BigBusa Posted November 5, 2001 Share Posted November 5, 2001 Hey guys, I recently went to tweeter to buy a sub cable for my new ksw15. I read on this forum that for a 6 decible gain ( tI think) I should also get a y cable to connect both left and right jacks to a single sub out from a reciever. The fairly knowledgable salesman said I did not need the y cable. That all the sub needed was a signal to one or the other rca jacks since the sub is mono. I got it anyway. What's the real deal? ------------------ My system thus far: 1980 Cornwalls (mains) 19?? Heresy II's (rears) 2001 KLF-C7 (center) 2001 KSW15 (Subwoofer) HK AVR 510 (reciever) Kenwood DV402 (DVD) Sony KV 27V55 (9 year old 27" TV) Quote Link to comment Share on other sites More sharing options...
Underhanded Penguin Posted November 5, 2001 Share Posted November 5, 2001 It's like you said: You get a 6db gain when you use the y cable. Without it, you don't get the 6db gain. Simple as that. I have a ksw-15 and I use the y cable. You just get more output. But realistically, if you did want more output, you could just turn the gain up on the subwoofer. With the y cable, you would be able to get 6db over the maximum gain allowed on the subwoofer, which really isnt needed, because nobody puts the sub gain on maximum anyways. I still use the y cable anyways because I bought one. -UP ------------------ I love you Aki Ross! Quote Link to comment Share on other sites More sharing options...
boa12 Posted November 5, 2001 Share Posted November 5, 2001 yea from what i've seen using the Y to both L&R you'll get a more efficient output gain from the ksw. should also make them wake-up from standby more readily. just the way they're designed. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
NIMROD Posted November 5, 2001 Share Posted November 5, 2001 My dealer told me to use the y-adapter and put one leg on left and the other on lfe in. seems to work fine, dont understand why he told me this though. Quote Link to comment Share on other sites More sharing options...
boa12 Posted November 5, 2001 Share Posted November 5, 2001 nim, though it shouldn't be a problem I don't understand the advice to use both the LFE in & the line inputs. the LFE should be an nonfiltered which bypasses the sub's crossover. i'd think it's an either/or as far as the line linputs or LFE. actually the LFE should be best to use w/ filtered sub outputs. but then again the ksw subs are foreign to me. I guess they call it LFE in case one has a seperate LFE output on their receiver which I've rarely seen. but as I understand it it's a nonfiltered input & would be best to use w/ an a/v receiver filtered sub output. but then u may not get the higher output by connecting 2 inputs w/ a Y. i give up on the ksw subs. wonder if they followed the same design on the new rsw? ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
bacevedo Posted November 5, 2001 Share Posted November 5, 2001 I think the answer varies depending on your setup. The KSW 15 actually has 3 RCA inputs - Left and Right PLUS an LFE input. The LFE input totally bypasses the internal crossover on the sub. It is there to take the output of a receiver that has a built in crossover. Since there is only 1 of these, you wouldn't use a Y adapter for it. If you use a Y adapter between the LFE and Left input, you are sending a signal to the sub that is bypassing the crossover and also using the crossover at the same time. I am not sure what gain there would be to this. My recommendation on the KSW 15 only, is to use the LFE input, with the cable going directly in (no Y adapter). You could also just use the Y adapter and plug into the Left and Right, but then you would have two crossovers in line. Usually you don't want this, but you could just set the KSW 15 crossover to its max setting so it wouldn't interfere with the receiver's crossover. On the KSW 12 and 10, there is no LFE input, so you only have a Left and Right input. This I would recommend you using a Y adapter, and turning your subs crossover to its highest setting, so you don't have dualing crossovers. The RSW subs have only a Left and Right input (summed), but have a crossover bypass switch (a better design if you ask me) so that you can pass a summed input signal without the crossover interacting with it. My Velodyne SPL1200 has this as well, and it makes it easy to see the interaction between the crossovers by turning the switch on and off, and playing with the subs crossover. And as far as the 6db gain, you can easily make up for it by turning your sub gain up (or your receiver sub level up - but you could add distortion if you turn it up too much). I have read that on most subs, the gain is really a trim, and setting it to max is not amplifying the signal, but allowing it to pass through without being touched. Some people recommend setting your sub level to max, and cutting the receiver sub level as low as possible to get rid of distortion. Some setups can't cut the sub level enough on the receiver, so you could just trim back your sub level until it is where you want it. I know that was a lot, but I really have been thinking a lot about sub set up lately, and these are what I have taken from it. I am still tweaking my sub, but I use all these techniques to find out what sounds the best and go from there. Bryan Quote Link to comment Share on other sites More sharing options...
TheEAR Posted November 5, 2001 Share Posted November 5, 2001 Bryan summed it all well. The KSW15 has the LFE in,no need for any Y adaptors. On all subs with no LFE you get a dB boost when using a Y adaptor.All with a LFE in dont need any Y. TheEAR(s) Now theears Quote Link to comment Share on other sites More sharing options...
BigBusa Posted November 6, 2001 Author Share Posted November 6, 2001 How about when I crank one dial all the way up and then slowly turn the other up toward its stop ...the thing starts making a crazy feedback that shakes the whole block?! I love doing that but is it bad for the sub? Is it bad for my spleen or other internal organs!? ------------------ My system thus far: 1980 Cornwalls (mains) 1990 Heresy II's (rears) 2001 KLF-C7 (center) 2001 KSW15 (Subwoofer) HK AVR 510 (reciever - coming soon!) Kenwood DV402 (DVD) Sony KV 27V55 (9 year old 27" TV) Quote Link to comment Share on other sites More sharing options...
TVodhanel Posted November 6, 2001 Share Posted November 6, 2001 There's no preset 3/6dB gain when using a splitter, it will depend on the circuitry of the amp to some degree. Here's some good text on the subject, ***This line level connection to the subs' power amp is a low level, high impedance connection where almost no current is drawn and we want to present a relatively low line level voltage to the subs amplifier input with as low a noise floor as possible. We're not concerned with power transfer here - the preamp acts as a voltage source.Since the split signals are in parallel, they remain the same voltage and since the current is quite low as a result of the rather large impedance mismatch between the preamp output (typically 100 ohms) and the subs' power amp input (typically 10K to 50K), you may split the signal to your two or even three subs as others have already suggested without a noticeable change in volume.If you did indeed notice a small volume change, increase the sub out level slightly from your preamp.But, remember with each split, that the impedance that the preamp sees, will be reduced. If you are feeding two amps with input impedances of 10Kohms, well the preamp will see 5Kohms.....and so on as you continue to split. You are also increasing the capacitance that the preamp has to deal with, each time you add another long cable in parallel. Mind you, capacitive reactance at sub frequencies isn't really an issue.***** TV Quote Link to comment Share on other sites More sharing options...
bacevedo Posted November 6, 2001 Share Posted November 6, 2001 But what does it all mean? What is the effect of the impedance from the pre-amp changing? More distortion? Noise? And it says two long cables in parallel - what about one long cable and a short Y-Cable? Just wondering how all this affects the sound. Bryan Quote Link to comment Share on other sites More sharing options...
Klipsch-daddy Posted November 7, 2001 Share Posted November 7, 2001 I have a ksw-12 and it does have a LFE input. I use a y-adapter on it. I was told to set the crossover to 120 hz to get the full benefit of the LFE but the sub seems to muddy at that hz. I leave it on 70hz. ------------------ My HTS: MAINS: RF-3's CENTER: KSC-C1 REAR: SS-1's SUB: KSW-12 TV: TOSHIBA THEATER VIEW 50" RECEIVER:KENWOOD VR-4080B DVD: SONY S-360 DVD PLAYER Quote Link to comment Share on other sites More sharing options...
MattG Posted November 8, 2001 Share Posted November 8, 2001 Matched impedence gives you the most effecient power transfer. If you used an unbalanced system it probably require you to turn the source power up increasing your chance for distorsion. I don't know how much this will effect the sound. MattG ------------------ Denon 3802 Klipsch Quintets (6) Both in route to my house! Quote Link to comment Share on other sites More sharing options...
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