bi amping a 7.1 system

[Brian Clark]

A while back I bought a new 7.1 AV Receiver, on setting it up i discovered I could re-configure 7.1 to 5.1 by bi-amping my front speakers. As I already had a 5.1 system with my front speakers capable of bi-amping I set it up that way. Since then I have read and heard that this achieves nothing. While I do understand that power wise you can never get something for nothing, could anyone tell me during the set-up process when I designate bi-amping my front speakers what does this achieve, what if any are the changes this makes to the equipments behaviour.

 

[tyhjaarpa]

Just use the jumpers and wire your speakers normally. BI-amping is not worth the effort and risks it comes with as most likely you wont benefit from it at all. There are speakers that can benefit from it, but I would guess you have some generic speakers that do not as you dont mention what speakers / receiver you have.

 

[Swerd]

A while back I bought a new 7.1 AV Receiver, on setting it up i discovered I could re-configure 7.1 to 5.1 by bi-amping my front speakers. As I already had a 5.1 system with my front speakers capable of bi-amping I set it up that way. Since then I have read and heard that this achieves nothing. While I do understand that power wise you can never get something for nothing, could anyone tell me during the set-up process when I designate bi-amping my front speakers what does this achieve, what if any are the changes this makes to the equipments behaviour.

Your AVR allows you to reassign two of the output amplifier rear or surround channels so they instead play the front left and right channels. It gives owners the false impression that they can make use of amplifier capability that they would leave unused in 5.1 surround system.

In most or all AVRs and amplifiers, there is one large transformer with multiple wire windings for each individual amplifier channel. The maximum power available is limited by the size and capacity of the power supply transformer. It does not matter whether you choose to use all 7 channels, or fewer channels, such 5 or 2, there is only so much juice available. Redirecting the power out put does just that, it redirects it. It cannot create more power.

It may help to think of the power supply transformer in a receiver or amplifier as similar to a car's engine, and the output channels as similar to a car's transmission. You can choose 2-wheel drive or 4-wheel drive, but the engine and its power remains the same.

The only way more power can be had is by adding another amplifier with its own power supply transformer.

 

[lovinthehd]

The basic difference is that the way the avr and your speakers are set is for passive bi-amping, which is window dressing from the marketing teams. Active bi-amping can be valuable (and is what active speakers use) but you can't actively bi-amp your setup without at least removing the passive crossover components in your speaker and using an external crossover before the amplifiers (which your avr doesn't have unless perhaps you have an Onkyo 818 which actually did provide some limited capability in this regard), and you are still unlikely to achieve better results than your speaker designer did....

 

[Brian Clark]

Thank you all for your assistance. My basic question seems to be answered, I left my original post vague because I am in the process of gradually replacing my old system. The AVA was first, sub-woofer second, book shelf speakers are about to be bought replacing towers because of new furniture restrictions. My current book shelves were pre-wired for bi-amping so to use them as a fill in required setting up either bi- wiring or bi-amping. The speakers I was planning to replace them with were SVS Ultra bookshelf (SVS Sub-woofer) This raises two new questions (1) Would my alternative speaker choice SVS Prime bookshelves give sound quality equal to the Ultras at half the price they would obviously only need to be close. (2) Are the bi-amping facilities on the Ultras in this price range also window dressing, because these speakers are in my price range but the type of system needed to gain maximum benefit I should imagine isn't.

 

[Swerd]

(1) Would my alternative speaker choice SVS Prime bookshelves give sound quality equal to the Ultras at half the price they would obviously only need to be close.

Because of the price difference I'd guess they are unlikely to have the very same sound quality. I've heard the Ultras, but not the Primes.

However they might sound close enough. You'll have to determine if the difference in sound qualities are worth the difference in price.

(2) Are the bi-amping facilities on the Ultras in this price range also window dressing, because these speakers are in my price range but the type of system needed to gain maximum benefit I should imagine isn't

When you say "bi-amping facilities" do you mean 2 pairs of binding posts, like in the picture below?

If yes, then it is window dressing. No 2-way speakers that I've heard benefit from bi-amping. I'd go so far as to say that probably no 2-way speaker benefits from bi-amping. Forget bi-amping, bi-wiring, and high-priced speaker cables too.

The Ultra bookshelf speakers cost double that of the Primes, but the second pair of binding posts and the slightly different internal wiring may account for no more than about $10 of the difference. The real difference in sound quality comes with different drivers, crossovers, and cabinet construction.

 

[KenM10759]

The only time I've seem the twin binding posts on speaker be effective is when it's a two-way speaker and you can feed and equalize the high frequency (tweeter) and mid-low frequency (driver) completely separately. Linn now does this very effectively by actually removing the crossover and sending an amplified signal to each individual driver with their Exaktbox technology. That's pretty expensive stuff though.

 

[Swerd]

The only time I've seem the twin binding posts on speaker be effective is when it's a two-way speaker and you can feed and equalize the high frequency (tweeter) and mid-low frequency (driver) completely separately. Linn now does this very effectively by actually removing the crossover and sending an amplified signal to each individual driver with their Exaktbox technology. That's pretty expensive stuff though.

If a 2-way speaker needs equalization, done by the user, to sound good, I'd argue it was poorly designed in the first place. All speakers with more than one driver require a crossover. It can be either passive and analog or active and digital, but there must be some form of crossover.

 

[KenM10759]

I'm not suggesting any well made 2-way speaker needs equalization, so please don't think that.

What I mean is that if you feel an overwhelming urge to control everything about a speaker's performance, twin binding posts are handy.

That is all. Carry on.

 

[Swerd]

I'm not suggesting any well made 2-way speaker needs equalization, so please don't think that.

I didn't mean it quite as strongly as it came out . I aimed that comment more to the OP who seems to understand that bi-amping is window dressing, but also may cling to the idea that bi-amping speakers is somehow superior to normal wiring.

 

[MR.MAGOO]

So I can undo my bi-amped front speakers, regain Zone 2, and put speakers on my computer desk as Zone2 and run my iTunes through Zone2 via AirPlay?

 

[KenM10759]

Sure, why not? You could even send the signal to a wireless amp setup and power those speakers with just A/C current. That would eliminate running long speaker wires from one room to another.

 

[MR.MAGOO]

Sure, why not? You could even send the signal to a wireless amp setup and power those speakers with just A/C current. That would eliminate running long speaker wires from one room to another.

You lost me. So I need to buy a Sonos wireless amp system?

 

[PENG]

I don't believe in passive biamping making any audible difference either but it does offer theoretical differences in terms of providing separate path for the high/lo signals. so if anyone wants to try and see if they have golden ears, there is nothing to lose if he has the wires and the time. In terms of power gain, again there could be some gain, however small that is depending on the AVR. For example, the older HK AVRs focussed on investing in larger power supply and are relatively speaking, amplifier limited (power transistors etc..). In such cases, bi-amping the front channels with the unused channels should get you a little more, may be 1dB or less, considering not all channels will be driven to full output at the same time.

Again I agree any such gain will be so negligible aside from being theoretical. I am saying this all just for technical argument sake, hope you guys won't take that as being argumentative.

 

[king2b]

Why do they even put two sets of binding posts on speakers if they don't make any difference when you bi-amp or bi-wire. My tower speakers are a four-way design that is rated at 4ohms.

 

[lovinthehd]

Speaker manufacturers don't want to lose out on sales if they just provide the basic terminals, more about marketing (and the avr manufacturers go along with their passive bi-amp provisions).

 

[j_garcia]

I don't believe in passive biamping making any audible difference either but it does offer theoretical differences in terms of providing separate path for the high/lo signals. so if anyone wants to try and see if they have golden ears, there is nothing to lose if he has the wires and the time. In terms of power gain, again there could be some gain, however small that is depending on the AVR. For example, the older HK AVRs focussed on investing in larger power supply and are relatively speaking, amplifier limited (power transistors etc..). In such cases, bi-amping the front channels with the unused channels should get you a little more, may be 1dB or less, considering not all channels will be driven to full output at the same time.

Again I agree any such gain will be so negligible aside from being theoretical. I am saying this all just for technical argument sake, hope you guys won't take that as being argumentative.

I have already tried it. Heard no difference. Tried it bi-wired to my integrated and biamped with a separate amp on the highs. There *may* have been a slight difference in sound, but even when cranked up it was negligible to questionable. My philosophy on it is if you need more power then an amp that has enough is the answer, not biamping.

The sound is already amplified before the signal hits the wires, so to me there will never be any benefit to biwiring. With biamping, you may get a small reduction in reaction of the amp to the load and if you are using SEPARATE amps, you ultimately have more power because of separate power supplies, but how many people really own speakers that will need that kind of power? Not many IMO. If you are at that level, then you should probably be looking at active biamping anyway.

 

[PENG]

I have already tried it. Heard no difference. Tried it bi-wired to my integrated and biamped with a separate amp on the highs. There *may* have been a slight difference in sound, but even when cranked up it was negligible to questionable. My philosophy on it is if you need more power then an amp that has enough is the answer, not biamping.

The sound is already amplified before the signal hits the wires, so to me there will never be any benefit to biwiring. With biamping, you may get a small reduction in reaction of the amp to the load and if you are using SEPARATE amps, you ultimately have more power because of separate power supplies, but how many people really own speakers that will need that kind of power? Not many IMO. If you are at that level, then you should probably be looking at active biamping anyway.

Passive biamp has a little bit of theoretical benefit, biwire would have negligible theoretical benefit. I also don't believe and didn't find such theoretical benefits audible to me. As you mentioned, in passive biamp, the preamp will have to amplify the signal before it hit the wire, while the power amp will also amplify everything in terms of voltage, but in terms of current/power amplification, it will be dictated by the impedance characteristics of the specific crossovers so there will be different effects on different speakers. Again, any such effects will be theoretical and almost certainly not audible, yet there are golden ears who claim the benefits are audible. We really shouldn't be surprised about that though, there are no shortages of people claiming to hear difference between audio interconnects, digital or analog, don't matter, they all sound different.

 

[Pogre]

I have a 7.2 avr capable of bi amping. this thread inspired me, so last night I switched my speakers from passive bi amp to putting the jumpers on and just using 2 channels. I really can't tell a difference aside from my avr maybe running a little cooler, which has been an issue for me.

I want it to work, but I'm just not picking up any more from listening to it.

 

[MR.MAGOO]

You'd think speaker and AVR manufacturers would stop including bi-amp / bi-wire features since it seems to offer no benefit.