2. amps-preamps
  3. 169118-133618

Pass Labs Xa60.8 Class A or should it be called class A/B?

I'm looking at possibly purchasing the Pass Labs Xa60.8, but am puzzled by one of its specifications.  One reviewer stated that "The XA60.8 doesn’t leave pure Class A until it reaches 122 peak watts. Then it moves into Class AB for unheard of headroom for a 60-watt amp".  I've confirmed this headroom is on the specification sheet, but if the amp actually can transition into A/B, shouldn't it really be called class A/B?  Also, I'm confused as to if this headroom is available as continuous watts or just peak.  Can anyone clarify?
dfairc777a
dfairc777a OP
60 posts
 
Yeah, I read that too and understand that it's pure class A, but what's this transition to AB thing?  Do all class A amps have a peak transition to AB point or is this unique to Pass?
arcticdeth's avatar
arcticdeth
1,549 posts
 
122W until leaves class A....
that is a class A amp of the highest order!

  I don’t think my brothers McCormack dna-750 monos even do any class A at all, they sound great all the time, and my Odyssey kismet amps are 10W of class A, they are very refined, and have a spectacular sound until the volume gets pretty loud, at a normal to average loud volume, the class A is great!!

 Wish I had a pair of class A amps, they are simply flawless!

 Class A is sublime!

  
dfairc777a OP
60 posts
 
Indeed they are impressive.  I'm really impressed by the entire XA line, but as far as I understand, all AB amps run at some point in class A and then transition. Yes, most transition way less than 122 Watts, but I'm still confused as how a class A amp can leave class A and still be called a class A amp (Unless that's the way they all work). 
tomcy6's avatar
tomcy6
2,544 posts
 
Technically it is a Class A/B amp but Pass sells it as a 60 watt Class A amp and it does operate in Class A up to 60 watts.  He does this in order to distinguish it from his X series amps that operate more like traditional Class A/B amps (10 -15 watts in Class A then switch over to Class B).

Most people know this about Pass amps and give him a pass on it.  Now you know it too.  If you think this is wrong, contact Pass Labs about it.  
don_c55
1,025 posts
 
All ‘class A’ power amps transition to A/B at high levels!

Nothing sinister going on here.
More to discover