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

[rob725]

Originally Posted by damacman

Well, simple math shows that a 13.5" diameter driver displaces 4.3x the area of a 6.5" driver. When you factor the massive delta in excursion capability of the JL driver and a comparison is made between Volumetric Displacement (Vd) of each, it may take a dozen or more of the 6.5" drivers to equal it.

Multiple smaller drivers working together lever a phenomenon called mutual coupling. This is akin to two cars traveling faster than one in NASCAR by the rear car drafting the first and splitting the wind resistance. However, in order for mutual coupling to be maximized, drivers must be mounted as near as possible to one another.

Smaller vs larger is a personal preference. I like both when executed well.

Correct; my bad. Simple math is always better than the simple-minded math I used. I lot more than driver size goes into the quality of bass in a speaker. Larger woofers, with larger surface area, don't need to move near as far in both directions, so if anything they have the potential to be faster.

I am very pleased the quantity and quality of bass produced by the 1.1s. I have no doubt though that the 2.1s, with both more and larger drivers, take it to the next level.

[dag johnsen]

Originally Posted by damacman

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.

Thank you for good information. Appreciated! Dag

[dag johnsen]

Originally Posted by 62caddy

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.

Thank you for taking time to share, very clear info. Dag

[dag johnsen]

Originally Posted by tom1120s

Bi-wire.

4ohm tap for the bass and 8 ohm tap for the mids/highs. Yes, you can do this plus I bet the speakers will sound better than if you just used the 4 ohm tap for everything.

Those are very capable amps so I think the 4 ohm tap will suffice for the lows.

They worked really well from the 4 ohm tap. The banana plugs were too long to fit in the 2 ohm taps so I never got to try. I now have new speakers that are perfect for the 4 ohm tap, Piega Classic 80.2. Very impressive full range speakers with coax ribbon mids/highs. The Kappas are now in room no 2. A lot of fun there too

[dag johnsen]

Originally Posted by rob725

Dag,

I've not heard 2.1's, but looking at the driver make-up, they may be. The 2.1s handle below 150hz with 6 8" woofers vs the 1.1 using 4 6.5". Yet, they both use 2 6.5" drivers for mid-bass. Also, the 1.1s crossover to the high-frequency panel sooner at 400hz vs. 450hz for the 2.1s. Then, the 1.1s use 24 2" midrange and 40 3/4" tweeters vs. 28 & 45 for the 2.1s. Given that the panel is larger on the 2.1s, I'm goings to guess that the high frequency drivers are more spread out on the 2.1s. Given all of that, it would not be surprising if the balance tilted hotter on the 1.1s.

Unless you really want authoritative bass at or below 20hz, the 1.1s do not need a subwoofer; I don't use mine for two-channel. Using testing recordings, I can hear 20hz, but it's not real loud. I did have to go around my room fixing light fixtures, aircon return grates, projector screen housing, because the 1.1s had no problem rattling the room 25-80 hz. The 2.1s must be incredible down low.

Using the crossover on the 901's I currently attenuate the panel about 1.5db. I say currently because they have consistently improved in this regard. Switching to the tubes on the 901s helped, cabling, esp. power, has helped and all of the components, including the 1.1s, breaking in has helped smooth everything out. It just keeps getting better. What this means in practical terms is I can both turn it down lower for normal listening and turn it up higher for incredible slam.

Thanks!

I envy your speakers and really trust you enjoy them a lot!
I measured the bass respons on the 2.1 and in the room we were they came alive at 18 hz. The slam from all those woofers can really fill a big room. I trust the 1.1 can really do a lot of the same.

My choice went another direction this time. Long term 1.1 or 2.1 will be a goal.

I just purchased some speakers that really have very interesting qualities.

Piega Classic 80.2.

Real 22 hz response, great headroom and a special mids/highs ribbon coax that sound so good. Wish I knew how to post pictures here

Dag

[dag johnsen]

Originally Posted by W9TR

Please let us know the results. I’m envious - those are great amplifiers you have Dag.

Hi again, the speaker cables I had could not fit in the 2 ohm taps, to narrow below the lid. Anyway 4 ohm worked as it should, and then I bought a pair of Piega Classic 80.2 where I run the 4 ohm tap. Very potent and impressive full range speakers I must say.

Dag

[dag johnsen]

Originally Posted by cleeds

Will you please explain what this means??

Charles,

thanks for all the feedback in your posts.
I read them carefully all of them.
I moved the Infinity Kappa speakers to my second room, and just bought a pair of Piega Classic 80.2 that in my mind can do pretty much everything a speaker should. Very capable in every way, interesting how they are made with the ribbon coax. They have similarities with vintage Infinity IRS speakers because of the ribbon midrange, not very common.

Best regard Dag

[W9TR]

Originally Posted by dag johnsen

Hi again, the speaker cables I had could not fit in the 2 ohm taps, to narrow below the lid. Anyway 4 ohm worked as it should, and then I bought a pair of Piega Classic 80.2 where I run the 4 ohm tap. Very potent and impressive full range speakers I must say.



Dag

WoW - those look awesome. Enjoy your new speakers.

[damacman]

Copied from page 2 of the MC2600 manual. Read it carefully and you'll have a better understanding of what such an amp is capable of and furthermore what Mc engineers are capable of.

[dag johnsen]

Originally Posted by damacman

Copied from page 2 of the MC2600 manual. Read it carefully and you'll have a better understanding of what such an amp is capable of and furthermore what Mc engineers are capable of.

Thanks! That was useful to read, it states that these amps can easily cope with low impedance dips.

No need to worry then.

Dag