Correct tap 2 or 4 Ohm for the 1,7 Ohm curve

[Rick U]

Dag how did those Kaaps’s sound with all that clean current? I had a pair of those in the late 80’s. Loved them

[dag johnsen]

Originally Posted by Rick U

Dag how did those Kaaps’s sound with all that clean current? I had a pair of those in the late 80’s. Loved them

Hi Rick,

mine are the 9.2i series 2 version. I must say for their age they are incredibly good.
Really punchy bass, overall huge soundstage that are impressive. The weak spot are the upper mids from the 3" Polydome. But that has advantages as well, because they are voiced in a dark way so you can play any kind of recording or music genre without getting tired or stressed out. But not the last word in resolution. But impressive!https://infinity-reparatur.de/infini...ity-kappa-9-2/

[damacman]

Well, the current specs Mc publishes on amplifiers are derived by connecting a load equivalent to 20% of the tap's rating.

[dag johnsen]

Originally Posted by damacman

Well, the current specs Mc publishes on amplifiers are derived by connecting a load equivalent to 20% of the tap's rating.

So do that mean the 8 ohm tap will handle 1.6 ohms and 4 ohm tap will handle 0,8 ohm?

Dag

[dag johnsen]

Originally Posted by Charles

I would use the 4 ohm tap. I don't like the 2 ohm tap on Macs. You have ample current with a 2KW, no question. I am not of the camp to impedance mismatch with Macs. If it sounds better with using an 8 ohm tap with a speaker with a 1.5 ohm minimum, you don't have a big enough Mac amp, IMO. So by severely stressing out the Mac amp you can create a larger amp, no question, but Mac does not recommend it and neither do I. It shortens the life of the amp. Off the 4 ohm tap I run an XVX with a minimum impedance of 1.6 at 326 Hz with nominal impedance of 4 ohms. My 1.25's rarely exceed 12 watts and never become hot even under very high sound levels. I am sure your 2K's will drive the Infinity's in a breeze with the 4 ohm tap and sound great. Check to see if they get really hot. I doubt they will.

Best Charles

Charles,

do you dislike the 2 ohm tap because the high output impedance can make the sound bright?

Dag

[62caddy]

Originally Posted by dag johnsen

So do that mean the 8 ohm tap will handle 1.6 ohms and 4 ohm tap will handle 0,8 ohm?

Dag

Using a higher tap than the impedance seen will cause the amplifier to generate more heat (depending on how hard driven) just as would be the case with a DC amplifier without separate impedance taps.

Otherwise different taps should have little to no effect on the sound.

The main advantage of autoformer amplifiers is to provide optimal coupling between the outputs and the speaker load (on average) for cool operation which translates to better reliability and long life.

[damacman]

Originally Posted by dag johnsen

So do that mean the 8 ohm tap will handle 1.6 ohms and 4 ohm tap will handle 0,8 ohm?

Dag

What it means is that McIntosh designs amplifiers to be able to output a lot of current into a load of a nominal rating even when said load has a wildly fluctuating impedance curve. The Infinity speakers are a great example. Connecting them to the taps which correspond to their nominal rating allows the amplifiers to drive the speakers the way the designers intended for them to be driven. When impedance dips down low, the amplifier delivers the current required.

Connecting the speakers to the taps which correspond to their minimum impedance at a given frequency prohibits this by handicapping this current delivery. Well designed amplifiers have excellent power supplies. Such amplifiers are designed to maintain output voltage even when impedance dips and ... and this is the big one ... when voltage and current are not in phase with one another.

Heat is simply a byproduct of power. The more power a given amplifier makes, the more heat wasted as a result of efficiency losses. Heat wicked from devices by the heat sinks. While it is true that McIntosh amplifiers lever the autoformers in such a way to minimize heat (4 Ohm nominal load connected to 4 Ohm taps for example) and thereby reducing the amount of heat sink mass required, they by definition also limit power (compared to a 4 Ohm nominal load connected to a direct coupled amp where 8 Ohm power is doubled for example). A quick comparison of heat sink mass of McIntosh power amps vs others of similar power ratings tells the story as it pertains to continuous power delivery over time. Fortunately, as music is dynamic in nature, McIntosh amplifiers fare quite well in managing heat - even when the user understands how to leverage that.

[Charles]

Originally Posted by cleeds

Will you please explain what this means??

This is how I understand it. Run off the 8 ohm tap into 4 ohms the 462 will put out 720 watts/ch with both channels driven simultaneously. At 4 ohms off the 4 ohm tap the output was about 550 watts. This is before clipping. Ditto for the 8 ohm tap into 8 ohms. Ditto for the 2 ohm tap.

Folks have found over the years that stressing the amp (driving a speaker with minimal impedance of say 1.5 ohm off the 8 ohm tap) by making it produce much more current than it really should be producing for driving the speaker in question makes the speaker sound better. This makes the amp run very hot and up to a point creates a larger amp.

In such an instance I believe it is wise to simply get a larger Mac amp and run the low impedance speaker off the correct tap for the nominal impedance of the speaker.

I personally don't like the 2 ohm tap but this comes from my prior experience with older Mac amps. The modern Mac amp probably sounds great off the 2 ohm tap.

Best

Charles

[Charles]

Originally Posted by dag johnsen

Charles,

do you dislike the 2 ohm tap because the high output impedance can make the sound bright?

Dag

No. The old binding posts seem to not "like" the 2 ohm tap. Don't know why. The new binding posts probably insure this will not be a problem. I honestly don't know if I will upgrade to the new 2.1KW when it finally arrives. But a new 2.1KW is needed because of the advancement in parts and the new binding posts.

[cleeds]

Originally Posted by damacman

... Heat is simply a byproduct of power. The more power a given amplifier makes, the more heat wasted as a result of efficiency losses ...

That is not quite accurate. Heat is a byproduct of inefficiency, right? After all, a perfectly efficient amplifier would produce no heat.

An inefficient Class A amplifier will produce heat even at idle. As it required to produce more power, it will produce the same amount of heat, so it is not correct to state that as power increases, "more heat is wasted as result of efficiency losses."