Can anyone help recycle SVS driver into car sub ?

Discussion in 'Archived Threads 2001-2004' started by Brian Fellmeth, Mar 9, 2002.

  1. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    Here is my hairbrained scheme. I've got some 18 inch sonotube in the garage and a SUV that needs a sub (according to my son anyway). Could I do the driver upgrade to my early SVS 25-31 PC and mount the old driver into about 3 feet of the 18 inch sonotube with a port or ports, get a car amp and crossover ? Any suggestions about number of ports, diameter, legnth and power requirements ?
     
  2. Denton

    Denton Stunt Coordinator

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    Things are much simpler if a sealed box can be used. Check the response curve you get by plugging in the T/S parameters in your favorite software for a system Q of ~ 0.8. If the F3 is in the 40's (or lower), the response is likely to be acceptable in the car.
     
  3. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    Sealed would be great if it doesn't roll off too high. Would like to be down 3 db at say 28-30 Hz. Only have about 3 cubic feet to work with. Do not have the T/S parameters for TV's driver nor software to simulate.
     
  4. Mike_A

    Mike_A Stunt Coordinator

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    tom at one point posted the following T/S parameters for the old SVS driver:

    Fs/21hz

    Qts/0.38

    Qes/0.39

    Qms/6.6

    Vas/4.6

    Re/3.2

    those were off the top of his head he claims, but should be good enough to get something going.
     
  5. Dave Crigna

    Dave Crigna Stunt Coordinator

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    Hi Brian,
    Using the t/s mike gave I would put that driver in a 2 cf box stuffed with about 32oz poly fill. You would get a free air f3 of about 37 and a q. of @7. very tight sound for autosound and should go very deep. Also, once you get some power into it you will probably see the q go up to about .8 which is still very nice. Your in car f3 if I had to guess will be around 15hrtz as you have to remember the cabin gain in a car is easily double that of your average room gain starting from about 80hrtz down in a medium size sedan for example. Also for power anything from 200w to 350rms will due very nicely. Hope this helps[​IMG]
     
  6. Denton

    Denton Stunt Coordinator

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    I'm getting a sealed box of about 1.5 cu ft with about 1.5 pounds of polyfill. Don't let this apparent discrepancy alarm you. One of the great things about sealed designs (especially in the car) is that you have some wiggle room without ruining the result.
     
  7. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    Thanks Dave, Denton, exactly what I needed to know. Sealed it is, and at 1.5-2 cubic feet there may even be some room for cargo. Any suggestions for the electronics ? Are there any crossover/amp combo's in one unit ? Any good sites to learn about car stuff ?
     
  8. KyleGS

    KyleGS Second Unit

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    Go to the forums on Sounddomain.com to do more car audio research. Depending on what you want to spend there are many great sub amps out there with built in xovers. One to look at is the JBL BP300.1 which is a monoblock amp that will push 300w at 2 and 1 ohm mono. What is the VC configuration on the sub?
     
  9. Denton

    Denton Stunt Coordinator

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    Kyle's question about voice coil configuration is a good one. Most car amps are stable into a 4 ohm load when bridged. (i.e. when 2 channels are bridged to drive one speaker.) If your driver is 4 ohm, or if it has dual 8 ohm coils, about any quality high power amp should do. In recent years, we've seen a lot more mono sub amps designed to handle 2 ohm (or even lower) loads. These work great, but if your load is 4 ohms, you will get less power than the projected rating into 2 ohms. (You knew that).

    Amps with built-in crossovers are the rule these days. Look for adjustable, steep slope crossovers. Also look for bass EQ options and "subsonic" filters. These can help get the best performance out of your sub.
     
  10. Dave Crigna

    Dave Crigna Stunt Coordinator

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    Glad it helped you Brian. As for electronics is all depends how much you want to spend. If it was me, I would be looking at the class d mono amps that are stable to 2 ohms and put max power into 2 ohms. Even though you will only be running it 4 ohms it allows some more flexibility down the line if you decide to ad another sub or changes subs with different ohm ratings. Also they are very efficient, tend to run cooler, compared to an a/b amp of same power output. Let me know what you budget is. You may also want to check out elitecaraudio.com They have a decent forum.
     

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