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need help - ksp 400s - bad sub amps

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Just now, T2K said:

why should i use the LFE instead?


Read the Manual concerning LFE. Page 9 I think.

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On 08/21/2017 at 10:27 AM, T2K said:

You can use the LOW IN Line Level RCA input and not connect speaker wire/ jumpers to the far left pair of binding posts (they're marked 'LOW IN'). See that? Then connect RCA cable from sub output on receiver to LFE IN on each speaker.


hi keith


i'm still confused by those two sentences. they seem to be saying use the 2 different inputs.


it's moot at this point because i got my amps back and all the caps and rectifiers were replace and i'm still getting a bad hum (though not as loud as before).


does anybody have any thought on this?




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Maybe I'm a little confused too. Nevertheless, think of the speakers as any other pair of speakers that have only one pair of speaker binding posts. If you have all 3 pairs of speaker binding posts jumpered together on the 400's, then that's basically what you have. 


For LFE, you need to run an RCA/subwoofer cable from your receiver sub out to the LFE inputs on the speakers. The LFE effects will play much louder than the bass, as your manual states.


How long have you played the speakers since your amps were worked on?



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if i jumper all 3 binding posts, then doesn't that send the amplified signal from the surround amp to all 3 speakers in the k400s? (woofers, mids and tweeters...)


then if i run the sub woofer out INTO the sub woofer INPUT or LFE INPUT to the panel at the bottom of the speakers, then aren't i sending 2 different signals to the SUBS?

a LINE OUT signal and a signal powered by the surround amp?


that doesn't make sense to me. (and i'll be the first to admit i'm a neophyte at this surround sound stuff, even though i've had my own sound studio for a number of years.)


i started looking up LFE info and found this:




Q: “In surround sound, isn’t an LFE channel the same as a subwoofer channel?”

A: Actually, LFE and a subwoofer are two very different things. Typically, the term subwoofer refers to a speaker that reproduces very low-frequency information that the main channel speakers (however many there are) are incapable of effectively reproducing, or at least augments them such that low-frequency sounds normally found on the main audio channels are directed to the subwoofer speaker for added punch in the low range. In this way, a subwoofer acts as a complement to extend the range of the main speakers, which may find it difficult, if not impossible, to reproduce these low frequencies in the quantities needed. The LFE is a separate channel that has its own, dedicated track in the audio production. The LFE channel is often specifically produced with low-frequency information exclusive to it. Content producers create emphatic sound effects for it, such as, crashes, gunshots, and such. Ultimately the purpose is not all that different from the goals of conventional subwoofers, and subwoofer speakers are quite often used for playback of LFE information, which is typically bandwidth limited to lower frequencies best suited for subs. It’s just important to understand the distinction between the two.


anyway, i'll try running the amps (with no load on them) to see if the noise goes away



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