Newb to Amp's/ Bi-amping

BradPeart · 03-25-2005, 10:43 AM

Hey all,

Last year I upgraded my satellite speakers with Infinity Alpha 50's. I've been nothing but impressed with them. I'm pushing them with a Sony STR-DE895 (100w per channel).

Then my buddy got me thinking--

He says I can spilt my sub channel and send bass to my sub, and send it through the new amp to the 8" of L and R. Does this sound right? Is this the correct way to do this? What kind of amp would I need?

Thanks in advance.

Brad

Brian Fellmeth · 03-25-2005, 11:22 AM

This is not easily doable and its a bad idea if it was. However, you do have the option of crossing low (40-60 Hz) if your receiver allows or running the alpha50's "large".

BradPeart · 03-25-2005, 11:25 AM

If I'm not mistaken, the standard way of bi-amping is to take the L & R into the amp then HPF to one set of post and LPF to the other?

John S · 03-25-2005, 12:33 PM

Hmm, somehwat entertainign idea on a cheap effective bi-amp setup. Not sure it would really wash in real use though.

For true bi-amp with a sub...

Each channel out of a pre-amp needs a 2 way, electronic cross over, the sub is still left as the sub. You need one of these devices for each channel except the sub channel. You also need 2 power amps for each channel at this point., one to power the low end driver, and one for the mid/high end driver(s)....

I want to try this so bad, but the new AVR I purchased to try it with lacked real power amp inputs, so I sent it back.

Conventional wisdom conveyed to me on here is that the power running on Home Theater Systems is not enough to realize the bi-amp benefits. I'm pig headed though and I am going to try it anyways.

You would never want all your low end drivers and sub to be playing the same mono signal though. That is pretty much a no no anyway you look at it. It would actually hurt performance most likely.

Bob McElfresh · 03-26-2005, 01:50 PM

Quote:

He says I can spilt my sub channel and send bass to my sub,

Your reciever might do this for you.

Use your recievers setup menu and set the L/R speakers to "LARGE". This will cause the receiver to send low-frequency sounds from the l/r/center to the L/R speakers.

Check the subwoofer setting. Some recievers have a "none", "sub", and "both" setting. If "both", the .1 channel and low-frequency sounds from all the other speakers will flow to the sub as well.

But - while lots of separate subwoofers pushing sound is impressive (like a boom-car), it's not really good audio.

Multiple subs create complex waves/interactions in a room. To minimze problems and make it easy to setup, you really only want 1 subwoofer operating. Generally - a self-powered external sub is the best for several reasons. One is: your reciever is freed from having to send power for the low frequency sounds to your other speakers.

But it wont hurt to experiment. Check the reciever manual or play with the setup menus. Hint: write down the original settings first.

Good Luck.

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Wayne A. Pflughaupt · 03-26-2005, 03:30 PM

Quote:

Then my buddy got me thinking--

He says I can spilt my sub channel and send bass to my sub, and send it through the new amp to the 8" of L and R. Does this sound right? Is this the correct way to do this? What kind of amp would I need?

Biamping could be done this way, but it would be highly problematic. The sub signal from the receiver is going to be from about 80-100 Hz and down, and that’s what would be fed back to the Infinity’s low freq drivers.

The first problem is that the woofers in most mains do not crossover anywhere near that low. So everything above 80-100 Hz that they were getting before would be lost, creating a huge hole in response in the upper bass and lower midrange.

The second problem is that you won’t be able to set your mains to small, as they should be, because then the receiver’s high pass filter will eliminate everything the low pass is sending to the Infinity’s woofers.

Bottom line, this is a really poor way to biamp.

Regards,
Wayne A. Pflughaupt



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