altoncustomtech

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to the forum!

Sure. Are you certain you can slide in a box at those dimensions? If you've not already tested it I would suggest doing so with a cardboard mach up box to test the fit first. I'll go ahead and start on a design and drawing tho, no problem.

I'm sorry but there's GOT to be a number getting put into that calculator wrong. It's usually very close to correct.

The problem comes in with the port. If you take a port that is 3.5" wide like I mentioned earlier it takes up ~1.22cuft of volume inside the enclosure. To tune to 32hz it needs to be about 36.5" long, 3.5 x 13.5 x 36.5 comes to 1724.625cuin or just under 1cuft. Then add the thickness of the wood at .75 x 13.5 x 36.5 which comes to 369.5625cuin or .21cuft which totals 1.21cuft taken up by the port itself. So if you're working with your original dimensions of 15 x 34 x 20 the max volume you have to work with from the beginning is 4.69cuft, subtract the 1.22cuft and get 3.47 cuft left, then subtract the sub displacement of .36 and you get 3.11cuft NET volume. That's a quite basic rundown of how that's calculated and subject to change in accordance with the actual physical port length, bracing, baffles, flush mounting, etc.

7.9cuft? How are you calculating this? Even using the absolute MAX dimensions of 15 x 34 x 32 (13.5 x 32.5 x 30.5 internal dimensions assuming 3/4" MDF) I only get 7.74cuft and that's GROSS not NET. I think you're not subtracting the thickness of the wood correctly or getting something off on the calculation in the first place. GROSS volume includes subwoofer displacement (.36cuft in the case of the 12" BL's) and the displacement of the port itself. The wood used to create the walls of the port also has to be calculated. 15 x 34 x 20 (13.5 x 32.5 x 18.5) only yields 4.69cuft GROSS to work with, 15 x 34 x 25 (13.5 x 32.5 x 23.5) only gets 5.96cuft.

Going to 25" on the depth helps, but it's still not near perfect and even at 32" doesn't quite get to what I'd consider using myself. However, I know I'm not using near optimal port area for my Q's and don't suffer any ill effects that cause issues for our listening habits. Output may suffer, there is probably port compression present, and I'm sure it makes audible noise when the subs are pushed hard, but it's not easily noticed. However the pair are rarely pushed to the limit as the output is more than enough for our regular listening habits. When we do decide to push them hard the ensuing results border on the impossible to detect any issues with response as trim panels, body panels, and everything else that can move becomes a cacophony of noise accompanying bass too loud to listen to properly in the first place. If anyone has ears sensitive enough to hear the negative effects of what the smaller than optimal port does to the response of those subs, it wouldn't be that sensitive for long. My point is, I made the decision to live with the results of having my enclosure designed the way it is and as yet I'm not unhappy with the results and I don't think you'd have any real issues with what can be designed inside those dimensions (including the 25" depth) that would negatively impact your listening pleasure from the subs. If a person can give up all the necessary space for a perfectly optimal enclosure, then by all means do so, otherwise this hobby is all about compromise and more times than not the compromise is easily lived with for most people.

You're running right down at the low end of Fi's recommended space for those subs with those dimensions. I'm calculating you can get a hair over 3cuft NET volume with a 3.5" wide port tuned to 32hz. The problem is that's NO WHERE near enough port are for those subs and not have major issues with port noise. Without more space to work with you're going to have an issue. I recently helped a guy with a design for a pair of XCON twelves that the final dimensions ended up being 14.75" H x 38" W x 32" D with 5.25cuft NET volume and ~100sqin of port area (7.5" W x 13.25" H) and it still slides into his trunk. While it still wasn't completely optimal but it is far closer than the limitations you're trying to stay within. Out of idle curiosity, what is limiting the enlcosure to those dimensions? Do you think that maybe a little creativity could possibly yield a little more space to work with?

Happy Birthday my City Mouse brother!

^^ This is exactly what I'm thinking. It's truly amazing they lasted as long as they did, that is if the new M3B's you keep mentioning were on them the entire time. If they weren't on those amps for the last three/four years then your answer should be self evident to anyone. You CAN'T expect ANY brand or model of sub to last forever when you exceed the manufacturer's specifications, period, which is why 99.9% say up front the warranty is void when you do so. Also, IMHO any manufacturer who claims you can run double rated power to their products without worry is very suspicious at the very least. Most of us have seen where someone was able to give 4x rated power to a sub for a fairly long period of time without much trouble and we've also seen where someone has blown a good 2kw sub with a lousy 500 watts. Speakers are dumb and they only do what you tell them to do in the environment you put them in. Both the extremes I just mentioned were those rare cases that come up from time to time. Technically speaking you can run any speaker with any amount of power, but at the same time once you exceed the speakers limits it's going to fail. That's just the way it is. It may happen very fast, it may take years, but it will certainly let you know (as yours have) when you've exceeded the limit that causes them to fail.

Yep it's a BS line so they can make sure they're not responsible for the entire cost on the items shipped by them. I'm also certain that it's in some fine print somewhere and you agree to it by default as soon as you hand them the package that way they've always got everyone who ships through them by the short hairs.

to the forum!

Sorry Senchez and chocolate, it got bought up fast a lil while ago. Amp is sold!

I replied to your pm on FB

Oh.... I'll have to go check FB then, I almost never get on there, lol.

I responded to ur PM. Would be just fine to come see it if you want to.

The sub isn't sold yet. Yes it's Dual 2 ohm voice coils, so wired in series it would give a 4 ohm load.

Happy Birthday dude!!

Still can't believe the lack of interest. BUMP, again. It must be me, otherwise these would have sold MONTHS ago.

Out of idle curiosity OP, have you had a chance to order anything and get it put in yet, or found the source of the rattles?

Price drop Bumpity.... Great amp and BRAND NEW NEVER USED sub here! Amp now $150 shipped Sub is now $225 shipped New prices are shipped to the CONUS.

Happy Birthday!!

What worries me is that the op says it moves easily when he presses on it. My Q's would barely budge when I pressed on them when they were new. Still aren't the easiest things to move by hand now. When you pull the sub out to check it, reach under the cone and push it up. Make sure the spiders move up with the coil when you do that. Check all the way around too because it seems something is really wrong somewhere, that's for certain. You said you had a BTL before, so you Fi builds solid drivers. If that sub is mechanically damaged it either happened during shipping or they did it at the shop, and not necessarily on purpose.