I'm installing a low-budget (that is to say, cheaper than a night out drinking) marine stereo in my boat. It came with some 6.5" speakers. I have no numbers on the speakers but instead of cutting big holes in the boat to mount them I plan on making some boxes for them. Should I worry about box size, or just make some little boxes that fit? The purpose of the boxes is primarily to make a place to mount them without cutting the boat. I know they'll never sound wonderful, but can you give me some tips on making boxes that will at least guestimate on making the best of things?
Replies (15)
swez on 04/6/2007 08:09:02
Since we don't know much about your speakers, consider a sealed box that is about 8" H x 8" W x 7" D and use 5/8" thick wood. This nets about 0.15 cf per box internally and should sound pretty good for most 6.5" speakers.
Since this is for marine use, the box should be coated or painted with water proof material like marine paint or urethane or epoxy based clear coats. That will protect them from water and they won't fall apart in short order.
Also, consider PVC tubing as an option. Here, an 8" I.D pipe, a set of end caps and an internal length of 6.5", will net a 0.15 cf air space as well. PVC is water proof and can be painted as well. The result is a short tube that can be mounted in any way you see fit.
In either case, a small amount of polyfill stuffing, (1/4 lbs/enclosure) will help dampen the rear cone waves and reduce resonance issue too.
Comments?
Swez
ShootuhMcBustaCap on 04/6/2007 13:31:31
Good call with the PVC pipe there Swez! Definitely a creative Idea.
swez on 04/6/2007 13:43:20
I like to think outside the box once in a while. It's easy to find, low cost, minimal fabrication needed and it works too!
Swez
ShootuhMcBustaCap on 04/6/2007 17:50:43
Outside of the box, and inside of the pipe? LOL!!!
cplkittle on 04/6/2007 20:02:02
Since they are designed for free air use normally, any size would be fine. I wouldn't go any smaller than what Swez recommended, but larger is fine too.
Victor on 04/7/2007 16:26:08
At the max what I would recommend is 0.5 cuft.. anything larger will add to a lot of distortion and very less control over the cone...
cplkittle on 04/7/2007 19:10:49
how is that when they are designed for free air applications?
If they are too large they may become boomy, but I wouldn't think they would distort due to loss of control over the cone.
swez on 04/7/2007 20:03:09
After experimenting with a pair of 5.25" MB speakers a while back, I noted a substantial improvement in MB and good midrange performance in a 0.15 cf cylinderical enclosure at about 75 Wrms.
I was playing with a 3-way box design and used passive crossovers and tried a 12" woofer, 5.25" MR and a 1" Metal dome tweeter. All 3 speakers were car audio drivers and there was not much low bass due to the low efficiency of the woofer and high efficiency of the MB/TW. Bi-amping would be the best choice over a complex passive x-over network.
I was so dissappointed in the initial results, I tossed the tweeters in the trash can, (Very shrill, harsh and overbearing) removed the MB/MR driver and tried it alone in a test tube I had made up with a Folger's container. Wow... was I shocked at the performace of this small speaker in terms of punch, got pretty low and did MR very well too.
Honestly, I had no idea how solid of MB these little Bahn speakers could deliver until using a 12 band EQ to blank out low bass, (under 60 Hz.) and rolled off the mids at 5KHz. (Minus 12dB/oct slopes on both ends, active filtering)
I stuffed the container with a small wad of polyfill and then snapped everything back together and turned on some music. At moderate volume, they sounded pretty darn accurate and good punch too. When I dial up the power to 60-75 watts, these little puppies came to life and the kick drum thumps were so robust, the endcaps at the back of the enclosures just blew right off. Hummm.... think I'm on to something here fellas?
Yes, this was just a general test of performance and no, I did not use test tones, a signal generator and RTA to measure how good the numbers were. (No LEAP Plot) But when all was done and I demo'd several tracks of soft ond high energy MB/MR cd's, the results were definitely worth the effort.
This was completely imperical testing and I just wanted to get an idea what size sealed enclosure would work well for these speakers. The enclosures came out to about 0.15 cf each. So, for a 6.5" round, I am guestimating that a 0.2 cf enclosure should do a pretty good job here too. A tad larger may be OK as well. It all depends on the speaker compliance and how robust the surrounds are for excursion purposes.
Take all this for what it's worth... just a simple test that showed some definite promising results. "Free air speaker performance can be enhanced notably with an enclsosure."
That's all folks,
Swez
curtis73 on 04/11/2007 22:05:25
Great tips and that's exactly what I was looking for. The PVC is probably my choice.
I figured that one day I'm sure I'll get the audiophile bug for the boat, too, so might as well have the good boxes ready for good speakers. I'm scrambling to get this boat on the water this summer and I was at Cabela's last week. They had a "Dual" brand 25w rms CD with speakers combo for the whopping discount price of $65 on clearance. It'll get me tunes for this summer anyway.
Anyone know of some good marine speaker makers? I know Sony and Kenwood makes marine stuff, but I'm not a big fan of them. MBQ maybe?
swez on 04/11/2007 23:20:33
JBL makes marine speakers as does MTX. The main thing, are we talking fresh water or saltwater as your main domain?
Swez
curtis73 on 04/12/2007 01:35:49
Mainly fresh. Maybe never salt, but I'm sure the temptation will lead me to salt maybe once a year.
ShootuhMcBustaCap on 04/12/2007 09:56:58
Alpine also makes a few marine speakers, but am not sure how expansive they are on this. They had a pair of 30RMS 6.5's for marine applications at car toys, but they were discontinued. Maybe sell better at Boat Toy's?
swez on 04/12/2007 10:37:01
Once a year in salt water is not a big issue for most electronics on a boat. Marine specific units are more robust against saltwater, but in fresh water, as long as things don't get heavily soaked, they will usually be fine with the normal car audio speakers that use non-paper cones.
When buying electronic gear at a boat store, the prices are often outrageously high priced. Probably due to low volume purchasing and high profit margin markups too. If one had a 2-5 Million dollar inventory of boats and supplies, the markups on smaller items would have to to be high to make up for the low margin sales on big ticket items.
Car dealerships have the same thing to contend with. Why do you think parts and service prices are so high there? (Overhead and profits need to be generated here as they have huge inventory costs)
Swez
curtis73 on 06/5/2007 21:33:17
I appreciate all the replies. I went to the store and sifted through a bunch of 6" and 8" PVC. The 6" would have worked with some combinations of parts, the problem is, 6" fittings aren't cheap. It would have taken about $60 worth of material; not bad, but there would have been a bunch left over and I couldn't do it without some interesting gluing.
A friend offered me some 3/4" MDF for free so I couldn't pass it up :) I built two boxes for the 6.5" speakers that spec out to 6.5" x 7.5" x 7.5" inside which comes out to 0.212 cu ft. I figured I'd make them a little big and I can fill them with MDF scraps depending on the specs of future speakers.
I also had enough to build some nice boxes for 6x9s later. They are 10.5 x 6.5 x 7.5 inside for 0.296 cu ft. A little small for most 6x9s but I think they'll work nicely.
I mixed up some epoxy and coated them and tomorrow they get paint. Thanks for all the ideas and guidance.
swez on 06/5/2007 22:49:43
Sounds like you may have a workable plan here Curtis. If the bass on these 6.5" speakers seem a bit sloppy and poorly defined, start adding wood filler boards until you get a nice, crisp sound.
Good luck!
Swez
PS Care to make a donation to the CK operating budget? We're getting a mite thin on cash reserves and could use the extra support.
Replies (15)
swez on 04/6/2007 08:09:02
Since we don't know much about your speakers, consider a sealed box that is about 8" H x 8" W x 7" D and use 5/8" thick wood. This nets about 0.15 cf per box internally and should sound pretty good for most 6.5" speakers.
Since this is for marine use, the box should be coated or painted with water proof material like marine paint or urethane or epoxy based clear coats. That will protect them from water and they won't fall apart in short order.
Also, consider PVC tubing as an option. Here, an 8" I.D pipe, a set of end caps and an internal length of 6.5", will net a 0.15 cf air space as well. PVC is water proof and can be painted as well. The result is a short tube that can be mounted in any way you see fit.
In either case, a small amount of polyfill stuffing, (1/4 lbs/enclosure) will help dampen the rear cone waves and reduce resonance issue too.
Comments?
Swez
ShootuhMcBustaCap on 04/6/2007 13:31:31
Good call with the PVC pipe there Swez! Definitely a creative Idea.
swez on 04/6/2007 13:43:20
I like to think outside the box once in a while. It's easy to find, low cost, minimal fabrication needed and it works too!
Swez
ShootuhMcBustaCap on 04/6/2007 17:50:43
Outside of the box, and inside of the pipe? LOL!!!
cplkittle on 04/6/2007 20:02:02
Since they are designed for free air use normally, any size would be fine. I wouldn't go any smaller than what Swez recommended, but larger is fine too.
Victor on 04/7/2007 16:26:08
At the max what I would recommend is 0.5 cuft.. anything larger will add to a lot of distortion and very less control over the cone...
cplkittle on 04/7/2007 19:10:49
how is that when they are designed for free air applications?
If they are too large they may become boomy, but I wouldn't think they would distort due to loss of control over the cone.
swez on 04/7/2007 20:03:09
After experimenting with a pair of 5.25" MB speakers a while back, I noted a substantial improvement in MB and good midrange performance in a 0.15 cf cylinderical enclosure at about 75 Wrms.
I was playing with a 3-way box design and used passive crossovers and tried a 12" woofer, 5.25" MR and a 1" Metal dome tweeter. All 3 speakers were car audio drivers and there was not much low bass due to the low efficiency of the woofer and high efficiency of the MB/TW. Bi-amping would be the best choice over a complex passive x-over network.
I was so dissappointed in the initial results, I tossed the tweeters in the trash can, (Very shrill, harsh and overbearing) removed the MB/MR driver and tried it alone in a test tube I had made up with a Folger's container. Wow... was I shocked at the performace of this small speaker in terms of punch, got pretty low and did MR very well too.
Honestly, I had no idea how solid of MB these little Bahn speakers could deliver until using a 12 band EQ to blank out low bass, (under 60 Hz.) and rolled off the mids at 5KHz. (Minus 12dB/oct slopes on both ends, active filtering)
I stuffed the container with a small wad of polyfill and then snapped everything back together and turned on some music. At moderate volume, they sounded pretty darn accurate and good punch too. When I dial up the power to 60-75 watts, these little puppies came to life and the kick drum thumps were so robust, the endcaps at the back of the enclosures just blew right off. Hummm.... think I'm on to something here fellas?
Yes, this was just a general test of performance and no, I did not use test tones, a signal generator and RTA to measure how good the numbers were. (No LEAP Plot) But when all was done and I demo'd several tracks of soft ond high energy MB/MR cd's, the results were definitely worth the effort.
This was completely imperical testing and I just wanted to get an idea what size sealed enclosure would work well for these speakers. The enclosures came out to about 0.15 cf each. So, for a 6.5" round, I am guestimating that a 0.2 cf enclosure should do a pretty good job here too. A tad larger may be OK as well. It all depends on the speaker compliance and how robust the surrounds are for excursion purposes.
Take all this for what it's worth... just a simple test that showed some definite promising results. "Free air speaker performance can be enhanced notably with an enclsosure."
That's all folks,
Swez
curtis73 on 04/11/2007 22:05:25
Great tips and that's exactly what I was looking for. The PVC is probably my choice.
I figured that one day I'm sure I'll get the audiophile bug for the boat, too, so might as well have the good boxes ready for good speakers. I'm scrambling to get this boat on the water this summer and I was at Cabela's last week. They had a "Dual" brand 25w rms CD with speakers combo for the whopping discount price of $65 on clearance. It'll get me tunes for this summer anyway.
Anyone know of some good marine speaker makers? I know Sony and Kenwood makes marine stuff, but I'm not a big fan of them. MBQ maybe?
swez on 04/11/2007 23:20:33
JBL makes marine speakers as does MTX. The main thing, are we talking fresh water or saltwater as your main domain?
Swez
curtis73 on 04/12/2007 01:35:49
Mainly fresh. Maybe never salt, but I'm sure the temptation will lead me to salt maybe once a year.
ShootuhMcBustaCap on 04/12/2007 09:56:58
Alpine also makes a few marine speakers, but am not sure how expansive they are on this. They had a pair of 30RMS 6.5's for marine applications at car toys, but they were discontinued. Maybe sell better at Boat Toy's?
swez on 04/12/2007 10:37:01
Once a year in salt water is not a big issue for most electronics on a boat. Marine specific units are more robust against saltwater, but in fresh water, as long as things don't get heavily soaked, they will usually be fine with the normal car audio speakers that use non-paper cones.
When buying electronic gear at a boat store, the prices are often outrageously high priced. Probably due to low volume purchasing and high profit margin markups too. If one had a 2-5 Million dollar inventory of boats and supplies, the markups on smaller items would have to to be high to make up for the low margin sales on big ticket items.
Car dealerships have the same thing to contend with. Why do you think parts and service prices are so high there? (Overhead and profits need to be generated here as they have huge inventory costs)
Swez
curtis73 on 06/5/2007 21:33:17
I appreciate all the replies. I went to the store and sifted through a bunch of 6" and 8" PVC. The 6" would have worked with some combinations of parts, the problem is, 6" fittings aren't cheap. It would have taken about $60 worth of material; not bad, but there would have been a bunch left over and I couldn't do it without some interesting gluing.
A friend offered me some 3/4" MDF for free so I couldn't pass it up :) I built two boxes for the 6.5" speakers that spec out to 6.5" x 7.5" x 7.5" inside which comes out to 0.212 cu ft. I figured I'd make them a little big and I can fill them with MDF scraps depending on the specs of future speakers.
I also had enough to build some nice boxes for 6x9s later. They are 10.5 x 6.5 x 7.5 inside for 0.296 cu ft. A little small for most 6x9s but I think they'll work nicely.
I mixed up some epoxy and coated them and tomorrow they get paint. Thanks for all the ideas and guidance.
swez on 06/5/2007 22:49:43
Sounds like you may have a workable plan here Curtis. If the bass on these 6.5" speakers seem a bit sloppy and poorly defined, start adding wood filler boards until you get a nice, crisp sound.
Good luck!
Swez
PS Care to make a donation to the CK operating budget? We're getting a mite thin on cash reserves and could use the extra support.
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