Tempest @ PE 250W questions regarding LFE

Discussion in 'Home Theater Projects' started by Alex_P, Feb 27, 2004.

  1. Alex_P

    Alex_P Stunt Coordinator

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    I just finish built the tempest. It's a Mid Q sealed from Adire (21" cube). I have a question regarding LFE. I have the DVE disc w/ me and SPL meter. I just did a bass management test from 15hz - 150hz. I didn't seem like I hear anything until it hits 30hz. Anything wrong w/ that? I watched Fight Club at 12db below reference and the bass seemed fine. It shaked my apartment [​IMG] How do I measure how low can my Tempest hits? I turned on Black Hawk Down, on chapter 4 Irene. I didn't hear any bass when the guy said "f*ckn' Irene" Am I missing something?

    I'll probably going to paint my box tomorrow if it's sunny outside...

    TIA,
    Alex
     
  2. AndersP

    AndersP Stunt Coordinator

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    Hi

    It´s very difficult to measure the low frequency response because of room resonances clouding up the picture. The response will also be different as you move the mike to another listening spot. I don´t know your particular test tone CD, but warble tones can be very useful. They are a mixture of many frequencies in a narrow band.

    You don´t hear much below 30 Hz. You feel it. The senses are not very acurate either at those frequencies so the only way to be sure you have the "minerals" is to measure the response. Try to take a couple of readings from different listening spots and correct the dips and peaks that are common for all listening spots.

    The way to correct dips and peaks in the response as above is by means of a digital parametric equaliser. The industry standard on this forum seems to be the Behringer Feedback Destroyer ( BFD ), but there are several other brands that work as well.

    You are running a Tempest in a closed box. That is great, but you didn´t say anything about amplification. Do you have eq in the amp? Do you use any form of eq or crossover outside your receiver/preamp?
    Uncorrected closed boxes don´t have much of sound pressure below 50 Hz. The best way to correct this is with a Linkwitz Transform Cirquit ( LT ).
     
  3. Owen Bartley

    Owen Bartley Second Unit

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    I'm pretty sure that amp has protection built in so that it rolls off below pr0bably around 20Hz. That might explain the lack of sound during the Irene scene. Also, I'm guessing your sub is tuned much higher than that particular passage goes. Just a guess.
     
  4. Alex_P

    Alex_P Stunt Coordinator

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    AndersP and Owen, I'm running the 250W amp from PE. I don't know if it has any kind of protection from LFE which might cause a roll off somewhere. How can I find that out? I am feeling like it lacks some real low freq at around 25hz or low... And like Owen said, the bass seemed to roll off... I checked for air leak and can't find any. Seemed like my box is air tight... I've watched a few movies, the bass (anything above 30hz) is there loud and strong, anything below 30hz seemed like it got rolled off... I'm just curious if it is normal for Mid Q sealed Tempest to perform this way or am I missing something that I don't know?

    I recieved a lil manuel from PE on how to adjusting EQ for bass boost. It requires soldering and basic electronic skills. I have no experience on those at all. From what I read, it didn't seem to be difficult. Just changing the 2 resistor values can boost the bass up to 6db. Have anyone done this? Where can I find more info regarding the EQ adjustment for bass boost on that PE 250W amp?

    Thanks in advanced...

    Alex,
     

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