DrWho Posted March 23, 2006 Share Posted March 23, 2006 I really need to start keeping a journal of all my audio adventures...mostly so I can remember specific model numbers of anything. I'm sure the long stories bore everyone, but at least I've got pretty pictures this time [] Anyways, it has been spring break this last week and I carpooled home with a friend on campus (we were actually high school buddies and went to Germany together, it's so aweseom that we ended up at the same university). We both have very similar musical tastes and he wanted my opinion on the sound system in his car. He's got the stock "premium" sound system in his truck and we both felt the high end could use a little help. But alas, we are college kids and that means finding the cheapest way possible of finding a good remedy. I mention that partsexpress has a bunch of tweeters for dirt cheap and that there were some $5 tweeters I was considering putting in my car (which has the same problem). We decided that this would be a great way to kill time while on break - which was the ultimate concern (everyone calls it "naperthrill"). Monday rolls around and since we were looking for stuff to do we decided to shop around and see if we couldn't find cheap tweeters at any of the local stores. A couple hours later our best option was $150 (and they'd have to be ordered) Yikes! Off we go to partsexpress and have them express shipped so that we could have something to do.(http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=275-030) So it's Monday and only 3pm...we decide to tear off one of his door panels to see how things are wired and to figure out how we will connect the tweeters. 2 hours later we get the passenger door panel off and get her figured out. In the meantime we noticed that there were speakers in the rear behind the seats. A couple minutes later I make mention that I have a bunch of promedia woofers laying around and we decide to remove the rear speakers and install a new subwoofer in his truck too. So at 5pm we entered the design stage and 12 hours later we completed the sub (with 4 hours worth of breaks for dinner and a movie in the middle). We had to make some compromises with the design because there was barely any space to work with and so the finished cabinets ended up being 75% the size of the original promedia subs. But that was ok, because we were no longer implementing the EQ that was built into the promedia amp and we had a lot of cabin gain on our side. There is a nasty resonance in the system, but it's nothing that can't be taken care of with a simple low pass filter (but the problem there is a HPF filter will cost $20). Tuesday was my birthday and it was funny to be greeted by my mom at 6am offering to cook us breakfast. It worked out well though because Tuesday was filled with the typical birthday stuff and thus we had stuff to do. Wednesday rolls around and our tweeters arrived at 2:30pm. Up to this point we hadn't decided on a method of mounting the tweeters to the car and figured it could best be figured out when we had an actual tweeter to play with. Off we go to Home Depot....3 hours later and 2 designs later we came up with a very basic velcro solution (the original designs all involved some form of clamping mechanism that we were going to clamp to both the tweeter and the plastic on the A frame). After a long break for dinner we begin work on the tweeters at 7pm. Wiring up the passenger side was pretty easy. I think it took about an hour. With the tweeter purchase we also bought parts for building a crossover. Just one of each for each tweeter:(http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=027-336)(http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-024&DID=7)This was my first crossover build ever and so was a bit nervous about really screwing stuff up. But in the end it couldn't have been a better transition - it was an amazing shot in the dark [H] Wiring up the driver side took forever though as we were unable to access the speaker wire at any point along the path (the radio was inaccessible so we had to splice into the wire by the doors). But in the end we figured out a way (like 4 hours later). It was kinda funny because mounting the tweeter on the left was easy, but we were having problems on the right side...thus why there is a sandal holding the tweeter on the right. So we pretty much finished at 3am this morning and for under $80 we totally transformed the audio in his car. We didn't finish listening to tunes until 4am...and it sounded pretty good with our critical ears on. I can't wait for the ride back to school where we won't be as tired and won't have our critical ears making it sound worse. One little oops in the design was I totally forgot about the new impedance after wiring the tweeter in parallel....so we are now presenting about a 3ohm load to his amplifier (after crossover losses are considered). At least I think wiring a 6 ohm tweeter in parallel with a 4 ohm woofer comes to about 2.4 ohms? I'm not sure if it's different considering that they aren't playing the same bandwidth...I would think the impedance would be higher. Anyways, it was something I totally forgot to think about until we were about to power them up....but we had it cranked pretty loud and there didn't seem to be any problems. So ya, that's my story...hope you enjoy the pics: Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 23, 2006 Author Share Posted March 23, 2006 the other side Quote Link to comment Share on other sites More sharing options...
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DrWho Posted March 23, 2006 Author Share Posted March 23, 2006 A quick question for you experts out there... What is the best way to attach capacitors and air core inductors to a piece of wood? As you can see they are duct taped right now, but that probably won't work as a permanent solution - especially in the car. And then how does one go about covering it up to protect from the elements? In case anyone is wondering...we couldn't get the ports out of the stock promedia subs so we just cut the wood out with a jigsaw and mounted the whole thing to the baffle. There is also a vertical support seperating the subwoofer into two seperate cabinets...they are being fed a stereo signal so it made sense to isolate each woofer from the same airspace (that way a bass note in one woofer wouldn't cause the other to become a passive radiator). We also stuffed the crap out of the cabinet, which helped to get rid of some of the resonance issues we were having (but I think it actually reduce the low frequency extension). I think I am going to suggest that we turn the design into a 6th order bandpass. We've got left over wood and this would be an acoustic way of implementing a LPF filter. There isn't much space to work with, but I think it can be done. Quote Link to comment Share on other sites More sharing options...
boom3 Posted March 23, 2006 Share Posted March 23, 2006 The simpliest way to mount components to wood is to drill holes on each side and use zip ties. A piece of foam tape over the components, especially caps, is a wise precaution to keep the zip ties from compressing them too much. Don't use silicone seal or hot glue. As far as protection from the elements, if they are inside the cab they are protected from moisture well enough. It's impact and maybe a misplaced foot or piece of cargo I'd worry about. I'd put a piece of acrylic on standoffs over the crossover board to keep stray things from making direct contact with the components. You could also mummify the crossover board with electrical tape. That provides extra sealing and is easy to remove when you want to change the crossover. Just looks kinda tacky. Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted March 23, 2006 Share Posted March 23, 2006 What happened to sunny locations, perhaps an alcoholic beverage and definitely scantly clad women during spring break? I lived it up more but you will definitely live longer. Am impressed with your work, good luck. Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 23, 2006 Author Share Posted March 23, 2006 Hey, great idea boom...and it's cheap. Thanks. Btw, the crossovers are already mummified in electrical tape - it's just hard to see under the blanket of duct tape. As far as spring break is concerned, it was just too fricken cold to do anything fun outside. The original plan was to bust out some Kuk Sool Won, but alas cold wet grass isn't pleasant on the bare feet. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted March 24, 2006 Share Posted March 24, 2006 A hot glue gun also works very well to secure the parts and they won't rattle or move. Drilling holes and using zip ties works also but the hot glue requires much less effort. If you friend wants a killer amp to power that system to potential on the cheap. I will sell you my Orion XTR-450 for $100 plus shipping. She ain't pretty but she sings like you would not believe. Much better than the crap that is being peddled in the car audio world these days. You can easily drop this amp to 1.5 ohms in stereo and it puts out consideraly more wattage than the official rating especially when fed 13.8-14.4V. I am now using it's big brother in my car. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9703116911&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1 Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 25, 2006 Author Share Posted March 25, 2006 If you friend wants a killer amp to power that system to potential on the cheap. I will sell you my Orion XTR-450 for $100 plus shipping. Hey, thanks for the offer. But $100 is more than double what we spent on everything (I sold him the promedia drivers I got off ebay for like $5 each). Gotta love cheap upgrades [] Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted March 26, 2006 Share Posted March 26, 2006 Dr.Who, Great story. Thanks for posting. Sounds like a very good spring break. Quote Link to comment Share on other sites More sharing options...
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