Need help with subwoofer calibration, please.

Discussion in 'Speakers & Subwoofers' started by Nathan Gillmore, Sep 11, 2003.

  1. Nathan Gillmore

    Nathan Gillmore Stunt Coordinator

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    I just can't seem to get my sub calibrated correctly, and I believe the fault lies in the way I'm doing it. Let me go over what I'm doing and you all can point out the obvious flaws [​IMG]

    Ok, first of all this is a HSU VTF-2 I'm talking about here, which I got along with my Ascend system. My Onkyo 797 reciever has the speakers set to "small" and the sub set to "on" and it is hooked up via the input that bypasses the sub's crossover. I have it in a corner of the room, and it is set in the "one port closed" position for deeper extension.

    When I first calibrated it, I set the volume knob to 1/4 of the way up, and after using a RS SPL meter I ended up with the sub at just +1 on the reciever. However, this didn't seem to give it much punch. I then read somewhere on this board (can't find the post now) that I should set the volume up to 75% (or 50% if that was too high) and set the db's on the reciever to like -9 and calibrate from there. I tried this, but now when I play something with heavy bass (like the asteroid shootout scene in Episode II) the sub makes a loud POP! when something really strong happens.

    I've not experienced this in a sub before, but I can only assume this is the sub bottoming out or something equally bad, so I turned it down. Now I'm wondering how exactly should I approach calibrating it to encompass everything (the channel level setting on the reciever, the sub's own volume knob, etc.)?

    Should I try maybe setting the speakers to "large" and trying to use the sub's own crossover? I'm not sure what the Ascends' lowest hz is, but I could find that out I'm sure.

    Sorry if this post has been long, but I'm really disappointed in my subs current performance, any help would be greatly appreciated.

    Thanks!
     
  2. steve nn

    steve nn Cinematographer

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    Hi Nathan. The first thing I would suggest is unplugging the port. A plugged port will give you higher spls in the lower regions but at a expense. Your sub will be more acceptable to bottoming out and detract from the punch you are looking for. I would calibrate in it's stock tune and see what you think.

    Try setting your gain on the back of your sub to 35-40% then and calibrate. Your receiver will most likely be at -4 or close? The plate amp on the back of subs are not meant to be ran at 75% +. A sep amp with a passive subwooer is. I used to wonder on this also. Do not set speakers to large.> Long story.

    What size room are you in and do you have your sub corner loaded?
     
  3. Nathan Gillmore

    Nathan Gillmore Stunt Coordinator

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    My living room is about 15'x16' but open on the backend to the kitchen. The sub is in the corner, yes. The HSU has a switch on the back to tell if one port is open or both are open, so I'll try removing the plug and setting it to "2 ports open" and see how I like that. The manual states that I won't get as deep extension that way, but will notice a dB increase.

    I'll try out your suggestions on setting it to about 35% or 40% and see how that works with both ports open. Thanks for the suggestions!
     
  4. Wayne A. Pflughaupt

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    Nathan,

    A 150 watt/10” sub is marginal for home theater use unless you have it in a very small room – not your situation, judging from your description. That’s why you’re having trouble with it bottoming out.

    I’d recommend a more substantial sub, but if that’s not an option I concur with Steve’s advice that unplugging the port is what you need to do. As he said, you’ll loose out on the lowest frequencies, but what you do get will be able to play louder.

    Regards,
    Wayne A. Pflughaupt
     
  5. JohnnyG

    JohnnyG Screenwriter

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    You want as much gain as possible going into the sub, so the best combination in usually to set the sub level on the receiver at 75% or so.

    Also, what are you using for test tones? Those built into the receiver, or a test disc of sorts? I get wildly different results at home between the test tones on AVIA, the built-in tones of my H/K AVR8000 and the test tones on the RABOS CD for my Infinity IL60's. I ended up using RTA software to figure out what was really going on. It turned out they were all wrong to some extent! The AVIA results were off the most (too low).
     
  6. steve nn

    steve nn Cinematographer

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    I find that sub calibration is very useful and I like it for a reference point. On the rare occasions when I listen to 5.1 music> Most of the time I like a minus sub calibration and with some movies/material I might like as high as a +6db sub calibration. Many factors come into play here.

    Running up your SW setting on your receiver to 75% is not my recommendation. 25-50% on your receiver and the same 25-50% on your plate/sub. From your previous calibration attempt figures> I am fairly confident this will work out well and the popping noise should be cleared up with both ports open. If you were in a smaller room with the listening level moderate? Your sub would be able to perform much better with 1/2 of it's port mass blocked.

    Nathan can you give us your seating position? The VTF-2 ought to be able to rumble your HT for you in its stock tune unless you are sitting in a unfavorable location like the middle of the room. I do agree with Wayne that in a room that size it would not hurt to have more horse-power though. I have a AV15 over in the Hardware for Sale section? (Sorry, I just had to say that)........ [​IMG]
     
  7. Nathan Gillmore

    Nathan Gillmore Stunt Coordinator

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    I guess I needed to have done more research before my purchase, I figured the VTF-2 would be sufficient. Since upgrading would cause my immediate murder by my wife, I'm stuck with it for a year or so heh. I tried playing around with it some this weekend and ended up facing one of the open ports (both open now) toward a wall about 12" away, and that improved things. I have it now about 1/4 the way up on the volume and at -1 on the reciever.

    I'll try more of your suggestions and see what I can come up with. Opening both ports might allow me to crank the gain up some more, I'm just not sure what I should be setting the reciever on.

    Would it be better to have the volume fixed and adjust the actual spl with the +/- on the reciever, or vise versa?
     
  8. JohnnyG

    JohnnyG Screenwriter

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    Signal to noise is higher at lower output levels. That's why you want a 'hotter' pre-amp signal. When you amplify, you ampifly the sound as well as the noise and the lower the noise level, the better the sound.

    Too high is no good and too low is no good.
     
  9. Bill Kane

    Bill Kane Screenwriter

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    Nathan,

    It sounds like with the foregoing advices you are getting nearer to finding the sub output balance point that works in your room with your equipment.

    Placement IS important, and that's why a front two-wall corner is most often recommended, to better "amplify" the low frequency soundwaves. At this low frequency, it really matters not if the sub driver is pointed out, backward or down.Many report a move as small as 6-inches can make for more dBs tested at the seating area. Yes, it's a tedious project -- test, move, test, move.

    As Johnny says, a calibration goal is keeping the rcvr's SWFR level as well as the sub amp's gain control in the middle ranges on their respective scales.
    The Golden Mean thing.

    [My Yamaha rcvr SWFR Level scale is -20 to 0 dB. Yamaha uses a strong output (4VDC) and I only need to calibrate to -15.5dB to get a 85dB reference level sub output using the Avia disk and SVS sub amp knob in the middle.]

    Once you've rebalanced the sub to the main, leave the sub amp knob untouched and forgetaboutit. It's much easier to sit with the remote and call up the SWFR Level to adjust up or down 4-6dB depending on your music, television or DVD soundtrack material. If later you find the sub's AUTO ON feature cycles off during some quiet playback, just add a higher output at the rcvr level and turn down the sub amp gain a little to compensate. And keep that SPL meter handy.

    bill
     
  10. Cesar

    Cesar Extra

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    I would recommend asking Hsu directly (on their forum) for placement, settings assistance. I also have a VTF2 in a bigger room (15' x 22') and it MORE than does the job. I have to turn the volue down because it wakes up my wife on the other side of the house!

    I drive it with a Pioneer 45TX, it's placed next to the wall near a corner but not in a corner. Speakers set to small, crossover at 80 Hz (i think, it's default), 1 port open. I have the sub dialed at 9 o'clock. I'm very happy w/ my results.

    I agree that you would benefit from placement. Have you done the "subcrawl"? I did and found the best place was unfortunately unfeasible (in the hallway). However, the compromise was still good.
     
  11. Nathan Gillmore

    Nathan Gillmore Stunt Coordinator

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    I haven't done the "sub crawl" because my subwoofer cable isn't very long. I may try getting some cheap rca cable that's really long and trying that out, though.

    I'll also try your suggestion and post on HSU's board. I'll draw up a simple diagram of my living room first, since I have a feeling that has a lot to do with it (very odd shaped room with a vaulted ceiling and a fireplace taking of an entire corner).

    Thanks for all the help/suggestions!
     

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