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Pass Labs XA-25 Impressions
Pass Labs XA-25 Impressions
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Old 17th July 2019, 10:12 PM   #1
Manolo47 is offline Manolo47  Puerto Rico
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Default Pass Labs XA-25 Impressions

I bought this amplifier on May, and had been waiting for a proper burn in to write about its sound. I guess it must have more than 500 hours of music playnig time. Context: Loudspeakers - Spatial Audio M4 Triode Masters, linestages- Supratek Chardonnay w/ 6SN7 tubes and Pass diy ba-3. I listen to CD’s and computer downloads and ripped CD’s using a Mac mini and Audirvana.My other amplifier is a First Watt F4, factory made.

So, firstly, how does it compare to the F4? To me they sound more different than similar. Both are very transparent and musical in their own way. The F4 does not have the bass control and extension of the XA, not close. It might seem to give a more clear and transparent presentation, and I guess is because of that attribute. The XA images are denser and instruments appear to be bigger, it’s about density here. And even if it seems to sound a little bit darker, all the details are there in a more startling way. It is smoother and sweeter than the F4 also. With the Supratek, the F4 comes closer to the XA, due to its nature. The XA, with the Supratek might be too much of a “good thing” though, I have to listen more to this combination. One interesting aspect of the XA is that even after being on standby mode or even full on before a listenning session, at least an hour of music playing is needed for full bloom. It gets really hot also, like the F4.

Supposedly, my Spatial’s are not bass producing stars, but with the XA the bass is deeper and powerfull sounding with superb control. I wonder how would their 12 ohm impedance effect the performance of the XA. Power delivery, would it be less than 25w? Thanks to Nelson for this design! And like it’s said in spanish “Paz y felicidad” which translates to “peace and happiness “ it might be said “Pass y felicidad” !
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Old 18th July 2019, 06:50 PM   #2
Nelson Pass is offline Nelson Pass  United States
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Pass Labs XA-25 Impressions
It's not spec'd, but I looked it up and it was about 40 watts. You can also infer this
from the Stereophile measurements of the 8 ohm figure of about 80 watts at 1% thd.

Pass Laboratories XA25 power amplifier Measurements | Stereophile.com
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Old 18th July 2019, 10:42 PM   #3
mpmarino is offline mpmarino  United States
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How can a 25W amplifier produce 80W?

These are outright lies, and someone needs to answer for this.
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Old 19th July 2019, 12:01 AM   #4
Hikari1 is offline Hikari1  United States
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It's a 25W amplifier at .01% THD.
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Old 19th July 2019, 01:12 AM   #5
Dennis Hui is offline Dennis Hui  Canada
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Pass Labs XA-25 Impressions
No lies at all. As Hikari said, just conservatively rated at low THD.

The voltage rails are high enough to produce very clean output at significant
higher wattage. I believe the higher voltage rails help with lower distortion
but I don't presume to know if that may the reason for their use in this instance.

Question: Manolo mentioned a standby mode. Has the XA25 been revised
to include one? The copy I'm familiar with does not appear to have one. (It
seems to just have a single on/off switch on the front).

Cheers,
Dennis
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Old 19th July 2019, 01:25 AM   #6
mpmarino is offline mpmarino  United States
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Aw, I was just joking. Sorry.

Congratulations on owning such a great pair of amps.
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Old 19th July 2019, 01:40 AM   #7
Dennis Hui is offline Dennis Hui  Canada
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Pass Labs XA-25 Impressions
My apologies....I knew your comment was tongue in cheek, but I left out my smilie.

I read some of the comments on the linked review in Stereophile and one person
did seem imply this conservative rating was somehow done to try to "fool readers".
Kinda perplexing....
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Old 19th July 2019, 02:11 AM   #8
Manolo47 is offline Manolo47  Puerto Rico
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Default It has 2 switches...

master in the back panel and one in front... for standby mode I guess. The inside is also a little bit different to the pictures in the net also ....
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Old 19th July 2019, 08:17 AM   #9
Soundhappy is offline Soundhappy  France
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Do XA.25 benefit of " Square Law " ?
Attached Images
File Type: jpg 510FF5DB-7009-4AA9-A751-703C3FD7C0A9.JPG (420.7 KB, 282 views)
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Old 19th July 2019, 10:03 AM   #10
Dennis Hui is offline Dennis Hui  Canada
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Quote:
Originally Posted by Manolo47 View Post
master in the back panel and one in front...
Thanks for the info!
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