How do you calculate watts per channel?

If you vertically biamp a speaker with two monoblocs at 100 wpc each monobloc, is the resulting watts per channel 100 wpc or 200 wpc?

I know that If only one monobloc is driving the same speaker, the wattage is 100 wpc.

If you tri-amp with the same speaker and monoblocs, will the rated wpc 300 wpc?
If I understand you correctly, you are using two single channel 100W amps on each speaker; one amp for the woofer and one amp for the treble. So yes, that would be 100W per driver or 200W per channel. You'll have four single channel 100W amps total.

Scaling to a 3-way speaker would have you using 6 single channel 100W amps total and that would be 300W per channel.
No, when you vertically biamp, the power does not add together as some folks think. You will still effectively have only 100 watts per channel whether you bi-amp or tri-amp. To get more power you really need more powerful amp(s).

At best you will have no crosstalk between the right and left speakers and you may gain a little bit more headroom because one amp channel will be relieved of bass duty if you're using a stereo amp. If you're using mono amps the one on the midrange/tweeter section should have a tiny bit more headroom.

This is the simple answer as it's usually a bit more complex in reality, considering the varying impedance/load issues.
As you can see, there seems to be a lot of confusion on this topic, so let me explain it in more simple terms.

If your preamp sends a signal to play a midrange note at 500Hz, the amp that is hooked up to your midrange/tweeter section can only pull 100 watts out of a 100 watt amp. It cannot borrow ANY power from the amp hooked up to the bass section. Thus, you still cannot get more than 100 watts to either speaker section...

Effectively, you have individual 100 watt amps, each supplying 100 watts (not 200) to their respective speaker sections and power bands... Likewise the bass speakers cannot borrow any extra power from the midrange amp when it amplifies a strong bass note. It is limited to the 100 watt amp that it is actually hooked up to.
Some reading that may help a little.


As I stated above, I tried to give a simple answer. The article you quoted goes into depth on the subject and is an interesting read.

What I got out of it was that if you're going through the speakers internal passive crossovers there will not be much, if any, power gain from using multiple amps.

The way to get the true benefits of bi-amping is to use an electronic crossover rather than going through the internal passive electronics.

This approach certainly has power benefits, as you are limiting the power bands of the amplifiers and there are no passive components in the way to drain off power.

I'm not sure if electronic bi-amping is what Mitch4t was referring to, but I suspect not. It would entail removing all the passive crossover components from the speakers and then buying a good electronic crossover or having a custom electronic crossover made for the particular speaker system. This could get costly by the time you add the price of the extra amplifiers and electronic crossover; plus many folks would not have the wherewithall to tackle such a project.

But if you did undertake such a project who could resist upgrading the internal wiring and maybe having it all cryo-treated, including the connectors. But why stop there?...
Plato, it's a question of semantics. The amount of power available for one channel will be the sum of the power available for each driver on that channel. But, it's really a meaningless concept when using multiple amps per speaker. The thing that is important is the amount of power available to each driver.

Kind regards,
Great article Dave, and yes Plato you are correct, my illustration was not meant for using an electronic crossover....even though I do actually use one in my system. Plato's article has whetted my appetite to try a tube amp on the top end of my system.

Thanks to all of you for your excellent contributions to this thread.........