am coming to the opinion after many many demos of uber high end gear that amps sound more alike than different, obviously more so when presented with a load they are comfortable to drive........(ducks for cover) :a>

                  In fact, I am questioning the whole concept of spending silly money any more on components, as everything to my ears these days just sounds a bit different, rather that exquisitely better. Recent demo's of high end electrocompaniet, Nemo's etc etc, on some Spendor and Sonus faber, ended up preferring my modest rotel pre/power class d on the 803D's.....maybe that was a testement to the speakers??

                  Maybe im going deaf, or, common sense is getting the better of me, or both?

                  Comment

                  • 1oldguy
                    Senior Member
                    • Dec 2008
                    • 459

                    #10
                    Originally posted by WelshOne
                    I prefer my Rotel 1575 to my previous Nad 218THX 2x225 Class AB, and more recently an Audionet IV Class AB which I had on loan for a few weeks.

                    In both cases the class D sounded smoother. The above amps sounded hard and edgy, but the differences were very small.

                    Never tried any others at home in my own system..........but I am coming to the opinion after many many demos of uber high end gear that amps sound more alike than different, obviously more so when presented with a load they are comfortable to drive........(ducks for cover) :a>

                    In fact, I am questioning the whole concept of spending silly money any more on components, as everything to my ears these days just sounds a bit different, rather that exquisitely better. Recent demo's of high end electrocompaniet, Nemo's etc etc, on some Spendor and Sonus faber, ended up preferring my modest rotel pre/power class d on the 803D's.....maybe that was a testement to the speakers??

                    Maybe im going deaf, or, common sense is getting the better of me, or both?

                    I hope Rotel gets their HDMI sorted out.I would get the same 1575 in a heartbeat if it only worked as intended.
                    A Man should never Gamble more than he can stand to loose.

                    Comment

                    • wettou
                      Ultra Senior Member
                      • May 2006
                      • 3389

                      #11
                      I can reproduce the sound of very high end system with my






                      AH-D7000

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                      Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                      Comment

                      • Randell
                        Junior Member
                        • Feb 2010
                        • 16

                        #12
                        I'm hearing a lot of good things about Rotel's RB-1572 (class D) too.. As well as Wyred 4 Sound ST-500 stereo amp. seems to be better than their previous class Ds.

                        So is it safe to say these new class Ds are more comparable / just as good as Class ABs?

                        Seems to me a cool running amp will probably have a longer lifespan too.
                        Yamaha HTR-6290B (130w x 7)
                        B&W 683s (front)
                        B&W HTM4S (center)
                        Pioneer bookshelfs (surrounds)
                        SVS PC12-Plus subwoofer (525w)

                        Comment

                        • style
                          Super Senior Member
                          • Feb 2006
                          • 1562

                          #13
                          Hi,

                          the very Pure Class A can be "hard" to listen....Question for what I need
                          this "quality?" not for listen "Madonna"!!!
                          with the great jazz (M.Devis, Mozart, very classic music, a guitar very special..,) PassLabs combo -> XP10 & XA30 (or more, but the Acccuphase is sure at the level or better from the pass!!!!

                          For the movie is a shi**, really money wasted!!!

                          in the last time the D /Ice is always more "inside" the news HT receiver!
                          and is not bad! I had a 2xRotel Rb1092 and a 1091...of courfe the JeffRw. use the Ice and more expensive vs. Rotel... why? I dont know ops:

                          the AB used from Classe and more others is a ampli more big in dimension, more "hot sound",.. but the all the system make the final sound!! not the only power ampli.

                          Style

                          Comment

                          • Skyblue
                            Senior Member
                            • Jun 2009
                            • 504

                            #14
                            Wettou, what amplification do you use for your ah d7000?
                            B&W 800 Diamond, B&W805S, B&W DB1, Classe SSP 800, DIY Icepower ASX2 600W monos, Ayre QB9, JPlay.

                            Comment

                            • wettou
                              Ultra Senior Member
                              • May 2006
                              • 3389

                              #15
                              Originally posted by Skyblue
                              Wettou, what amplification do you use for your ah d7000?
                              None straight out of my SACD player
                              Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                              Comment

                              • Skyblue
                                Senior Member
                                • Jun 2009
                                • 504

                                #16
                                Originally posted by wettou
                                None straight out of my SACD player
                                I have the 5000 model, and they do sound better with a headamp (in this case a heed cancamp). However, as I have an ayre qb9 as source, its clearly the amp that is the weakest link, so I'm looking for alternatives.
                                B&W 800 Diamond, B&W805S, B&W DB1, Classe SSP 800, DIY Icepower ASX2 600W monos, Ayre QB9, JPlay.

                                Comment

                                • ssabripo
                                  Senior Member
                                  • Dec 2005
                                  • 336

                                  #17
                                  do yourself a favor and RUN.....dont walk, but RUN, to your nearest pass labs dealer, and audition either their XA series (class A), or their X series (class A/B)... they will leave you speechless.

                                  I'm gone from Krell, to parasound, to cinenova, and now from the X250 to a pair of X600 monoblocks, and believe me, I'm done! I've found the perfect amps for my 802s!

                                  yes, they are expensive, but they will probably be the last set of amps you will ever buy!
                                  My simple HT setup
                                  4π using LMS, anyone?

                                  Comment

                                  • AV-OCD
                                    Senior Member
                                    • Aug 2008
                                    • 568

                                    #18
                                    Originally posted by ssabripo
                                    do yourself a favor and RUN.....dont walk, but RUN, to your nearest pass labs dealer, and audition either their XA series (class A), or their X series (class A/B)... they will leave you speechless.

                                    I'm gone from Krell, to parasound, to cinenova, and now from the X250 to a pair of X600 monoblocks, and believe me, I'm done! I've found the perfect amps for my 802s!

                                    yes, they are expensive, but they will probably be the last set of amps you will ever buy!
                                    Do they make an AVR? :roll:

                                    Just kidding.

                                    Everyone I've ever known that has tried Pass has pretty much stuck with them, even a friend that goes through amps like it were his job.

                                    Comment

                                    • ssabripo
                                      Senior Member
                                      • Dec 2005
                                      • 336

                                      #19
                                      Originally posted by AV-OCD
                                      Do they make an AVR? :roll:

                                      Just kidding.
                                      no, but they make some of the best Preamps money can buy.... sufficeth to say that the X2.5 will be my 2channel preamp for at least the next decade
                                      My simple HT setup
                                      4π using LMS, anyone?

                                      Comment

                                      • wettou
                                        Ultra Senior Member
                                        • May 2006
                                        • 3389

                                        #20
                                        Originally posted by ssabripo
                                        do yourself a favor and RUN.....dont walk, but RUN, to your nearest pass labs dealer, and audition either their XA series (class A), or their X series (class A/B)... they will leave you speechless. I'm gone from Krell, to parasound, to cinenova, and now from the X250 to a pair of X600 monoblocks, and believe me, I'm done! I've found the perfect amps for my 802s!

                                        yes, they are expensive, but they will probably be the last set of amps you will ever buy!
                                        Interesting, I was looking at Pass Labs they are so expensive!!
                                        Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                                        Comment

                                        • bnieman
                                          Senior Member
                                          • Jun 2006
                                          • 202

                                          #21
                                          I prefer my Class D Rotel RMB-1085 over my old Class AB RMB-1075.

                                          On the other hand, I couldn't distinguish a difference between the RMB-1085 and RMB-1075's big brother Class AB RMB-1095 (that says worlds about the RMB-1085 ... less power, next to no heat, and a fraction of the size)

                                          Cheers
                                          Guide: Ripping DVD-Audio Discs (DVD-A) to FLAC in Windows

                                          Comment

                                          • wettou
                                            Ultra Senior Member
                                            • May 2006
                                            • 3389

                                            #22
                                            If money is no object Class A would work great :T
                                            Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                                            Comment

                                            • Randell
                                              Junior Member
                                              • Feb 2010
                                              • 16

                                              #23
                                              Which one would be better though for the money.. Say a used McIntosh MC 202 (200wpc) could be had at about the same price as a new Rotel 1572 (250wpc) or W4S ST-500 (250wpc).

                                              In other words, would those older class A/B amps beat the newer and cheaper class Ds of similar specs?
                                              Yamaha HTR-6290B (130w x 7)
                                              B&W 683s (front)
                                              B&W HTM4S (center)
                                              Pioneer bookshelfs (surrounds)
                                              SVS PC12-Plus subwoofer (525w)

                                              Comment

                                              • wettou
                                                Ultra Senior Member
                                                • May 2006
                                                • 3389

                                                #24
                                                Originally posted by Randell
                                                Which one would be better though for the money.. Say a used McIntosh MC 202 (200wpc) could be had at about the same price as a new Rotel 1572 (250wpc) or W4S ST-500 (250wpc).

                                                In other words, would those older class A/B amps beat the newer and cheaper class Ds of similar specs?
                                                Class A/B are my favorite but that just me
                                                Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                                                Comment

                                                • aarsoe
                                                  Senior Member
                                                  • May 2004
                                                  • 795

                                                  #25
                                                  My personal opinion is that it all depends on so many factors that the overall question of running in class A, A/B, D, T or what ever is just one of them.

                                                  Hence the question of which class sound better becomes futile.

                                                  The only reason to look at how efficient a design is - is if you are thinking about the environment (global warming or your gear being placed in a cabinet with poor ventilation) or if legislation will band in-efficient designs.

                                                  Comment

                                                  • wettou
                                                    Ultra Senior Member
                                                    • May 2006
                                                    • 3389

                                                    #26
                                                    Originally posted by aarsoe
                                                    .... if legislation will band in-efficient designs.
                                                    Like where??
                                                    Farming looks mighty easy when your plow is a pencil, and you're a thousand miles from the corn field."Dwight D. Eisenhower

                                                    Comment

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