Sub is complete... but a couple of questions

Discussion in 'Archived Threads 2001-2004' started by Robin Smith, Jul 2, 2002.

  1. Robin Smith

    Robin Smith Stunt Coordinator

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    At long last my sub is finally complete! I was quite nervous hooking it up for the first time but it all seems well and good. I have a couple of questions.

    I am using the Parts Express 250W plate amp. I took the single RCA subwoofer out and hooked it up to just the right line level input of the mixer as I do not have a Y cable. What is the impact of this. Tomorrow I am going to go buy a Y cable, just curious to know what the single side hook-up will do versus both sides. Should I expect even more from this sub? I am impressed enough as it is!

    My second question relates to calibration. What is the correct way to calibrate the level on this thing? So far I ahve just listen to a 200 - 20 Hz sweep and tried to even the sound out by ear. What is the "proper" way to calibrate this beast.

    Last of all, I have not modded my amp in the way many others have. If I do the resistor mod, what change in performance can I expect. While it is tuned to 15.4Hz, it does not seem to go as low as this? Will the mod allow it to go lower.

    Thanks in advance.

    Robin Smith.
     
  2. Dustin B

    Dustin B Producer

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    Congrats on finishing the sub. I still remember the feeling when there was nothing left to do but fire it up.
    Don't even bother with the Y cable. Not necessary and won't make any difference.
    I'd recommend picking up Avia or something similar along with an SPL meter. Best and easiest way to calibrate. Unless you have an EQ for the sub, then you need to do a little more.
    I'd check with PE or whoever you bought the amp from as I think a few months ago the 300-794 started being shipped with the boost disabled. If it isn't disabled, I'd definately suggest getting it changed. As a well designed DIY sub doesn't need any low end help and doesn't need a rumble filter kicking in until under 20hz.
    What exactly have you built and when do we get to see pics [​IMG]
     
  3. Robin Smith

    Robin Smith Stunt Coordinator

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    Thanks for the reply Dustin, and for your previous help!

    I just want to confirm that hooking the subwoofer RCA to only one channel on the amp is fine then?

    I have Video Essentials on DVD. Are the test tones on their, combined with a Rast Shack SPL meter good enough for calibration purposes? Basically, I want everything set to register as the same db, even the sub tone, right? I have no sub EQ.

    I am hooking my sub up to a Denon 1802 receiver. It has multiple sub-related settings. What are the general rules of thumb for large vs small speaker setting. I have dual 8" woofer PSB Century 600s for my mains. In my pre-sub days (i.e. yesterday) I had them set to large. Today I set them to small, is this the best way to go. What about the crossover frequency on the plate amp? I have it set to 160 right now, should I reduce it to 80, below which is what the Denon manual speaks about as "low frequency".

    My sub is 214L with a single Dayton DVC 15" driver. It is constructed from 20" sonotube with 1.5" endcaps (1" of which is inside the tube). I went with a single 4" Precision flared port and tuned the sub to 15.4 Hz.

    The plate amp is the MCM Electronics 250W equivalent of the PE/Adire amp. I think the bass boost is enabled on mine. It was right after I bought mine that I started reading that it was disabled, I don't know if MCM have switched to disabling the bass boost at all.

    Thanks

    Robin "No longer a DIY virgin" Smith
     
  4. Dustin B

    Dustin B Producer

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    I only run one on mine.

    Yep, VE and a SPL meter is all you need for basic level matching. Just get all the channels reading 75dB and you set. I find this too loud though. I prefer about 10dB under reference with the sub 2-4 dB hot.

    Nope you've got it set right now. All speakers should be small and the amp's crossover should be at 160hz.

    With that sub I'd definatly make sure the boost is disable or set to the 1dB of boost at 25hz with the 17hz corner frequency for the rumble filter. I have a bunch of pics from when I did it on the PE 300-792 amps used on my parents and roommates subs.
     

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