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signal through sub


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Hi guys! I haven't been able to post a lot lately, my new job at an audio/video/electronics/computer store is taking all my time.

I have a question: when you run the amplified speaker level signal from your amp through your sub to use its crossover so that the bass goes to it instead of the speakers, does the bass get "re-amplified" somehow by the sub? I know approximately how a crossover works, and how the high frequencies get sent to the speakers, but I was wondering if it was the amp driving the sub or if the sub's amp, which is often much more powerful, took over for those frequencies.

Just wondering if it was my Sony str-db830 driving my 12-inch PW2200 Paradigm...

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seb, it's the sub's amp driving i think because the inputs/networks have such a high impedance they don't draw hardly anything from the receiver/amp power - sub amp treats it more like a preamp signal.

i've been seeing recommends to turn the sub output down like 10 or 12db on the receiver & use the sub's output control in place. seems to make sense for possible tighter bass from certain receivers. going to try that w/ my velo when it comes home.


Klipsch KLF 30 (front), KLF C-7, Cornwall I (rear)

Velodyne HGS-18 sub woofer

Monsterbass 400 sub interconnects & Monster CX-2 biwire & Z-12 cable

Marantz SR-8000 receiver

Sony DVP-C650D cd/dvd player

Sony Trinitron 27" stereo tv

Toshiba hi-fi stereo vcr

Technics dual cassette deck

Scientific Atlanta Explorer 2000 digital cable box

Boa's Listenin Lounge:

Klipsch RF-3 (front), RC-3, cheap little Technics (rear)

Monster MCX Biwires

Sony STR-DE935 a/v receiver

Kenwood KR-9600 AM/FM stereo receiver (vintage 1975)

Russound AB-2 receiver switch to RF-3

Teac PD-D1200 5-disk cd changer

Technics SL-1950 turntable/AT LS500 cartridge

Sega Genesis game player

Sub: None yet

rock on!

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Depends on the sub.

If the sub has a built in amp (which pretty much means if you have to plug it in), then in every case I'm aware of, when using the speaker level inputs, the subwoofer's crossover is "looking" at the signal coming from the amp, and uses that signal as the input to the subwoofer's own internal amplifier, which actually powers the subwoofer. The amount of signal the subwoofer "taps off" from the amp's speaker outputs is so miniscule compared to the signal driving the speakers that the amp, for all practical purposes, doesn't even know the subwoofer is there.

Depending on the sub, the signal going to the main speakers may be passed through with no alteration (REL and others do this), or the same crossover that's tapping off the low frequency signal and feeding it to the subwoofer may be rolling off the low frequencies before feeding the signal on downstream to the main speakers. Your sub can do this.

If the sub doesn't need to be plugged in, then it's a passive sub, and the amplifier is driving both the subwoofer and the main speakers. Most passive subs filter the signal going to the main speakers, rolling off the low frequency of the signal that passes on to the mains.

Your Paradigm has a bit of everything. The 2200 has its own built in amp, and in every case it is this built in 250 watt amp that is driving your subwoofer. The 2200 can take inputs at speaker level, or line level. If using speaker level, the subwoofer can give you a rolled-off (high pass, which means low frequencies are reduced) signal to feed directly to your main speakers. If using the line level inputs, the 2200 can give you a high pass filtered set of left and right LINE LEVEL outputs, when you then route back into your receiver or amplifier, amplify, and pass on to the main speakers. Because the line level outputs are active, the low frequency attenuation is more aggressive on the line level main speaker outputs (18dB per octave) than the passive, speaker level main speaker outputs (6dB per octave).


Music is art

Audio is engineering

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thanks guys!

most of this i had already figured out, but i just wanted to know exactly how it worked.

ray, i have another question: how do you fit all that information in your brain? or are you using some kind of bioelectronic storage device?

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