How to evaluate my new sub? (1 Viewer)

[Wes Nance]

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

 

[Patrick Sun]

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").

 

[Jack Gilvey]

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

Sounds like how I'd expect that alignment to sound, smooth,easy, and free of dynamic compression, and reflects the trade-offs we discussed during your design stages. As I mentioned, my sub, with its lower Vb/higher Fb was designed for "max-punch" while sacrificing some depth. I think your alignment is better overall for classical, etc.

Sealed really doesn't determine or guarantee "punch", it's all in the way it's implemented. My PR sub is much punchier than the same DVC in a small sealed box...go figure.

Also, I'd say that the effect of frequency response anomalies can't be underestimated, and a 50Hz dip is right in the "punch" region.

But(!), your box gives you all the freedom in the world to make it sound just the way you want. So, how about removing some of the Mms to get that higher tuning we talked about with the original 1050grams (I think that was John's original recommendation)? Or, you could get really close to the alignment I used by leaving them @ 1400g and reducing your Vb by carefully placing something in the box to take up room...bricks, wood blocks, books, anything to displace some air. You really couldn't move it around, of course, but it might be worth the experiment. Something more permanent could be implemented later.

 

[Wes Nance]

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

 

[Jack Gilvey]

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.

It's certainly nice when you build something and can correlate all those numbers and curves to sound. By all means model different curves and modify the sub to see how you like it.

 

[Wes Nance]

Were you to remove mass down to 1050g in your current box, you would have that kind of "peaky" response to which you refer, which is why I recommended going with the 1400g in your 85L in our discussion in this thread . I thought it best for the wide use the sub will see in your house.

Jack, I hope you don't feel like you're having to explain things to me more than twice!
If I take all the washers off the diaphrams, with no nut, I'd probably be at around 1150g- I could try that and see how it sounds. I probably won't mess around with weight until I take everything out to veneer it in a month or so. I'm going to mess with placement for now.
We're also probably moving to a new house in the next few months, so all permanent tweaking (bass boost, etc) will probably wait until it's in the new room.
Wes

 

[Jack Gilvey]

Jack, I hope you don't feel like you're having to explain things to me more than twice!

Not at all, bro'.
Happy tweaking!

 

[Wes Nance]

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. . .

 

[Wes Nance]

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

 

[Jack Gilvey]

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.

Yeah, I've been following their development since they were a rumor. I imagine they have the dynamic quality I've noticed in mine in spades.

 

[Jack Gilvey]

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?

I couldn't guess, Wes. Maybe John would have a suggestion?

 

[Wes Nance]

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

One thing i can think of is that when the screw was tightened, it pulled the glue somewhat that holds the surround to the basket. Then when you loosened it up, it isn't holding tight anymore. It makes kind of a sticking sound, like if you take masking tape, wrap it around your hand and then keep touching and pulling it off of something. That may be what you are hearing, and if it is, i can send you glue to fix it. I guess the easiest way to check is to pull the PR out of the enclosure, hold it by the frame and shake it back and forth like it would move during normal use. If you hear a sticking sound, then that is the problem.

When I got the PR out, I couldn't duplicate the sound by shaking it, so I figured it was a sealing problem. I put a drop of silicone caulk in each screw hole, and used some 3/4" weather stripping that fits the rabbits great.

Result- no leak! I can hear a very minor leak on the other side now, so when I take stuff out to veneer, I'll just be more thorough when installing. . .

I also added a brace from the vertical brace to the front of the cabinet. The vertical brace was really ringing before I did this. I think it helped dampen things down. . .

Then I corner loaded the sub more like I was going to do before I heard the leaking. It sounds much more powerful, of course, and I had to turn the gain way down again. . . I still have some funky stuff in my room response, I think, but the sub sounds so great! It has a lot more impact now, so I'm guessing part of the problem before besides placement was the leaking letting air out on peaks. . .

Thanks again, everybody-

Wes

 

[Jack Gilvey]

Great news! Enjoy.

 

[Wes Nance]

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

 

[Jack Gilvey]

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.

I don't see an advantage to this, really. If you model 85L and 1250g with heavy fill, the F3 goes up.
As far as excursion, the only place I see any problem with any of these and 250w is below tuning. The higher you tune, the more chance you have to encounter frequencies below tuning. I'd think the high-pass/rumble filter on your amp, being -3db @ 20Hz, should be quite adequate to really keep things under control down there, although there's no way to model it in Unibox.
If it were me , I'd try all of 'em. That's the fun part.