MC 462 Stereophile Review -May '19

[clpetersen]

Read the MC462 review in Stereophile. The measurements are impressive - a highly refined, thoroughly tested design.
I did look at MA8900 and MA9000 on the McIntosh site as well. These are impressive as well for the amount of technology built into one chassis.

However, I could not determine if the integrateds use the same quad-balanced topology as the dedicated amplifiers.

Anyone know?

[Charles]

Originally Posted by clpetersen

Read the MC462 review in Stereophile. The measurements are impressive - a highly refined, thoroughly tested design.
I did look at MA8900 and MA9000 on the McIntosh site as well. These are impressive as well for the amount of technology built into one chassis.

However, I could not determine if the integrateds use the same quad-balanced topology as the dedicated amplifiers.

Anyone know?

Although I am sure there are other refinements, you have hit on an important point. The MC2KW has separate power modules the outputs of which are combined in the autoformer module to create the ultimate quad balanced design. The 1.25KW has a similar arrangement but in the same chaise. The 611 only has one power supply, not two so it would not be fully quad balanced, although Mac claims it is. But you do have two power supplies, i.e. one for each mono amp. With the 462 you have one power supply period with each channel dependent on that lone supply. However the rest of the quad balanced circuitry is utilized. With the 9000 Mac utilizes a balanced design but not quad balanced. With quad balanced there are two power amplifiers per channel. That's roughly my understanding.

I think most folks that are not Mac aficionado's may not understand just how much Mac has refined their power supplies over the years. The 1.25KW has two independent power supplies, each one of which can store over 450 joules of energy, a 50% increase over the 1.2KW. Put this together with the autoformer which allows you to optimize the amp impedance to the speaker impedance and you have technology that is far superior in my humble opinion to anything on the market even close to Mac's prices in the SS arena. In the past I believe Mac relied on their superior design and did not build robust enough power supplies. However, the current generation of Mac amps all have very robust power supplies. Nevertheless I think it still prudent not to miss match the amp impedance to the suggested speaker impedance. I hear, "well it sounds better in my system". But does it, really? How can an amp that is operating inefficiently (amp operating at 8 ohm and speaker rated 4 ohm with dips to below 2 ohm be operating efficiently)?

All other manufacturers amps have one impedance that provides optimum efficiency. Macs have three. I was always taught that for optimum operation a SS amp should be at about 10% or less in terms of actual watts. The less stress the better the sound.

[Roni]

Very interesting, thanks.

[clpetersen]

Thank you Charles. Did some perusing this am - it seems 'quad balanced' is used in the highest power amplifiers, starting with the MC462. Basically, as stated above, and in posts earlier in this forum and elsewhere, two independent amplifiers are used in a balanced mode, summed at the autoformer input. 2 amplifiers x 2 channels = quad balanced.

Lower powered units, the 352, 152, and the integrateds use a 'complementary push-pull' configuration, still balanced but in EE terms, differential, rather than two independent amplifier channels. Parts count is halved and noise increases very slightly.

Bryston uses complementary push-pull as well (called 'quad-complementary' to help clear things up )

The noise floors are below 120 dB down for quad-balanced, and a mere 115 dB (or so) down for the complementary designs. These both offer an abundance of headroom over all source materials.
More a statement of engineering prowess and design choice.

Not too bad.

[FreddieFerric]

Originally Posted by clpetersen

Read the MC462 review in Stereophile. The measurements are impressive - a highly refined, thoroughly tested design.
I did look at MA8900 and MA9000 on the McIntosh site as well. These are impressive as well for the amount of technology built into one chassis.

However, I could not determine if the integrateds use the same quad-balanced topology as the dedicated amplifiers.

Anyone know?

The integrated amps are not quad balanced. But don't be discouraged, the MA8000 and the newer MA9000 sound terrific with plenty of refined power.

[lucab617]

I love my 462

[Bob Bubeck]

Originally Posted by lucab617

I love my 462

+1

[jimimac]

O.K the Mc2KW has two toroidal Transformers and A big Autoformer with two C cores I band strap together. The 1.25KW has one large toroidal Transformer and A similar Autoformer. They both put out massive amounts of Power.Way above there ratings.The 611 has an EI type Transformer and Multi channel amps have torrid and Large capacitors. Mc2301 has two of the largest EI type Autoformers in one can and A large power Transformer...

[jimimac]

Just sayin A company that sells Bryston and not McIntosh is going to favor What they sell ???

[Charles]

Originally Posted by jimimac

O.K the Mc2KW has two toroidal Transformers and A big Autoformer with two C cores I band strap together. The 1.25KW has one large toroidal Transformer and A similar Autoformer. They both put out massive amounts of Power.Way above there ratings.The 611 has an EI type Transformer and Multi channel amps have torrid and Large capacitors. Mc2301 has two of the largest EI type Autoformers in one can and A large power Transformer...

According to the OM's of the 1.25KW, 611, and 462 respectively:

"To compliment the fully balanced design of the MC1.25KW there are two high voltage power supplies; one for each of the two amplifier circuits, allowing each amplifier circuit to be optimized using its own power supply. Refer to figure 23."

I note that Figure 23 includes a power transformer.

"To compliment the design of the MC611 Power Amplifier Circuitry, there is a high current high voltage power supply. Refer to figures 23 and 26."

I note that Figure 23 includes a power transformer.

"To compliment the design of the MC462 Power Amplifier Circuitry, there is a high current high voltage power supply. Refer to figures 23 and 26."

Again, Figure 23 includes a power transformer.