My humble review of the Benchmark AHB2 and LH4

Discussion in 'Audio Hardware' started by Tone?, Jun 1, 2021.

  1. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    FYI per the Stereophile measurements of the AHB2 the gain per sensitivity setting is kind of counter intuitive and as follows:

    setting
    22dbu = 9.2db gain
    14.2dbu = 17db gain
    8.2dbu = 22.9 db gain.
    basically the lowest sensitivity setting = highest gain
     
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  2. Helom

    Helom Forum member

    Location:
    U.S.

    All you have to remember is that the higher the switch position, the higher the gain.
     
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  3. elvisizer

    elvisizer Forum Resident

    Location:
    San Jose
    The higher the level of the incoming signal the less gain you need, seems pretty straightforward?
    Those aren’t really sensitivity settings they’re the incoming line level.
     
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  4. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco

    It will be super easy to tell once you connect everything anyways.
    don’t worry.
    The volume will go up noticeably.
     
  5. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    And 6dB more if you bridge to mono.
     
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  6. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco

    Kal, you have 3 AHB2’s running correct?

    which amps did you choose the AHB2 over or had in the past which you preferred the AHB2 ?

    just curious as to how good of an amp do you consider it to be.
     
  7. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    Browse here: power amplifier rubinson site:www.stereophile.com
     
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  8. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco
  9. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    excellent point i did not catch the first time.
     
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  10. Bill Mac

    Bill Mac Forum Resident

    Location:
    USA
    Same here.
     
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  11. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    Something flakey about link management here. Try copy/past this into Google: : power amplifier rubinson site:www.stereophile.com
     
  12. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco
    all I see are reviews that you have done.
    Is that a link to one site which lists all the power amps you have reviewed?
     
  13. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
    equates to sensitivities for full output, 28.3 V
    9.75 V, gain 2.9x, 9.2 dB
    4 V, 7.1x, 17 dB
    2 V, 14.2x, 23 dB
    :D
     
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  14. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    Yes. That returns a list of all the amplifier reviews that I have done.
    I wish there was but, afaik, there is no way to do it.
     
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  15. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco

    Ah Ok. Got it now.

    so after all those amps you chose the AHB2 as your reference.

    Im assuming you don’t find the AHB2 flat or non-3 dimensional sounding ?


    Thanks
     
  16. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
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  17. Helom

    Helom Forum member

    Location:
    U.S.
    It’s washboard flat dude. Like original Nintendo flat. ;) :laugh:
     
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  18. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco
    lol
     
  19. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    I do not. Nor do I find it lush or liquid. It is transparent.
     
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  20. Tone?

    Tone? Forum Resident Thread Starter

    Location:
    San Francisco

    Did ya hear that @Helom !

    lmao!

    thanks Kal
    Don’t mind me and helom. We are goofs


    Yeah I find my AHB2 paired with the LA4 amazing and detailed.

    you run yours with a Preamp or the multichannel DAc you have?
     
  21. Slippers-on

    Slippers-on Forum Resident

    Location:
    St.Louis Mo.
    No…but guys these days call each other bros…lil bro…little bro, or bro all the time. You know what I mean, bro?
     
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  22. RZangpo2

    RZangpo2 Forum Know-It-All

    Location:
    New York
  23. RZangpo2

    RZangpo2 Forum Know-It-All

    Location:
    New York
    As I wrote above:
     
  24. Kal Rubinson

    Kal Rubinson Senior Member

    Location:
    NYC
    One of the multichannel DACs, atm.
     
  25. Ingenieur

    Ingenieur Just a dog looking for a home...

    Location:
    Back in PA
    the absolute SN is 3 dB lower since noise stays about the same but you double power (+3 dB)

    when you look at relative noise the stereo seems quieter. Not that you could hear either.

    full power
    Output noise voltage, A-weighted, inputs shorted
    -103 dBV, 7.1 uVrms, Stereo Mode
    -100 dBV, 9.8 uVrms, Mono Mode

    They say dBV can be used to estimate audible speaker noise:
    dBV + speaker sensitivity - 9 dB = SPL dB noise

    stereo, speaker 86 dB
    Audible noise = -103 + 86 - 9 = -26 dB SPL
    Hearing threshold is 0 dB for a youngster

    mono ~ -23 dB, so 3 'louder', but you can't hear it.
    The typical room ambient SPL is +30 dB, >50 dB below ambient room noise!

    ~ 1 W
    Output noise relative to 2.83 Vrms, A-weighted, inputs shorted
    -112 dB, Stereo Mode
    -109 dB, Mono Mode

    It is even lower at normal listening levels.
    Stereo -35 dB below threshold, - 65 dB SPL below room!
    Mono -32 and -62 dB SPL

    No matter how you slice it you are not hearing ANY noise from this amp, stereo or mono.
    Impressive
     
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