dewthedru Posted January 7, 2015 Share Posted January 7, 2015 all right...it's been almost a year since i asked my last questions and i still haven't built them. BUT...i have a Sony VPL-HW40ES on a UPS truck somewhere hopefully close to my house and a 135" screen hopefully on the way as well. and since i have to rewire front and side surround speakers, i might as well just keep going and pre-wire for these subs since i still want to build them. 1 - is it a bad idea to pre-wire subs since you don't really know where they should be placed without doing all the metering sorcery you guys all talk about? 2 - assuming i don't use onboard amps and use something like the following, what kind of speaker wire do i use in the wall to drive them? http://www.amazon.com/dp/B005EHINAS/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1THPEY0T0GK11&coliid=I2S5YRCXZ9NFBS this is what i'm using to drive my current speakers: http://www.monoprice.com/Product?c_id=102&cp_id=10239&cs_id=1023901&p_id=2816&seq=1&format=2 will it drive the subs? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted January 7, 2015 Share Posted January 7, 2015 If you're building 4 subs and plan on centering them on the walls or putting one in each corner, you'll be fine running your wiring there. 12 ga is fine. Quote Link to comment Share on other sites More sharing options...
dewthedru Posted January 7, 2015 Share Posted January 7, 2015 thanks. just building 2 of them. i think 4 be way too much given the limited nature of the rest of my system. heck...i'm not even using an amp yet. just driving my RF-35's with my denon x4000 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted January 7, 2015 Share Posted January 7, 2015 1 - is it a bad idea to pre-wire subs since you don't really know where they should be placed without doing all the metering sorcery you guys all talk about? 2 - assuming i don't use onboard amps and use something like the following, what kind of speaker wire do i use in the wall to drive them? I should have prewired for subs, no its not bad, I'd recommend just purposely wire too much. Its easier to neglect a drop or two rather than to run wire behind drywall later. For normal power I think even 14 gauge is ok up to 25 feet. Theoretically it depends on how long the wire is and how much power you've got. There are charts and stuff out there but realistically speaking what you're asking about is probably fine. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted January 7, 2015 Share Posted January 7, 2015 (edited) I'm surprised you can stack these but maybe the rubber feet is the secret, especially with them being on the outside. My two UltiMax's flex so violently that I can't keep anything on top. There is just enough vibration that stuff scoots around or rattles. That's with heavily braced baltic birch too. Have not tried rubber feet though. Double wall boxes would be better but the boxes you bought aren't made like that. Edited January 7, 2015 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
Scrappydue Posted January 8, 2015 Author Share Posted January 8, 2015 My boxes could be heavier since they are Mdf? Mine flex just as much and I can sit anything on top of the boxes. I wouldn't think little thin rubber feet would make that much difference? But maybe so. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted January 8, 2015 Share Posted January 8, 2015 Mine flex just as much and I can sit anything on top of the boxes. There shouldn't be any flex to a properly braced box. Quote Link to comment Share on other sites More sharing options...
Scrappydue Posted January 8, 2015 Author Share Posted January 8, 2015 Woofer flex is what metro is referring to. Mine don't move at all. Box is braced properly. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted January 8, 2015 Share Posted January 8, 2015 (edited) It may not be the walls flexing, just the whole box vibrates a tiny bit on some higher frequencies when I hit it hard, even on places where I know a fat brace is attached. Plywood may have some resonances that MDF doesn't. Mine are built in a rectangle shape, I tried to put THX's on top which is on the short panel that should be the strongest and flex the least especially considering how I braced it, but it rattled something inside of them. Tried to lay them sideways and put an RC-64 on top which did not rattle but I didn't have any feet or that rubber padding so after a short while of hitting hard the whole thing would scoot backwards until it hit a wall. Some of that rubber padding may fix that. I went a different direction and haven't tried it in awhile. It was mostly only on very hard hitting higher subwoofer frequencies, the super low and slow stuff wasn't an issue. Edited January 8, 2015 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted January 9, 2015 Share Posted January 9, 2015 That's a characteristic of a single driver box. The only way to stop it is to weight the top with a slab of granite or similar. Dual opposed driver boxes normally don't have that problem due to mechanical cancellation. Bear in mind any vibration or box movement is wasting energy that should be projected into the room. Quote Link to comment Share on other sites More sharing options...
Edgar_in_Indy Posted February 21, 2016 Share Posted February 21, 2016 (edited) This thread has been in the back of my mind the last couple years, and so I finally decided to dip my toe into the DIY waters. I wanted to start modestly before jumping in whole hog, so I ordered a 3.0 c/f flatpack from Parts Express, as well as a Dayton DCS385-4 15" driver. Even though my ultimate plan is to build a couple 18" subs using the UM18-22 driver, I figured that I would be able to use this 15" sub somewhere else in the house, or maybe resell it on Craigslist and get some of my money back. The build went fine (although it was more work than I expected) and the sub looks good, but I'm having some trouble with it. It sounds okay and can make some decent bass, but whenever I try turn the volume up to get a more satisfying amount of slam, the woofer makes popping noise in scenes or passages where the bass gets really intense....where it goes low and loud. When I dial things back, it sounds fine. But at that point, the overall sound is not much more impressive than running my RF-7's by themselves. So the sub works, but it's just not very impressive. At this point, I wouldn't trade it for my 8" Velodyne MiniVee, or even my BIC v1220, which is only $188 new. Can anyone tell me what those kinds of sounds mean? Does it mean I'm pushing it too hard? Is it trying to go too low? Or does it maybe need more power? I'm using a BASH 300s amplifier for it. It's the amp that I normally use for my Tuba HT, and for that application it is more than enough power. Is this amp simply too wimpy for a big sealed sub? According to the specs, the driver is rated for 300W RMS/600W peak. At this point I'm feeling pretty discouraged, like I just flushed about $300 and a weekend's worth of work down the drain, so any advise would be greatly appreciated! My wife doesn't let me get away with spending too much on my toys, so any money wasted hurts! Edited February 21, 2016 by Edgar_in_Indy Quote Link to comment Share on other sites More sharing options...
Rowan611 Posted February 21, 2016 Share Posted February 21, 2016 (edited) How low? That driver doesn't go terribly low. Might be a bad driver. Best way to know that is to test it in free air. Should do that with all drivers before hand. Edited February 21, 2016 by Rowan611 Quote Link to comment Share on other sites More sharing options...
Edgar_in_Indy Posted February 21, 2016 Share Posted February 21, 2016 How low? That driver doesn't go terribly low. Might be a bad driver. Best way to know that is to test it in free air. Should do that with all drivers before hand. Pulling it back out to test it would not be a problem. What procedure do you use to test it? What do I look for? How high do I set the gain? etc. I don't have any fancy equipment, but I can run one of those online tone generators from the computer. Quote Link to comment Share on other sites More sharing options...
Rowan611 Posted February 21, 2016 Share Posted February 21, 2016 Without a multimeter to measure voltage going to the driver you have to be careful. Run speaker wire to the leads and run a 20hz tone to it. Gently increase the volume. See if it makes the same sounds. Then, try a lower tone. Your just trying to reproduce the sound in free air. Typed on a tiny keyboard, excuse any grammatical errors. Quote Link to comment Share on other sites More sharing options...
Edgar_in_Indy Posted February 21, 2016 Share Posted February 21, 2016 Without a multimeter to measure voltage going to the driver you have to be careful. Run speaker wire to the leads and run a 20hz tone to it. Gently increase the volume. See if it makes the same sounds. Then, try a lower tone. Your just trying to reproduce the sound in free air. Typed on a tiny keyboard, excuse any grammatical errors. Makes sense. I actually do have a multimeter though. How should I use it during the test? Quote Link to comment Share on other sites More sharing options...
Rowan611 Posted February 21, 2016 Share Posted February 21, 2016 Turn the dial to volts or amps, put the leads to their corresponding + - on the amp and measure how much the amp is sending out. If you start the volume low, you might just be able to skip this step. I did this while breaking I'm my driver before I built me THT, haven't used mine since. Lol Typed on a tiny keyboard, excuse any grammatical errors. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted February 21, 2016 Share Posted February 21, 2016 You may want to start a separate thread in the subwoofer section since it is not related to the original post. My quick thoughts, the amp! Quote Link to comment Share on other sites More sharing options...
Edgar_in_Indy Posted February 21, 2016 Share Posted February 21, 2016 Turn the dial to volts or amps, put the leads to their corresponding + - on the amp and measure how much the amp is sending out. If you start the volume low, you might just be able to skip this step. I did this while breaking I'm my driver before I built me THT, haven't used mine since. Lol Typed on a tiny keyboard, excuse any grammatical errors. Is this while the amp is hooked up to the speaker? Quote Link to comment Share on other sites More sharing options...
Rowan611 Posted February 21, 2016 Share Posted February 21, 2016 I'd do it without the sub hooked up. Typed on a tiny keyboard, excuse any grammatical errors. Quote Link to comment Share on other sites More sharing options...
Edgar_in_Indy Posted February 21, 2016 Share Posted February 21, 2016 I'd do it without the sub hooked up. Typed on a tiny keyboard, excuse any grammatical errors. Should I be sending any particular frequency(ies) to the amp during the test? Quote Link to comment Share on other sites More sharing options...
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