What Are the Benefits of Bi-Wiring Vs. Bi-Amping?

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Q I just bought Polk Audio Monitor 40 Series II speakers and want to know how to install them using bi-wiring. Do I connect two separate wires from the positive and negative outputs on the receiver and run them to the separate positive and negative input sets on the speaker? What benefits will that provide? —Kris Green, via email

A Yes, to bi-wire your speakers, you can either connect two separate sets of speaker wire in the manner you describe or use special four-conductor cables designed for that purpose. Note that you will first need to remove the conductive metal jumper strips connecting the Monitor 40 speaker’s dual-input terminals for the bi-wiring to provide any potential benefit.

Which brings us to part two of your question. While some experts maintain that bi-wiring can have a beneficial effect by allowing the high- and low-frequency portions of the audio signal to be separately routed to the high- and low-frequency drivers in the speaker, others claim there are no audible benefits to bi-wiring and you are simply buying more wire (buywire, ha).

In all likelihood, a more sensible use for those dual-input sets is to bi-amp the speakers. With bi-amping, separate amplifier channels power the speakers’ low- and high-frequency drivers. Bi-amping is fairly common in systems where a 7.1-channel AV receiver is matched with a 5.1-speaker setup: instead of letting those two extra amp channels go to waste, you re-route them to the front left/right speakers. The catch here is that the receiver needs to permit re-routing in its setup menu, though many current models do allow for that. And bi-amping isn't limited to receivers with unused amp channels, since you can also add an external stereo amp to a two-channel integrated amp or 5.1 setup.

SuicideSquid's picture

If you know how to draw circuit diagrams, I encourage you to draw one of a bi-wiring setup, vs. a single set of wires bridges at the speaker terminals.

These circuit diagrams are identical. There's literally no difference at all between a bi-wiring setup with bridges on and bridges off. The only potential difference between a bi-wiring setup and regular wiring is that you physically have more wire running between your amp and speakers, so if you're listening at high volume and delivering a lot of current, you might see a small advantage, but no different than stepping up to a heavier gauge wire.

Bi-amping is a different story. Most modern receivers and integrated amplifiers have a "Zone 2" that can be set as a second amp for bi-amping. I have a relatively small and lightweight amp that delivers 60wpc - not really enough to drive my power-hungry floor standing speakers, but the amp has a Zone 2 which allows me to bi-amp and deliver 120wpc to my speakers.

jeffhenning's picture

On the subject:

Biwiring offers less benefits than can be had by using single, heavier gauge speaker wire since you are increasing the inductance of the circuit. Whether that inductance increase is audible is as debatable as bi-wiring. Also, over the run of cable that can be expected in the standard home, quality 10 gauge wire and connectors is more than good enough and it's less expensive. Unless your speakers are 100 feet away. In that case, find a closer location for the amp.

As to this type of passive bi-amping, it's a giant waste of money with no worthwhile return. Yes, you are asking less of the amp by only showing it part of the passive crossover circuit, but it's most likely a pretty crappy amp or crossover that requires this topology to get the most out of it (or both). Also, you are now doubling the cost to power your speakers with negligible return.

Multi-amping your system and doing it with electronic or, better, DSP crossovers works incredibly well. It can be done, but it's not for people who aren't tech nuts like me. That, though, is another topic.

When I'm bored, I design active loudspeakers in my head.

RTPBob's picture

Does it matter what the ohm rating of the speakers are? If they're lower ohm speakers how would that affect the receiver?

SuicideSquid's picture

Are you hooking the speakers up to a dedicated second zone output, or to the "B" output of your amp's "A / B / A+B" output?

If it's A/B, you're not really doing anything as the A and B are being driven by the same amplifier circuit, and if you have low-impedance speakers, you may overload your amplifier.

If you have a dedicated "Zone 2" on your amplifier, this will actually be a separate amplifier circuit and will drive speakers of whatever impedance your amp is rated for. If your amp is rated to drive 4ohms and your speakers are 4ohms and you properly bi-amp them by plugging them into both zone 1 and zone 2, you should be golden.

Olaf the Snowman's picture

McIntosh has a new (expensive) tube/transistor amp MC901, which can be used for bi-amping :-) ........

Philt56's picture

I currently biamp my B&W 703s (original version) with my Nad t787. Only running 5.1 so i biamp p with the rear surround amps.

I’m looking at updating my receiver and trying to decide between the nad t778 which has 9 channels and anthem 740 which has 7 channels. If I decide to add 2 atmos speakers, I’m good with the nad model but if I go with the anthem then i either have to skip biamping or add another 2 channel app for the atmos which I prefer not.

Each receiver has its own plus and minuses, so this just another factor to consider. So is biamping a major consideration? I have to admit it’s been so long,I can’t say how much different the speakers sound if I switch back to single amps for front and left. All I know is they sound good now.