Am I missing something??? (Bi Amping my Mains isn't working..)

Discussion in 'Archived Threads 2001-2004' started by Brett DiMichele, Dec 9, 2002.

  1. Brett DiMichele

    Brett DiMichele Producer

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    Hey Folks...

    Okay maybe I am missing something so simple someone else
    can say "Well duh" and smack me upside the head because at
    this point I am confusled..

    Okay here is a description of the equipment..

    I am running an Onkyo TX-DS787 Receiver which is a THX Select
    Model and as such uses the THX 80Hz Crossover Frequency and
    is not user changeable.

    I am also running an Onkyo M-282 Power Amp

    My main speakers are Bi-Amp/Bi-Wireable AR9's which have
    a 10" Sub per cabinent on the LF side of the X-Over and
    Dual 5.25 Mids with a 1" Tweet on the HF side of the X-Over.

    I took a RCA Y-Apapter and plugged that into the single RCA
    SUB Out of the 787 and ran dual RCA Cables to the L and R
    Input of the M282 Amp and I set the Mains as "Small" and Sub
    as "Yes" in the bass management of the 787.

    Unless I am missing something, setting the mains as small
    and sub as yes should send any and all frequencies below the
    80Hz X-over to the M-282 amp and then into the 10" subs on
    my AR9's.. I am using the regular Front L/R output of the
    787 to power the High Frequency drivers.

    This should give me 200 watts RMS going to the speakers total, 100 to the LF and 100 to the HF.. 100 watts RMS
    should make those 10's SLAM.. But it's not.. Infact I wasn't
    getting any output at all through the sub out with the mains
    set to small.

    So I connected the L/R Front "Pre Out" to the input of the
    M-282 and I am getting bass now but it's not the kind of
    Bass a hundred watts should be...

    Something just ain't right here..
     
  2. James Bergeron

    James Bergeron Supporting Actor

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    I'm a tad bit confused.

    Are you "subs" in your speakers "subs" or are they just 10" drivers. IE are they powered subs?

    I'm wondering if your speakers are expecting line-level input for the subwoofer.

    If not and you are just trying to bi-wire them you are doing this wrong. You are not suppose to use the LFE output to drive your 10" driver in your speaker. Giving it more power is not going to give you better bass if the speaker is not made to do this. If your just trying to bi-amp with no sub then do this but set sub to no and use your L & R inputs to your external amp not the sub-line out.

    What you are doing should in theory work if your speaker is just a 10" driver but it is not proper and could be damaging.
     
  3. Brett DiMichele

    Brett DiMichele Producer

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    James,

    A "Sub Woofer" is nothing more than a terminology to
    describe a high excusrion low frequency driver AKA Woofer.

    These are not internaly powered 10's they are completely
    passive.

    Just think of it as a 10" Sub in a box with no internal
    power.. They are built into the lower section of the towers.

    When they were Bi Wired I got tons of bass and that was
    just from 100 watts per channel from the receiver. Now
    I get next to nothing and I am sending a dedicated 100 watts
    RMS to just the 10" driver and another 100 watts RMS to the
    mids and tweeters....

    Makes NO sense..

    Even if I use the Front L/R "pre out" I still get barely
    ANY bass...

    These things should be shaking the house on some of the
    music I have, they did when they were just Bi Wired to the
    Receiver...

    *Scratches Head*
     
  4. Rob Rodier

    Rob Rodier Supporting Actor

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    Sounds like you wired up everything right. I would look for something faulty. Start with anything extra that was not used in the biwire config (y-adapter?). Then Check the amp to make sure it does not have a low pass that is enaged/ etc. Last I would run a source signal strait into the amp (bypass the receiver). If you get your results, you will know something is up with the reciever.

    good luck

    -rob
     
  5. Craig Morris

    Craig Morris Stunt Coordinator

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    First, do not use the LFE out and the 80Hz crossover. Your speakers still have passive crossovers and doubling up on crossovers is a bad idea.

    Second, the output level of the separate Onkyo amp may not but the same as the receiver (explaining your apparent lack of bass). Biamping is usually achieved with two identical amps, or at least two amps with carefully matched sensitivities (or whatever they call it).
     
  6. James Bergeron

    James Bergeron Supporting Actor

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    Brett, I totally understand what a sub is, I was just trying to clarify since there are speakers that are powered towers.

    I do think it to be kind of odd that you would use your LFE output to power your towers, It's not what it is intended for. Why not just set your receiver to NO sub and bi-amp that way, this should result in better results, you will be powering your low frequency driver and your high frequency driver with separate amplifiers, which is what you were trying to accomplish. The only issue is if these amps differ in power everything will be off balance. But I'll assume the amp is matched for the receiver like my POA-5200 is for my denon 4800.
     
  7. Patrick Sun

    Patrick Sun Moderator
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    Why don't you set the speakers to large, sub to no, and then use the L/R outputs and feed that to the extra amp which is feeding the 10" drivers?

    The way you've hook it up, you've got a valley in the response from 80 Hz to wherever the midrange kicks in (depends on the crossover point between the 10" woofers and midrange).

    The LFE channel output is supposed to only send 125Hz and under to the subwoofer (based on the Dolby spec, IIRC).
     
  8. Brett DiMichele

    Brett DiMichele Producer

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    Hey Folks,
    Sorry I didn't respond sooner I work night shifts so I was
    sleeping all day [​IMG]
    I agree using the LFE out was a wrong move, after I thought
    about it and realized I was doubling up on the crossover
    that's not good...
    I am running the Front Left and Right Pre Outs into the
    M-282 right now and I am getting bass I have the sub set
    to No right now and mains set back to large. Later when
    I get my 500 watt AV12 sub built I will of course run mains
    as large and sub as yes..
    I just thought (I guess) by setting to Sub = Yes and Mains =
    Small that all of the bass below 80 would be diverted to
    the 10's but that's stillnot a good idea seeing as I am
    not sure what the AR9's internal Crossover point is for the
    LF side of the crossover (I will have to dig the white papers
    out)
    As far as matching levels, the M-282 has adjustable gain to
    match them up. But it still just seems to me like my 787
    put out more spunk than this dedicated amp is, and that is
    NOT possible.. I took both apart and while the receiver is
    well contructed, the M-282 is ALL amp inside the same size
    enclosure as the receiver.. It's 100WPC x 2 @ 8Ohm and 110
    per channel @6 Ohmn
    And I just feel like it should drive them harder than it is
    and I am not about to use tone controls to boost the bass.
    I don't think there is any setting in the OSD for Preouts..
    I will have to read the paper work, there still could be
    something I am missing..
    But anyway it does sound better now.. much better dynamics.
     
  9. Brett DiMichele

    Brett DiMichele Producer

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    Hey Folks,
    Sorry I didn't respond sooner I work night shifts so I was
    sleeping all day [​IMG]
    I agree using the LFE out was a wrong move, after I thought
    about it and realized I was doubling up on the crossover
    that's not good...
    I am running the Front Left and Right Pre Outs into the
    M-282 right now and I am getting bass I have the sub set
    to No right now and mains set back to large. Later when
    I get my 500 watt AV12 sub built I will of course run mains
    as large and sub as yes..
    I just thought (I guess) by setting to Sub = Yes and Mains =
    Small that all of the bass below 80 would be diverted to
    the 10's but that's stillnot a good idea seeing as I am
    not sure what the AR9's internal Crossover point is for the
    LF side of the crossover (I will have to dig the white papers
    out)
    As far as matching levels, the M-282 has adjustable gain to
    match them up. But it still just seems to me like my 787
    put out more spunk than this dedicated amp is, and that is
    NOT possible.. I took both apart and while the receiver is
    well contructed, the M-282 is ALL amp inside the same size
    enclosure as the receiver.. It's 100WPC x 2 @ 8Ohm and 110
    per channel @6 Ohmn
    And I just feel like it should drive them harder than it is
    and I am not about to use tone controls to boost the bass.
    I don't think there is any setting in the OSD for Preouts..
    I will have to read the paper work, there still could be
    something I am missing..
    But anyway it does sound better now.. much better dynamics.
     
  10. Brett DiMichele

    Brett DiMichele Producer

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    James,
    Sorry I hope I didn't come across like an idiot I was just
    trying to clarify what my setup was.. I purposely bought
    completely passive towers for flexibility reasons. I didn't
    want an integrated amp, The AR7's are the same tower only
    the LF side is actively powered by internal amps I didn't
    want that.
    Yes the M-282 Amp from Onkyo is matched and actually was
    made for the TX-DS787 Receiver. It's the amp to add on the
    power for the 7.1 setup but I am choosing to use it as a
    Power amp for the subs.
    Ya know.. I should have just bought the dang Parasound 5
    channel amp.. [​IMG] It's only $2100.00 [​IMG] LOL
    I will own that amp!
    230 watts a channel.... 460 watts to each speaker... Hmmmm
    Yep I could live with that [​IMG]
     

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