2. amps-preamps
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Pass Amps Class A operation

I just started using a Pass Labs X150.0 power amp. Love it so far. I know that it operates in Class A mode up to a certain point - I think 10 or 15 watts. How does that translate into approximate volume level? Is 15 watts coming out of this amp (into Sonus Faber Grand Piano speakers) generally enough to drown out all conversation in a 20 x 15 room? Or is 15 watts a volume level that is easily and typically surpassed, except when listening at midnight in an apartment with thin walls. In other words, I am trying to gauge how much of what I am listening to is Class A mode and to get a general sense of where the Class A/B transition point is. Is there a way to tell? The meter on the amp never seems to get more than approx 25% towards pegged (or move much at all for that matter). I also have read that this amp actually puts out much more than 150 watts (200-250?), even though 150 is the published rating. Is the Class A crossover similiarly conservatively rated, or is that a more precise number?
gipp

Showing 1 response by dne

dne
141 posts
 
As an owner of a Pass 150.5, it transitions from Class A to A/B at 15 watts. It's just as Studio 68 said above -- the needle doesn't move in Class A, and moves up from rest when the amp goes to A/B.

So, the answer to your question, since you already own the 150.5 and the SF speakers, is simply to try play it and watch the meter. Question answered.

BTW, I'm always surprised at how much volume those 15 Class A watts can produce, even on my Magnepan 3.6's (85db sensitivity). For most material, it's reasonably loud.
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