240V power amps

[Mike Diack]

The Xti amps are indeed auto sensing. They have a relay (K2) which pulls in after a few seconds if a 110 volt line is detected and this changes the bridge to a doubler. I remove this relay in any amp I see for service because we are a 230 volt country and dodgy generators can cause these sorts of amps to make really bad life choices.

 

[Tim McCulloch]

The Xti amps are indeed auto sensing. They have a relay (K2) which pulls in after a few seconds if a 110 volt line is detected and this changes the bridge to a doubler. I remove this relay in any amp I see for service because we are a 230 volt country and dodgy generators can cause these sorts of amps to make really bad life choices.

Mike, I take it this means 208v would be no-go?

 

[Mike Diack]

Mike, I take it this means 208v would be no-go?

Yes, but for other reasons. The Xti would work in the higher voltage regime, but it would be bloody awful. Xtis are particularly sensitive to undervolt situations and even with a 10% drop in mains, they cannot achieve anything like a decent output. The clever little MCU controlled clip counter starts overachieving and compresses the output to within an inch of its life. Put one of these amps on a variac and reduce the mains a little (not a lot in 230v lands or the other scenario will come into play), and you'll see the output duck and dive astonishingly. In light duty (never go near clip) situations they would be happy.

 

[Gene Hardage]

Yes, but for other reasons. The Xti would work in the higher voltage regime, but it would be bloody awful. Xtis are particularly sensitive to undervolt situations and even with a 10% drop in mains, they cannot achieve anything like a decent output. The clever little MCU controlled clip counter starts overachieving and compresses the output to within an inch of its life. Put one of these amps on a variac and reduce the mains a little (not a lot in 230v lands or the other scenario will come into play), and you'll see the output duck and dive astonishingly. In light duty (never go near clip) situations they would be happy.

Interesting - we had a horrible gig out in a field with little or no shade in the heatwave of July 2015 and of course the generator was a bad Home Depot variety. The motor was racing and idling and back and forth all day. My rack mount strip claimed we were getting around 115ish before I turned anything on and it dropped a bit after it all powered up. When the bands played the voltage would dip more and of course the sound was special. We limped it along by turning everything down quite a bit. My tube guitar amps continued to work all day but some people could not get there newer types to even fire up so they had to use mine. There was a particularly ugly noise that came from the generator every time someone took their hands off the guitar strings with the volume up on the guitar - it coincided with the wavy motor sound. The low point of the voltage went down to 87 for a brief moment while the strongest band played. Most of the 6-8 hours were spent in the 100ish volt area and - NO SMOKE!