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View Full Version : Should i put them in a sealed box??



skydog
04-10-2005, 06:47 PM
Hi guys i bought a MTX amp 75 watts X 2 at 4 ohms.
They are going to drive two 5 1/4" seperates. They are going in my Allison G.S. I am going to cut them in the sides, but it is not sealed all the way. Should i build some boxes for them for bass?? Or will they sound all most as good with no box?

Thank you Skydog

pyro
04-10-2005, 06:52 PM
5 1/4"s don't produce much bass without distorting, either way.

If you mount them in a side panel, just make sure the edge of the hole is mounted as far away from the nearest edge of the panel as possible. Otherwise, sound waves from the front and rear of the speaker will cancel each other out, reducing bass response.

bigbore
04-11-2005, 04:30 AM
hey this is kevin with the hydrostream,i have actually been keepin my eye out for ya,hey my friend brian lives over by you,i think i told you that last summer when i seen ya at the chill out spot (the sands)but i have seen you out a couple of times,and now i know its you cause brian was tellin me he saw the ally over there a couple of times.anyway remember when we were chillin down at davis park and we were playin around with my stereo a bit,i had that alpine sub in there at that point and time,anyway yea i can get into some stereo equipment also and as far as that question goes yea you do need to make a box for em,and also are you sure you want 5 1/4s i can tell ya being that there going in a boat you might want 6 1/2s obviously if you got good 5 1/4s and you dont want to take them back thats fine.alright what those need is actually a descent sized box cause those are built to be a free air speaker made for a door panel kinda like 6/9s sound good in a rear deck of a car but sound like **** in a small sealed box.so basically they need room to breath.i got a good idea what your gun rails look like and i know that making the back of the sides is a pain but you should try to seal the box somewhat at least and make the box at least .5 cu.ft.and its not a bad idea to get some insulation and put in there to.and also with me livin about a mile from ya you can launch here to if ya want.

pyro
04-11-2005, 06:27 AM
He's right. If you want good sound without adding a sub, 6.5" speakers will sound a lot better.

It's OK to mount them without a box, as long as their baffle (aka the panel they are mounted in) is large enough and the speaker is not mounted close to the edge of the panel.

Post a picture of the potential mounting location.

bigbore
04-12-2005, 03:29 AM
if you dont want to spend the time building a box they do make foam for the baskets on those that you can install.if you go that rout then pyro is right you need to somewhat block off the the back sides.

pyro
04-12-2005, 09:27 AM
The foam is a good moisture barrier for car door speakers, but it is ineffective for blocking phase cancellation in a small, open baffle, because bass frequencies pass through very easily. A "box" must be rigid, such as wood or heavy molded plastic, to be effective as a speaker enclosure. If the speaker can "vibrate" the cabinet, then it can radiate bass frequencies. The end result is weak, muddy low-end tone. The rear 5 1/4" speakers in my Lebaron convertible suffer from this problem. The baffle is open on the back side, and the speakers are mounted near the top of the panel on either side of the back seat.

The crude drawing below shows what happens when a free-air speaker is mounted too close to the edge of its baffle. The short side of the baffle on the right allows low frequencies from the front and back sides to "collide", thus "cancelling out" certain tones of low-end. (shown by opposing sound waves intersecting.)

To simulate this effect, try setting a pair of large old-school hi-fi stereo speakers closely side-by-side. Sit in front of them and listen for a minute. Now, re-connect one of the speakers backwards by reversing the black and red wire. Listen to the same some and notice how there is no bass. One woofer is cencelling out the other woofer's bass tones. This is the effect of "phase cancellation."

A speaker can still be mounted close to the baffle edge if some kind of board is fastened to the back side of the baffle, affectively extending it. Think of an open-backed guitar amp. The amp has "partial" panels at the rear. Basically, they're getting the acoustic effect of mounting a 12" speaker in a 3 foot-by-3-foot baffle, but instead, the baffle is "wrapped around" the back to create an amp cabinet. Any frequencies low enough to phase-cancel are lower than those a guitar produces anyway. Since low-frequencies have long wavelengths, the larger the baffle, the less of the bass is lost due to this phenomenon. Check out the second picture. Both of those rectangular panels in the rear serve a purpose, and they affect the tone of the amp.

-chad

bigbore
04-13-2005, 10:47 AM
hey how you gettin those pictures on there,i mentioned in my old motor forum i was tryin to get my digital camera to upload pictures and the forum upload kept sayin that the file was to big.i played around with the settings on my camera and never was able to get them small enough to upload.

bigbore
04-13-2005, 10:59 AM
hey pyro is right the way to do that correctly is to actually build a box,you will be much happier with the way they perform in a box.you can make the box as small as .5 cu.ft. but to actually make 6.5s or 5.1\4s sound good is to put an enclosure around them and i would go a solid .75 or 1 cu.ft.the sides dont have to be perfectly tight to the gun rail but i would be somewhat picky about the way they fit.also if you are worried about space you could go .5cu.ft. but i would use insulation at that point to surrounnt the interior of the box cause the way insulation obsorbes sound waves and air movement it makes the speaker think that the box is bigger than it is,and i know that to be a fact.plus it does make the sound more efficient also.by the way my #is 815-633-2388.

bigbore
04-13-2005, 11:09 AM
i forgot to tell ya i would also go buy some construction paper to make a pattern for the wood,i had to do that myself for some of the wood i was cuttin for the hydrostream so i can tell ya that target has got that stuff over behind menards.also menards actually has shelving board that is already painted and its made out of the same stuff that you would go buy for box materiel anyway (partical board)im thinking its only colored in white though,but that would probably somewhat match your seats.

skydog
04-16-2005, 01:15 PM
How you doing!! I have got to take you for a ride this year! I got the radio all done. It sounds good and is pretty light. Thank you for all the great info on radios!!(Pyro,bigbore) You still have your boat?

Thank you guys!! Skydog (Matt) Home 636-0032 Cell 289-2555 :D

skydog
04-16-2005, 01:16 PM
I am off of Venture now. Where do you live again? I think we need to just HOOK UP!!

Skydog