McIntosh MPM4000 Power Meter Review

[amirm]

This is a review and measurements of the McIntosh MPM4000 Power/dB vintage stereo meter. It is on kind loan from a member and costs used from US $500 to $999.

It had come out in 1997, aimed at automotive market so requires 12 volt power. As you can see in this sample though, it can be readily used in home systems with a case and external power supply.

Unlike every other VU meter we have tested so far which are just for show, the MPM4000 is supposed to be calibrated for a 4 ohm speaker. The purpose of the review then is to see if there is an impact on the fidelity and accuracy of its markings.

FYI the sample I have has very dim lighting. I suspect the originals were brighter.

McIntosh MPM4000 Power Meter Measurements
For testing, I configured the Purifi reference amplifier for 1 watt output. Here it is by itself:

As we expect, distortion is vanishingly small. Let's now connect the MPM4000 in parallel to left (1) channel:

There is no impact whatsoever which is a relief.

Now let's test for accuracy. I measured the above on the meter and it was accurate, subject to optical error. I then jumped to 10 watts and it too was accurate:

I then went up to 100 watts and it too was accurate. So mission is accomplished!

Conclusions
We have had many discussions of vintage meters on power amps being accurate (or not) in the context of new versions which clearly are not. I did not know what to expect but was pleasantly surprised to see that not only is it transparent but that it is also accurately showing power output of the amplifier.

The only negative is the astronomical pricing of it. I guess half of that is for the "status" sake.

I am going to recommend the McIntosh MPM4000 power meter if you don't have to tap into kid's college education fund to buy it!
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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/

 

[renaudrenaud]

Yeah! With this price you can buy a system. But this is the star of the show. Now we have to wait a Chinese company checks the schematic to know understand what to do.

 

[Hayabusa]

I assume the meter was connected to a 4 ohm dummy-load in this case?

 

[DanTheMan]

Seems like McIntosh gets everything right except speakers. They always look great too—any and every vintage I’ve seen.

 

[Blumlein 88]

Any info on the meter ballistics with music?

 

[amirm]

I assume the meter was connected to a 4 ohm dummy-load in this case?

Of course.

 

[GXAlan]

@Fosi Audio
@Douk Audio

Go make a budget version of this! This is what people want. No impact to audio, and calibrated output of power.

Besides the accuracy, you can see the ballistics here.

 

[amirm]

Any info on the meter ballistics with music?

Didn't get a chance with play with it that way. It seemed rather fast jumping to the actual power level.

 

[Bleib]

Yeah! With this price you can buy a system. But this is the star of the show. Now we have to wait a Chinese company checks the schematic to know understand what to do.

Fosi Audio LC30 likely sounds transparent enough

 

[TheWalkman]

Seems like McIntosh gets everything right except speakers. They always look great too—any and every vintage I’ve seen.

…and price, in a more competitive 2025 audio market.

As a silly college kid, I lusted over McIntosh amps (and the Bose 901s they often powered.). No longer.

I’ll judge SPLs with my ears rather than using my eyes and needing thousand dollar McIntosh power meter to do so.

 

[CedarX]

I’ll judge SPLs with my ears rather than using my eyes and needing thousand dollar McIntosh power meter to do so.

I assume you mean “judging when it’s loud enough”… or are you launching another objectivist/subjectivist debate about SPL?

 

[JayGilb]

Fun stuff. Thanks for another review.

 

[DanielT]

Thank you for your review Amir.

The only negative is the astronomical pricing of it. I guess half of that is for the "status" sake.
Maybe, or it's too McIntosh's owner who for example bought a McIntosh MC1502 tube amp for $12,000.00 no astronomical price to just to add a MPM4000?

A new VU /Power/dB stereo meter from McIntosh costs $1,800.00. Wait it was "just" a mantle clock:

MCLK12 Clock

Illuminated meters for ease of sight Temperature compensated Quartz movement ----SPLIT---- The McIntosh MCLK12 mantle clock is a celebration of time while being a tribute to classic McIntosh design. Constructed with the signature McIntosh blue watt meters, the MCLK12 demonstrates the same easy...

shop.mcintoshlabs.com

 

[Multicore]

Go make a budget version of this! This is what people want. No impact to audio, and calibrated output of power.

Not quite. A modern version should have an adjustment that allows you to dial in the nominal load impedance.

 

[ssashton]

Yeah I want that... just not the price. I'll pay $150.

 

[Miley_B]

Assuming a constant pure resistance load across the audible band and using only equal amplitude sine waves as stimulus would this unit indicate the same power at 60Hz as 1kHz etc?

 

[Ajax]

It's obviously a nonsensical toy that costs a lot of money and provides no real purpose besides looking good.

I think I'll get one .

 

[beagleman]

But specifying it is accurate into exactly 4 ohms, while great in one way, speaker loads are very reactive, so in reality it can not by its very nature be any more accurate then any power meter.

Are we saying it does a "Good job" of measuring a 4 ohm dummy load, or a good job of showing the power while connected to a speaker?

 

[Sokel]

What I see as negative is the range,a little over 100W.
Bring me a kW one and I'm sold!
(Nahhh,although I respect Mcintosh they are too colorful for me,a little like the SMSL of amps in terms of colors )

Thanks Amir!

 

[CedarX]

But specifying it is accurate into exactly 4 ohms, while great in one way, speaker loads are very reactive, so in reality it can not by its very nature be any more accurate then any power meter.

Are we saying it does a "Good job" of measuring a 4 ohm dummy load, or a good job of showing the power while connected to a speaker?

Was wondering the same… At the same time, are car speakers—the original target—behaving differently? Less reactive? Less variable resistive impedance?