Marantz MM9000 4-ohm stable?

Discussion in 'AV Receivers' started by Christian B, Oct 13, 2003.

  1. Christian B

    Christian B Agent

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    Looking to run one of these to some Polk LSis but want to make sure it's 4-ohm stable before I purchase one. If it is, any idea how many watts it makes at 4-ohms? THANKS! I was also considering making a dual-fan using heavy duty computer case fans to cool the amp if I will be running it at 4-ohms. Think this will help? THANKS!
     
  2. John Garcia

    John Garcia Executive Producer

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    Which LSis? Marantz recommends 6 Ohm minimum for the 9000, as well as my 8300. All the recent monos (6100, 700, 500) and my PM7000 are rated for 4 Ohm operation. I asked this a while ago about the 8300, and got no real answers, but I am running 4 Ohm mains right now, and it does not appear to be a problem, but all 4 Ohm speakers might push the 9000 a bit too hard. My mains are very similar to LSi9s, though mine are higher efficiency.

    Fans are not going to make a dramatic difference.
     
  3. Christian B

    Christian B Agent

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    When I posted this I was entertaining getting (4) LSi9s and (1) LSiC, but now I'm leaning toward (2) LSi15s BI-AMPED (which would be 2x8ohms) and running the center channel off the last channel, at 4-ohms. The room I'm putting it in, in my townhouse doesn't allow me to easily have surrounds so I will have to do without surrounds I'm thinking for 2 years when my fiance and I build our house. If I really want to listen to a movie with a superb surround soundtrack I have 2 Polk RTi600s I can place just for the time we listen to the movie and run them off the rear channels of the receiver.

    Would you recommend the Marantz MM9000 at $699 brand new with shipping from an authorized dealer or do you think there's something better out there for the money?

    THANKS!
     
  4. Aaron Gilbert

    Aaron Gilbert Second Unit

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    6 ohm minimum? That sounds like a receiver specification, not a high powered THX ULtra separate amplifier!

    I happen to own a THX Ultra amplifier (130 x 2 at 8 ohms), and the manufacturer told me that THX's spec. at the time required said amp to be stable into two ohms loads in stereo. Maybe THX has lessened up over the years (I bought the amp over five years ago), and no doubt requirements for THX multi-channel amplifiers are a bit less strict.

    Nevertheless, there are plenty of receivers which will handle five four ohm speakers. I've always been of the opinion that one of the benefits of using a separate amplifier in the first place is being able to run low impedance/complex load speakers. If you can't do that, why even bother?

    Incidentally, I'm running four ohm speakers right now on my Kenwood VR-5090, and it's only THX select. Interestingly, I note that my receiver is exactly four pounds lighter than the MM9000.

    Cheers,

    Aaron Gilbert
     
  5. Chuck Kent

    Chuck Kent Supporting Actor

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    THX Ultra (which is the original THX plus a few more surround-based specs) amps are supposed to be stable for continuous wattage output into impedence loads as low as 3.2 ohms.

    THX has never been very forthcoming about specifics on specs (why, I don't know.) But the impedence measurement was one they released many years ago.
     
  6. John Garcia

    John Garcia Executive Producer

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    Just because it says 6 Ohm speakers does not mean it is not stable to 3.2 Ohms...just that you wouldn't hook a 3.2 Ohm speaker to it and get good results. My receiver is also THX (not ultra), says 6 Ohm minimum, and I am running 4 Ohm speakers right now (about 2 months). THX also recommends using THX cert speakers, which are designed to be used with an 80Hz x-over.

    I think that price is pretty good. I recommended to to a friend and I've even been considering it myself. [​IMG] It looks like it's been discontinued, thus the price drop.
     
  7. Yohan Pamudji

    Yohan Pamudji Second Unit

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    I think that's a good price. But! I'm not familiar with the speakers you're getting, but I've hooked up an MM9000 to a pair of Paradigm Studio 80s and made the MM9000 clip at loud but not unbearable levels. As a point of reference, I usually listen to movies at 20-15 dB below reference levels. 10 dB below reference is usually too loud which should help show you what I consider "unbearable". This along with the fact that the Studio 80s are pretty efficient speakers says to me that the MM9000 is not a strong performer. What is it rated at, 150Wpc? I know I wasn't pushing that much when I tested them, but the clip light came on.

    At moderate levels it is a nice performer, but push it a bit and all bets are off.
     
  8. John Garcia

    John Garcia Executive Producer

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    I think it would work OK with the LSi9s at normal listening levels, but I'd probably look for something else if you went with the 15s. My mains are 91.5dB efficient, which is a fair difference compared to the 9s at 88dB (which suggests they will like a lot of power).

    MAN, the new monoblocks look evil!! They are definitely 4Ohm stable - 600W @ 4Ohms... [​IMG]
     
  9. Christian B

    Christian B Agent

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    A guy I've spoken to a few times is running 5 LSi9s off an HK AVR7200 and says he's never had the amp clip or turn off. Says it does run a bit hot at times but it can handle the load the LSi9s give it. I'm sure the Marantz is built better than the 7200's amplifier structure. The problem is I'm working with a VERY tight budget. My fiance is ready to kill me for getting ready to spend $1000-$1300 on the Polks and she doesn't even know about the receiver and amplifier yet. Can you guys recommend any other amp to drive these speakers that won't make her leave me? [​IMG] I've checked Audiogon for the last 3 weeks and haven't seen a single amplifier on there in my price range, along with Ebay.

    THANKS GUYS!
     
  10. JackS

    JackS Supporting Actor

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    Christian- I think someone has already mentioned it but I would like to suggest that you buy a two channel amp now, the rest can be purchased at another time. Small steps are often better than trying to aquire everything at once. This solution is also more fun since you will now be looking for deals which come along several times a year. Not only will this solve your immediate need for power, it can save you money and also prevent you from making a purchase you might regret. Consider my reasoning.
     
  11. Christian B

    Christian B Agent

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    Thanks Jack. Can you forward me to any good 2-channel amps that are reasonably priced? If they're near the $699 price of the Marantz MM9000 I might as well just get that one and bi-amp my fronts and run the center off the remaining channel. That would make sense to me. But of course, I'm all ears to suggestions!

    THANKS!
     
  12. JackS

    JackS Supporting Actor

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    Amplifiers are the one component that should last your liftime and possibly your childrens. For this reason, used amps are really the bargain. I would accept any well regarded amp that is reasonably powered and priced right. The amps that I'm familiar with are Norh,Aragon, SAE and Carver. All these amps served me well and a couple of them still are. If you want to buy new, I'd search the usual sites such as Audiogon, Audio Advisor, Ebay etc. The Outlaw monoblocks may also be a consideration. Mid priced amps such as Parasound, Rotel, ATI and others are all well regarded around here and one of these used could really be a nice buy. If you look around and are not too brand specific, I'm confident you'll find a very nice amp.
     

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