powered speakers

Nikko · 07-11-2006, 05:12 PM

I was talkig to some guy at a local retailer about powered main speakers and having to split the LFE channel to actually get the bass to them. He was saying that everytime you split the LFE channel you loose 3db of sound. So with the def tech having powered mains, centers, and surrounds you end up loosing 12db of bass in a 5 speaker set up.
So my question is, how true is this and does it make buying powered surrounds not worth it? And if my crossover point for the LFE channel is at 80hz and the crossover piont of the surround bass-to-mid is at like 200hz, is all the sound from 80-200hz still powered?

John Garcia · 07-11-2006, 05:54 PM

You do lose some strength when splitting, but you would have to split the signal quite a few times before you lost 3dB of signal, IMO. If you use a single Y, you are definitely NOT loosing 3dB.

I don't see what powered speakers and LFE have to do with each other? Do you mean speakers that have powered subs (with an LFE input) or ones that are simply self powered (active)? If using a sub, the LFE is still directed to the sub, and has nothing to do with the other speakers, which can still be powered. If using the preamp outs, you would not be sending LFE to any of the other speakers either, just each channel's information. If you are saying each speaker has a powered sub and you want to send the LFE to each speaker via splitters, I still don't think that would result in a loss of 3dB, but it probably isn't a good idea - you'd be better off with a subwoofer.

Wayne A. Pflughaupt · 07-11-2006, 06:33 PM

Nikko,

John’s right – you’ll get a slight loss with a signal split, but nothing approaching 3 dB-per. I’d be surprised if you lost 3 dB total splitting out to all five channels. Most receivers have an LFE level adjustment that will minimize the problem.

Regards,
Wayne A. Pflughaupt

Nikko · 07-12-2006, 12:33 AM

ya, I mean surrounds with a powered sub. They have two 6.5" powered subs in each (bipole). So I know that to get the low frequencies to the speakers I must have an LFE channel plugged into them. They are supposed to reach down to 31hz. And if I don't run the LFE channel to them, is the bass from the LFE cutoff to the crossover still powered?

LanceJ · 07-12-2006, 01:28 AM

If you want the LFE signal to go to the front mains without messing with extra cables, IMO just program the receiver for "no subwoofer" and "fronts/large".

As far as directing the LFE signal to the surround speakers.....why would you want to do that?

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Nikko · 07-12-2006, 01:50 AM

the surrounds have built in powered subs, as do the mains and the center channel. http://www.definitivetech.com/loudsp.../surround.html

John Garcia · 07-12-2006, 09:21 AM

DefTech is well known for exaggerating (or rather misrepresenting) their low end extension. The number given is likely -10dB, where the normal spec is -3dB. LFE and bass are two different things. LFE is the .1 channel, and is not present on any other channels, and as a result, should not be sent to the other speakers. What you want to send them is a full range signal or one that is crossed over as low as possible, say at least 80Hz or lower.

Nikko · 07-15-2006, 04:42 AM

actually, it is best if rather than have a .1 channel, you have a .2 or .3 channel. This allows for a much more even and controlled distribution of bass without as many room interferences.

John Garcia · 07-15-2006, 11:00 AM

Multple subs at multiple locations causes MORE interaction, not less, and makes calibration of the sub channel much more involved. Tower speakers are really not going to hit the lowest of the lows the way a good sub will because they are really not designed to do so in most cases.