HT sub set back............and Q for Adire guru's

Discussion in 'Home Theater Projects' started by Chris Brock, Jan 28, 2004.

  1. Chris Brock

    Chris Brock Second Unit

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    well as some of you might know......
    i recently ordered a Nady XA900 amp and a Dayton 15" DVC. I have had the sub for a couple days and it has been patiently waiting for the amp to arrive. the amp got here today and it looks great. strong construction, good packaging, and the fans are quite compared to some ive heard.

    well i hooked it up and turned it on at very low level. and immediatly i notice a strange noise. it sounded like it was coming from the sub. so i turned it up just a hair and bent over right in front of the speaker. there seemed to be a strange crackling and poping noise that sounds like it is coming from directly behind the dust cap of the driver. this is at pretty moderate levels with only a few mm of movement. it progressivly gets worse as the volume goes up. i removed the speaker and im in the process of returning it to parts express. should i have any problem getting my money back? i dont feel i should since it was clearly defective.

    i also just ordered a Tempest from www.acoustic-visions.com
    [​IMG] [​IMG] so here is my updated situation. I have a enclosure that is 5.25 cubic feet and tuned to 21hz with around 44sq/in of port area. I have a Nady XA900 amp that is rated to produce 675wrms x 1 @ 4ohms. What kind of performance can I expect from the Tempest in this setup?
    thanks alot to everyone who has helped me so far!!
     
  2. Aaron Gilbert

    Aaron Gilbert Second Unit

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    No, you should have no trouble at all. Parts Express has a 45 day return policy and great customer service. Even it were defective four years down the road had you kept it, you still would get a replacement because it has a five year warranty. [​IMG]

    With that size box and that tuning frequency, I would expect extreme output levels above 20Hz. You may not be able to use all the power of that amplifier, but too much power is always better than not enough, as long as you know what distortion sounds like. A final note, I would strongly consider tuning the box to 18Hz instead, maybe even 16Hz. With your 21Hz tune, group delay at 20-30Hz is pretty high, and your steep rolloff starts in the mid 20's. If you tune to 18Hz, your 20Hz output is exactly the same, F3 goes up a negligible 1-2Hz, but the steep rolloff doesn't start until below 20Hz. Plus, group delay is considerably lower at 20Hz and above.

    Aaron Gilbert
     
  3. Chris Brock

    Chris Brock Second Unit

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    Thanks for the reply. that defintly makes me feel better. i think the DVC would have sounded great but i guess i am kinda superstisous and when i get something that doesnt work out i take that as a sign.

    As for the box, this one is just a temporary setup. i am planning on building a new box in the next 6 months that will be along the lines of the Adire EBS alignment, 10 cubes and tuned to around 16hz or so. would it be a safer bet to run the amp in stereo @ 8ohms per channel? this would give me a total of 400wrms to the driver.
     
  4. Kyle Richardson

    Kyle Richardson Screenwriter

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    You shouldnt have a problem returning the DVC but are you sure that it was the driver at fault and not the amp? I guess you'll know for sure when you get the Tempest though [​IMG]

    You can run it bridged at 4 ohms but you'll have more power than needed or you can run it with each channel connected to each VC in 8 ohm and have a little less power but still should be plenty for you. I'm not familiar with that amp, but if it has a "parallel" mode where it sends the same signal to both channels from a mono source then you will want it set to that for the stereo setup.

    Its best if you have a dual input cup and wire each VC to the individual inputs on the cup so you can play around with the wiring easily and experiment to see which setup works best for you.
     
  5. Chris Brock

    Chris Brock Second Unit

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    hi kyle! yes, just to completly eliminate the amp, i hooked the amp up to drive my mains with full range music for a bit and it sounded wonderful, clear and accurate with practically limitless volume. i built my first enclosure in 1996 and I have never heard a poping and rattling sound like this. it literally sounded like someone had put a steal ball bearing under the dustcap.

    how would suggest wiring to sub kyle? I can wire it in stereo on the amp and the sub will see 400wrms or i can bridge the amp and the sub will see around 675wrms. would i be risking damage to my tempest with tht much wattage?

    edit!
    sorry, you just answered my q!
     
  6. Chris Brock

    Chris Brock Second Unit

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    actually......
    kyle or anyone, what would you honestly suggest for my enclosure situation? i can easily seal up the port and i would have 5.25 cubic foot sealed or i can leave it alone at 5.25 ported @ 21hz. i would rather be safe then sorry.
     
  7. Chris Brock

    Chris Brock Second Unit

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    thanks for all the help Kyle!! i am very excited to get my Tempest.
     
  8. Luis Cruz

    Luis Cruz Stunt Coordinator

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    Not to move away from the main subject but I have a question about the Nady XA900. I thought it was only 300 watts x 2 into 4 ohms? Does that mean you are able to bridge it to 675 watts?

    And if it can output 675 watts into 4 ohms bridged would that be ok for a subwoofer that can only handle around 500 watts (i.e. SVS 25-31CS+)?
     
  9. Chris Brock

    Chris Brock Second Unit

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    actually i have been wrong all along. when i saw your post Luis i went and looked at the manual to be sure. here are the actual listed specs..............

    Stereo = 2 x 200wrms @ 8ohms
    2 x 350wrms @ 4ohms
    2 x 680wrms @ 2ohms

    Mono = 1 x 675wrms @ 8ohms
    1 x 900wrms @ 4ohms
     
  10. Luis Cruz

    Luis Cruz Stunt Coordinator

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    Thanks for the response Chris. This amp has really peaked my interest. And at the price point I think this might be the way to go. Thanks for telling me the specs straight from the manual, that bit of info is helping me make a final decision on whether to get this amp or not. Can't wait to see what your initial thoughts are when you get your sub completed and everything.
     
  11. Chris Brock

    Chris Brock Second Unit

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    i am very excited to get my sub. this is really the final piece of my HT. hopefully somtime i will actually get aoudn to taking some pics of my sub and amp, my mains and my center channel and show them to everyone here. i know that one thing about buildgin my own speakers is that i have a great sense of pride in them and the way they sound. it is a good feeling a accomplishment.
     

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