Benifits of adding a EQ to run SVS subs?

Discussion in 'Archived Threads 2001-2004' started by Craig Ball, Jul 19, 2001.

  1. Craig Ball

    Craig Ball Second Unit

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    I have the Samson S700 and two 20-39CS sub right now, i have the amp cranked to max and have my yamaha sub level set at +4 to get a 75db reading on my SPL meter.
    This setup sounds great to me right now, but I want to take these subs to there max and don't know If there near that point now or not.
    I know a lot of people add eq for room nulls bumps ect, I don't think I have a problem with this right now but I'm definately no expert just want to get the best out of these subs that I can.
    So will adding a EQ to my setup benifit me in any way if i'm not having any problems right now?
    SVS reccomeneds the ART 351 EQ It must be a good choice if they use it. Right?
    I've also read on here about people reccomending the behringer destroyer I think it's called is this one better? Exactally what model number are you talking about.
    And finally if i decided to add an eq are they really difficult to set up? Will the owners manuel help out using these eq with subs?
    Thanks
    Craig
     
  2. DieterM

    DieterM Auditioning

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    I'd like to add a related question.
    I have had problems with overdriving my 20-39CS sub on very low bass (big room). Will the subsonic filter on the ART 351 EQ allow me to lower the subsonic levels while retaining the flat response at higher bass frequencies? And if so, will this allow me to run my entire system (including sub) louder without it bottoming out?
    Basically, can I give up some of the ultra lows to get more of the mid and upper lows, and is the ART 351 EQ the best and most economical way to do this?
    -- Dieter
     
  3. Deane Johnson

    Deane Johnson Supporting Actor

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    Craig:
    I think your question can only be answered based on what problems you may have with humps or spikes.
    Have you measured your low end results with an SPL meter to see what they look like?
    Remember, EQ is used only for the correction of some problems, mostly room spikes (humps) and some minor nulls. You cannot remove deep room induced nulls. These are caused by a cancellation of certain frequencies in the room, and the more your try to pour into them, the more they cancel.
    If you have some serious humps, some EQ can work wonders. I find it hard to imagine that you would be lucky enough not to have any, but stranger things have probably happened.
    I had a terrible room spike, 16db at 42 Hz. Removing it with a Berringer worked wonders. Basically what was happening was that I would have to lower the sub level to accomodate that high output at 42 Hz. This resulted in other sub frequencies being attenuated a great deal. Removing the spike allowed all of the sub frequencies to be raised and now my sub is lower, louder and solider.
    I have worked with both the Berringer and ART equalizers. The Berringer allows more precise adjustment and is more flexible, the ART is easier to adjust.
    Deane
     
  4. Bob McElfresh

    Bob McElfresh Producer

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    Deane: How did you determine what frequency had the humps? Did you use a SPL meter and a CD of different frequency tones, or did you have something better?
     
  5. Deane Johnson

    Deane Johnson Supporting Actor

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    I used the sweep tones on AVIA. They move kind of fast and I would like something better, but they told the story. I also used the RS analog SPL meter. I have the digital model also, but prefer the analog. I used a tripod for the meter so I could have my hands free to operate the DVD remote and make notes.
    I recently purchased Stryke's Basszone Test CD Vol. 1 which has stepped tones of longer duration. I haven't tried it yet.
    Remember, you don't need to do this work at reference level. Just find a comfortable volume so you don't blow things up when you pass certain frequencies.
    You should also realize that you will never get a flat line frequency response. There are just too many variable at different frequencies. What you're after is a reasonalbe curve free of big humps. You will probably have a null you have to live with unless you were to get into fancy bass traps and other acoustical modifications to the room, something most of us aren't going to do, and don't need to do. Nulls go by unnoticed, it's the spikes that mess things up.
    While you can't EQ out nulls, you can raise the bottom end a few DB if you need to.
    Deane
     
  6. John Morris

    John Morris Guest

    I agree with everything that Deane said except for the BFD. I have owned and tried a BFD and just found it to be effective but a bit more noisy than I liked. I found the Art 351 and two channel Art 355 to be much quieter but did not offer the opportunity to cut or boost specific frequencies or freq ranges. In the end, I found my EQ nirvana with a Symetrix 551E. This EQ is a poor mans Rane PE-17(which I consider the best parametric EQ within reasonable cost). Here is some info on the Symetrix 551E
    If I were you, and at one point I was, I'd run the sweeps and map out your response curve. Then check to see if the available frequencies on the Art EQ matches those you need to cut or slightly boost. If so, buy the Art. If not, you'll need a parametric EQ. You should also try the BDF since many folks are perfectly happy with theirs... it just may be that I am a really picky person who hates silent passages which aren't TOTALLY silent. Finally, I've been messing with a computer program called Spectra Plus which actually maps the frequency response using the miked sensing of a swept tone. It looks pretty cool and eliminates the need for a tripod held analog meter and eliminates human errors in reading the meter.
    Finally, if you're using subwoofer with full range speakers and see peaks at the upper subwoofer bass area, you can also try lowering your LFE low pass setting to 60Hz or so. On my system, I use it set to send LFE to both my front speakers and my subwoofer. When I get the SVS Ultra, I may need to only send the LFE to the sub to eq my system properly.
    Good Luck with your system, and Have Fun!
    ------------------
    Take Care,
    merc
    [Edited last by John Morris on July 19, 2001 at 07:16 PM]
     
  7. brucek

    brucek Second Unit

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    Craig,
    Here is a review I did last month at AVS on my BFD (Behringer Feedback Destroyer) that might interest you.
    http://www.avsforum.com/ubb/Forum3/HTML/005017.html
    I'm surpised John has audible noise from the BFD if he's using it in his sub chain only. Certainly it's going to give you hiss in anything but the sub chain. Are you talking about hum?
    brucek
    [Edited last by brucek on July 19, 2001 at 07:24 PM]
     
  8. Deane Johnson

    Deane Johnson Supporting Actor

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    John:
    I'm curious about the noise in the BFD you mention. Are you running audio through it other than for a sub, or are you hearing noise in the sub region from it?
    Deane
     
  9. John Morris

    John Morris Guest

    As for the BFD noise that I referred to: my system exhibited a number of annoying noise and noises with the BFD engaged. First, when listening to music with my subs engaged, I could detect a slight background grain... not at all like a hum, almost like a non-distinct crosstalk. It was constant while the unit was receiving input. My wife couldn't hear it, but I could and it bothered me. I prefered listening to music without the unit engaged. I'm guessing that it was probably due to the analog to digital to analog conversion process. Next, the unit HAD to be turned on first, before my amps, or else my subs thumped something awful. Finally, since my rack is only 5 feet to the left of the sweet spot, I could hear something from the actual unit itself. It made a sound not unlike the Soundstream Monoblock units make from their transformers. So, I returned the unit to the dealer, who said that the unit was probably faulty. He offered to replace it but by them I had bought an Art 351 which was totally silent. Judging by the many happy BFD owners, I'm inclined to either think that I got a bad unit, or I am just a very picky person with my audio playback... or maybe both. [​IMG]
    If you have any other questions, get back to me.
    ------------------
    Take Care,
    merc
     
  10. BruceD

    BruceD Screenwriter

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    I would recommend visiting the following site;
    www.etfacoustic.com
    to read about the example demo room. There is a lot of useful information about how to deal with room modes (peaks and valleys of room frequency response) as well as information on sub crossovers, distance to each speaker, etc. It also draws wonderfull logrithmic frequency curves like those in the magazines.
    The program runs on a PC (I use my notebook) and doesn't need any test disks. Instead it uses a professional MLS impulse signal from the PC souncard (need a full-duplex soundcard) and a microphone input- like the RCA out of your RS SPL meter.
    It has really helped me understand my room's bass problems, and I just bought a BFD to correct some peaks. This program will help me decide the center frequency and how narrow to make the parametric EQ corrections.
    BruceD
     

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