2 ch vs. 6.1

Discussion in 'Beginners, General Questions' started by steve___t, Mar 16, 2004.

  1. steve___t

    steve___t Auditioning

    Joined:
    Mar 16, 2004
    Messages:
    8
    Likes Received:
    0
    hi,

    i am looking at buying my first stereo......i really dont watch very many movies but i am ALWAYS playing cds. is just a 2 ch stereo reciever just as good as the recievers with like 6.1, and dolby decoders ect..... (do any of those decoders effect music or are they just for movies?) what should i look for in a reciever keeping in mind i only want it for music?

    what makes a quality reciever.....basically the only specification i know about is thd.....the reciever i am looking at has 100 watts a channel at @ .09 THD.....also as far as thd goes, while i am comparing various recievers some of them have added info such as @ X ohms, or @ 20hz to 20khz, what does this info mean?
     
  2. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    Hi Steve. Welcome to HTF!

    Modern AV recievers will usually support 2-channel music either from analog (L/R) inputs or optical/toslink.

    If you have more than 2 speakers, many of these recievers will apply Digital Signal Processing (DSP) tricks to route sounds to speakers never intended to carry them. It does create a fuller sound, but audiophiles dont like any alteration to the original intent. It's fine to buy a AV reciever as you can usually turn off the DSP effects and run it in straight 2-channel mode.

    On to your questions:


    Here is the trick: the power output from a amp (and the THD) varies by the frequency it is amplifying.

    Better reciever companies promise things like Power, THD across a large range of frequencies like 20-20,000 hz.

    Some cheap recievers will say things like "High Power" and the fine-print says "at 1000 hz". Watch for this and avoid these units.

    X ohms - Speakers have the same problem as amplifiers: they change their impedence with the frequency.

    Speakers usually say something like "8 ohms" or "6 ohms" - but a word is often left out: 8 ohms nominal

    In truth - an 8 ohm speaker changes it's impedence from about 3 to 30 ohms as the frequency changes from low to high.

    When you measure power from an amp most people use a 8 ohm speaker. But.. you can make your amp look more powerful if you use a 6 or even 4 ohm speaker.

    A 4 ohm speaker will draw twice the current of a 8 ohm speaker. And when you measure power - it is nearly twice the power with a 4 ohm speaker.

    So a reciever that claims "120 watts with 4 ohm speakers" will only provide about 60 watts with a 8 ohm speaker.

    So when you are looking at specs, be sure to look at:

    - The frequency range it promises to work under
    - The THD at the frequency range
    - The load that was used (8/6/4 ohms)

    One of my favorite companies is Yamaha and their web site usually lists power for each of 8/6/4 ohm loads.

    PS: One other thing I forgot to tell you. Look for text like "All Channels Driven".

    Some poor companies promise "100 watts of power (in stereo mode". This means for a 5-channel system, each speaker would only get about 40 watts.

    My old Yamaha 793 is a lowley 80 watts per channel home theater receiver, yet it made a dramatic difference over my old 120 watt-per-channel Fisher stereo. How can this be? Do the math:

    80 watts per channel - all channels driven means the reciever can produce 80 x 5 = 400 watts of power continous. It's a 400 watt power plant.

    When I play stereo music - there is lots of reserve power for the 2 channels. No - it cannot provide 200 watts to each speaker (there is a current-limit issue) but the reciever has extra capacity.

    Shopping Advice: stick with the name-brands such as Yamaha, Dennon and the newer Kenwoods. While there are some stand-out models among Sony, Pioneer and Harmon Kardon - some of the other models are not so good.

    Good Luck. And check out the reciever fourm for more detailed discussion of various amps and receivers.
     
  3. steve___t

    steve___t Auditioning

    Joined:
    Mar 16, 2004
    Messages:
    8
    Likes Received:
    0
    hey thanks for the help!!! the only thing that i am still a little confused on is if there is something "cheap" about a 2 ch reciever? for example if i had a stereo reciever with the same specs(as far as power,thd, and freq response) as an av reciver, would one sound better than the other (assuming using the av reciver in stereo mode)?All the decoders are strictly for surround sound mode right?

    thanks
     
  4. SethH

    SethH Cinematographer

    Joined:
    Dec 17, 2003
    Messages:
    2,867
    Likes Received:
    0
    As long as you are purchasing a good 2 channel receiver (meaning reputable brand and well reviewed model) you will be fine. One thing to consider since you do like music is if you will want to listen to SACD and/or DVD-A in the future. If so, it may be worth it to spring for a multi-channel receiver. If you have no interest in those formats then 2 channel is perfectly fine.
     
  5. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0

    Opps. Sorry - I did not mean to give that impression.

    Some poor-quality 5-channel reciever manufacturers make their units look more powerful by only driving 2 speakers and brag about the power. This is kind of like a car braging about 0-60 mph performance, but with fine print like "tested without passengers, fuel tank, body panels or interior compartment installed".
     
  6. steve___t

    steve___t Auditioning

    Joined:
    Mar 16, 2004
    Messages:
    8
    Likes Received:
    0
    hey guys thanks for the info. very helpful
     

Share This Page