Mac Amps - all are Class A?

[SiliconTi]

Hi All,

So, I am trying to figure out if the amp in my Mac 4100 is Class A or A/B. Anyone know definitively?

 

[Pio1980]

Most likely class AB.

 

[chuckworkb]

If I were a betting man I would say A/B. Class A would run much hotter in a solid state amp requiring much larger heat sinks that your receiver doesn't have the room for.

 

[moewillis]

Are any Mac amps class A?

 

[62caddy]

To my knowledge, McIntosh never made a Class A amplifier.

 

[SiliconTi]

I agree that is has to be A/B. It runs too cool for class A. I have two class A amps and they run very hot, even with little current going through them (Sony ES receiver and a Haffler 220).

 

[62caddy]

MAC4100 is a direct coupled amplifier unlike most of Mc's standalone amplifiers which are Autoformer (AB). So that's one difference.

4100's literature doesn't seem to indicate.

 

[ron-c]

Class A/B of course.

 

[motorstereo]

MAC4100 is a direct coupled amplifier unlike most of Mc's standalone amplifiers which are Autoformer (AB). So that's one difference.

4100's literature doesn't seem to indicate.

So the 4100 doesn't have autoformers even though it has the power guard circuitry?

 

[ron-c]

Output Autoformers and Power Guard are two separate technologies. McIntosh direct coupled amps have used Power Guard since the 1970s.
Ron-C

 

[SiliconTi]

So the 4100 doesn't have autoformers even though it has the power guard circuitry?

Correct.

 

[miniman82]

The manual to my MC2125's says the output stage operates in class B

 

[MACKIE1975]

Of course, McIntosh amps are "Class A" because it is the best.
Who care what class. It sounds sweet.

 

[62caddy]

The manual to my MC2125's says the output stage operates in class B

Shame on me for not knowing this, owning two.

However, Mc was quick to point out this Class B design does not have notch type distortion (for which Class B amplifiers are generally known to exhibit).

 

[damacman]

Shame on me for not knowing this, owning two.

However, Mc was quick to point out this Class B design does not have notch type distortion (for which Class B amplifiers are generally known to exhibit).

I've seen LOTS of Mc designs with Class B output stages - look at the top of an MC2300. This is not at all uncommon nor is it bad when crossover distortion is eliminated.

 

[62caddy]

I've seen LOTS of Mc designs with Class B output stages - look at the top of an MC2300. This is not at all uncommon nor is it bad when crossover distortion is eliminated.

Indeed. If Mc saw fit to use the design, that's enough for me.

 

[SiliconTi]

Indeed. If Mc saw fit to use the design, that's enough for me.

Agreed. I only ask for clarification. On another forum I'm in a bit of a urinating contest with someone that insists they are class A. My experience, even without knowing the class, shows them to not be A, as they run way to cool.

 

[chuckworkb]

There was a similar Class A thread started here back in January. There were a couple of urination contests going on there that were moderated out, and it turned out to be a good conversation in the end. Best to leave the urination to the bathrooms.

 

[AdamAnt316]

The block diagram in the service manual for the MC2505 refers to it as a "Class B Output Stage". Sounds good to me.
-Adam