The McIntosh MA230 - A half century of audio excellence

[jdandy]

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Considering the McIntosh MA230 is half a century old it is interesting to note the features available on it. Just like today's McIntosh amplifiers, the MA230 integrated amp delivers its full rated output of 30 watts per channel into 4, 8, and 16 ohm loads. There are separate output transformer taps on the rear panel that allows the user to select the correct left and right channel speaker impedance by moving two terminals to the correct taps. You will also see two phono inputs and a tape head input plus a L+R mono output capability.





The MA230 offers bass and treble tone controls. Even more unique is both bass and treble controls allow independent left and right channel adjustment capabilities using dual concentric control knobs that are friction coupled.

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If offered at all, most tone controls on modern amplifiers allow for plus or minus 6dB to 10dB of adjustment at the fixed points. The MA230 allows for a plus or minus 15dB adjustment.





It is widely recognized that human hearing has a lower sensitivity to low frequencies and extreme high frequencies at lower volumes. McIntosh includes a Loudness Compensation adjustment on the MA230 that can be activated with a toggle switch that introduces a compensated tone curve that follows the typical Fletcher-Munson curve. This is used when the volume is set low and allows the music to continue to sound rich and full. It is unfortunate that McIntosh no longer provides Loudness Compensation with the exception of the occasional reissued preamplifiers.

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For decades McIntosh offered output switching options that provided a user with advanced control over how the left and right channels were output to the speakers. This control feature was unique to McIntosh integrated amplifiers and preamplifiers. It was gradually phased out in the modern McIntosh preamplifiers and is no longer offered. This control function was quite useful for listening to mono recordings and for trouble shooting.






By today's standards the McIntosh MA230 still manages to deliver commendable performance that its specifications clearly reflect. Total harmonic distortion is rated less the 0.5% at full rated output from 20Hz to 20,000Hz. Intermodulation distortion is less than 0.5% at any combination of frequencies from 20Hz to 20,000Hz. Remember, this is a 50 year old integrated amplifier. The frequency range of the amplifier is rated +0, -0.5dB 20Hz to 20,000Hz and +0. -3dB 15Hz to 70,000Hz. The signal to noise ratio is 75dB below rated output.

As McIntosh's very first integrated amplifier, the MA230 represented then and now remarkable performance. That a half century old audio component can stand tall against modern competitors costing multiples of 20 times or more its original cost is quite astonishing. It is clear testimony to the commitment and dedication Frank McIntosh, his engineers and factory assemblers had and still have to manufacturing remarkable and long lasting audio components.

[chessman]

Well, dang Dan, now I want one.

[jdandy]

Originally Posted by chessman

Well, dang Dan, now I want one.

Randy.......Start your search. There are some clean MA230's out there.

[damacman]

And it's got 7591s for outputs! Although I've never heard an MA230, I've had several MC225s (still own one) and the sound is seductive. There is something very special about 7591s.

[jdandy]

Originally Posted by damacman

And it's got 7591s for outputs! Although I've never heard an MA230, I've had several MC225s (still own one) and the sound is seductive. There is something very special about 7591s.

damacman.......The other McIntosh amplifier that uses the musical 7591 output tubes is the wonderful MC225 power amp. It was manufactured during almost the same time period (1961 to 1967) as the MA230 (1963 to 1966). It uses the same two 12AU7 tubes and one 12AX7 tube as the MA230 but adds two 12BH7 tubes not included in the MA230 circuits. There are plenty of McIntosh MC225 owners who love these power amplifiers.

[62caddy]

Originally Posted by damacman

And it's got 7591s for outputs! Although I've never heard an MA230, I've had several MC225s (still own one) and the sound is seductive. There is something very special about 7591s.

Tony, I would bet the MA230 would work well with your Altec Barcelonas.

[jdandy]

Originally Posted by 62caddy

Tony, I would bet the MA230 would work well with your Altec Barcelonas.

Eric......I guarantee the MA230 will sound amazing with the Altec Barcelona's. I powered Altec Valencia's with my original MA230 for years with astonishing results. The Barcelona's present an 8 ohm load and their sensitivity is 91dB. Altec took their sensitivity measurements using 1 watt pink noise measured at 4 feet. The speaker is rated to handle 60 watts but 3 watts will produce a very good volume level. The McIntosh MA230 would be fine amp the Altec Barcelona speakers.

[damacman]

Dan / Eric:

I actually own the 9846-8A (the studio monitor version of the Barcelona). I do also still own an MC225. Although the speakers are collecting dust currently after being my mains for 20+ years, I have a C28 and MC225 to pair with them. I just have simply not had the time to set this system up.

Dan - I had my MC225 refurbished by a friend of mine, Stephen Mantz of Zed Audio. After Stephen finished it, this is the printout from his AP on its frequency response:

Frequency____Ch1_______Ch2
100.000 kHz -1.885 dB -2.574 dB
73.5750 kHz -0.893 dB -1.486 dB
51.1250 kHz -0.399 dB -0.814 dB
39.8000 kHz -0.170 dB -0.453 dB
29.2750 kHz -0.078 dB -0.259 dB
21.5500 kHz -0.046 dB -0.174 dB
15.8500 kHz -0.034 dB -0.114 dB
11.6600 kHz -0.030 dB -0.086 dB
8.57750 kHz -0.026 dB -0.062 dB
6.33100 kHz -0.022 dB -0.050 dB
4.64250 kHz -0.014 dB -0.034 dB
3.41500 kHz -0.010 dB -0.022 dB
2.51250 kHz -0.010 dB -0.022 dB
1.84775 kHz -0.006 dB -0.014 dB
1.35925 kHz -0.006 dB -0.014 dB
1.00000 kHz -0.002 dB -0.014 dB
735.750 Hz -0.006 dB -0.014 dB
541.250 Hz -0.006 dB -0.010 dB
398.000 Hz -0.006 dB -0.014 dB
292.750 Hz -0.006 dB -0.006 dB
215.500 Hz -0.006 dB -0.006 dB
158.500 Hz -0.018 dB -0.014 dB
116.600 Hz +0.025 dB +0.025 dB
85.7750 Hz +0.021 dB +0.021 dB
63.1000 Hz -0.008 dB -0.004 dB
46.4250 Hz +0.007 dB +0.013 dB
34.1500 Hz +0.029 dB +0.033 dB
25.1250 Hz +0.061 dB +0.064 dB
18.4750 Hz +0.126 dB +0.119 dB
13.6000 Hz +0.279 dB +0.237 dB
10.0000 Hz +0.570 dB +0.473 dB

Stephen himself was simply amazed. Many of today's amps can't achieve similar performance. This is a 50 year old design.

Well done McIntosh. Well done.

[jdandy]

damacman......Absolutely spectacular measurements. This amplifier can go head to head on the bench with so many of today's present offerings. Thanks for posting those results. Impressive to say the least.

[damacman]

Dan, I couldn't believe my eyes when I saw this. Would you believe that the amp didn't even have matched output tubes when these measurements were taken! Two originals and two RCAs ... after seeing that I've left it exactly that way.

I've had a few dozen Mc tube amps over the years and this is certainly one of the more enjoyable examples, coming in 2nd only to some modded MC60s I had that I'm still kicking myself for selling.