How to evaluate my new sub?

Discussion in 'Archived Threads 2001-2004' started by Wes Nance, Feb 18, 2002.

  1. Wes Nance

    Wes Nance Stunt Coordinator

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    Hi everybody,

    There have been some *great* discussions on this board lately, very helpful. Thanks!

    I've been listening to my new Stryke 12.3 sub, and I really like it. I don't really have any reference, though, to compare it to, as my former sub was a tiny Polk PSW250 8" that really didn't have any output below 35hz.

    I'm wondering if I could get any guidance about what to listen for and how to evaluate my new sub? I'm a musician by trade, so my ears are highly trained. This sub has to do everything- classical, pop, jazz, etc., plut HT. I've read that PR subs have a distinctive sound.

    I notice that the sub has a very open and easy sound- not compressed at all, and I've not heard it sound like it's even working hard at all on any music.

    But things like kick drum don't have quite the punch I thought it would, but I'm wondering if that could be:

    1. This isn't a sealed box sub

    2. I seem to have a hole in the room around the mid 50hz

    I know this is all highly subjective stuff, but any guidance/advice would be great. Mostly I want to make sure the sub is put together right, eg no leaks, braced enough, etc., as I won't be building another one.

    Thanks for all the info-

    Wes Nance
     
  2. Patrick Sun

    Patrick Sun Moderator
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    Lack of punch is mainly due to low tuning, that's what you give up for being able to extend the response down low in the low 20's. Sub's always entail compromises (size, extension, output - pick any 2 out of 3 => "Hoffman's Iron law").
     
  3. Jack Gilvey

    Jack Gilvey Producer

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  4. Wes Nance

    Wes Nance Stunt Coordinator

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    I understand better now about the tuning. I'm not really bothered by lack of punch, just curious. I'll assume that most punch is achieved by more overemphasis on upper bass than a natural flat frequency response. I'm just starting to come to terms with what a given alignment sounds like, since really I only know what it "looks" like in Unibox.

    Jack, I'm also curious to experiment a bit with the PR tuning. I was actually thinking of adding 2 lbs or so of polyfill to make the box look bigger, and then lighten the PR's a bit. I know that won't give me more punch, but I want to see how the sound changes. I'm going to play around in Unibox and see what looks good- this alignment is a really flat and balanced one- John did a good job setting it up.

    And of course, I can always make the box look smaller as you suggested, by filling it with something, to get that punch.

    Now to try some more sub placements to try to get rid of that 55hz "hole". . .(I'm glad I went with only single layer MDF- this thing is darn heavy as is)

    Wes
     
  5. Jack Gilvey

    Jack Gilvey Producer

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  6. Wes Nance

    Wes Nance Stunt Coordinator

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  7. Wes Nance

    Wes Nance Stunt Coordinator

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    Jack,

    Reading in the other "design" thread, there is some talk about transient response in PR design being a possible trade off in the design.

    This leads me to some questions- does Unibox model transient response anywhere? What dictates this in a PR enclosure- is the transient response have anything to do with the mm of the PR itself? Does your sub have faster response than mine because the PR's are lighter, or the box smaller?

    If this is an issue with PR subs, if even a small one, could you get around it by telling your receiver that the sub was further away than it really is so it's getting sent a couple milliseconds sooner? Am I completely off my rocker? These questions may show my complete ignorance of the subject. . .

    Wes

    ps speaking of PR subs, have you looked at some of John's HE15 designs over on the Stryke website? 2 HE15's with 6 18" PR's weighted to 1800 each? Holy cow- definitely as expensive as it is heavy. . .
     
  8. Wes Nance

    Wes Nance Stunt Coordinator

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    I moved my sub farther into the corner tonight, to try to get some more measurements and see if it worked better. Output seemed more powerful, but when I was using the Stryke Bass Cd at 20hz, at about 95db, I'm hearing a spitting/vibrating sound from one edge of one of the PR's that definitely sounds like what I would think would be a leak! I think I can feel air coming out there a bit. It's centered right over one of the screw holes.

    So, I took out the PR (had to get the amp out to push from the back) and replaced the weather strip gasket with a thicker one, and more carefully tightened it down, hooked everything back up, and *the same sound again!*

    I don't know what to do- I'm pretty sure the PR went in rotated differently from before, but the sound is centered over the same mounting hole in the cabinet as before.

    Anyone have any ideas?

    I'm wondering if I somehow damaged the PR (although it seems to be recurring in a particular place in the cabinet, not the PR) or what else would cause this?

    Help!

    Wes
     
  9. Jack Gilvey

    Jack Gilvey Producer

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  10. Wes Nance

    Wes Nance Stunt Coordinator

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    Update on my leaking problem- here is a reply I got from John at Styke
     
  11. Wes Nance

    Wes Nance Stunt Coordinator

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    Jack,

    I have a couple tuning questions for you- I've been running some possibilities in Unibox, and when I run your numbers (or close to them) the driver excursion maxes out at 20hz or so at 250 watts- is that consistent with your model?

    I was thinking of raising the PR tuning on my sub to around 1250g (I'm thinking it would be around that if I took all the washers off. . .)I'm guessing my box volume is around 77l or so with the drivers, amp and bracing, this gives me an fb of 22.8 and an f3 of 22.1. Still a pretty low tuning, but bumps up the response closer to flat at 30 and 40hz. But driver excursion runs out of room closer to 20 hz.

    But I'm wondering, if I stuff the box and use Tom Nousains's figures, to increase the box volume to an apparent 95l (approx) and use the 1250g, I get an fb of 20.7 and an f3 of 20, and more room for driver excursion and a flatter response curve than what I'm running now.

    So, I'm thinking about throwing a couple pounds of stuffing in my box, and reducing the mass on the PR's to 1250g.

    Am I missing anything important in looking at this?

    Thanks,

    Wes
     
  12. Jack Gilvey

    Jack Gilvey Producer

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