Bridging the Mcintosh 402 amp

Excellent, everyone. Thank you!

As a point of information, the MC402’s mono mode doesn’t bridge the two channels, it puts them in parallel. Which is actually better, as bridged amplifiers often don’t do well sonically when driving 4 ohm speakers such as yours.

Although I don’t have the user manual to look at, in looking at the rear panel diagram in the service manual (at hifiengine.com), and assuming the 4 ohm impedance spec of your speaker is reasonably accurate (as opposed to being significantly lower than that at many frequencies), I believe you would use the amp’s 8 ohm taps, and as Mike indicated you would connect jumpers between those taps. You would also set a switch on the rear of the amp to "mono parallel" mode rather than stereo mode, and you would connect the preamp to the amp’s right channel input, balanced or unbalanced as you prefer (setting the input mode switch correspondingly).

Good luck. Regards,
-- Al

Look at pgs 12 and 13 of your manual. This explains in detail how to change it to Mono operation.

Excellent. Thank you Mike!

Take a look inside the manual for your amp, it's in there. I bridge a MC252 for the center channel in my HT/Music room. You will simply be connecting a couple of jumper cables between the speaker terminals on your amp. Which ones will depend upon your speaker, there are two ways it can go. The manual lays out both ways but again, which way will depend upon your speakers. Hope that helps.
Mike