Matching the sensitivity of two amps for bi-amping

I too agree with ZD. I would add, with respect to the passive biamp configuration you are proposing, that in most cases it would not be correct to match the sensitivities of the two amps. What should be matched is their gain, the relation between voltage out and voltage in.

Sensitivity is the input voltage required to drive the amp to some power level, usually its maximum rated power. Since the max power ratings of the two amps would probably be different, if sensitivities were matched the same input voltage would result in different output voltages from them, and hence different output powers for a given load impedance.

Power amp gains are often unspecified, but are commonly indicated in measurements provided in reviews, such as those in Stereophile. Also, gain can be approximately calculated from the sensitivity and max power capability specs of an amp, as I described here.

Finally, I see that your present amp is rated at 8 watts. A point to be aware of is that if you were to passively biamp that amp with a much more powerful solid state amp, that is somehow properly gain matched, you would not be able to utilize most of the power capability of the solid state amp without driving the lower powered amp into clipping.

Regards,
-- Al

Nikmilkov hi,

All you need to do is purchase a solid state amp that has higher sensitivity than your AN amps that also has input level controls.

Set the level controls so your bass sounds balanced in your system with the AN amps, an then your CJ preamp volume will be the master volume for both amps.

Cheers George

I've been biamping a pair of DIY speakers that are similar in design to the Legacy Focus using a pair of Peerless 12" woofers per side as well as Eton midbass, midrange, and tweeters. The bass drivers seem ever so slightly less efficient than the rest so biamping was the only way to get the sound I was looking for, otherwise the speakers seemed bass shy and 4 12" woofers shouldn't sound that way.

My sources are mostly cdp or universal players though I occasionally hook up a Revox B261 tuner. All of my sources have at least 2 outputs, the universal players having the stereo outputs as well as the full range FRONT outputs for surround. The tuner has fixed and variable outputs. I connect the stereo outputs to my main amp (presently a JAS Array 2.1 integrated using 805 and 300B tubes with a passive linestage) and the FRONT outputs to the amp I will drive the woofers with. In the past, I've used an integrated amp for this purpose, a Consonance Calaf, with great results. Presently I use pro amps, having both a Hafler and a Face Audio that see duty (only 1 at a time).

You could go from your source(s) into your preamp with 1 output and and use that to drive the Audio Note amps and into a pro amp with attenuators with another output on the same source or an integrated or get another preamp that will drive a separate amp for the woofers. If your source(s) doesn't/don't have 2 outputs, you could get the same result using a Y-cable. You don't see many high-end Y-cables out there so you may have to build your own or have someone build you such a cable. I've used soniccraft for this and their work is very good and affordable.

I've always found the bass to blend in well with rest of the range only standing out if turned up to high like any subwoofer. You should be able to get not only acceptable results but much better results than biamping with another pair of the Audio Note amps as you can use whatever solid state amp you wish. One issue with the pro amps though is that most use XLR and don't have RCA inputs. Just use XLR to RCA interconnects. If you have a pair of unbalanced interconnects that you like, you can always have XLR's installed at one end. Good luck!

Thank you fellow audiophiles for your input. I didn't reply for a couple of days for the purpose of getting more opinions. It looks like the passive bi-amping is a contradictory approach. Will try to gain some experience by using amplifiers from friends and at that point i will refrain myself from buying. The specific requirements needed for the second amplifier(s) further limit the possible choices. Yes, I do have Y-splitters - two Audioquests that I am using from my CD player for sending the signal to two different set-ups - one for a higher quality system and one for a conventional system used when I am doing fitness. I do have also balanced and unbalanced outputs from the CD player (Esoteric DV 50 S) but the preamp has only unbalanced inputs, so I am not using the XLR's. Some Mcintosh amps have gain knobs, should I try this?
Regards to all of you and happy listening.

"Some Mcintosh amps have gain knobs, should I try this?"

Yes this is the way to get the right balance between the amps so long as the Mac is higher in sensitivity than your AN amps, and then use your CJ preamp for the master volume.

Cheers George