All I wan't to know is the slew rate of my Amp but Rotel won't tell me

Discussion in 'Archived Threads 2001-2004' started by Kevin. W, Mar 7, 2002.

  1. Kevin. W

    Kevin. W Screenwriter

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    I decided to e-mail Rotel to get the inner specs of my Rotel RMB-1066 just so I could know what it takes to make the sound it produces. Plus if I ever get into discussions on specs, I'll have some info. Well, wouldn't you know Rotel doesn't give out the Slew Rate of their AMPs. Other manufacturers post this on their sites. Why would Rotel not?

    Kevin
     
  2. John Doran

    John Doran Screenwriter

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    kevin,

    while i'm not altogether surprised that rotel deosn't publish the slew-rates of their amplifiers on their web-site, i AM rather surprised that they refused to disclose them to you upon request. i asked for the slew-rate of a classe amp, and they gave it to me...

    the only thing i can think of is that it's a number that's unimpressively small when compared to the slew rates of other competitive amplifiers, and they don't want to give people the idea that their products are somehow deficient.

    the idea being, of course, that slew rates are fairly unimportant indicators of an amplifiers sonic abilities - but in a specification-focused market, where numbers can be paramount, rotel perhaps fears that their products will be negatively impacted by having figures that are smaller-than-the-other-guy's.

    but i don't know. maybe the guy you asked just didn't know it and didn't want to seem like he wasn't on the ball...

    and besides, i would imagine that the acoustic ipmact of slew-rates is as much debated as other issues in this forum.

    - jd
     
  3. John Sully

    John Sully Stunt Coordinator

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    Slew rate is pretty closely related to bandwidth. If the bandwidth extends out to 100K or so, you can be pretty sure that there are not going to be any slew rate related distortions. If it is more like 30K then slew rate is not going to be that impressive.

    In my experience, high bandwidth amps tend to sound better than narrower bandwidth amps. Whether the two factors are directly related or not is open to debate.
     
  4. chung

    chung Stunt Coordinator

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  5. Kevin. W

    Kevin. W Screenwriter

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  6. ClaudeD

    ClaudeD Extra

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    Maybe the guy on the phone didn't know, and maybe they think it isn't an important stat. It reminds me of Rolls Royce dealers who, in the past anyway, would answer the question: "How many horsepower does it have?" with "Sufficient."

    Claude
     
  7. Jeff Hipps

    Jeff Hipps Stunt Coordinator

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    Rise time is the reciprocal of the bandwidth. Slew rate is a different spec.

    As to why they wouldn't disclose it, I can only surmise that slew rate is not on the standard spec list that the factory supplies to the US marketing operation and that the US mraketing arm must make a special request to the factory to get it. In my experience, factories don't always respond to these requests.

    Also, IMO, slew rate rarely limits performance in today's amps.

    Jeff
     
  8. Sankar

    Sankar Second Unit

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    I agree. I think that with modern SS amps, the slew rate is unlikely to be a limiting factor. Many amps have slew rates in the vicinity of 1000, while I remember reading somewhere that anything over 100 is good enough to not be a bottleneck in handling transients.
    Having said that, I could not resist providing the following link: [​IMG] "All I want is the THD and frequency response, but Bose will not tell me"
     
  9. John Doran

    John Doran Screenwriter

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    Power Bandwidth : This is usually taken as the maximum frequency at which the amplifier can produce 1/2 of its rated output power (this is the -3dB frequency). A 100W amplifier that can produce 50W at 50kHz will be deemed as having a 50kHz power bandwidth.
    Slew Rate : Closely related to power bandwidth, the slew rate is the maximum rate of change (measured in Volts per microsecond) of the amplifier output. The higher the amplifier power, the higher the slew rate must be to obtain the same power bandwidth.
    check out this site.
    incidentally, i have never heard of an amplifier with a slew rate of 1000V/microsecond. ever.
    i'd be very interested in checking one out, though, if you could direct me to the right place.
    - jd
     
  10. Sankar

    Sankar Second Unit

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