Bi-amp question

I have a 7.1 amp/receiver at 85 watts per channel. If I bi-amp my front speakers are they putting out a full 170 watts doing this?

 

Yes, or at least the capacity is there. I'm doing the same thing with a Pioneer VSX-1021-k and a pair of Polk Monitor 70s. The difference is audible. I've heard it is more dangerous to under power speakers because of clipping, but have no experience of that (blown speakers) either way.

 

Are you saying that you're going to run one portion of your front speakers with the amp that's in your 7.1 receiver and then you're going to add another 2 channel amp that you'll run from the front channel RCA outputs of your receiver and send that to another portion of your front speakers?

Is that what you mean when you say bi-amp your front speakers?

 

No...

I am running the two extra speaker connection from the same 7.1 am see that I have only a 5.1 set-up. So my front speakers will be taking advantage of running two of the 85w channels each

 

So you're running a 5.1 system but your receiver is a 7.1 system so you're going to use the 2 channels that aren't currently being used to power either the upper or lower portion of your front speakers?

Aren't those channels processed for a specific purpose? As in a surround upper or surround mid position setting? I like the idea but I didn't know this could be done.

Have you done this yet? Is this what klockwerk is doing too?

 

Yes that is what I am doing, Bowers and Wilkins 683 S2 are the speakers. From what I understand when you bi-amp the lower speaker terminals will handle the woofer section of your speaker and the upper ones the mid and tweeter.

 

[QUOTE="Is this what klockwerk is doing too?[/QUOTE]

Some 7.1 channel receivers have an option to switch to a 5.1 system and use the 2 left over channels to bi-amp the front 2 speakers. I assume Toms system can do this, it's CRAZY to think about doing this if your receiver can't switch to this mode.

 

First off, you are not bi-amping as that requires separate amplifiers, each with it's own power supply, not a shared one like in your AVR and the use of active crossovers. Anything less is simply ghetto bi-amping.

In addition, your AVR, like most other AVR's cannot supply the rated power when more than 2 channels are driven. By the time you are driving 7 channels the wpc will drop like a stone. With an AVR rated at 85 wpc (2 channels driven) you might be lucky to get 40 wpc driving all 7.

 

I am not driving all seven while I am playing music. I have it set up to play in the pure direct stereo mode with only the front two speakers and my two subs receiving a signal.

 

I agree w/F1. Bi-amping requires 2 separate amps. Your AVR has only one amp so it is not possible to bi-amp.

 

So this is what I am doing then...

Bi-wiring refers to separate wire runs from a common amplifier output to two different inputs on the same speaker. This requires a speaker specifically designed with bi-wiring in mind as the speaker’s passive crossover must be designed to allow this. Also, the speakers must have two sets of external binding posts connected by removable jumpers or "bus bars."

In ordinary use, you simply leave the jumpers in place and connect the amplifier to either set of binding posts with a single run of dual-conductor speaker cable. For bi-wired operation, simply remove the jumpers and connect each set of binding posts to the same amplifier channel with separate runs of speaker cable. (Many manufacturers make special "bi-wire" speaker cables that reduce bi-wiring’s visual intrusion by jacketing four conductors in one larger cable.) Bi-wiring’s advantages are generally considered to be more subtle than bi-amping and center around better control of back EMF (electromotive force) from the speaker drivers and increased definition. However, remember that conventional bi-wiring is also much less expensive to implement than bi-amping as it does not require separate amplifiers or electronic crossovers.

 

I am not in agreement with basically anything posted in this thread, at least in its entirety. Some points made, but most are not applicable, some are just wrong, and none really answer the OP's questions. I'd be happy to discuss it with you, Tom, if you'd like to call me.

The first questions was about full power output, basically asking if an 85w channel and another 85w channel connected to a single speaker system (with a dividing network, a passive crossover) will yield 170w of total output. The answer is simple. No, it won't. The reason for that answer is not so simple and would be best suited to a phone conversation rather than a forum post. But one of the reasons is that the amplifier will never be asked (hopefully) to even put out 85w. There are several other reasons as well, but none as practical as that one.

Second, it never fails that when someone who clearly states that they either have limited funds or a particular pair of amplifiers, that someone gets up on a soap box and decries that they can't possibly bi-amp without a huge investment in amplifiers, active crossovers, and speaker modifications. Now, we can argue about the definition of bi-amping, best practices, and semantics but I think it is more practical and helpful to limit our responses to what will actually help the person asking for help. Yeah, ideally you'll need huge amps, expensive active x-overs, and completely passive speakers without their own x-overs. That is really so far over the top that very few people ever do that, especially in a home environment. You would definitely do that if you were hired to power a PA system for a Metallica concert.

What you are doing, Tom, is neither really bi-wiring, nor bi-amping, but really a sort of hybrid. I'd have to give it a nod to bi-amping simply because you are assigning more gain and current potential to the speakers than before. However, I also agree with what F1nut is saying about not getting the power that you are expecting from that receiver, especially in the configuration that you are using it in. Some amps / receivers are more capable than others in this regard, but almost none, certainly no receivers that I am aware of, can really do what is expected of a separate amplifier. My advice here is to not worry about it, or make a significant upgrade, as you are really just re-configuring your amp / speaker interface without any concrete improvement.
-Bill

 

That's bi-wiring ... totally different that bi-amping. Bi-wiring is pointless if you have an adequate gauge wire running from your source to the speakers (and would have nothing to do with the extra channels in your AVR)

Bi-amping makes some sense .. but not when the same amp is providing power to both sides.

The most common use for bi-amping is to have a tube amp drive the high end and a big solid state amp driving the woofers. Best of both worlds,

 

I'm sorry but that's just easily proven wrong. Listen. Some speakers only use filters and don't have internal crossovers... You WILL notice a difference in sound. Bi- wiring (and in my case Tri-wiring and Bi-amping) defiantly do make a difference. It will sound different... Sometimes. It all depends in the Cross overs or lack of.

What the OP is doing can sound wonderful. It can stiffen the bass and add punch. In some cases it can heighten the soundstage, bring out more detail or even change the presentation form laid back to in you face. It depends on you r gear and preference.

There was a day not long ago when I believed in the coat hanger Urban Legend. After actually trying on several systems it's obviously changing the experience in several scenario's.

And this is the point in the conversasions that the new sayer or the embarrassed previous posters chime in and scream "Plecebo". Well, if it's Plecebo then about 12 people in one instance were unanimously tricked. On a mother occasion 4 more were unanimously tricked. It's just fact to me. It makes a difference.

 

Running two sets of wires from the same amplifier output = one set of wires and jumper strips at the speaker terminals .. it has nothing to do with what's on the other side of the binding posts.

 

If the unit the poster has can actually send a true (front) right and left low level input into the unused (amp) channels and then use these channels to drive the upper or lower portion of his speakers, I assume it will work. I once had an Onkyo 7.1 system but I never used the two channels that were assigned for the mid-side channels. And this was accomplished via the set-up menu of the receiver. I don't recall having the ability of re-purposing those channels to drive existing channels or drivers.

If he can do this, I would think that it could be beneficial but too, the unit shares the same power supply for all amplifiers and I don't really think it would be a true value-add.

Thing is, if those 2 amps can be used for this purpose, wouldn't the unit need to be in a surround mode? And if so, won't you lose your 2 channel stereo option and the center and rear channels are going to operate?

I guess I could try to locate the receiver on line and see if there is a manual available.

 

I have removed the jumpers, they are not in play with what I am doing.

 

I used to run my Onkyo TX-NR818 like this. I used that in stereo only mode (no multichannel at home) and had bi-amped my then Tannoy DC4s. So yes, you can do it. I still have the amp but use it in pre mode.

 

MARANTZ
SR8002 User Guide
AV Surround Receiver

 

No I'm sorry but I don't agree. The wire combined at the output post of the amp supplies power directly to each section or driver of your speaker through its own wire. With one wire and jumpers each driver is competing with the other to get what it wants from the wire. It flat sounds different with many speakers.

Each driver has different needs, different speeds even. With its own wire it has less to negotiate. Some lab coat wearing, beaker caring, pocket protector engineer will chime in saying something about now.. thats how these threads go. To that I say go do it on enough speakers and report back.

My buddy has a great sounding system. Im very familiar with it and heard it through many equipment changes. At his house no matter what amp we heard no difference with bi-wiring. but once he changed from Monitor Audio Silvers to Snell D speakers... Now you can hear the difference. Its all in the or not in the crossovers. Sure the amp matters too, but the cross overs are a big part of it.

 

Well no, the only thing that would accomplish is to increase the effective wire gauge, which may or may not be if benefit.

One could accomplish the same with one run of heavier wire gauge with the same wire used in place of the stock jumpers plates.

 

Each driver need its own communication. So you have three signals.. three conversations going on. Using a dedicated wire for each conversation makes a difference.

Imagine 6 kids talking into a can and a string. Three kids talking into one can at the same time and three kids on the other end trying to make sense of what they are hearing so they can repeat it accurately. Now Imagine each pair of kids having their own can and string. Now whats being said and whats being heard is clearer. Now the kids on the receiving end can accurately repeat what they hear.

Remember this is a two way conversation. The amp says "Hey I have all this to say". The base woofer says "Hey cool, I want to hear about the bottom" The mid's say "Can you tell me about whats in the middle" The top ends say "tweet me a high baby, its all a care about.. don't confuse me with the rest of that info."

 

What you are talking about in loose terms is bi-amping with separate power amps and active crossovers. That is not the case when using a single power supply feeding multiple channels such as the OP asked about.

 

Nope. One amp is sending whats requested. yes it pushes the signal but only while being told what to send. One amp has all that info going out of and available at one set of posts.. The speakers ask for or negotiate what they want to hear. So they fight for the attention of that amp.. Their argument or fight gets all stuffed into one cable and then the response gets all jammed into that one cable. Or.... each has its own line to the same post and request right there separately. Then the amp sends through that line whats negotiated or wanted by that woofer or driver.

Now with Bi or Tri-amping the amp is only sending or pushing one signal...so its even more isolated and specific in the frequencies it sends.

If you hook up an 8 ohm speaker it draws 8 ohms from the amp.. or close to. If you hook up a 4 ohm speaker it draws more power... and it changes things, not just the power output but it changes other measurable stats. Same with each drivers request of that same amp. Hence a dedicated speaker wire allows it to ask for what it want with more clarity. The amp doesn't care but its primarily sending whats being requested through that specific wire.

Again, this applies to a speaker or drivers that are NOT connected internally. If your speaker cabinets have crossovers the whole Bi or Tri wiring looses its argument, Your crossovers just say give me everything and Ill sort it out.

 

I believe the OP is capable of bi-amping, and to me in his situation, would be to some benefit. To bi-amp with separate amplifiers that aren't part of the main system's power supply, would be a better benefit.

Bi-wiring, I don't see much benefit in this approach.