Sub Woes

[tige']

Well, like I said earlier you guys are on page 962 and I am only up to about page 11 now.

I will listen to it some more and see what I think.

I was just suprised at how much different it sounded when it was just a hole. I thought if I made it a true port it would be even better.

But, if the best thing to do is leave it as it is, well that is even easier for me. I can do nothing all day long if I need to

Thanks again guys!!

[rushin]

tige'---did you use the same screws to mount the grill as the sub. Does the same screw go through the grill and sub to the mounting point?

[tige']

Yes, the same screw can be used. The holes line up almost perfectly.

There are recessed holes for the screws on the sub. When using the grill there will be a gap between the bottom of the hole and the grill but only where the holes are. The rest of the grill rests on the outside rim of the sub.

I supposed you could put a spacer in there so that you are actually holding down the sub by the mounting flange and not the outside rubber ring. You would probably get a more rigid mount that way? But I don't think it is necessary.

[tige']

Maybe I am a glutton for punishment (or just having too much fun to quit) but I think I am going to make another box that is a bigger and incorporate a port to see what kind of sound I get.

I have enough MDF left over (that I don't have any other need for) and, if I am going to try it I should do it BEFORE I finish all the carpet work again. So I figured why not??

I will just adjust the length of my current enclosure design to get it to the 1.4 cu ft. (I need to add about 4.6 inches to the length, going left to right in the picture).

Looking at the attached picture, the cushion to the right will run horizontally almost right through the middle of the triangular end of the box.

So my port could either be a slotted one above the cushion or a round port that fires into the cushion. It will be very close to the cushion, probably less than 2 inches away.

Plus, I am considering extending the top of the box clear over so it can be used as a shelf instead of just stopping short from the end of the boat. This shelf would cantilever the end of the box. And would trap the sound coming out of either port design (round or slotted) into the lower outside corner of the box. Would that be bad? ( I hope that makes sense??) - Basically the end of the box would stop 2 inches from the cushion but the top board of the box would go over the cushion and be even with where the horizontal carpet edge is in the back of the picture.

[tige']

The vented box is temporarily complete!! It is all glued together except for the ported side. I have a straight PVC tube in there for now (I just ordered a flared pipe that I should have Thursday).

I was able to listen to it briefly and depending on what you are listening to it does sound better in most cases. Some songs are REALLY REALLY good - just what I have been trying to get and others are about the same as the sealed box.

I haven't spent that much time listening to it yet (the kids were already in bed by the time I was done with it and I didn't want to wake the little buggers up).

I will listen to it more this evening and let you know how it compares to the sealed box.....If I opt for the vented box I will have to go get more resin!!!

[tige']

I'mmm sooooo confused.....

I can't decide what setup I like better - the sealed box or the vented enclosure.

Here are MY observations, maybe accurate - maybe not :

The good (vented) - Some songs sound REALLY good with the vented box. These songs must have the bass at the tuned frequency of the vented enclosure. They are songs where you would expect to hear some pronounced low end bass and the vented enclosure delivers it, much more than the sealed boxed could. You can really FEEL the bass with the vented enclosure.

The bad (vented) - With the vented enclosures some music sounds "muddier". There is more "distortion???" (maybe not the correct word). There just seems to be more sound (probably bouncing around from the port) that sometimes gets in the way of the sound that should be there.

The good (sealed) - The sealed enclosure is definitely tighter bass. It isn't as loud but delivers more accurate bass that doesn't muddy the air. It is more tinny (real word??) but cleaner, the whole system sounds cleaner.

The bad (sealed) - the real deep bass isn't there as much (if at all). The bass it delivers isn't a whole lot lower than what the in-boat speakers are already making (this probably isn't a true statement but I can turn the wired remote bass gain down on some songs and not really notice too much difference, even on songs that have bass in them). I understand the the sub is still delivering lower notes than the in boats but it just isn't as noticeable as the vented box.

So.....I don't know what to do!!!

I ordered a flared vent tube that should be here tomorrow. Maybe that will help clean up some of the sound.

It is soooo hard to get an accurate comparison. There is so much difference between songs, style of music and playback devices I can't say one is better than the other (in my opinion and current situation anyway).

It takes a while to switch the two boxes and I really need to change the settings to make the most of either one. So, by the time I am done I forget what the first one sounded like!!

Are there any tips to get a good feel for settings, tests, comparison ideas, etc that could help me figure out what will work best?

Are there any other advantages / disadvantages of the 2 boxes? Will the speaker live longer and be happier in a sealed box?

I could probably use either one and be happy.

At this point, for me, the required space is not an issue and neither is the time to complete the new box (I still need to resin coat it and finish the vented pipe install). I am trying to base my decision on what delivers the best all around sound. I figure as much work as I already have in this a little more won't hurt.

I want to get this done but I may have to wait until I get the boat on the lake or at least out of the garage to get the best real work comparison. I just hate it that my winter project has turned into my spring project and I am still not done!!

Maybe when I do get done I can write a book "My Winter as a Sub Box"!!

[philwsailz]

Hah ha hah!!!

You sir, have just encountered the day-in day-out issues that plage many, if not all acoustic engineers. You have experienced and very accurately described the relative differencs and trade-offs between the two styles. It is a compromise, always.


There is one thing we have not addressed at all, yet. What is the box volume you are venting, and what is the diameter and length of the port? We need to tune the enclosure for it to work properly; it is too easy to get it wrong.

At this point, you have a given enclosure volume and you have defined the port diameter. We need to dial in the length to give you the proper tuning prior to making any firm decisions either way. If you tune too high, the subwoofer will be a "one-note-wonder" with poor power handling, and if you tune it too low, you ehd up with an enclosure that sounds almost like it sealed.


Let's see if we can figure out what you need in the way of tuning and go from there. Cool?

[tige']

Very cool, any help will be greatly appreciated..

My box design is modeled directly after the info provided in the Wetsounds manual. Their optimum vented enclosure is a 1.4 cu ft box with a 3" diameter 9" long vent.

My box is an irregular wedge shape box but I would guess I am within 3% of the 1.4 cu ft. The current PVC vent is dead on.

I am not sure how to cut the flared vented tube that should be here today - 9" overall length or 9" straight tube length, maybe even somewhere in between??

Thanks again

[philwsailz]

Awesome!

Glad to know we have a defined port. Lots of times the flared port kit will have instructions; it might tell you on the length compensation.

I seem to recall that half-way in-between provides a proper length.

So, for example, if the flared section(s) combined equal 3", use 1.5" as an equivalent length and make the straight part 7.5" If the total stack-up of the flared section(s) is 4" consider it has an effective length of 2" and cut the straight portion to 7"

Zat make sense?

Tim might have some insight too, and he is way more familiar with the woofer, so hopefully he will chime in!

Keep us posted!

[tige']

I had an e-mail out to Tim and just seen his reply - he said the "overall length or something close to it". I will read the instructions too and see what they say

I will try to get the flared tube in tonight. I would expect this to make a little bit of improvement but expect to have the same scenario of what works or sounds better..

I like the deep bass, that is what I have been trying to get out of this sub all along. I want the sound from the sub to be distinctively lower then the in boats - so the vented box does this.

But, at the same time I don't want a muddy sound filling the boat.

I probably really need to get it outside and see how it sounds??

The problem of getting this done isn't making the box but finishing the carpet - I can't do that until I decide, for sure, which box I want to go with.

Thanks!!

[tige']

I have finally made my decision.

I am going with the ported enclosure.

The deep low bass is what I have been after along. The 12" sub helped but the vented enclosure really seals the deal.

The sealed enclosure has great sound too but I guess I am willing to sacrifice a little "muddiness" for the low thump and boom of the vented enclosure. I think once I have the boat outside and on the open lake the deep bass will be more noticeable and the muddiness won't matter so much, especially when the boat is moving.

I can always turn the bass down a little too.

It is not installed yet, I ran out of resin but will get more tomorrow. I want to give it a couple of coats before I install it.

My next big question is the carpet....I don't think you are supposed to put the carpet under the sub mounting flange. But, it would seem that is the easiest way to do it - cut the carpet to the exact size of the hole (cut after the carpet is on and before the sub is installed around the circumference) and let the sub hold the carpet down.

How big of a deal is it to leave the carpet under the sub? Do most people do this?

I am also installing a grill (Polk Audio), but it isn't designed for this sub (Wetsounds) so the grill doesn't reach the carpet and won't help hold it down. Also, it will actually rest on the outer rubber flange instead of on the rigid mounting flange itself. So between the grill and the carpet I would have a "spongey" mounted sub.

I could make little spacers to take up the space between the grill and flange, so the back of the grill hits the spacers and the the other end of the spacers hits the flange (I might need to include a picture??).

So my long winded question is - should I make spacers and do the detailed carpet trimming to get the most rigid mount possible?

Thanks

[wetsounds1]

Glad you finally got it to your liking!

As for the sub mounting, even though the grille doesn't touch the carpet. It shouldn't matter as the screws should suck in as far as the can go and the woofer will be tight. I would just make sure that the woofer is solid in there. If it is, you can use a gasket to fill the gap or use some of the carpet. The carpet may fill it anyway and you would never see it.

But include a pic so we are following along. As long as the sub frame is sitting against the box nice and tight and solid. A small gap from the grille to the box is not going to hurt anything unless it is keeping the woofer from holding tight

Tim
Wet Sounds

[tige']

Hey Tim!

Here is a picture of the grill. My concern is that the grill actually rests on the outer rubber ring of the sub. It has to squish the rubber to hold the mounting flange to the wood.

Without the grill the screws go into the recessed holes and actually contact the mounting flange. So you are getting good contact between the screw heads and the mounting flange.

The concern on the carpet is if I put the the sub over the carpet that there would be a soft contact spot on the other side of the mounting flange (between the sub and box).

So, between the two I would have a spongey mounted sub.

I could cut the carpet around the outside of the mounting flange but, as you can see in the picture, the grill won't reach the carpet to help hold it down. So I would have to rely on the carpet glue to hold it in place. I am ok with how it looks, I just like the idea of the sub or the grill holding the carpet down.

My options would be to do as you mentioned earlier, use 4 screws in the sub and 4 in the grill. Or, make 8 little spacers to fill in the recessed spots in the rubber ring to get a good hard joint between the grill and mounting flange.

Then I didn't know how big a deal it is to leave the carpet under the sub?? I don't mind trimming the carpet out a little further than the circumference of the hole if that is the best way to do it.

Thanks!!

[wetsounds1]

LOL, I think you are over thinking it a bit!!

Just run the carpet all the way to the hole. Then get a razor blade and cut it out so the carpet is even with the inside lip. Mount the sub with the grille. and you are done!

You will be fine like this. As long as the sub is tight. None of the other stuff will matter. Having the grille on top of the rubber lip, or having the sub mount on the carpet. This is actually better anyway's as it creates a seal around the woofer. Many use a foam gasket and some subs even come with a foam gasket anyway. Also, all pre made boxes have the carpet all the way.

Tim
Wet Sounds

[tige']

OK, that is the easiest way. Seems too simple after everything else I have been through!!!

I was concerned because I have only been using 4 screws to mount it (I kept switching between boxes) and one time I must not have gotten it back in the hole correctly. I could hear the air getting pushed under the the flange and actually feel the speaker move.

It just got me thinking about the grill on the rubber not holding it down tight.

Thanks - almost done and hopefully for the last time!!