MC225 Enough for KEF 105.1 Speakers?

I'm looking for a tube amp to replace the B&K SS power amp in my setup and the MC225 is at the top of my list as far as vintage amps go... my KEF 105.1 speakers are 86 dB sensitivity, is the 25 watt rating of the MC225 enough to drive the KEF's?

Also, if I were to go with a modern amp, I'm looking at the Rogue Audio Atlas Magnum... besides the obvious power difference, does anyone have any input on what the differences might be between the MC225 and the Atlas Magnum?

Thanks in advance for any input.

The 225 is a wonderful little amp. Unless you are in a very small room and never listen loud though, I wouldn't use it on 86 db speakers. Maybe a 275?

If the Kef's have bi-amp connections you could remove the jumpers and run the low end with the b&K and the top end with a Mc-225.

The 225 really shines in the mids and highs. Great amp for horns like Lowthers and Tannoys.

2sixR said:

I'm looking for a tube amp to replace the B&K SS power amp in my setup and the MC225 is at the top of my list as far as vintage amps go... my KEF 105.1 speakers are 86 dB sensitivity, is the 25 watt rating of the MC225 enough to drive the KEF's?

Also, if I were to go with a modern amp, I'm looking at the Rogue Audio Atlas Magnum... besides the obvious power difference, does anyone have any input on what the differences might be between the MC225 and the Atlas Magnum?

Thanks in advance for any input.

Click to expand...

Yes. I drove my speakers (87db) with one and it's super nice and quiet loud.

If your MC225 is standard, yes you may lack deep lows. If the power supply has been upgraded with bigger caps, then you get nice lows.

But since I did like apachef1 suggests. Bi-amp your speakers with the MC225 for mid and highs, and use a nice beefy SS for the low. The results is fantastic.

The best you can hope to get with 86dB sensitive speakers with sort of standard settings on the SPL potential calculator is 96.3dB. Make no mistake--that's pretty loud. But it's not "rocking the house" loud. Going with an MC275 would bump your potential up to 101.1dB which is significantly better.

If you really want to go with tubes for such difficult speakers, I'd suggest a pair of MC275s going mono. That'll get you up to 104.1dB. You may someday want for louder--but you're getting into "rockin'" territory there.

You would need a pair of 3500's or 2301's or maybe a pair of 275's in mono to get the full potential out of your Kefs. That said the out put would only be about 109 db. Subtract a 10 db peaking factor equals 99 db. Listening at 10 ft would reduce the output to 91 db, which for the average person is acceptable. But for some one who appreciates life like concert levels falls way short.

They are beautiful looking speakers and love the british sound. The KEF's were built duing a time the big transistor amps ruled the audio landscape Levinson, Krell, Theshold and the mighty Jeff Rowland #9.

To really get their full potential strap a Levinson 23.5 or a Threshold Class A amplifier to the KEF's and you will think you are listening to a different speaker. Of course a McIntosh amp will be my first choice.

I own an MC225 and it is definitely an enjoyable amp. For low listening levels it'll perform admirably. Dynamic requirements of well recorded music with higher playback levels will push the amp into clipping pretty easily on such inefficient speakers.

Why not consider a more powerful Mc amp?

I love my MX110z > MC225 > KEF LS50 setup. I use it for both CD, vinyl, FM and even for home theater. After break in (probably have 200+ hours by now) I don't even feel the need for a sub anymore as the lows have improved considerably. That said my room is about 12x16, and I really don't listen to things super loud. Still this setup is stronger than I thought it would be, and I was originally hesitant to purchase the small KEFs though this combo has worked out just fine. Different model speaker than you asked about but similar efficiency.

One of the things that confounds a lot of people is that 25w is actually a lot more than you think. 16w gets you a 12dB output increase over the sensitivity rating and 25w will give you a total of about 13.5dB.

From 1w to 25w, you gain about 13.5dB
From 25w to 250w, you gain only another 10dB.

It's why I laugh hysterically at AVR companies that differentiate their models by saying that the lower end has a 110w amp and the higher is 120w. That difference is so small as to be meaningless but they'll charge you $200 extra for it.

*ahem*

But back on topic: if I were in your shoes and wanting tubes, I'd be looking at least at a pair of MC60s, MC75s, or an MC275.

I love KEFs and I have 105.2 but I felt my MC60's were not enough for them...
When replaced 103/4 with 105.2, meters on my MC2205 ran noticeably higher; after all there's 6 dB difference.
So, I would get more powerful amp...

Having said that, I am sure you could get a great sound with combo, albeit not too loud.

You have a great speakers, and I hear MC225 is the one to have as well.
Cheers