Am I thinking straight? MC255 vs 152 and 301

[MrG]

I would really appreciate your input, thoughts and suggestions.
I am planning on replacing two of the amplifiers in a multi amp system. They are both solid state, one a monobloc and the other stereo.
The monobloc is connected to an active crossover on one end and a large horn loaded subwoofer on the other.
The stereo amp is fed by a different active crossover and is connected to the 15in bass drivers of the "satellite" speakers.
The sub is crossed over at 80Hz and the satellites at 450Hz.

Looking over the McIntosh offerings I was considering the MC152 as the stereo amp and the MC301 to replace the mono. But...………. What to my wandering eyes did appear?...…….
THE MC255...…… I am thinking:

I am only using these amps for the lower registers - Should be a strong suit for the 255
The center channel can be connected to the sub. 250 wpc is plenty of power
As you know balancing the output of the drivers is critical and the crossover feeding the amp has a variable control, so I am good there.
The left and right pose a bit of a different problem as the current amp has both volume and L to R balance which simplifies the adjustments. However my mid-high frequency reference amps have gain controls. I think I can easily change my procedure by setting the bass levels first, then bringing in the sub and finally the mids and hi's. ( I use a sound generator, calibrated mic's and a real time analyzer )

By my way of thinking the MC255 would actually be a better choice in this application.
Thoughts???
G

[W9TR]

That’s an interesting system you’ve got there.

I think the biggest difference between the MC 255 and the MC 301 / MC 152 combo is that the MC 255 does not have autoformers while the MC 301 / MC 152 do.

I think the MC 255 is a nice update to the venerable MC 205 five channel amplifier which is a favorite for home theater customers and offers a lot of power in a small package- but again, no autoformers.

If you have the physical space I would also consider the flexibility of having separate amplifiers vs a single box solution.

Tom

[SMC23]

It’s all about those Autoformers if your speakers are mains and/or you want the best possible sound from your speakers then go with the Mc152 and Mc301 combo. I think gives you the best flexibility as well down the road if you want to add additional mc301 to power the mains.

[MrG]

Thank you for your thoughts, its a point I hadn't considered. Looking closely at pictures of the amps I can clearly see the 301 and 152 have multiple transformer tap connections and the 255 does not. I also realized I don't know the impedance of my woofer drivers... duh.
Thanks again for your input.
G

[AVphile]

What is the function of the autoformers, and why are the McIntosh amplifiers which have them better than ones which do not?

[Cohibaman]

https://www.audioaficionado.org/showthread.php?t=19689

[W9TR]

Great article by the master. One other thing I’d add. Autoformers enable McIntosh’s proprietary quad balanced architecture which significantly reduces distortion and noise.

[jayvis1]

I've always had the opinion that using individual amps to power single drivers in loudspeakers is ridiculously excessive. Can someone please provide an understandable reason for doing this other than looking for ways to spend money or an attempt to validate an inaudible mathematical theory?

[W9TR]

If the amps are being driven by a dsp based crossover then you have a true state of the art multi-driver design. The Bryson active loudspeakers are a good example.

If you have a speaker with a normal passive crossover and using multiple amps driving the passive crossover sections then you are very deep into the land of diminishing returns, which is what this website is all about.

[sgbroimp]

You can just shop Mc amps by weight like I do. If they weigh like a small bank vault, buy them as they have autoformers. If they are much lighter, stay away at least for mains. This is a little tongue in check but not wrong.