Mono-blocking my two Mc Intosh MC-2205's ???

About three years ago, I got a deal on two Mc Intosh MC-2205's from a trusted friend who resides in the suburban area of Chicago (MINT CONDITION!!!).

These amps are extremely heavy and well built to say the least. Since I own two of them , and have yet to hook them up...., I was thinking of bridging/mono-blocking each unit to obtain a 'whooping' 400 watts per channel, to feed my hungry but deliciously sounding Infinity speakers.

Knowing the repretation of these units, and reading the reviews from the archieves, the MC-2205 was a 'kick-butt' amp that was manufactured between 1975-1979. Living up to the Mc Intosh repretation, according to the reviews, they showed no weakness anywhere across its massive power band.

I need to know how to correctly hook/wire each unit to obtain my goal. I don't want to hurt these precious 'solid state' senior citizens.

I have read that mono-blocking is not a good technique? I have also heard that mono-blocking is a poor way to achieve a true 400 watts per side, because there will some wattage loss given the design nature of mono blocking. I've even been told to ditch the old Mac's and go out and purchase a single amp that would meet my 400-500 watts/channel desire. (I don't have deep pockets, so I must work with what I have. I can't afford 5-9K for a new Mac)

I need to learn the proper way to bridge these two amps, so that no harm will come to them..., and if mono-blocking is a great idea? These amps will be feeding a pair of (year 1976) Infinity Concert Series - Quantum Line Source, which can swallow up 500 watts per speaker in a hurry!!

Help please,

Darren T. Jackson
I thought that just because I own a Mc Intosh MC-275, a MC-225, a C-2200, and a C-32..., I knew everything.

What happened ?

Have you looked at the owners manual to see if this can be done or not ?

While this information is from a few years ago, it still might be useful someday should something happen :
Don't have a Mac but according to the lit, there is a switch on the back for mono operation. Typically, but not specifically to the 2205, you would flip that switch to mono, use only the right channel input only (both amps) and connect the speaker wires to both left and right positive (+) terminals on the amp. Again, I can't confirm any of that specifically for the 2205. My experience is with Plinius and has been positive.

Macs are ruggedly built and the output impedance is halved when bridged this way (0.5 ohms). If the Infinity speakers are the same vintage, this should be a benefit.

There are many amps that should not be bridged but I doubt you could damage the Macs unless you screw up the wiring. I remember reading in the Plinius manual that connecting the negative(-) speaker terminals could be fatal to the amp but it's a possibilty the Mac mono switch is more inclusive. I also don't have independant gain knobs to deal with but I doubt that should be a problem.
Looks like I was wrong. McIntosh don't bridge, they parallel, which explains why the output impedance drops and the power only doubles. I thought that might have something to do with transformers. All you need is jumpers between the left and right speaker posts. Choose whichever input works.
Some of the Mc amps are mono bridge and some are mono parallel. For modern (i.e., low impedance) speakers, the latter is the clear and obvious choice. Lucky for you, you have mono parallel switched amplifiers. Monoblocking will give you vast improvements in all aspects of sound quality compared to a single amp, IMO.

Also, be sure to try the high sensitivity switch. Moving it from 2.5V to 0.75V will improve dynamics and detail by a considerable amount in many cases. Just be sure to turn your preamp volume all the way down before turning everything back on because they will play much louder than before.

Play with the gain controls too. I had a 2125 that sounded best with them all the way up but I've since heard some that sounded best at like 2:00. Experiment and see what you get.

Enjoy your new amps! They will sound incredible once you figure out the right settings.

I suggest you call McIntosh Labs and ask them about bridging/mono-blocking your two McIntosh MC-2205's. It is important to get the right answer and Mcintosh should be able to help you.