Pass XA-100.5 Help

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Mechnutt

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Nov 18, 2013
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Minnesota
Hi guys, a friend of mine and fellow AS member just bought a pair of Pass XA-1005 mono's. When he turned them on the needle on the meter was to the right of center which is not normal at least with my experience with my X250 amp. His preamp was powered down. The needle should be to the left of center.

He shut them down and turned one back on and the meter needle is sitting at 12:00 with the preamp powered down.

Any thoughts?
 
Mechnutt said:
Hi guys, a friend of mine and fellow AS member just bought a pair of Pass XA-1005 mono's. When he turned them on the needle on the meter was to the right of center which is not normal at least with my experience with my X250 amp. His preamp was powered down. The needle should be to the left of center.

He shut them down and turned one back on and the meter needle is sitting at 12:00 with the preamp powered down.

Any thoughts?
Click to expand...

I think I have heard that the meters work differently in Pass Class A/B and Class A amps.

In my x250.8 it sits to the left and starts moving when I leave class A. The XA amps are however in Class A all the time, so it sits in the middle.

This might be incorrect, but I thought I might have heard something like this.


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I think you are right but it would be nice to hear from someone that has an XA series Class A amp. The images on google show needles sitting at midline.
 
Sometimes you can clean the glass of the meter with an anti-static cloth or one of those dryer sheets after it has been in the dryer. I had a pair of XA100.5's and one meter was wildly off to one side. I forget which. I cleaned the glass on both amps like I stated earlier. Fired them up and wouldn't you know it, they were almost identical after that. That trick came from Pass Labs.
 
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My 100.5's are to the far left when the Amp is in standby and just a hair left of center when powered on. Regardless of volume level, this Amp never goes into A/B.
HK
 
I have XA100.5’s and at initial power on the needle is slightly to the right of center, meaning a higher bias current is flowing. As the amps warm up, the needle will drop to slightly left of center. The amps have a thermistor which is used to adjust the bias current based on temperature, which is why you see the bias current become lower once warmed up.
 
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