Possible to passively bi-amplify two speakers with any two-output amplifier?

Does an amplifier necessarily need to specify "can be used to passively bi-amp," or should any amp with two speaker outputs be able to do this?

I ask because I recently read that passive bi-amping does not require any more current draw or power than regular amplification, considering the four binding posts on the speakers are bridged in the regular configuration.

Also, sorry about the long title... I didn't mean to scare anyone away.

Bump for those who haven't seen this before...

Is there any reason why passive bi-amping wouldn't be possible with any multiple speaker amp?

I'm going to answer my own question!

Yes, it is possible to use an amplifier to passively bi-amplify a pair of speakers if it has more than one simultaneously selectable speaker output. However, the results were not what I expected.

I tried it with my Pioneer Elite A-35R integrated amplifier and Boston Acoustics VR-M60 speakers. First, I removed the bridges between the four binding posts on each speaker, then I used Blue Jeans Cable 10 AWG to the bottom two posts and BJC 12 AWG cable to the top two posts. The difference in gauge was simply due to the fact that I only had two of each cable.

I turned on both speaker outputs and wow, it sounded very different. The amount of detail was extreme, but it was also very bright. The lower mid range and bass were suddenly recessed-sounding in comparison. The amplifier didn't appear to be working hard... Actually, it seemed to work a little easier.

In any case, though the amount of detail was unreal, it was much too bright to listen for very long. The A-35R was not designed for bi-amplification, so it could be true that providing equal amounts of power to both the woofer and tweeter would lead to a bright sound, considering low-range frequencies require more power to reproduce (from my understanding).

This experiment has certainly increased my interest in bi-amplification, because the clarity was amazing, but with the A-35R, the speakers sound much better bridged.

Just thought I'd share... Hopefully someone else is interested in this stuff.

Oh, whoops, you're right... I guess using another output from the same amplifier doesn't count. I thought "passive" might refer to the fact that the amplification was from the same amplifier, but now I wonder where I got that idea.

Some of Pioneer's receivers (including the lowest-end VSX-516 on up through the Elite line) claim to have a bi-amplification option that redirects the "surround back" outputs in a 7.1 system to the front channels. Perhaps these have two separate amplification systems?

In any case, I mixed up my terms. The "passive" in passive bi-amping refers to the fact that an active crossover is not used in place of the speakers' internal crossovers.

Just for clarification, bi-wiring would require two wires from each speaker terminal output on the amplifier, correct? I've heard that bi-wiring has little effect compared to bi-amping, but would also bet that the metal bridges between the speaker posts are not of the highest quality and would like to get them out of the way.

I'll try it the next time I'm home... I wonder if bi-wiring will yield the same result as using both speaker outputs, and if not, I wonder what exactly was happening to make the treble range stick out in my experiment.

Ah, you're lucky. My amplifier only has one output (+ and -) per channel, so I would have to use the first method. I'm still curious about what was happening with my experiment, though... The difference in sound wasn't subtle at all.

Sorry for dragging up an old and potentially misinformative thread, but I'd like to add an update.

Since my experiment, I've been interested in bi-wiring (since bi-amplification isn't an option at this point). As an early birthday/Christmas present, I bought myself a 6' pair of Canare 4S11 cables from Blue Jeans Cable to test. I've been quite happy with both the Belden 10 and 12 AWG cables they sell and recommend as their best. However, the possibility of bi-wiring was too difficult to resist trying after hearing what my speakers could do without the gold-plated bridges connecting the four binding posts.

Wow. Bi-wiring truly makes a difference in my setup. I'm not exactly sure what's contributing to the difference. If I had room in the binding posts on my A-35R, I probably would have purchased two more Belden 10 AWG cables, but the 14 AWG Canare 4S11 barely fit, so that wasn't an option. Perhaps the Canare cables are inherently better in some way? They reject the electromagnetic field around the cable more than the Beldens, but BJC says that this probably isn't a concern. I have a feeling it has more to do with the electrical properties of the bridges that are no longer in place. Now that they're out of the picture, it seems that everything can receive its own separate signal without interference. I'm very pleased, and it was a sub-$20 upgrade.

Careful, that's starting to sound "too extreme." At that point, you might as well move up to Belden 10 AWG for each set of binding posts.