Posted January 27, 200817 yr I'm in the process of building a home theater sub using one of the Mach 5 Audio MJ-18s, I'm going with the recommended 8.8 cubic foot enclosure and was using Win ISD to plot the slot port. I have 2 questions, 1.) What type of vent should I use with this? Should I go with the slot vent or use the conventional round vents? 2.) How much power should I feed this sub? Does anyone have a recommendation for an amplifier for this sub? I don't care if it's conventional or a plate amp. Thanks again everyone.
January 27, 200817 yr Which MJ18? There's an 8 ohm version and a 4 ohm version. Each models differently and has specific requirements.
January 27, 200817 yr Author Which MJ18? There's an 8 ohm version and a 4 ohm version. Each models differently and has specific requirements.4 ohm model, it was the one with the lower FS and most home stereo sub amps are rated at 4 ohm. I thought it looked like the better choice.
January 27, 200817 yr The 4 ohm version models a little better. Two 4 inch flared ports 21.75 inches long would tune it to 18hz. The 300 watt Bash amp from Mach 5 is a good match for this sub. WinISD shows Spl to be 106db down to 18hz, and then you add room gain on top of that. A slot port would work too, although I'ver never built one. I've always used flared ports.
January 29, 200817 yr Author I got a smoking deal on a BASH 500 amp today (the exact same BASH 500 parts express sells). All the stuff's on the way so hopefully I'll have this together within the first half of Febuary! Does anyone have input on using a slot vent for this woofer? I'm considering doing that in a wide "coffee table" looking box or doing a really tall box with the woofer down firing. How much do I have to compensate if I down fire the woofer?
January 29, 200817 yr Depends on what surface the woofer is firing into. For solid floors, you shouldn't have to compensate at all. For carpet or rugs... its kind of hit or miss what to do.
January 29, 200817 yr Author But the enclosure volume or port won't change? I thought you had to compensate for the mass of the cone? I'll pretty much always have it on rugs and such so It sounds like I'll make the coffee table style box and work out something to hide it, turn it into a lamp or a chair or something.
February 4, 200817 yr Author I got the BASH 500 amp the other day and tested it out on my JLW3, it will absolutly peak this sub in the 1.5 cubic foot ported enclosure it's in. DHL is supposed to drop off the 18 today and I'm going to start drawing up the enclosure now. This should be interesting, that JL 10 was extremely loud on the 500 watt amp.*Small world, as I was writing this the DHL guy dropped off the sub!* Edited February 4, 200817 yr by Brian10962001
February 5, 200817 yr Author IT LIVES! I got the enclosure finished last night and did a small listening session with it. This thing is UNGODLY loud. I really didn't realize how big the enclosure was going to be while putting it together, I ended up with an 8.97cft chamber and a 1.5 X 14 X 25.25 vent. I didn't know the exact sub displacement so I guessed it and it seems to have worked out fine. This thing is too loud, I seriously think I overdid it this time! I'm surprised how musical the sub is, even before it was broken in it surprised me at how well it kept up with music, very unexpected! I have to honestly say this is the best 300 bucks I've ever spent but moving it is going to be one HUGE pain.
February 9, 200817 yr Author I have pics taken specifically to put them on here but there's no basic upload controls, do they have to be HTML'd in? I"ll throw them up on my Photobucket and post a link. I honestly haven't been able to play this sub long eough to break it in, I need to get a test tone cd and let it rip at 20hz for a while.
February 9, 200817 yr Author Pics!http://i254.photobucket.com/albums/hh93/19...ow/DSC00489.jpghttp://i254.photobucket.com/albums/hh93/19...ow/DSC00492.jpghttp://i254.photobucket.com/albums/hh93/19...ow/DSC00490.jpghttp://i254.photobucket.com/albums/hh93/19...ow/DSC00494.jpghttp://i254.photobucket.com/albums/hh93/19...ow/DSC00495.jpg
February 13, 200817 yr Admin We have a gallery here just for this purpose. Just start your own album, upload some pictures, right click the picture, copy the picture address, paste into a post with tags.
February 15, 200817 yr Author I wondered how the image hosting here worked, I just used photo bucket because I already had the account and didn't have the energy to investigate it at the time. As for finishing the box, I'm still debating if I should wood grain it or if I should just spray it down with some truck bed liner. I like doing the bed liner because it seals the box and makes it waterproof but a nice big oak looking cabinet would be nice and match my Mitsubishi tower speakers. I'll post up some pics when i finally finish it. Last night we placed the sub in the corner by my TV and it really enhanced the sound with the corner loading.
February 16, 200817 yr sorry to hi-jack this thread, but what is the recommended sealed HT enclosure size for the mj-18? lookin for a range like 4.5 -7cu ft instead of just one size
February 19, 200817 yr Author It didn't take much more effort for me to build the slot vent into my enclosure, and it's not alot bigger than 7 cubes. Plus with the vent it's way more awesome on the sub bass. The sub is plenty musical, I'de just do the vented design like I did. Otherwise just go as big as you can with the sealed; it won't drop as low as the same size vented enclosure and you probably won't notice much of a difference in bass definition.
February 21, 200817 yr It didn't take much more effort for me to build the slot vent into my enclosure, and it's not alot bigger than 7 cubes. Plus with the vent it's way more awesome on the sub bass. The sub is plenty musical, I'de just do the vented design like I did. Otherwise just go as big as you can with the sealed; it won't drop as low as the same size vented enclosure and you probably won't notice much of a difference in bass definition.uh-uh, i did 7 cubes with my tempest 2 summers ago........... that thing was too big, even after i got used to it
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.