biamp rt55i speakers or go 7.1?

mr_natural78

i finally found a good deal on some rt55i speakers that i'll probably get this weekend. would it make much difference to biamp them or do you think i'd do better by pushing my rt35i and rt25i back a spot for a 7.1 setup? I have room behind my main seating position to run back surrounds. any thought or input is greatly appreciated.

tonyb

Bi-amp with a receiver ?? That's not bi-amping, but don't waste your time. Your preference to run 5.1 or 7.1. Just note the more speakers added, the less power all receive.

strider

When I biamped my RT55's I didn't notice much of a difference vs using one amp. I'd just roll with the 7.1 set up and call it a day.

WLDock

Biamping a bookshelf with a receiver is questionable at best. However, do give it a try and try 7.1 also....you never really know until you try it yourself with your own speakers in your own room using your own ears.

mr_natural78

tonyb wrote: »

Bi-amp with a receiver ?? That's not bi-amping, but don't waste your time. Your preference to run 5.1 or 7.1. Just note the more speakers added, the less power all receive.

I'm confused. My receiver's owners manual says it will biamp by using the front output and back surround output. Why is that not by amping?

pitdogg2

mr_natural78 wrote: »

I'm confused. My receiver's owners manual says it will biamp by using the front output and back surround output. Why is that not by amping?

Marketing foolery to truly Bi-Amp you need 2 amps and an active crossover. You only have ONE power supply in that receiver so you are just not getting the true power. In reality say a receiver put out 100wpc when you "bi-amp" your lucky IF you get that full 100wpc let alone 200wpc. I but that with 7.1 you could be down to only 50wpc.

Easy Runnin

I'm also confused. If I have a avr that has a powered zone 2 where I can watch a movie in 5.1 in one room on one source and my wife can listen to music in stereo in zone 2 on a different source and at a different volume, I still only have one power supply and my avr is still not capable of bi-amping? really?

Now i follow the part about not getting 200 WPC, but if I use the front connections in zone 1 together with the connection from zone 2 won't that give me close to twice the power of the front connections in zone 1 alone?

nguyendot

Easy Runnin wrote: »

I'm also confused. If I have a avr that has a powered zone 2 where I can watch a movie in 5.1 in one room on one source and my wife can listen to music in stereo in zone 2 on a different source and at a different volume, I still only have one power supply and my avr is still not capable of bi-amping? really?

Now i follow the part about not getting 200 WPC, but if I use the front connections in zone 1 together with the connection from zone 2 won't that give me close to twice the power of the front connections in zone 1 alone?

No, not even close.

A) Biamping requires separately powered amps - you're still feeding off the same power supply.
Biamping requires an outboard (typically) crossover so you aren't feeding the same frequency range to both binding posts.
C) Please search, this topic has been covered hundreds of times.

strider

Easy Runnin wrote: »

I'm also confused. If I have a avr that has a powered zone 2 where I can watch a movie in 5.1 in one room on one source and my wife can listen to music in stereo in zone 2 on a different source and at a different volume, I still only have one power supply and my avr is still not capable of bi-amping? really?

Now i follow the part about not getting 200 WPC, but if I use the front connections in zone 1 together with the connection from zone 2 won't that give me close to twice the power of the front connections in zone 1 alone?

Think of it this way: the power supply of any amplifier can only provide x amount of power. If you only have two channels hooked up, that total available power gets split up two ways. If four channels of the amp are used, either by running 4 different speakers or by connecting to the HF and LF of two channels, your dividing the power supplies output by 4.

Same theory with playing two different zones.

WLDock

mr_natural78 wrote: »

I'm confused. My receiver's owners manual says it will biamp by using the front output and back surround output. Why is that not by amping?

As others have stated....your unit will drop down past the 135 watt rating with 7 channels driven. The TX-NR807 which is rated at 135 W a channel like your unit(Maybe yours has a better power supply?) dropped down to 29.9 watts per ch w/ 7 ch driven.

http://www.soundandvision.com/content/onkyo-tx-nr807-av-receiver-ht-labs-measures

Five channels driven continuously into 8-ohm loads:
0.1% distortion at 105.5 watts
1% distortion at 122.0 watts

Seven channels driven continuously into 8-ohm loads:
0.1% distortion at 29.9 watts
1% distortion at 33.0 watts

But, this is not to say that all AVR's are bad in this regards. A stout unit like the Pioneer Elite SC-05 which is rated at 130 watts x 7 of ICEamp power did these numbers:

http://www.soundandvision.com/content/pioneer-elite-sc-05-av-receiver-measurements

This graph shows that the SC-05's left channel, from Multi input to speaker output with two channels driving 8-ohm loads continuously at 1 kHz, reaches 0.1% distortion at 168.1 watts and 1% distortion at 197.2 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 249.6 watts and 1% distortion at 338.4 watts.

With five channels driven continuously into 8-ohm loads (blue curve), the amp reaches 0.1% distortion at 119.7 watts and 1% distortion at 153.9 watts. With seven channels driven continuously into 8-ohm loads (green curve), the amp reaches 0.1% distortion at 137.8 watts and 1% distortion at 149.0 watts It's odd that the power output at 0.1% distortion with five channels driven is less than with seven channels driven, but that is indeed the case with this AVR. The test was performed several times to verify this result.

The manufacturer's stated distortion of 0.09 % was reached at 135.3 watts with seven channels driven into 8-ohm loads. This corresponds almost exactly with the specified power output.

Stout! So with an AVR like the Elite SC it can better meet the Bi-Amp or 7 ch output claim(but as stated, tru Bi-Amping is expensive!)....but with some others, you might be better off staying with a 5 ch system. Still, if you have extra wire laying around go for it and see what it sounds like to you.

WLDock

PASSIVE Bi-Amping claim I meant to say. True Bi-Amping is ACTIVE!

nwohlford

strider wrote: »

Think of it this way: the power supply of any amplifier can only provide x amount of power. If you only have two channels hooked up, that total available power gets split up two ways. If four channels of the amp are used, either by running 4 different speakers or by connecting to the HF and LF of two channels, your dividing the power supplies output by 4.

Same theory with playing two different zones.

While I would not encouraging biamping with an AVR, there are other limits to amplification namely the amplifier boards. Most decent AVRs can do close to full power over three channels, so that the total combined power before clipping is much over three channels than two channels.

There are lots of arguments over biamping in most situations (you are mostly just buying extra equipment with little if any gain), but in 2-channel with a mid to upper level AVR, biamping will work just as well as separate amps for the high and low frequencies. There really is probably not much lost in multi-channel, since in most passive biamping only the tweeters are in the high frequencies circuit and draw very little current. I am very skeptical that anything is gained, though.

mr_natural78

My reasons for even thinking of biamping the rt55i would primarily be for when listening to music in stereo with the sub also operating.

pitdogg2

mr_natural78 wrote: »

My reasons for even thinking of biamping the rt55i would primarily be for when listening to music in stereo with the sub also operating.

For the most part you'd be getting that power without "Bi-Amping" from the receiver anyway when running 2ch.

don0

strider wrote: »

Think of it this way: the power supply of any amplifier can only provide x amount of power. If you only have two channels hooked up, that total available power gets split up two ways. If four channels of the amp are used, either by running 4 different speakers or by connecting to the HF and LF of two channels, your dividing the power supplies output by 4.

Same theory with playing two different zones.

Can that power supply's X amount of power be enough to supply each of the four speakers with close to the rated power per channel?

WLDock

don0 wrote: »

Can that power supply's X amount of power be enough to supply each of the four speakers with close to the rated power per channel?

See my post above...the 807 model below the 809 model that the OP has is rated at 135 watts a ch w/ 2ch driven. It does 105 watts into 5 ch. and 29.9 watts into 7 channels.

mr_natural78

My 809 also 135x2ch. I just ordered the rt55i for 160 shipped to my door. To effectively run 7.1 With the rt55i, rt35i, rt25i, and cs245i center should I be looking into a separate amp? Maybe a 2CH for the rt55i?

tonyb

You don't NEED an amp. Will they sound better with one ? Yes.....but most any speaker will anyway. As long as you don't like to play all 7 channels at rock concert levels, you'll be just fine running with that receiver alone.