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Extended power on for Pass Labs XA.5 amplifiers

Has anybody experienced significant improvement in sound as your amplifier is left on for days? I was surprised to find how much can be extracted from Pass Labs XA 60.5 if they are left on for a long time. Unlike manufacturer recommendation, the first phase of stabilization in my case requires 4-5 hours at full power. The second phase is 4 days at full power.

I finally was able to leave them fully powered for 4 days, and today is the last and 5th day. That last ounce of realism at the mid range frequencies becomes available. But what's most pleasant to hear is that deep bass. Before this time, I could not increase the volume on the powered sub-woofer for each speaker very much without clouding the mid range and upper frequencies. Yet whatever it is that the extended power on has done to the XA 60.5, that extra bass just naturally fits into the rest of the sound. Concurrently that finer texture on the remainder of the music is certainly no triviality.
spatine
8 responses Add your response
rtn1
535 posts
 
Yes, there was a smoothness, suppleness, and a superior balance of frequencies and tone when my Pass X600.5 was left on for several days. I'd have difficulty specifying the exact amount of time, but it was at least 24 hours. Most people don't believe, but it was true.

Great during the winter, terrible during the summer.
guidocorona
4,298 posts
 
Yep, not at all surprised. . . also my Jeff Rowland 7M monoblocks reach their peak performance after a couple or 3 solid sweltering days of making music. . . . I still remember not so fondly when a few years ago my better half saw a January power bill. . . I had left the 7Ms powered up during the whole Christmas break so they could always give me their peak performance. Truth to tell, my current Rowland 312 or the Bel Canto REF 1000 Mk.2 monoblocks that I have just reviewed for PF, also take a couple of days to return to peak performance after having been off for several days. The Difference is only that I do not need to feel guilty letting the JRDG 312 or the Bel cantos stay at peek performance. They make music 24/7 for weeks at a time. . . and They are always almost cool to the touch, and when idling, they consumes as much as a modest light bulb. Got to be true because. . . better half no longer complains about power bills. G.
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usblues
1,217 posts
 
Consider yourself flamed,YMMV,Bob
spatine OP
84 posts
 
Beside the energy issue, it's not safe to leave expensive equipment on for extended period of time. That sudden surge after the power outage can destroy them.
weebeesdad's avatar
weebeesdad
139 posts
 
Are the advantages of extended powering up exclusive to solid state, or are tube amps equally served by leaving them on for long periods (tube wear issues aside)??
sm2727
115 posts
 
I have had many of the Pass amps and I would suggest your crossovers and speaker wiring are warming up and that is what you are experiencing. It takes a long time to warm up a dead cold crossover. I noticed this one spring when it got warmer.(Better sound earlier) I find it hard to believe any component has any chill left inside those incinerators after one or two hours.
magfan
1,583 posts
 
Weebeesdad, equipment can be zapped just by being plugged in.
Off? no real help. Any surge worth its name can easily bridge a switch and get you. Now, UPLUGGED, thats a different matter, but get the ICs, too.

My ICE gear seems to warm up and sound right within an hour. The largest changes occur within about 20" of power on. I can easily hear this, even using XM as a 'warm up' source before any serious listening. Than, it take the CD spinner, a CA840, another couple disks before IT settles down.
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