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Pass Labs AMP’s- What is the best Pass Amp Sound for You from past 10 years

So I have an XA-25 and its outstanding. I’ve tested the XA60.8 mono’s and there was not enough difference to move to them; no jaw dropping moments. Don’t get me wrong they were fantastic, but so is the XA25. Looking at the 350.8 or 250.8, etc.... even in comparison the Integrated INT-250... If you love it; want to explain what you like and why? I’m wondering what others are thinking... 
My set up: Wilson Sophia II’s, XA-25, Pass Labs XP-22 pre, Merging+NADAC. 
jahatl513

Showing 2 responses by georgehifi

georgehifi's avatar
georgehifi
10,312 posts
 

@georgehifi , I believe the Threshold S 500’s were rated to about 20% Class A; or 50 Watts. With impedance drops; as the power output doubled, the Class A output halved.

There are 20 output devices per channel for a total of 40. Though, I think something like 4 devices per side were used for the then trick Stasis circuitry.

To support 50w of Class_A in the S500 with 76v rails those heatsinks would have had to be 3 x the size. I’ve built enough Class-A’s to know how much heatsink is needed for the rail v used, some had to be water cooled.

There are 20 per channel but only 18 as outputs, two are used as drivers. https://ibb.co/9h2dGW9

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
The one I loved was the 250w Threshold S/500 STASIS OPTICAL BIAS II, biased up to approx 20w Class-A, nice and toasty, delicate but a brute when called for, 36 x bipolar output transistor, heaps of current.

Cheers George
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