3 ohm surround speakers vs. 8 ohm receiver

Discussion in 'Loudspeakers' started by Noach1, May 15, 2006.

  1. Noach1 Audiophyte

    Noach1
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    hola all! I am hoping for a relatively simple answer to the below question:

    Am I about to blow up my amp?

    I have a Sony STR-DG800 amp. It's rated for 100 watts per channel minimum RMS power with 8 ohm loads, both channels driven. It also lists:
    8 ohms 20Hz - 20kHz THD .09% 100W + 100W, 110W/ch
    8 ohms 1 kHz THD .07% 110W + 110W, 120W/ch
    8 ohms 20Hz - 20kHz THD 10% 125W + 125W, 150W/ch

    I don't pretend to entirely understand the above, but I figure it's just a range of power consumption.

    I also have five surround speakers from an old Sony DAV-C990 all-in-one surround sound system. The speakers are listed as 3 ohm impedance and appear identical. They each have four 2" woofers and one 1" balance dome tweeter. The amp from that system was rated at 75 watts minimum RMS, per channel with 3 ohm loads with both channels driven, from 150-10,000 Hz. It also lists:
    Stereo mode 100 W + 100 W (3 ohms at 1 kHz, THD 10 %)
    Surround mode Front: 100 W + 100 W
    Center*: 100 W
    Rear*: 100 W + 100 W (3 ohms at 1 kHz, THD 10 %)
    Subwoofer*: 100 W (3 ohms at 100 Hz, THD 10 %)

    OK. So here's my questions:

    1) If I hook up these five 3 ohm surround speakers to my 8 ohm stereo receiver in 5.1 mode (the subwoofer is powered and plugged in to the receiver's sub pre-out), am I going to blow up my receiver?

    2) If indeed the amp goes into Protect mode, have I permanently damaged it, or juts made it pout? (this has not happened yet)

    3) If add a pair of 8 ohm floorstanding speakers rated for 100W (let's say I hypothetically stumbled on a free pair of Sony SS-MF750H speakers) and change to a 7.1 setup, am I going to blow up my receiver even more? Or would that possibly improve things?

    If I blow the speakers, no problem, they have Outlived Their Usefulness. If I overheat the amp but it doesn't cause any permanent damage, no problem, I'll get better speakers. But if I permanently damage my new receiver, I will cry and self-recriminate unduly. Please help preserve my self-esteem. Lend me your wisdom.

    Or alternately, if these specs are insufficient to make an educated guess as to the stakes I'm playing for, let me know.

    Thanks all!

    -Noah

    Addendum: In a perfect world I would run the five surround speakers from the DAV-C990 system as the five surround speakers in a 7.1 system, with floorstanding speakers as the front left and right for a better sound when playing music. Yes, this whole thing is kludged together, but I'm pretty much totally out of money and would still like a surround setup that won't set off my smoke detector. I would think that two 8 ohm 200W 90dB-sensitivity front speakers would leech off the surround channels and even things out, but I have no idea what I'm doing and can't be trusted to plug in a toaster without permanent bodily injury.
  2. markw Audioholic Overlord

    markw
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    I don't think you should use those speakers. That three ohm rating scars me and I won't even venture a guess about the receiver recovering when, not if, it goes into the protect mode.

    But, good news. Odds are the speakers would survive...
  3. Noach1 Audiophyte

    Noach1
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    yeah, I have to push the system up to about 35 out of 70 on the volume knob before things are comfortably immersive (and I'm not hard of hearing, at least not yet).

    I don't really have room for floor-standing speakers, and I don't need a 7.1 channel system really, so a nice bookshelf pair, a center, and a pair of rear surrounds would do me. I have a Sony WM250 sub which already puts out more than enough bass for my taste - I'm in an apartment and I got neighbors. I really just want a nice warm widrange for music and sweet highs for those Matrix moments. I'm also poor, of course. So my price range for five speakers is $300 out ze door. I'm willing to return the sub which I bought for $90 if I'm going to get a better system total. Any suggestions? I can pick up the Sony SSMB350H / SSMB150H / SSCN550H trifecta for $212 but I'd rather stretch a little for a jump in quality.

    sigh.
    Last edited: May 16, 2006
  4. Buckeyefan 1 Audioholic Ninja

    Buckeyefan 1
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    That HTIB system isn't a horrible system - as far as HTIB's go. Why did you buy the Sony receiver? Did you not like the sound, or was it a logical upgrade to your love for HT? I see the new Sony's have HDMI connections.

    Your HTIB (nice sleek look next to a plasma):
    http://reviews.cnet.com/Sony_DAV_C990/4505-6740_7-9675236.html

    Your receiver:
    http://www.jr.com/JRProductPage.process?Product=4089717

    The only 5 speaker system worth anythign in that price range would be a BIC Venturi setup in my opinion. You can go with other brands, but you won't get the fullness out of bookshelves like the Venturis. You'll be slightly over $300, but it'll be worth every penny. Many members here have purchased these speakers and have little complaints for bang for buck value. You won't find 5 better speakers for a bit over $300 new.

    Get 4 of these:
    http://www.amazon.com/gp/product/B0...ref=sr_1_1/103-6110143-3539841?_encoding=UTF8

    And one of these:
    http://www.amazon.com/gp/product/B0...ref=sr_1_3/103-6110143-3539841?_encoding=UTF8
  5. Noach1 Audiophyte

    Noach1
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    yeah, I wasn't unhappy with the sound... I was unhappy that the DVD changer started swallowing DVDs without regurgitating, and then I was unhappy even more when the whole system developed a piercing high-pitched whine. The deck went bad. It was a refurb when I bought it, but... anyway.

    BIC, huh? Any other screamin' deals I should look for?
  6. Buckeyefan 1 Audioholic Ninja

    Buckeyefan 1
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    That stinks! Here's some cheapo bookshelves. These aren't up to the same standards as Polk's RTi series, but I'm sure they're fine for the investment. I highly doubt they have the same bass as the Venturi's. You'll still need to find a matching center - keep the center channel the same make/model line as the bookshelves for timbre matching.

    http://www.crutchfield.com/S-nt0VvsyjO9f/cgi-bin/prodview.asp?i=107R15
    Last edited: May 18, 2006

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