Need help with system setup - Mcintosh equipment

Discussion in 'Audio Hardware' started by Waylon9, Aug 9, 2018.

  1. Waylon9

    Waylon9 Well-Known Member Thread Starter

    Location:
    Lewisville, TX
    Okay, I am not an expert. Just need some thoughtful help. First I have
    infinity kappa 8 speakers,
    Mcintosh C28 preamp,
    Mcintosh mc-300 power amp,
    and two definitive technologies subs.
    I also have an older teac equalizer.

    I have turntables and reel tape decks too but I’m hoping they aren’t impacting this issue.

    I run my subs rca out of the preamp.
    I run my kappa 8s out of amp at 2 ohms.

    One complication is that I use an Audiocubics remote volume controller through which all sound is controlled other than subs (running directly out of preamp)

    So what is my problem? Probably my setup. Not sure. But I like my music really loud. I’ve been in a band for years so loud distortion free audio is what I want. Perhaps this is a simple issue, but my Mcintosh amp is constantly using the “power guard” feature I suppose because I run it so dang loud.

    Questions
    1 - do these infinity’s need a more powerful amp? In other words is it dangerous to continue to hit that “power guard” feature on MC-300?
    2 - does the Audio Cubics remote complicate my situation?
    3 - I know equalizers aren’t popular, but dang this EQ does wonders for the sound. Could it be the issue?

    Please ask any and all questions. I am not lucky to even have set this stuff up. I am a novice. Thanks!!!
     
  2. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    The power guard feature should not be engaging merely because of loud volume. Does it still happen if you run the amp directly off the preamp without any electronics in the chain?
     
  3. deadcoldfish

    deadcoldfish Forum Resident

    Location:
    Santa Rosa, CA
    Your speakers drop to a 2 ohm load at 90Hz, and this is more than likely the cause of the power guard protection on the MC-300. You'll need an amp that can handle that low impedance.
     
    McLover likes this.
  4. Waylon9

    Waylon9 Well-Known Member Thread Starter

    Location:
    Lewisville, TX
    Thanks for the question. It makes sense. Just hooked preamp to amp directly. At louder volumes still getting the power guard issue....I’m just plain confused.
     
  5. Waylon9

    Waylon9 Well-Known Member Thread Starter

    Location:
    Lewisville, TX
    I have thought about. This. Any suggestions?
     
  6. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    The MC-300 has 2, 4, and 8 ohm taps. Which are you currently using? (and try other ones, if that wasn't implicit :cool:)

    And no, you don't need another amp. If your speakers can't be driven by a 300 watt per channel McIntosh autoformer amp, throw them away and get speakers that aren't broken.
     
    Dennis0675 and McLover like this.
  7. Waylon9

    Waylon9 Well-Known Member Thread Starter

    Location:
    Lewisville, TX
    You have me a good laugh. I have thought forever that the amp should be able to handle this. I have it at 2 ohms.
     
  8. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    The internet says Infinity rated those between 4 and 8 ohms. Just because they can dip to 2 ohms doesn't necessarily mean you should run them off the 2 ohm tap. I'd try the others taps, probably starting with 8.
     
  9. deadcoldfish

    deadcoldfish Forum Resident

    Location:
    Santa Rosa, CA
    it's a known issue, as the 2 ohm dip occurs at 90Hz.

    Infinity Kappa 8's | Audiogon Discussion Forum

    Having owned Infinity since the early 70's, and Kappa 9's were here for a while I can tell you what you need to do.
    You won't like it but you need to step up to an amp capable of handling a 2 ohm load, one with high current capability. Me, I like levinson, on my current pair of RS1b's, I'm using a vintage ML3 levinson on the woofers, no problem.

    I would suggest Classe, older Krell product, Levinson 333 or 336. Do not even think of anything under 200W/channel.

    Step up to the plate and give the Kappas what they want. Until you do, you will continue to have problems.
     
  10. McLover

    McLover Forum Resident

    Location:
    East TN
    Yes, this amplifier can drive near anything out there. It isn't the problem. Speakers might have a technical issue. Try a lower tap if you haven't impedance wise.
     
  11. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    It is possible that one of your components is creating a DC offset - constant current that uses up your amp power or trips its protection prematurely.

    You have RCAs going to your subwoofer. Does your model subwoofer also have an RCA output for the main speakers, including a bass-cutting crossover? I would put a subwoofer in the RCA loop between the preamp and power amplifier, to remove subwoofer frequencies from your main speakers. The volume control unit can also go before the sub and would control all audio.
     
  12. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    I dunno, out of curiosity I read up on those speakers and the stories of people blowing up amps trying to drive them. I'm sure they sound like a chorus of angels, but that still might not be worth all the hassle involved.
     
  13. McLover

    McLover Forum Resident

    Location:
    East TN
    Try the 2 ohm setting if you didn't. Takes a lot to blow up a McIntosh amplifier with AutoFormers. Not your average amp, or built or engineered like nobody else did. McIntosh is tough, conservatively built, and engineered. And can take shaker tables, tough loads all day long.
     
  14. CraigVC

    CraigVC Forum Resident

    Location:
    Portland, OR
    Weird. This thread has several who claim that a McIntosh amp with these speakers is the cure for blowing up other amps (and/or the speakers' drivers) with them:

    Infinity Kappa 8's, who has them?
     
    McLover likes this.

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