Bridged amps vs stereo vs monoblocks.

I don’t have any real issue, but I’m curious about how the bridging of an amp functions. I have a 80 W stereo amplifier, which can be bridged to provide 220 or so power into a load. This amp also has a hefty power supply which makes it work beautifully with my Magnepan’s. However, I used to have two of these amps bridged.  One of which I lost due to it breaking so i replaced with an unbridged stereo amp, which I’m only using one channel. So what a strange hodgepodge of connections, right? It sounds great and I am have no problems but I’m curious if I was doing some thing that is easily changed to provide benefit. Mixing two different amps for example.  Or I read when an amp is bridged it is sensing a four ohm load as a two ohm load and therefore what does that even mean? Also, using one part of a stereo amp is odd, but does that change anything, especially if there’s one power supply? Curious, if there any principles I could learn about this from those more familiar with those equations thanks!


Thanks @jasonbourne71  so if I understand I just don’t bridge to avoid stressing the power. That’s interesting a as to what stressing does. Shorten the life of the components? Isn’ta power supply just a coil of wire? Uses more energy? @mulveling i think you’ve touched on something. However this works it sounds great. I’m sure if I fiddle with it I may lose something, but such is this hobby. A bit of science and a bit of voodoo. 

If you do as jasonbourne71 suggested, and switch the bridged amp back to stereo, and use one channel of each amp per speaker, you may find that it sounds better in an unbridged mono block configuration. You’ll retain the benefit of the separation of the mono blocks, and the power supply will have less responsibility. It may be subtle and is hard to predict how audible it will be, but I think it’s worth a try.


Your original setup, two identical STEREO amps bridged MONO makes sense if more power was needed. A great solution if you start out with one, change your speakers to inefficient ones.

Balancing volume L/R was an issue (as is any stereo amp with separate Gain for L/R like my McIntosh mc2250. Happily, full gain matched (as advised by McIntosh: use preamp for volume). That MC2250 tested 305 wpc within specs, dead silent. I changed speakers, back to very efficient horns, sold the SS, moved back to tubes.

Lack of remote volume is why I finally changed from my wonderful pair of MONO amps (fisher 80az) Steve at VAS checked them for me pre-sale and made me sell them to him!

Now Stereo Cayin Tube AT88T, with remote volume behind a vintage McIntosh tube tuner/preamp mx110z.

As I understand it when you bridge an amp you will double its output at 8 and 4 ohms, but not 2 ohms. If your speakers dip to 2 ohms, depending on your speakers design (and listening levels?) their output potential (sound) may be compromised. FWIW

As I understand it when you bridge an amp you will double its output at 8 and 4 ohms, but not 2 ohms. 

That is not always the case - it depends on the amp. If you have one with a sufficient power section it will 'double down'

I own a pair of amps that put out 40 W into 8 ohms stereo, and 230 W into 1 ohm. I run them in bridged mode and they put out 160 W into 8 ohms and 500 into 1 ohm loads.  I am not using them with speakers that require that but when I bought them they were happily driving one of the harder speakers, a pair od Apogee Scintillas in 1 ohm setting.  The poster would have to research the amps he is considering to know whether they will be happy with a particular load.

You are correct, though, in thinking that it isn't always a strict doubling of power. My bridged amps put out 160 - 280- 400 - 500 W into 8 - 4 - 2 - and 1 ohm loads.