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  1. #1

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    Default Powering Polk Lsi

    I have an ADCOM GFA 7605 AMP with a ADCOM GTP 830 pre-pro with lsi 15's,lsi center and lsi fx surrounds.My amp is rated at 125 w per x 5.When I play cd's at my preferred volume level the amp is near it's limit at -10 and the sound is muddy,thin in the midrange and dull,loose in the bass.DVD audios sound great at -25 and any more volume is excessive.Is my amp not powerful enough for these speakers to sound best with cd,s,is my pre-pro not up to it or are both underperforming.Please be brutally honest on your opinions on how much power these speakers need and about ADCOM.

  2. #2

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    Default

    Hi RJ. Welcome to the forum.

    One thing you could do is get a sub and use the Adcom's preamp crossover to send all low bass signals below 60 - 80 hz to the sub and set your LSi 15s as well as the rest of your speakers to small. Calibrate your speakers using a decibel meter and the test tone or a DVD made for speaker calibration. This will free up some power on your Adcom amp and help the midrange out.

    LSi are a 4 ohm load and not easy to drive. Adcom should be able to handle it although you may be the first person that I have read about using Adcom with LSi. A lot of us here with LSi use NAD, Rotel, B&K, or Outlaw for amplification.

    How many watts are necessary? I would say 175 - 200 watts at a 4 ohm load, especially since you like your music loud.

    Paul

  3. #3

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    RJ,
    Welcome to the forum, I agree with Paul, a sub would help relieve your Adcom. Also, have you calibrated your system? your pro has some kind of Dynamic range control, is it possible that you might have it engaged? I have an old Adcom 535II, and it's such a trooper, drive any load I throw its way.
    I am sorry, I have no opinion on the matter. I am sure you do. So, don't mind me, I just want to talk audio and pie.

  4. #4

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    Default POWERING POLKS

    Thanks for the suggestions and the advice.I forgot to mention in my original post that I am using a powered svs sub and I have no concerns with the bass on my system on the whole.My main concern is the mid range sound quality.I believe my pre-pro's dynamic range only functions with dvd's and not with cd's but I will check.Iwill also set my speakers to small.Any thoughts about my using a HK AVR 430 as a pre-pro and at the same time use the HK to bi-amp the upper range on my lsi15's?One last question,is my ADCOM 5 channel amp bridgeable so that I could use 4 channels to power mains,one for my center and use HK receiver to power rear surrounds?Thanks in advance for any advice or ideas.I know these speakers are capable of amazing sound and I am glad I discovered this forum to find out how to get them to reach their potential.

  5. #5

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    RJ,

    Does you Adcom's Distortion LED come on when you are having this difficulty in the midrange? If so, I believe you are just asking the amp to do to much for you. I would swap the line level inputs / outputs for the main speakers just to check out the other amps in the adcom (move interconnects and speaker wire around just to make sure the amp channels are okay). Set all of your speakers to small and calibrate using a sound meter. Set your crossover at 80 hz.

    I would not bridge your amps the way you are describing with a receivers amps mixed in there. Usually people biamp with the same type of amp with the same type of watts to keep everything in balance.

    I looked up the specs on your amp and it is 175 watts X 5 into 4 ohms. Something is fishy though if it is okay for DVD Audio to you but doesn't sound good for listening to cds. What cd player do you have?

    P.

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