AVR-3806 & 4 ohms 8 ohms mixed speakers

PoppaDog
PoppaDog Posts: 8
New to the site and I'm using this forum as a great resource as I believe and entry level Home Theater enthusiast but I think its starting to get a little over my head with a few issues. Any help or suggestions would be greatly appreciated.
After all of my reading and research I and still questioning what my problem is.
I am running into the problem that I mixed the ohms ratio because all of my other speakers are 8 ohm and the new speakers I purchased are 4 ohm. How much of an issue will this cause with the AV I have?
Just purchased the Denon AVR-3806 with newly purchase LSi7's for my surround (with free PS10/Bonus!!) but I am reading that my Denon has the following specs:
-Power Output; Watts Per Channel 120 All Channels Rated @ 0.05 THD
-Equal Power Amplifiers 7 ch Low Impedance Drive Capability
- High-Current/Discrete Amplifiers
My question being is since the AV that I have has the equal power amplifiers for each channel would I have to preamp out and get an amplifier or could I change each internal amplifier for each individual ohm rating? Anyone have this style AV that could help with my setup??
Post edited by PoppaDog on

Comments

  • John K.
    John K. Posts: 822
    edited December 2006
    PD, welcome. There's no need to be concerned about using speakers that have different impedance ratings; they don't have to be "matched". Back in the tube amplifier era(and some examples exist today)equipment often had output transformers with different taps(e.g. 4, 8, 16 ohms)to match the impedance to the impedance of the speakers used and more efficiently transfer the power. Modern solid-state amplifiers don't use output transformers and by design have very low output impedance on the order of 0.1 ohm or less, which is suitable for speakers of the usual impedances. The regular 8 ohm setting on the receiver should be used even if some of the speakers are rated at 4 ohms, despite any suggestions to the contrary in owners manuals(which are there because of legal requirements arising out of FTC regulations and UL certification). Using a 4 ohm switch or menu setting(if available) simply reduces the maximum voltage that the receiver can put out, and therefore the maximum current and power(Ohm's Law)available.

    Your 3806 is a quite powerful amplifier and should be more than enough for your needs. Although they haven't lab tested the 3806, note the results for the 3805, which is substantially identical with respect to power, in the Hometheater Magazine test . Relax and enjoy your setup.
  • jcaut
    jcaut Posts: 1,849
    edited December 2006
    Are you actually having a problem, meaning something's not working right? Or do you just have a concern that something you're doing might cause a problem? From reading the original post, I think that there is a concern that mixing the 8 Ohm and 4 Ohm speakers may cause a problem.

    So, if I'm understanding this concern correctly, my answer is that I think it will be okay. Here's why: The LSi7's, while rated 4 Ohms, are not particularly hard to drive, and the Denon is a pretty good receiver. Now if you had a full set of LSi's, or had some of the larger LSi's , it might be time to start looking for an amp. I wonder how much they've actually changed the internal amps vs. the old 3801 like I have- Mine gets pretty hot driving an all RTi theater setup.

    What are your other speakers, and at what position will the LSi7's be used (fronts, surrounds, etc.)?

    Jason
  • dorokusai
    dorokusai Posts: 25,577
    edited December 2006
    I have a friend running an older Denon 3805 AVR with 5 LSi9's...no problems. YMMV.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
  • MSALLA
    MSALLA Posts: 1,602
    edited December 2006
    I'm running Lsi7's with Monitor 30's in the back off my receiver with no problems. My wattage is about the same (130 per channel/ 10 watts is nothing) and haven't had any heat issues or protection mode.
    Michael


    Samsung 50" HD DLP
    Yamaha RX-V2500
    (2) Outlaw 200
    Adcom GFA 555
    Sony BDP300
    Denon 2900 DVD
    Lsi9's mains
    Lsi7's rear
    Lsic center
    12.1 SVS driver in 4.53 cuft. tube
    Harmony 880
  • PoppaDog
    PoppaDog Posts: 8
    edited December 2006
    Thank you all for the input. Actually everything is working fine and I love it but after reading throughout the website my main consern was heat or protection mode popping on and it made me wonder if I made a mistake in getting the new speakers or if I'll need more power to push the speakers I just got.
    jcat - M70's for the Mains and I'm using the LSi7's for the surround L/R
    Thanks john for the link Great Resource!
  • cfrizz
    cfrizz Posts: 13,415
    edited December 2006
    Welcome PoppaDog!

    You can never have too much power! And since your 3806 does have preouts you now have a future upgrade path when you get a bad case of upgraditis.

    If you think your system sounds good now, just wait until you add say a 200wpc 5 channel amplifier to take the strain off of your receiver.

    To put it mildly...YOU AIN'T HEARD NOTHIN YET!!!:D
    Marantz AV-7705 PrePro, Classé 5 channel 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony XBR-49X800E TV, Polk S60 Main Speakers, Polk ES30 Center Channel, Polk S15 Surround Speakers SVS SB12-NSD x2
  • swchma
    swchma Posts: 49
    edited December 2006
    Dude, as the chick is saying, don't feel complete untill you get at least 200 amp at 4 ohm. until then, enjoy your great setup
  • reeltrouble1
    reeltrouble1 Posts: 9,312
    edited December 2006
    preparation H applied.

    RT1
  • PoppaDog
    PoppaDog Posts: 8
    edited December 2006
    Any good suggestions where I could start looking for a good 200wpc 5 channel amplifier?
  • cfrizz
    cfrizz Posts: 13,415
    edited December 2006
    Outlaw Audio for new, Audiogon if you don't mind going used. Look for Rotel, Parasound, B & K, etc. The list is endless.
    Marantz AV-7705 PrePro, Classé 5 channel 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony XBR-49X800E TV, Polk S60 Main Speakers, Polk ES30 Center Channel, Polk S15 Surround Speakers SVS SB12-NSD x2
  • PoppaDog
    PoppaDog Posts: 8
    edited December 2006
    Well thats a start! Thanks Everyone and have a great and Happy Holiday Season!:)
  • TroyD
    TroyD Posts: 13,077
    edited December 2006
    swchma wrote:
    Dude, as the chick is saying, don't feel complete untill you get at least 200 amp at 4 ohm. until then, enjoy your great setup

    Another post spoken like a complete jackass. Chick? Great manners.

    Go bother some other forum, will you?

    The receiver is fine w/your speaks. As with most things though, better amplification will yield better sound. However, you aren't in danger of damaging anything under normal usage.

    Welcome aboard.

    BDT
    I plan for the future. - F1Nut
  • amulford
    amulford Posts: 5,020
    edited December 2006
    I'm just lovin' this a$$hole...

    Your fine, with normal use. An amp would help out for dynamics and body, but Rome wasn't built in a day...
  • MSALLA
    MSALLA Posts: 1,602
    edited December 2006
    swchma wrote:
    Dude, as the chick is saying, don't feel complete untill you get at least 200 amp at 4 ohm. until then, enjoy your great setup

    Put the bong down big guy. Normal speech will come back. Don't worry.
    Michael


    Samsung 50" HD DLP
    Yamaha RX-V2500
    (2) Outlaw 200
    Adcom GFA 555
    Sony BDP300
    Denon 2900 DVD
    Lsi9's mains
    Lsi7's rear
    Lsic center
    12.1 SVS driver in 4.53 cuft. tube
    Harmony 880
  • cfrizz
    cfrizz Posts: 13,415
    edited December 2006
    Actually that would be 200wpc at 8ohm you neanderthal!:p But until then he should enjoy his system.

    swchma wrote:
    Dude, as the chick is saying, don't feel complete untill you get at least 200 amp at 4 ohm. until then, enjoy your great setup
    Marantz AV-7705 PrePro, Classé 5 channel 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony XBR-49X800E TV, Polk S60 Main Speakers, Polk ES30 Center Channel, Polk S15 Surround Speakers SVS SB12-NSD x2
  • reeltrouble1
    reeltrouble1 Posts: 9,312
    edited December 2006
    good one Frizz!!!!!!!!!!!!

    RT1