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pass labs xa30 to valve amplifier.

hi all, i have the above amplifier direct to droplet cd player and zingali 20.6 ( i think thats model number) , chord anthem 2 xlr and epic speaker cable. no preamp as droplet has volume control.

ive been thinking of valve amps recently, but have never been able to hear one. the pass is excellent but i was wondering how a valve amp would change the sound. would a valve one have the same level of clarity and detail? i have heard valve amps offer a more laid back, spacial sound, with emphasis on soundstage? wht kind of price range should i be looking at to better the pass? any thought?
james123
james123 OP
61 posts
 
hi. isnt the pass xa30.5 pure class a? i thought it was.
pubul57
3,712 posts
 
I think it switches at some point to B for handling peak power demand - I'm sure it is addressed in the Stereophile review, perhaps Magfan can confirm the data from Atkinson's tests.
jr_w
27 posts
 
It's a confusing amp to rate for some folks.

Pass rates it as 30wpc class A. It's pure class A for 30wpc.

Stereophile got about 40wpc class A from it in their review IIRC.

Past 40wpc, their amp moved into class A/B operation. It didn't clip until it reached about 130wpc/8 ohms IIRC. So some folks feel it should be rated as a 130wpc amp that does 30wpc class A.

So it is pure class A for its entire rated power of 30wpc.

Pass has an article on their site titled "Leaving Class A" that explains it in more detail:

https://passlabs.com/articles/leaving-class-a

We get a lot of questions about this. A typical email reads, “I can’t sleep at night – I keep worrying about where my amplifier stops being Class A. As I listen to my system, I think I can hear the Klunk as the special Class A part of the amplifier kicks in and out!”

For starters, there is no special Class A circuit that kicks in and out, and for that matter, there certainly is no Klunk. There is just a push-pull amplifier output stage which is operated at a constant idle current known as the bias. In this regard, our power amplifiers are like other amplifiers on the market. The vast majority of amplifiers are push-pull designs with a certain amount of bias current.

Push-pull amplifiers generally operate in Class A mode up to a point where the output current is twice the value of the bias current. In the Class A region, both halves of the circuit share the signal simultaneously. Beyond that the signal is handled solely by the push (+) half of the amplifier or the pull (-) half.
pubul57
3,712 posts
 
There amps that never leave Class A? For some reason, I think my CAT JL2 worked that way, but not sure if that is even possible. Techheads?
james123 OP
61 posts
 
Thanks. Thats very interesting. The amount of sound it produces, it certainly sounds far more powerful than 30 watts.
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