Dual AV15 IB wiring

Discussion in 'Home Theater Projects' started by Tracy_L, Aug 28, 2003.

  1. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Here is what I've got to finish my IB with:

    Two DVC (2ohm per coil) AV 15 (in a ~20"^3 manifold)
    BFD
    QSC RMX850 capable of:

    Stereo Mode
    8 ohms 200 watt per channel 0.1% THD
    4 ohms 300 watt per channel 0.1% THD
    2 ohms 430 watt per channel 1.0% THD

    Bridged Mono
    8 ohms 600 watt 0.1 THD
    4 ohms 830 watt 1.0 THD

    I am beginning to understand wiring the VC's in order to obtain a certain load. What I'm not sure of is what would be better, for the speakers & amp, and for sound quality.

    I guess my options include using a seperate channel from the amp for each speaker vs. either bridging mono or using one channel for both speakers. Seems a shame not to use both channels either seperately or bridged.

    The power efficiency of the speakers is 500w, but assuming that power needs are reduced by roughly 40% in an IB setting, does that indicate around 300w for each speaker for a total of around 600w max (I know that is an extremely rough estimate)?

    If I ran both VC in series then both speakers in series that should give me an 8 ohm load, correct?

    If I understand correctly, you can run an 8ohm demand on an amp bridged to 4 ohms, but not vice versa. The amp should be rated for lower ohms than the speaker demand.

    Should I worry about the THD for each option, mono vs bridged? Less THD for an 8ohm load vs a 4ohm load....

    I guess what I am leaning towards is running it mono bridged for ease with the BFD, setting up one channel vs two. Does the BFD make any power requests on the amp? And should I consider that in making my decision?

    Any suggestions since I am obviously challenged in this area?[​IMG]

    Thanks
    Tracy
     
  2. Allen Ross

    Allen Ross Supporting Actor

    Joined:
    Sep 30, 2002
    Messages:
    819
    Likes Received:
    0
    The lower THD is better, less desertion.

    I would go with bridged into 8ohms if you say you only need 600 total.
    The BFD isn't a problem, it goes before the amp and after the receiver you are only feeding it one channel, but if you want to go two channels (turn one off you don't need the full output while watching the news [​IMG] ) you can get an RCA splitter and feed two signals.
     
  3. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Thanks Allen

    I was leaning towards 8ohms bridged with running the subs in series (with an 8ohm load).

    Are there any differences in running the amp in 8ohm vs 4ohm other than the increase in wattage output and the increase in THD? Is the increase in power the only plus to running 4ohm?
     
  4. RichardHOS

    RichardHOS Second Unit

    Joined:
    Mar 11, 2003
    Messages:
    454
    Likes Received:
    0
    Your two available options are essentially the same thing.

    You can:

    (A) Run the amp stereo, each channel into a single 4ohm load
    (B) Run the amp mono bridged into a combined 8ohm load

    There's no way using those two speakers to present the amp with a single 4ohm load, so you can't operate the amp in a bridged into 4ohm configuration.

    Since options A and B have the same power output, and the same distortion levels, I'd go with B simply due to wiring and BFD simplicity.
     
  5. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Thanks Richard

    I appreciate the replies. Now I just gotta finish installing so I can crank this sucker up!!!!! [​IMG]
     
  6. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    WOOOOHOOOOO [​IMG][​IMG][​IMG][​IMG][​IMG]

    Labor is almost done (save for actually cutting the hole in the ceiling) drivers are installed in the manifold and the manifold is braced!!!!

    Just a couple of wiring questions.....

    I think I want to wire the two av15's series/series to give me an 8 ohm load. + - + -...

    Now if someone would verify this is correrct :b

    POS of one VC on one driver to NEG on the other VC of same driver, then the same on the other driver.

    Then go POS of VC on one driver to NEG of opposite driver and same with the last POS & NEG left.

    Shouldn't that give me an 8 ohm load?

    Then to power, use one POS on a driver and a NEG on the other driver and run that to my amp?

    Thanks for helping me out, I'm pretty electronically challenged, but I'll muddle thru[​IMG]

    Tracy
     
  7. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Tracy

    Look HERE

    This a link off the FAQ page of the "Cult" forum
     
  8. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Thanks Thomas, I did read that before, over and over and over............

    I did not see the exact configuration that I am wanting to hook up.

    Drawing it out on paper, I think this may be correct to get an 8 ohm load and hook up to amp..

    connect one + to - between the VC's on each speaker.
    connect a + to - from a VC on one speaker to a VC on the other speaker.

    This would leave a + and a - on on each speaker, hook theese to the amp...... using a bridged 2 channel amp into 8 ohms....

    Anybody care to critique?

    Thanks
    Tracy
     
  9. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Just for giggles, I put a meter on the VC's to check my wiring.

    With all VC's hooked in series, leaving one POS and one NEG on each speaker open, I got around 5.5 to 6 ohms.

    Checking each speaker with the VC's run in series, I got around 2.7 to 3 ohms.

    Checking each VC I got 1.3 to 1.6 ohms.

    Is that correct? I'm no electrician so I don't know if these 2 ohm VC are supposed to be slightly less than 2 ohms or exactly 2 ohms......

    Is that safe to run an amp bridged at 8 ohms when I'm only reading around 5.5 to 6 ohms?

    Thanks
    Tracy
     
  10. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Tracy

    You're making this WAY WAY too complicated. Go to the link, scroll down to where you see the graphic below. Fill in the VC values in the calculator below the graphic. Then you'll see what happens with various wiring configs if you're using the amp bridged.

    The VC impedance varies with frequency, so the mfgr just takes a specific frequency to rate the VC.

    Don't over think this stuff.

    There are other calculators for other wiring configurartions

    [​IMG]
     
  11. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Thanks again Thomas

    I saw that diagram and that is most like what I am trying to accomplish, except that after wiring the VC's in series, they wired the speakers parallel, halving the ohms to 2. I'm going to wire the VC's series then series the speakers for 8 ohms.

    I guess the thing about that diagram that is throwing me is that they wire power (+ and -) to each speaker. With wiring everything in series, do I simply just run one wire to each speaker, one + and one -? Thats with everything run in series......

    Thanks
    Tracy

    ps
    that page was for series/parallel wiring, I couldn't find any straight series/series wiring diagrams...
     
  12. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    If you want everything in series, start by wiring the VC's of each speaker in series, then wire the speakers to the amp like this.

    [​IMG]
     
  13. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    Thanks again Thomas

    That's exactly what I was shooting for. I saw that diagram also and thought that was what I was doing [​IMG]

    I appreciate it
    Tracy
     
  14. Tracy_L

    Tracy_L Stunt Coordinator

    Joined:
    Jan 11, 2003
    Messages:
    70
    Likes Received:
    0
    OMG

    I finally got this thing hooked up after months of waiting on drivers, and working on it a bit at a time. I've done no fiddling with it yet, just hooked it up and turned it on. Haven't even installed the BFD yet.

    WOW!!!!!

    At first I had to wonder if it was even on. I set all of my speakers to small before turning it on and then realized that I had much more deep bass than before. It was so seemless. I literally had to go and put my ear against my JBL S36II's (fronts) to make sure the bass wasn't coming from them.

    It took me doing that to figure that the bass was not coming from them. It is quite invisible. I haven't gotten the chance to play with it much with the young'un getting to bed early. My xover is at 100hz, I can litereally be looking at the hole in the ceiling and not tell that's where the bass is coming from!!!

    Played with Monsters Inc a little, but couldn't find the door knock on the trailer some others described. Played Matrix, the attack on the building, the helicopter crash, Gladiator, wasn't bad, couldn't find any real low effects there. These still sounded loads better than before. Even the wife was smiling and said she was impressed with the sound and said that it really was like going to the theater with this sound system (patting myself on the back.....[​IMG] )

    Can't wait to get LOTR (1 & 2), waiting for them to be delivered.

    Played some bassy music thru it, Prodigy mainly, sounded great.

    Just gotta get a sound meter on it and get the BFD installed....

    Oh yeah, Ol' Lady says to get the hole in the ceiling covered up ASAP!!!! [​IMG]

    Thanks for all the help
    Tracy
     

Share This Page