Sub out (LFE) and normal 2ch Stereo Output

Discussion in 'Speakers & Subwoofers' started by Derek N, Jul 16, 2003.

  1. Derek N

    Derek N Agent

    Joined:
    Jun 9, 2003
    Messages:
    33
    Likes Received:
    0
    Trophy Points:
    0
    I have had the old subwoofer hook-up question for a while and the confusion was based on the polk article which recommends speaker level hook-up. A recent thread here has been very helpful in understanding the LFE hook-up but it also brought up an additional question.

    I have Polk satelites (RM6700)and had my system hooked up with the speaker line inputs. I just upgraded through CC my PSW202 for a Velodyne CHT-10 (i realize there are other options in this price range but this way I did not have eat the cost of the psw202 as the full refund is put towards the upgrade).

    Now that I am doing the hook up all over I was looking into this issue again.

    The sub out is certainly the cleanest hook-up and because I have a HK AVR-325 I have variable crossovers for all speakers built into the receiver. This should ensure that there are no "holes" in freq, or at least none that I create as apposed to the speaker type creating.

    Now the question (finally) - What about Stereo output? As in Stereo direct or non-digitized output. Will it still output to the sub or will it now only be the L and R which are set to small and not ideal for this application. I have read the manual and it is not clear on wether the sub gets a signal in plain stereo mode.

    Derek
     
  2. Jon D

    Jon D Stunt Coordinator

    Joined:
    Sep 29, 2000
    Messages:
    166
    Likes Received:
    0
    Trophy Points:
    0
    Derek, if I read your post right, you're askking if, in two channel mode, a signal will be sent to your sub? If you have the size of the speakers set to 'small' then yes. The crossovers that strip low bass from the main channels in movie soundtracks work the same way with 2 channel music.
     
  3. RickMo

    RickMo Stunt Coordinator

    Joined:
    Apr 19, 2003
    Messages:
    121
    Likes Received:
    0
    Trophy Points:
    0
    Derek: I too had a similar question recently and discovered the following with my set-up and hopefully this'll shed some light on your question: In 2-channel stereo I was getting way too much output from my sub (SVS). I realized I had the sub's volume control too high. On my Yammie receiver, I had the sub at -8db but I think -- THINK -- that that level refers only to LFE output. In 2-channel, the signal to the sub is not affected by this -8db configuration. So, I had to turn down the volume at the SVS, then at the receiver, set LFE to 0db, in order to get a balance between HT and stereo listening.
     
  4. Brian Fellmeth

    Brian Fellmeth Supporting Actor

    Joined:
    Jul 30, 2000
    Messages:
    789
    Likes Received:
    1
    Trophy Points:
    0
    Somebody smack me if I'm full of crap here, but I believe that the crossovers in HT receivers operate in the digital domain. The frequencies are separated by number crunching, not by filtering with caps and op amps. If this is the case, and you are using stereo DIRECT (ie, analog signals from the source into the HT receiver that the receiver just amplifies), then there are no numbers for the crossover to crunch thus no output for the sub. To get a signal to the sub with a 2 channel stereo source, either the bitstream must be decoded in the receiver (via an optical or digital coax connection) or the receiver do a A to D, filter the digital data, then D back to A to get a separate signal for the sub. In analog direct mode, no digital processing (including the crossover) is possible. So, if you want to listen to stereo with a decoder outside of the HT receiver and forbid the receiver to digitize the data (direct mode), then you either must resort to speaker level connection to the sub or use R and L preouts from the receiver (if it has them) and use the sub's crossover in either case.
     
  5. RickMo

    RickMo Stunt Coordinator

    Joined:
    Apr 19, 2003
    Messages:
    121
    Likes Received:
    0
    Trophy Points:
    0
    Brian: My receiver is sending info to the sub even when listening to the CD player (through analog connection). My sub is connected via the LFE input. That's what confused me because I too thought the receiver did all of its "thing" via digital. It could very well be that your explanation pertains to some, but not all, A/V receivers (????).
     
  6. BruceD

    BruceD Screenwriter

    Joined:
    Apr 12, 1999
    Messages:
    1,220
    Likes Received:
    0
    Trophy Points:
    0
    There are a number of different solutions used by the manufacturers in the arena of "2-channel and subs", but I don't know one which HK uses (I may not have hit them all).

    1) An analog passthru that only takes the analog input signal and passes it to the main L&R speakers, automatically assuming the speakers are Large (even if they are set to small in the speaker setup menu) with no sub output.

    2) An analog passthru that works similiar to #1, but also copies the incoming signal, does an A>D, runs it through a crossover, does the D>A, and sends the bass output to the sub in parallel with the analog passthru output going to the main L&R (which may still automatically assume the speakers are Large, even if they are set to small in the speaker setup menu). This is how Rotel and others do it.

    3) All analog input is automatically run through an A>D and is subject to the speaker setups sizes and crossovers.

    4) You specifically select the analog input to be digitized (A>D) and then it works like #3.
     
  7. Brett DiMichele

    Brett DiMichele Producer

    Joined:
    Sep 30, 2001
    Messages:
    3,181
    Likes Received:
    0
    Trophy Points:
    0
    When I was using my Onkyo 787 as a Pre it DID NOT send any
    Bass information to the SUB via LFE when operating in
    Direct Mode, only in Stereo would it send bass to LFE
    Out.

    That leads me to believe that in my case the BM was done in
    the digital domain and "Direct" was a complete analog pass
    thru and therfore in my case the sub no longer recieved a
    signal when in Direct. It was very annoying considering I
    always listened in Direct Mode since there is no way to
    alter the Boost/Cut of frequencies.
     
  8. RobWil

    RobWil Supporting Actor

    Joined:
    Mar 17, 2003
    Messages:
    733
    Likes Received:
    0
    Trophy Points:
    0
     
  9. RickMo

    RickMo Stunt Coordinator

    Joined:
    Apr 19, 2003
    Messages:
    121
    Likes Received:
    0
    Trophy Points:
    0
    Just to complicate matters: I was under the impression that some A/V receivers can be configured to have the sub (via LFE output) active only in HT. Conversely, it can be configured so that the sub is active in HT and for CD music. My Yammie doesn't offer that option.
     
  10. Brett DiMichele

    Brett DiMichele Producer

    Joined:
    Sep 30, 2001
    Messages:
    3,181
    Likes Received:
    0
    Trophy Points:
    0
    Rob,

    Also if your sub amp has numerous low level inputs like my
    ARS500 Amp which has both "LFE Direct" input and Stereo L/R
    input. This means you can run the Sub out on the Receiver
    into the LFE in and run the PreOuts on the Reciever into
    the Sub's L/R input.

    Or you can say forget it and get a good 2ch preamp like I
    did, and never look back [​IMG]
     
  11. BruceD

    BruceD Screenwriter

    Joined:
    Apr 12, 1999
    Messages:
    1,220
    Likes Received:
    0
    Trophy Points:
    0
    Rob,
     
  12. Derek N

    Derek N Agent

    Joined:
    Jun 9, 2003
    Messages:
    33
    Likes Received:
    0
    Trophy Points:
    0
    You have pretty much confirmed my thoughts that in "direct mode" the LFE would not get output. Didn't quite see how if the manual says it by-passes the processing and goes straight to the volume control, it could then also output to the LFE. (But was hoping it would).

    That having been said, it would make sence in todays day of satelite speakers that the subwoofer should get output at all times. They have crossovers so even a full range output would by suitably reduced for the range of output of the sub.

    I will try the variations this weekend and report back. Changing cables is no small task since access and receiver heft make it a major undertaking.

    Since I am getting the LFE through the L&R channels set to large and routed through the sub, am I losing anything? I really don't have an option it seems since the satelites dictate this arrangement (well i do have the option of getting a 2ch amp and then bi-amping a better set of bookshelfs but this would also make me and my HT homeless so soon after the "I just had to upgrade or would die speech" to my wife).[​IMG]

    Derek
     
  13. RobWil

    RobWil Supporting Actor

    Joined:
    Mar 17, 2003
    Messages:
    733
    Likes Received:
    0
    Trophy Points:
    0
     
  14. BruceD

    BruceD Screenwriter

    Joined:
    Apr 12, 1999
    Messages:
    1,220
    Likes Received:
    0
    Trophy Points:
    0
     
  15. Brett DiMichele

    Brett DiMichele Producer

    Joined:
    Sep 30, 2001
    Messages:
    3,181
    Likes Received:
    0
    Trophy Points:
    0
    Rob,

    Well... If you get a PreAmp with Unity Gain you can just
    loop through the Pre and out to the Receiver I guess..

    In my situation the only complicated area was the sub.. and
    my main 2 channel amp.. I run from my Reciever Pre Outs in
    to my 2 channel amp and I run out of my 2Ch Pre Amp into
    the 2 channel amp also.. Same goes for the sub output..
     

Share This Page