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In Reply to: RE: Audionervosa: Pass or Latino? posted by pictureguy on June 18, 2017 at 00:03:29
If the Pass amps are single ended, they can not have any a/b operation. An audiophile single ended amp is by circuit topology always class A.
Pass push/pull class a amps do go into a/b above their rating(which is their class a rating) and thus also do have head room.
From the Pass brouchure on the new products.
Still not content, we uniquely molded each model's front end to the speci cs of its output stage so that the nine ampli ers' front ends vary in size, voltage, bias current, dissipation, and single-ended vs.
push-pull bias distribution. The directly coupled front ends, which house the input and voltage gain stages,
maximize each model's output stage performance, while imparting to each model its own subtle and unique sonic signature
This is why I mentioned single ended V PP operation. Am I misreading or misinterpreting?
Too much is never enough
The Pass XA30.5 output is single ended for the first few watts.
From the Pass website:
In 2002 the first XA amplifiers were released, combining the X and Aleph topologies into balanced single-ended Class A amplifiers with many of the characteristics of both the X and Aleph series.
From the Stereophile review:
This simple, three-stage topology is common throughout the Pass line, the major differences being in the power supplies and biasing. In the XA.5 amps the bias is set quite high, so that the output stage operates in class-A up to the rated output and emulates a single-ended amplifier at low levels. Pass described this to me as "a push-pull output stage in parallel with a constant current source. The n channel, which handles the push, or plus, side of the push-pull, is biased at a higher level than the p, or negative channel. At very low power levels, the p channel doesn't see the current source and the output is effectively that of the n channel functioning in single-ended mode. At higher levels, both n and p devices contribute to the output as a push-pull pair, operating in class-A mode up to the amp's rated output and class-AB beyond that point."
Dark energy? Ridiculous!
We live in an electric universe.
A Pass XA30.5 (I tried 2 of them - returned the first one) couldn't handle a pair of Tannoy Turnberry speakers. 93dB?
I don't know what 'couldn't handle' actually means?
Wouldn't go loud enough?
93db is pretty sensitive and should be in the sweet-spot for the Pass 30 series. Anything else of note, like maybe magnet wires in place of real speaker connection, that sort of thing?
Too much is never enough
Wouldn't go loud enough without strain. Audioquest biwire cable, Pass preamp. Replaced with Yamaha integrated. All is well now. I tried 2 different XA30.5s. The meter on the first one behaved strangely. Pass wanted it back after seeing pictures. There was something wrong with it beyond the meter behavior, but I was never told what was wrong. (I asked via email if there was anything wrong besides the meter and was told yes. I asked specifically what was wrong and got no reply.) Both XA30.5s sounded about the same to me.
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