This is a review and detailed measurements of the McIntosh MC 427 (MC427) stereo car audio amplifier. It is on kind loan from a member. It has been discontinued but used ones go for about US $500.
Not much to distinguish the amplifier from other car amps other than the bright blue logo. Unlike all the others I have tested though, this one is class AB, not Class D.
There are two small fans which I don't like to see. Fortunately in use the amp ran very cool, barely getting warm and I don't think the fans ever came on.
McIntosh MC427 Amplifier Measurement
As usual we start with our dashboard of 5 watts into 4 ohm load:
Are you seeing what I am seeing? Distortion product at nearly -120 dB??? And in a car amp? Incredible. SINAD is noise limited and lands the MC427 neck and neck with a state of the art class D car amp:
Notice the high current usage of 7 amps to produce 5+5 watts of power (nearly 100 watts in!). Noise performance is excellent for a car amplifier:
Unlike most class D amplifiers, there is no load dependency in frequency response test:
There is an offset between the two channels though and they roll off differently but this may be due to age.
Crosstalk is not great:
It is similar to the last car amplifier I tested so there may be a common issue here with terminals they use or something like that.
Multitone performance is yet again excellent:
Guess what 19+20 kHz intermodulation performance is:
Yes, excellent.
Let's see if it meets the power spec of 100 watts per channel:
Of course it does and then some. But better have good supply of current seeing how almost 40 amps were drawn.
Here is 8 ohm:
Sweeping at different frequencies shows the class AB strength in not caring a lot but the amp did go into protection at lower frequencies:
I was pushing it into clipping though which often causes that.
Finally, the amp was stable on power up other than a minor glitch:
Conclusions
The MC427 delivers performance that is eye popping for a car audio amplifier. Distortion near -120 is insanely good, beating many home amplifier! Measured power exceeds specification. The only cost is much less efficiency.
This is really superb execution on behalf of McIntosh engineering. I don't know the merits of buying one used but the MC427 really shows how it is done.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Not much to distinguish the amplifier from other car amps other than the bright blue logo. Unlike all the others I have tested though, this one is class AB, not Class D.
There are two small fans which I don't like to see. Fortunately in use the amp ran very cool, barely getting warm and I don't think the fans ever came on.
McIntosh MC427 Amplifier Measurement
As usual we start with our dashboard of 5 watts into 4 ohm load:
Are you seeing what I am seeing? Distortion product at nearly -120 dB??? And in a car amp? Incredible. SINAD is noise limited and lands the MC427 neck and neck with a state of the art class D car amp:
Notice the high current usage of 7 amps to produce 5+5 watts of power (nearly 100 watts in!). Noise performance is excellent for a car amplifier:
Unlike most class D amplifiers, there is no load dependency in frequency response test:
There is an offset between the two channels though and they roll off differently but this may be due to age.
Crosstalk is not great:
It is similar to the last car amplifier I tested so there may be a common issue here with terminals they use or something like that.
Multitone performance is yet again excellent:
Guess what 19+20 kHz intermodulation performance is:
Yes, excellent.
Let's see if it meets the power spec of 100 watts per channel:
Of course it does and then some. But better have good supply of current seeing how almost 40 amps were drawn.
Here is 8 ohm:
Sweeping at different frequencies shows the class AB strength in not caring a lot but the amp did go into protection at lower frequencies:
I was pushing it into clipping though which often causes that.
Finally, the amp was stable on power up other than a minor glitch:
Conclusions
The MC427 delivers performance that is eye popping for a car audio amplifier. Distortion near -120 is insanely good, beating many home amplifier! Measured power exceeds specification. The only cost is much less efficiency.
This is really superb execution on behalf of McIntosh engineering. I don't know the merits of buying one used but the MC427 really shows how it is done.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
