Pass Labs int 60 vs. Luxman 590 uX ii

That would be a killer amp for my near-field listening set-up, George.

Got the perfect amp for your nearfield listening, look at a pair of only 25w into 8ohm monoblocks, like the Mark Levison ML2 monos of yesteryear they do an even better doubling act all the way down to 1ohm even.

Cheers George  

not really sure why you’d be throwing the ’fanboy’ slur around.

I was a big fan of Nelson with Threshold (bi-polar), but not so much with complimentary push pull Mosfets Pass Labs, as the P channel Mosfet always let them down big time for current delivery, but fine for easy to drive speakers, I tend to like ones that just happen to be pigs to drive Wilson Alexia etc etc
 
But there have been a couple of Mosfet amp manufacturers lately that have used only the N channel mosfet for both the complimentary push pull pairing, and they get just as much current from those as big bi-polars like the old Thresholds gave and today Gryphons. Agostino, Krell etc etc. I’ve yet to hear any of them, would love to though.
One is the Constellation Audio power

" Instead of the usual push-pull arrangement of N-type output transistors for one half of the waveform and P-type devices for the other half (each of which has somewhat different performance characteristics), within each Centaur Mono are a pair of carefully matched "floating" (ie, not referenced to ground) amplifiers, both using only N-channel MOSFETs. (There are eight transistors on each half-bridge, for a total of 16.) One amplifier is fed the balanced signal’s negative phase, the other the positive."

And this is what it did on test, and it a Mosfet!! (but only N-Chanel push pull)
520W into 8ohm
830W into 4ohm
1210W into 2ohm

Cheers George

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

For some one who loves Pass, you just did Pass a huge disservice.

Really!!
No, you just been caught out not knowing what constitutes low output impedance (good damping factor) in an amp and were pulled up on it, that why your backs ups, everyone knows your a Lux pusher.

I actually don’t like the Mosfet sound, when Pass built Threshold bi-polar amps, I much prefer the good ones of those.

builder3 Can you elaborate on your statement regarding the mid-bass, Erik.

Here’s the piece I find important.
Per Luxman’s website, the 590 has: Bipolar 3-parallel push-pull
But the 509 has:Bipolar 4-parallel push-pull
Implying a lower output impedance.

This is bi-polar v mosfet and the lower output impedance (amount of damping factor) can be a bit of a furphy builder3.
As the damping factor also comes down to the amount of "negative feedback" used (global or local), and size of the output resistors the output stage has, to what amp has the "lower output impedance" (better damping factor) it could very well be the Pass Int-60.

Cheers George