Who Uses an Equlaizer in Their HT?

Discussion in 'Archived Threads 2001-2004' started by Jason Wolters, Jan 17, 2002.

  1. Jason Wolters

    Jason Wolters Stunt Coordinator

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    I have heard a little bit about using an equalizer in a home theater environment. Does anyone here do this? If so why? Can you discuss all of the benefits you recieve from it? Also what is the manufacturer and cost?
     
  2. NathanP

    NathanP Supporting Actor

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    I use an EQ for my subwoofer..

    To bost the bass and really get more of one selected frequency out of it.

    I also was using an EQ because I had a spectrum analyzer to perfectly match my speeakers.

    I decided it wasn't all that necessary.

    Nathan
     
  3. Sankar

    Sankar Second Unit

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    I have the AudioControl Rialto for the main/center/surrounds and the BFD Pro for the sub. My personal experience is that the Rialto has been one of the best additions to my ht. Most of the controls are pretty close to flat, but I did use the unit in conjunction with Spectra Plus to match the freq response of the center and surrounds to that of the mains. Interestingly this had 2 benefits :

    a) much more seamless integration of the soundstage all around (the "ball of sound" test in AVIA is amazingly close now).

    b) Better matching of sub level .. before the addition of these, I had noticed that matching the sub level to the front usually meant that the sub level at the center/surround was not matched. Now they are all extremely close

    I suppose that if you have the perfect room and acoustics you would only be "dirtying" the signal with equalization .. however in my personal experience, it helped to compensate for room and speaker variations
     
  4. Jason Wolters

    Jason Wolters Stunt Coordinator

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    How are these equalizers connected? Especially how is the sub EQ connected?
     
  5. BruceD

    BruceD Screenwriter

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    Critical issue for sub EQs is to make sure you get what is called a parametric EQ.

    It is typically inserted between the sub-out on a receiver/pre-pro and a powered sub or sub amp input.

    The parametric EQ allows you select a specific frequency (unlike non-parametric EQs which don't and are typically called 1/3 octave EQs) to perform equalization (cut or boost) on.

    The normal use is to cut bass peaks that cause boomy or one-note bass in HT rooms.
     
  6. Greg Lee

    Greg Lee Agent

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    I'm using a BFD1124 to EQ the SVS25-31 in my middle-of-the-road system in a big room. It really gives a much superior result compared to no EQ. I used ETF software which revealed one very large peak (due the room) and several small peaks and nulls; flattening these out results in much better sound (for music as well as HT) - to repeat a cliche - you don't hear the subwoofer any more, just good bass.

    The BFD is connected to the sub-out of the reciever (you need two 1/4"phono plug adapters), then BFD out to the subwoofer amp.
     
  7. Sankar

    Sankar Second Unit

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    Jason,

    The BFD (which is a parametric equalizer) is connected betw the sub out of the receiver and the sub itself. The pre-outs from my receiver go into the AudioControl Rialto which sends its outputs to the power amps. If your receiver has a "tape monitor loop", then you could also put the equalizer in that path.
     
  8. Kevin C Brown

    Kevin C Brown Producer

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    Jason- I'm also using the slightly older BFD 1100p for my sub. Does a nice job of smoother out the peaks generated by the sub's (low freq)/placement/room interactions.

    Sankar- How do you like the AudioControl Rialto? I have been wondering about how eq'ing the mains would work. Analog or digital domain? 2 channels? How many filters? Parametric right? (Got to find a link on this somewhere...)
     
  9. Sankar

    Sankar Second Unit

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    Kevin,
    The Rialto is not a parametric equalizer and operates in the analog domain. It has 5 channels (main, center, surrounds) plus 2 sub channels.
    Check out http://www.audiocontrol.com/hometheater.htm
    I have been quite pleased with its performance in my setup.
    Cheers
    Sankar
     
  10. Kevin C Brown

    Kevin C Brown Producer

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    Sankar- Thanks. Another potential new toy to take a look at... [​IMG]
     
  11. Laurence_C

    Laurence_C Stunt Coordinator

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    I use 2 Audio Control C-101 series III EQ's for the fronts and rears. I use them for music only. I find there is no need to equalize a sub and the same goes for the center channel.
     
  12. RandyRush

    RandyRush Stunt Coordinator

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    I use the Sony 711 for my dtv inputs; can't really see that it makes much of a difference; does seem to slightly increase depth of sound;still trying to figure out how to connect it to both dtivo and ota inputs so it is functional all the time.
     
  13. Wayne A. Pflughaupt

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    Jason,

    There are two main “types” of equalizers for home theater: Subs and mains.

    The most popular equalizing for home theater is a dedicated sub EQ, which connects between the receiver and the sub. The low frequencies are the most problematic in any room; most rooms will exhibit at least one, often more, room-induced response peaks that can make a sub sound “boomy” or like it only responds to one note. Using a real-time analyzer (either hardware or software based), or a test disc and a SPL meter, you can identify these peaks and use the equalizer to eliminate (or at least reduce them). The result is much smoother and pleasing bass response.

    Equalization for the mains can be done on one or all channels, or any number in between, depending on your wants or needs. However, for any channel you want to equalize you have to connect it between the pre-amp outputs and the amplifier. Thus, you have to be using outboard amps, or have a receiver with pre-out and main-in jacks for the channel(s) in question.

    Equalizing the mains is typically done for different reasons than the subs. With subs you are mostly compensating for the room’s response (i.e., its effects on the sub). While that is true to some extent with the mains (primarily below 500Hz, where the room begins to have an effect on the speaker’s sound), you can also compensate for shortcomings in the speaker’s response in the midrange and upper frequencies.

    For instance, if you have ever seen a speaker review in magazines like Sound and Vision or [/i]Home Theater[/i], you have seen the frequency response graphs that accompany the review. And no doubt you have noted that a speaker’s measured response is usually somewhat (or in some cases, severely) ragged. With this information, or with readings culled from your own measurements, you can use the equalizer to smooth out the speaker’s response shortcomings. The result, of done correctly, will be improved sound.

    While just about any EQ will do for subs, it is important to use only high-quality equalizers for your mains. Unfortunately, they are not cheap, but the budget stereo equalizers made for connections to a tape monitor loop are not suitable for home theater use, because of limited adjustment capabilities and lack of headroom. An equalizer used for the mains needs to have extremely low THD, and high S/N ratio and headroom specs. S/N ratio is especially critical, to insure no noise is added to the system. Remember, for any band you boost in the midrange and higher frequencies, you have increased your noise floor by the same amount. If your equalizer has a high signal-to-noise ratio, you don’t have to worry about increasing noise higher than the receiver’s noise floor.

    Another “must have” for a graphic equalizer, in my opinion, is constant Q filters. Many equalizers have what is know as “variable Q” filters that cut a wide path when making minor adjustments. Boost or cut a band 2-4dB, for instance, and all frequencies are boosted to some extent for an octave or more in each direction. By contrast, a constant Q filter will retain its “shape” no matter how much or how little you boost or cut, minimizing “bleed over” to adjacent frequencies.

    Like Sankar, I’m using AudioControl equalizers on my mains (the front-three channels). My speakers had a broad peak centered at 6kHz, and a few other minor problems, that I was able to address with the equalizers. Switch them in and out and you can hear the remarkable difference they made.

    Hope this helps,

    Wayne A. Pflughaupt
     

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