chops Posted May 22, 2006 Share Posted May 22, 2006 Sat night, 9pm: So I decided to do something with the two spare Dayton 15DVC drivers I had sitting around (1 used, 1 new), so I built a push-pull subwoofer to save space and still get max output and extension. After driver and brace displacement, I'm guessing it's about 6.3 cu.ft. sealed from it's original 6.59 cu.ft. It's a 24" cube. It's not the prettiest thing, but certainly sounds darn good! Sun, 1pm: So once I figured out what I was doing for a sub, I went up to Lowes with my "other" brother and his SUV to get the 4x8 sheet of .75" MDF and have it cut there to my specs. I'm just tired of building all of my projects with a stinkin' jig saw all the time, hence why I had them do the cutting. I was expecting to pay $30 or so for the wood and cuts. The MDF was $20 and there were about 7 or 8 cuts @ $.50 each. The guy that was helping me was the department manager. He was a little light in his loafers too, if you know what I mean, but he was pretty cool and funny as hell. Anyway, he said he hadn't used that vertical saw in a while, and he made a couple of mistakes, being about an 1/8" off on a couple of cuts. So he ended up giving me the 4x8 sheet and all the cuts, plus corrected the cuts for a grand total of $10!! All because he appreciated us being so patient with him! 2pm: We get back home and I start measuring out the voids to cut out of the brace and the driver motorboards. I then ask my brother jt1stcav to give me a hand in cutting and assembling the cabinet. 6pm: After a lot of drilling and screwing and siliconing, and lunch break, I wire up and install the drivers (both VCs wired in parallel for 4 ohms on each driver) and connect them to the amp. Between 6-8pm, I clean up everything, eat dinner, play several different choice CDs, then setting down around 8:30 or so for a movie... AEon Flux According to one of the guys on the DIY Audio forum, he says that my sub should have a Qtc of about 1.0 and an F3 of 30Hz via BassBox software. Then when you consider the room gain (which comes on strong in my room below 30Hz), I'm getting solid clean output well below 16Hz. Efficiency is another amazing thing about this sub. With moderate volume levels, the amp is only reading between 0.5 and 1 watt! When I'm really cranking the volume with some of my CDs or in the movie last night, the meter only reached 30 watts and peaked 50 watts once or twice, and it was loud as heck in here. Louder than I would normally ever play my system. I would really love to know what the actual efficiency of this sub is. I'm thinking that it's maybe up there around 100dB or so. The amp I'm using is an old Technics SU-8099 integrated that was bought back in 1979 with the Cornwalls new. It's rated at 115W @ 8 ohms per ch and 180W @ 4 ohms per. I have the drivers wired to a 4 ohm load to each channel of the amp and have the sub line-out on my receiver going into the "Main In" on the SU-8099 which bypasses ALL tone and volume controls. Right now, it is nothing more than just a two-channel amp. Plus its freq resp is rated down to DC (0Hz) for the first 5 watts or so! I was thinking about getting a Samson Servo 600 amp to put 600 watts into this sub, but now I'm not sure I even need it. And I think I can safely say that this sub outperforms my old SVS PB12-ISD/2 that I used to have, even when tuned to its 16Hz setting. I know this thread should probably be in the "Subwoofer" section of the forum, but with all the stuff going on down there right now, I'd rather not have to go there. So with that all out of the way, on with a few pictures... of course! [] Quote Link to comment Share on other sites More sharing options...
tofu Posted May 22, 2006 Share Posted May 22, 2006 i too am using an old receiver to power my sub, but it's very quirky.. i can't get good output unless i connect it to the phono inputs on my receiver. if i connect it to the cd input, i have to literally turn my receiver volume up 100% to get output. i can't figure out why, and it drives me nuts. i also have tape in/outs but i haven't tried those. been using phono for now, but it's not too clean. any suggestion on an inexpensive subwoofer amp (preferably not plate.. i don't want to have to modify my enclosure again) i can pick up? don't need much power. sub is a 12" adire audio shiva using the plans for their 80 something litre sealed enclosure. thanks. -chris Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted May 22, 2006 Share Posted May 22, 2006 Nice job. You do good/quick work. How did you have the time with all the BOSE Cannon debate going on? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted May 22, 2006 Share Posted May 22, 2006 how are these wired ? Quote Link to comment Share on other sites More sharing options...
chops Posted May 22, 2006 Author Share Posted May 22, 2006 how are these wired ? The drivers have dual 8 ohm coils. I wired the VCs in parallel for 4 ohms per driver total. I am powering each driver with one channel of the amp. It's a 2-channel amp, one driver per channel. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 22, 2006 Share Posted May 22, 2006 Nice job. You do good/quick work. How did you have the time with all the BOSE Cannon debate going on? LOL Quote Link to comment Share on other sites More sharing options...
chops Posted May 22, 2006 Author Share Posted May 22, 2006 Nice job. You do good/quick work. How did you have the time with all the BOSE Cannon debate going on? LOL Come on people, let's not crap up this thread now. And to answer your question jacksonbart, I am quite capable of multitasking. Please, let's stay on topic. Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted May 22, 2006 Share Posted May 22, 2006 Nice job. You do good/quick work. How did you have the time with all the BOSE Cannon debate going on? LOL Come on people, let's not crap up this thread now. And to answer your question jacksonbart, I am quite capable of multitasking. Please, let's stay on topic. How did you handle the cross over or are you sending the full signal over? How does it work if both speakers are powered, vs say a passive speaker, doesn't it cause an issue if both are powered and in phase? Not being a smart @ss just trying to learn. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted May 22, 2006 Share Posted May 22, 2006 ok...clear. Quote Link to comment Share on other sites More sharing options...
chops Posted May 22, 2006 Author Share Posted May 22, 2006 How did you handle the cross over or are you sending the full signal over? How does it work if both speakers are powered, vs say a passive speaker, doesn't it cause an issue if both are powered and in phase? Not being a smart @ss just trying to learn. The sub is crossed over at 50Hz via the subwoofer output on my Pioneer Elite receiver. I'm not sure if it's a 16, 24, or 36dB crossover or not though. A passive radiator is nothing more than a tuned port, without actually being a vent. The drivers are in fact out of phase being that they face away from eachother. At the very bottom of this page, it gives you a good explination of the push-pull concept. This has been the design choice of M&K subs for years, since 1989 with the introduction of the MX 2000... http://www.danmarx.org/audioinnovation/theories.html http://www.mksound.com/timeline.htm Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted May 22, 2006 Share Posted May 22, 2006 Sweet, thanks. **this is a joke oh, does it shoot mellons?end of joke*** Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted May 22, 2006 Share Posted May 22, 2006 Meth........can be a useful tool and a wonderful thing. [<)] just kidding[] Terry Quote Link to comment Share on other sites More sharing options...
chops Posted May 22, 2006 Author Share Posted May 22, 2006 Sweet, thanks. **this is a joke oh, does it shoot mellons?end of joke*** No problem. BTW, it doesn't shoot mellons, but it does a great job of smashing them! LOL Quote Link to comment Share on other sites More sharing options...
Guest " " Posted May 22, 2006 Share Posted May 22, 2006 some food for thought i took a look the links...great links...but do you have a hybrid (both woofers installed normally, magnet inside the cab, wired normally) or are you actually installing one of the drivers back-wards as the web site explains...or are you reversing the wiring on the rear woofer assuming it is also installed magnet side in as the front? what i am curious about...if really set up as push pull...since you show woofers facing left and right rather than front and back...the speaker nearest the invertedly phased woofer (mounted back wards as push pull shows, or wired backwards) would interact in such a way as to cancel out a portion of the lower end closest to the operating frequency of the sub woofer. if there is any substance to this concern...with some further tweaking...sound potential might be more awesome than the current wireing config. Quote Link to comment Share on other sites More sharing options...
chops Posted May 23, 2006 Author Share Posted May 23, 2006 some food for thought i took a look the links...great links...but do you have a hybrid (both woofers installed normally, magnet inside the cab, wired normally) or are you actually installing one of the drivers back-wards as the web site explains...or are you reversing the wiring on the rear woofer assuming it is also installed magnet side in as the front? what i am curious about...if really set up as push pull...since you show woofers facing left and right rather than front and back...the speaker nearest the invertedly phased woofer (mounted back wards as push pull shows, or wired backwards) would interact in such a way as to cancel out a portion of the lower end closest to the operating frequency of the sub woofer. if there is any substance to this concern...with some further tweaking...sound potential might be more awesome than the current wireing config. Yes, both drivers are mounted facing away from eachother. As far as some bass being cancelled between the one phase inverted driver and the K-33 in the CW, I don't know if that's an issue or not. They are both crossed over at 50Hz, so... This is what you're talking about, correct? Here's a couple pics showing both sides... Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted May 23, 2006 Share Posted May 23, 2006 I think what he is asking is if one driver is wired out of phase with the other (in the sub). If it is, than wouldn't one driver be wired out of phase with your mains? Correct me if I'm wrong. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted May 23, 2006 Share Posted May 23, 2006 that was the question. but since chops said they are not wired special, then they are in phase....they both push the same direction with the same signal applied (they both go outward together...and inward together). the web site chops provided introduces a few types of speaker arrangements...the one that caught my eye was the picture with the woofer in the rear mounted backwards (I would imagine the same effect if you just wired the rear one backwards). discribed as push-pull.....with the same signal applied...the front woofer sends waves into the listening area...the second woofer sends waves into the cabinet (towards the rear of the front speaker). under this senerio....depending how close and what in direction the out of phase woofer was...it could cancel out some program at the lower end of the closest speaker...if a gentle slope xover was used. I did some playing around with dual speaker subs a few years ago and found, in spite of the info in the web-site...that the speakers sounded louder the way chops discribes his subwoofers are connected....rather than the phisical out of phase approach or electrically out of phase connected approach. Quote Link to comment Share on other sites More sharing options...
chops Posted May 23, 2006 Author Share Posted May 23, 2006 that was the question. but since chops said they are not wired special, then they are in phase....they both push the same direction with the same signal applied (they both go outward together...and inward together). the web site chops provided introduces a few types of speaker arrangements...the one that caught my eye was the picture with the woofer in the rear mounted backwards (I would imagine the same effect if you just wired the rear one backwards). discribed as push-pull.....with the same signal applied...the front woofer sends waves into the listening area...the second woofer sends waves into the cabinet (towards the rear of the front speaker). under this senerio....depending how close and what in direction the out of phase woofer was...it could cancel out some program at the lower end of the closest speaker...if a gentle slope xover was used. I did some playing around with dual speaker subs a few years ago and found, in spite of the info in the web-site...that the speakers sounded louder the way chops discribes his subwoofers are connected....rather than the phisical out of phase approach or electrically out of phase connected approach. Okay, you guys are starting to comfuse me. LOL So you are saying that I have it where both drivers are working against eachother, both pushing in towards eachother then away from eachother? I think it's supposed to be as if both woofers are physically attached to eachother, and move in unison. [:^)] Quote Link to comment Share on other sites More sharing options...
DrWho Posted May 23, 2006 Share Posted May 23, 2006 Ok, first of all your current configuration (regardless of wiring) is not a push/pull configuration. You simply have two drivers sharing the same sealed cabinet. And you want to wire the subs such that both drivers create a positive pressure on the outside of the cabinet at the same time. If one driver is moving in while the other is moving out then you will end up with a lot of cancellation and all you will be hearing is distortion. The whole reason we need cabinets in the first place is to keep the rear wave away from the front wave. I have attached a graph that shows your predicted output. Green = a true isobarik configuration Blue = your current configuration The SPL's shown are with 50W of input. The sensitivity for green would be a peak of 88dB and blue would be a peak of 94dB (6dB loss when moving to isobarik). Green has an F3 of 40Hz with a Q of .531. Blue has an F3 of 44Hz with a Q of .781. If you could post the dimensions of your room and how well you think it is sealed we can calculate what your performance after room gain might look like. Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted May 23, 2006 Share Posted May 23, 2006 Nice. I like Dayton DVC's - they are quite versatile. You may want to consider putting a round table top on it with a table cloth to give yourself a "stealth sub" and a table to use for whatever. Quote Link to comment Share on other sites More sharing options...
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