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To monoblock or not to monoblock McIntosh MC275's

Hi everyone,

I'd appreciate your opinions on the matter. I currently own an MC275 MK IV, running McIntosh XRT 28's. It sounds great - even though the XRT's can handle up 1200W and the MC275's output 80-90W.

I got my hands on a NOS (still sealed) MK IV, and I'm debating whether I should keep it and run as them monoblocks. The reason I'm not trying it personally, is because I don't want to open that new one that's still sealed.

So my dilemma is -  would running 2 MC275 as monoblocks make a BIG difference in sound quality?

I'm sure it will be louder, but for the sake of the argument, if my sound is now 100% - in your opinion
(hypothetically speaking) will it improve it to say 103% or 120%? Will I notice a big enough difference?

Thank you!
yyman23
yyman23 OP
147 posts
 
Thank you everyone. These are some good tips. However, someone offered me a really good price for the second one and apparently it was a MK V, not a MK IV, so I decided to sell it.

dentdog's avatar
dentdog
498 posts
 
I strapped a pair of MC 275s onto some JBl 250 Pyramids thirty or so years ago. Didn't really help. 
effischer
561 posts
 
FWIW, there is functionally zero difference between a series IV and a series V MC275.  Certainly not audible, but that's not a concern for you now anyway.

Increasing output by 3 dB (the smallest volume increase the human ear can normally discern) requires a doubling of power.  When bridged for mono, MC275 conservatively makes 150 W regardless of load, but as that translates to only 3 more dB, you likely won't get a big difference in output.

However, going dual monaural gets you essentially infinite channel separation at the amplification stage and more definition across frequency bandwidth.  That means better imaging and no two ways about it.

So, if you find a good condition series IV at a fair price, you can give the dual mono thing a shot to see if you like it.  Good luck & happy listening.

stringreen's avatar
stringreen
6,468 posts
 
Nope
mgreen27
147 posts
 

"Increasing output by 3 dB (the smallest volume increase the human ear can normally discern) requires a doubling of power.  When bridged for mono, MC275 conservatively makes 150 W regardless of load, but as that translates to only 3 more dB, you likely won't get a big difference in output."

Things are never that simple. If you read the original post, he's clearly looking for better sound quality, not more volume. If you have a big speaker that's very efficient, the drivers still need to be controlled, and that takes power. Wilson is a good example of this. In this case, though, the speakers are not that efficient. To be honest, I'm surprised he's getting good results with just the 1 amp. Adding a 2nd amp will yield much better sound quality at the same volume he currently listens at.

In most cases, bridging a stereo amp will give more power at the expense of sound quality. In this system, I don't think this will be the case for 2 reasons. First, the 275 has a history of working well bridged. A lot of people run them as mono's and are very happy with the results. Second, he needs more power. I'm willing to bet that if he called McIntosh, they would recommend not using just 1 275 to power both speakers. They may even say 2 bridged is not enough. Either way, another 275 will be a significant upgrade, and not a tweak.  

 


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