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Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by Almonds, May 18, 2018.

  1. Almonds

    Almonds Active Member

    Messages:
    238
    I just found this sheet of paper from when I bought my KA-9100.

    I'm not sure how good or bad these numbers are. Can anyone help me decipher them?
    Thanks! Screen Shot 2018-05-18 at 8.05.33 AM.png Screen Shot 2018-05-18 at 8.06.46 AM.png
     

    Attached Files:

     

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  2. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    21,266
    Location:
    SE PA
    You won't hear the issues with those specs but it does not meet the <0.03% THD with a reading of 0.06x at all the 4 watt test points.

    You won't hear the distortion as the amp is producing full power of about 115 wpc which is comfortably above the spec of 90wpc but your results sheet does not specify if one or both channels were operating so you have a 90wpc amp that does a fine job and benches at 115. The distortion above the 0.03% here is irrelevant as you are above the power rating and as the power peaks the distortion skyrockets. This is before the skyrocket.

    A find sounding amp. What was the age of the unit when the tests were made?
     
  3. Almonds

    Almonds Active Member

    Messages:
    238
    The unit was tested February last year.

    Thanks for the info. I thought I was reading that right, that it wasn't to spec, but it sounds amazing to me. I'm just wondering if it would sound better if it were serviced.

    Right now I have a Kenwood Model 600 that's being serviced and brought back to factory specs. It's been going on 3 months though now :(
    When I get that back, I'm going to do a blind A/B/C test with the KA-9100, the Model 600 and my VTA ST-120. If I can't tell the difference reliably, or if I don't have a clear preference, then I'm going to stop searching for "the perfect amp"

    I'm starting to suspect that I can't tell the differences between amps, other than how loud they can go. And, I've found that my KA-3500 gets my speakers louder than I need. I'm starting to think I'm spending too much money on amps and not enough on speakers. (Which several AK'ers suggested at the beginning.)

    It's fun experimenting and learning though!

    I also have 4 rooms with vintage amps in them, so at least they're all getting good use!!
     
    Depecheduran likes this.
  4. rjsalvi

    rjsalvi Well-Known Member

    Messages:
    563
    Location:
    San Diego, CA
    The most salient point is that both channels appear to be very well balanced. Besides, loudspeakers have far more (linear and non-linear) distortions and frequency anomalies than an amp, so I doubt you'll hear any difference between what yours is spec'd at and what the factory says.
     
    Almonds likes this.
  5. Almonds

    Almonds Active Member

    Messages:
    238
    Thanks for the info guys.
    Is that unusual that my amp is putting out 115 watts when it's only rated at 90?
     
  6. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    21,266
    Location:
    SE PA
    No ever since 1974 FTC rule on how to spec power all amps generally exceed spec by 15-30% all day long. The test was so hard, 1 hour at the most demanding power level (1-3) full frequency and then have the amp had been rode hard it was tested for power.
     

     

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  7. Almonds

    Almonds Active Member

    Messages:
    238
    I'm sorry, what?
    can you say that again a little clearer for me? I didn't get that at all.
     
  8. rjsalvi

    rjsalvi Well-Known Member

    Messages:
    563
    Location:
    San Diego, CA
  9. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    21,266
    Location:
    SE PA
    No

    Ever since the 1974 law about how power for a stereo amplifier must be specified, all amps generally exceed specification by 15-30%, they all have more power than the number in the spec sheets.

    The test required preconditioning, warming up the amp. This was done at 1/3 power the most heat producing power output for a typical solid state power unit back then. The preconditioning was done for 1 hour and the signal amplified was the full frequency response of the rated amp, generally 20Hz-20kHz.

    After the preconditioning the now hot amplifier was tested for power output.
    Specs must include:
    Power in watts RMS not peak or anything else.
    Number of channels driven, two for a stereo unit.
    The load into which the amplifier was driven, the 4 or 8 ohm speaker for example
    Frequency response of the power rating, usually 20-20k but some smaller amps were only rated down to 40Hz so they could have higher number.
    The total harmonic distortion limit of the spec.

    Because of the difficulty of the test many manufacturers built amps that when not beaten hard before a test would easily exceed the spec number. Additionally, if only one channel is tested the amp will do a bit or a good bit more power than spec.

    Your amp is typical.
     
    Roadrash and Almonds like this.
  10. oldboats

    oldboats Active Member

    Messages:
    111
    Location:
    Fargo, North Dakota
    That said - it is nothing to huff at. I am not sure why no one mentioned that the performance (while above specification) is also great at specification. What ever happened with your amplifier comparison?
     

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