bryan2 Posted January 22, 2002 Share Posted January 22, 2002 I'm planning to connect two subwoofers on my Kenwood VR-407 receiver (it only has one sub input). Will connecting a second sub (using a Y connector) affect the performance of the first sub (a KSW-12)? Or does two 250-Watt subs equal to one 500-Watt sub in performance? Thanks. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 22, 2002 Share Posted January 22, 2002 Bryan, I don't think I like the idea of two subs. If they are placed exactly right, they might give you 3 dB more bass, but I think they would have to be right next to each other or even one on top of the other to be sure they are in phase. I think I would try to connect them to left and right using the line level inputs and put one next to each speaker. With a receiver that might not be easy to do though! Al K. Quote Link to comment Share on other sites More sharing options...
soundog Posted January 22, 2002 Share Posted January 22, 2002 It is often suggested that two subs be placed in different positions (example: front corner and a side wall) to help prevent standing waves. Getting suggestions from the subs manufacturer or HT web sites might be a way to begin but rooms differ widely and it usually takes some experimentation. Al is right in some configurations phase differences might result in one canceling out the other. Experiment, experiment, experiment. ------------------ Soundog's HT Systems This message has been edited by soundog on 01-22-2002 at 04:20 PM Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted January 22, 2002 Share Posted January 22, 2002 I've have an SVS 20-39 & KSW-12 in use with my HT setup. The SVS is connected via LFE to an external amp, the KSW is connected to my receivers main speaker connection. However, my main speakers are also powered by external amps. Both subs are placed side by side in the listening room, much easier to calabrate, avoiding localization and standing bass waves. Could not get both to work off of a "Y" connection, was getting sub hum. So one via LFE and the other off receivers front speaker connection works for me. You can can give your method a try, "Y" splitters are inexpensive. If it doesn't work, give Al's or my suggestion a try. Have fun experimenting & let us know how it turns out! Wes ------------------ "KLIPSCH IS MUSIC"f> Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 22, 2002 Share Posted January 22, 2002 I wonder if a active x-over could make up for phase problems? (Invert signal at line level?) I don't know Al K's thoughts toward active filter design, but considering the passive components required for subwoofers, I would think this is a practical choice. IMO. I picked up a DIY 'Explorer' active crossover kit and trying to ponder out a sub design to suit my application. It really helps learning about active networks, Op amps etc... Though some of the equations get pretty rough, the kit has docs, and you don't really have to get that deep to build one. THANX! Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 22, 2002 Share Posted January 22, 2002 Hi guys, Well, this may be off the track, but my tests with an audio speep and x-y ploter shows that a flat response is NOT easy to get. I tried it with the 6 dB / octave crossover in my single LF-10 and it resulted in huge dips near the crossover. I went to a 24 dB / octave active network which helped a lot. Moving two subs apart changes the phase and changes it to different degrees according to the frequency. I really doubt if you could get a flat response using two unless they were both in the same place. I've not tried two of them though. Al K Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 22, 2002 Share Posted January 22, 2002 Did you build the 24DB octave active X-over as mentioned? (Linkwitz/Riley?) I'm sure I will never get a overall flat response, but I should come fairly close. Plus, I could always just push the subs together. I know it's going to be a process to match a pair of SVS 16/46's, to a pair of Chorus II's, which already have plenty of bass themselves. (Then I have to factor in room acoustic correction.) ARRGH! THANX! Quote Link to comment Share on other sites More sharing options...
User Name Posted January 23, 2002 Share Posted January 23, 2002 Bass is a non directional sound. Therefore no matter where you place the subwoofer in the room it will sound the same because the base is non directional. Some people put it in the front soundstage and others in the back, but in actuality they will sound the same. You may ask why some woofers are front facing and others floor facing. Doesn't really matter. With a front main speaker with the base woofer in the actual unit with mids and tweeters (like a KLF30 legend), you may notice a slight difference because you commonly tilt those speakers to the sweet spot. However, when using a subwoofer by itself (no mids and tweeters in the same cabinet), I would put it where you have the most room because the bass will sound the same no matter where it is in the room. User Name. Quote Link to comment Share on other sites More sharing options...
Craig6519 Posted January 23, 2002 Share Posted January 23, 2002 Sorry USER NAME, i guarantee you that if you move your sub around the room you will be able to pinpoint it's location from the sweet spot. To me thats directional, I've tried several locations in my room and the only place the bass even begins to sound non-directional is in the front corner of the room. Craig Quote Link to comment Share on other sites More sharing options...
User Name Posted January 23, 2002 Share Posted January 23, 2002 The term subwoofer is frequently misused. There are many audio systems that use a single passive bass module and refer to it as a subwoofer. If the unit produces directional information, it is not a subwoofer. Bass information is non-directional. Since Bass frequencies are so low you couldn't possibly hear them with your ear. Yo need an ocilliscope. The bass you think you hear is the frequency shaking your wall or floor but it's not a directional sound. And if that IS what your bass is doing, it's not set correctly. Quote Link to comment Share on other sites More sharing options...
boa12 Posted January 23, 2002 Share Posted January 23, 2002 great info md! but i can only put my sub in one general spot due to space. i have a huge reinforced pressure node from 20-38hz at my sweet spot. too wide to take care of w/ my b&k's notch filter. so i use it on the more narrow node from 46-54hz. i can live w/ that big reinfrcd node down low though ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
boa12 Posted January 23, 2002 Share Posted January 23, 2002 md, yea this b&k ref 30 certainly let's me twittle to my santity's content. from my seat, i can change the high pass point & slope, low pass point & slope, phase, sub distance, bass eq, notch filter & more. only downfall is the high pass crossover is universal for all speaks. hopefully they correct that w/ a dsp upgrade whenever that comes. rock on! ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 23, 2002 Share Posted January 23, 2002 Mike, I did "assemble" the sub crossover from a kit. It's two Marchand Linkwitz/Riley boards with the low outputs mixed with series resisters from left and right to the single sub. By the way, it's true that low frequency is non directional, BUT, the problem is that sound from each will be of different phase becasue of the distance between them. Since the wavelength is a function of frequency, two can only be working together at single frequency points unless they are in exactly the same place. My problem was blending them into the sound from the two flanking speakers at the crossover which are on opposite sides of the room! If you limit the frequency range over which they are both making sound, it's only over that range that interactions can happen. That's why I went to the faster crossover slopes. Al K. Quote Link to comment Share on other sites More sharing options...
wife-said-no Posted January 23, 2002 Share Posted January 23, 2002 2 things. After 10 years of car audio I have found that it is really hard to make bass non-directional. i.e. make it sound like it isn't comming from the trunk. Whether or not, it is vibrational energy or not is neither here nor there. It is still localizable. next, why is everyone so against 2 subs. My receiver has 2 sub outs as does many of them. Not to mention that most HT set up "how to" have one sub up front and one in the back. I know that the movie theater that I go to doesn't have just on sub supplying all the bass. Neither does my car. Of course my car has the speakers side by side but you can look at any SPL vehicle and see that there are many subs facing each other at different angles. No cancelation. ------------------ Come on honey why can't I spend some more money? My Home Theater Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 23, 2002 Share Posted January 23, 2002 Thanks Al K! Mdeneen, I must agree. The LF information that comes off a pair of locomotives idling by at 50 yards can never be acheived by subs. Or Jets, etc... Quote Link to comment Share on other sites More sharing options...
boa12 Posted January 27, 2002 Share Posted January 27, 2002 md, it's their newest preamp/processor/tuner combo for the digital realm. many features & it's easily upgradable (& sounds good) for me. just got a new bk 7 channel X 200W amp to put w/ it (my back is still healing). ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
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