Pass Labs int 60 vs. Luxman 590 uX ii

I am a Luxman pusher.

Everything else is projection. :)

dwest1023
I actually own and use the pass int 60. It is a smooth and warm in the middle amp. At the same time is is very transparent. It tends to get out of the way of the music and you just listen. Bass is very controlled and doubles its power into 4 ohm.

Many like the sound of Mosfets, they do tend to be more forgiving, myself I prefer the sound of big Bi-Polar amps, but they are less forgiving of bad material, when done right they can supply more big current into low impedances than mosfets, right down to 1ohm some of them, read this post I just put up in this thread.
https://forum.audiogon.com/discussions/filter-capacitance-how-does-it-relate-to-amplifier-performanc...


Then look at the tested Stereophile specs of the Int-60 below, it’s actually 79w into 8ohm and 120into 4ohm as you can see even "Pass Labs" under quotes the 8ohm wattage, to make the 4ohm look like it’s doubling!!!!.

"The INT-60 is specified as delivering 60Wpc into 8 ohms, our sample clipped at 79Wpc with both channels driven into that load.
Into 4 ohms the amplifier clipped at 125W"
This should be closer to 160w at 4ohms.

As for the 2ohm figure, complimentary push pull mosfets tend tend to **** themselves into 2ohms, as this Stereophile statement says

"The Pass Labs was less comfortable driving 2 ohms than it was with higher impedances, as shown by fig.7"

Cheers George

Thanks, Erik, I appreciate it. I assume the flip side of that is that some amps do well, i.e. double their power when the impedance is halved, others fall short. I don’t begin to understand enough about amplifier design to know the whys and why nots, wish I did.

George, I read your stuff with interest as well. That being said, not really sure why you’d be throwing the ’fanboy’ slur around. I’d be very interested in listening to Pass Labs. The chance hasn’t presented itself, though. I’m very happy with my Luxman, if your opinion is different, I’m okay with that.

I do like both, but Pass is beter in low. Both are detailfull and very open , 3D
I had the Luxman and was a little bit to “sharp” , Less detail in the lower area. Pass have a good combination between High-mid-low. I prefer Pass.

Builer,

It's a little more subtle than that.  Most amps will double in power as impedance is halved.... down to a point. 

From 32 to 16 to 8 to 4.  That's Fairly typical for most amps to handle.  As the speaker impedance gets close to the amp impedance though, this vanishes.  The power never gets to the speaker, and things sag.

It's my experience throough a lot of listening and cable comparisons, that amps _can_ be a little more sensitive to this problem, cable and speaker impedance, than we have thought.  How much it is worth to fix, whether it is bad, and what a particular amp/speaker combo will sound like is another matter.