I assume you have tried tuning the box while playing the driver.  Its amazing how much an inch of movement of that baffle does.

If the box begins sounding better and better, but all of a sudden your baffle is at the top, stuff the sealed chamber.

I have an Infinity in mine and it sound very good.  So I don't know how those other subs would compare with it....


Anything else I can offer would be to double check it is built to plans and is sealed up. But you already did that  ;)

Try moving the insert to cover half the port.

Your PPI are oonly 8 ohm?  Thats part of the problem then, they aren't drawing as much power a dual 4 ohm coils wired parallel.

John C.

Your PPI are oonly 8 ohm?  Thats part of the problem then, they aren't drawing as much power a dual 4 ohm coils wired parallel.

John C.


John,

That's true, but it's not a fantastic idea to run a Linear Power 2202 at 2 ohms mono, it's a voltage amp.  I like my shiny rails of TO-3 transistors unblackened and the power supply toroid intact.  The DB certainly was louder in the 4-Ohm mono isobarik configuration, but not in a flattering way, very boomy and uncontrolled.

To be fair, this is not a high budget project.  I selected the PPI's because I bought them at an auction for $30 several years ago in mint shape, and they were just laying around in hard-to-tell-from-new condition.

All the components in my system, down to the wiring, cost less than $200 total.  So I'm not expecting miracles, but it seems like it should do a bit better.  I have a 15" CV Vega 154 that's going in there aperiodic as soon as I pick up the requisite parametric EQ and find the time to fab the box, so this was intended to provide some low end in the meantime and just be something to toy with a bit.

I played with it a lot over last weekend, several hours total.  I will do some more movement of the insert and see how that changes things.  Not sure cancellation is the issue, as I've moved the box about and fired the port towards the driver's seat (where it is now), towards the side trunk wall, and towards the rear of the car.  I've tried reversing the speaker polarity.  Some changes in the sound were obvious, but not much of an improvement.  I'm happiest and it's the least boomy firing towards the driver's seat in the proper phase.

Here's some T/S params from the web, maybe this will shed some light on things?

   * Size:  10"
   * VAS: 68.14L
   * FS: 25.24Hz
   * Impedance: 4/ 8 ohm
   * X-Max: 9.97mm
   * Power Handling: 500 watts (max)
   * Sealed Box: .5-1.0 cu. ft.
   * Ported Box: .75-1.25 cu. ft.
   * Displacement: .065 cu. ft.
   * Voice Coil: 4 Layer TIL
   * Peak Excursion: 17.25mm
   * Sensitivity: 89.64dB

It's a pretty robust driver, at least compared to more traditional woofers.  It's not designed to be a W7 or something.

I'll play some more and report back, thanks to all for your replies!

Brian

OK, a quick update.  I now have the insert covering about 3/4" to 1" of the top of the port.  That helped the midbass boominess out a good deal and really tightened things up, but the bottom octave is still lacking.  I'm going to play some more.

Last night I fed the T/S params of the PPI woofer into BassBox.  I can't come up with anything I like.  The optimum single reflex BP is small, about the size of the DB, but it has a huge peak at 120hz.  Something like 9db.  That jives with what I heard.  It was so bad that at 18db/oct at 50hz lowpass, it was still pulling the image backwards from the front stage.  I tried modeling some interesting iso vented alignments with the PPIs too, and the response looks great, but the cone excursion is off the map and power handling is about 8 watts below 45Hz.  Think I may just get things as good as I can with sliding the insert and call it good for now.  Doesn't seem like a very compatible woofer.

Crutchfield has the Infinity Ref 10 right now for $59.99.  I might jump on it, but it's even cheaper to stuff my 15" CV into the 32-liter sealed box I modeled last night and have predicted in-car response that's nearly flat to 15hz.  The CV never gets even halfway to Xmax with a 500W input according to the model.  Going to give that a try first before I get interested in the Infinity, thanks for all the advice!

Brian

Just one more thing that someone eventually gets around to: once you have found what baffle position sounds best, you need to seal it in place no matter how air tight you think you built it. Then put a hurt on it with the amp.