Amplifier Triode/Ultra Linear Switch Pop sound

jadis

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Apr 28, 2010
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Hello all,

I'm writing on behalf of my friend, a newbie of sorts, who bought a Rogers 65V-1 integrated tube amplifier a couple of days ago. While he loved the sound on first listen, he found out that switching the toggle from triode to UL gives off a loud pop that is startling. Switching back gives the same pop sound volume. And upon shut down there is a pop that is not as loud.

He is bothered by this, and main concern is the pop might damage his speakers eventually. He also wondered if this is normal for a triode/UL switch to go on popping each time the switch is flicked. Any inputs would be appreciated.
 

jadis

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Not sure about Rogers amps specifically, but many tube amps with triode/UL switching recommend it only be switched when powered off.

Thanks, Bill. But my friend said that the Rogers always defaults to UL mode when shut down. So the only way to switch it to Triode mode is when it is turned on.
 

jadis

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I bet he’s not muting the preamp when he switches from one to another. Hence the loud pop

Thanks for the suggestion, Steve. He said there is no mute switch. I told him to switch to another input that has no connection, same pop sound.
 

audio.bill

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I just looked at the manufacturer's webpage for the amp but I can't find an online manual. I see that there's a switch to select between headphone or speaker output, so I'd suggest selecting headphones before changing between triode and UL modes and then switch back. I think that is likely to eliminate the pop heard through the speakers.
 
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jadis

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I just looked at the manufacturer's webpage for the amp but I can't find an online manual. I see that there's a switch to select between headphone or speaker output, so I'd suggest selecting headphones before changing between triode and UL modes and then switch back. I think that is likely to eliminate the pop heard through the speakers.

Great idea, will relay to my friend. Thanks again.
 

jadis

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Apr 28, 2010
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jadis

Well-Known Member
Apr 28, 2010
12,362
5,472
2,810
Manila, Philippines

jadis

Well-Known Member
Apr 28, 2010
12,362
5,472
2,810
Manila, Philippines
I just looked at the manufacturer's webpage for the amp but I can't find an online manual. I see that there's a switch to select between headphone or speaker output, so I'd suggest selecting headphones before changing between triode and UL modes and then switch back. I think that is likely to eliminate the pop heard through the speakers.


My friend just tried this process, Bill, and it worked! My friend is so happy now he could sleep well tonight. :D
 

jadis

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Glad we were able to come up with a viable solution, maybe it should be passed along to Rogers to be documented in their manual.

Will suggest to my friend. :)
 

DonH50

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The switch changes the bias condition of the output tubes. I'd expect a pop, and agree with those who say it should only be changed with the amp off. If the headphones are driven from the output and/or disconnect the speakers that will eliminate the pop, but I would wait a minute or so for the amp to settle before switching the speakers back on. A lot of tube amps (no idea about this particular one) have LF transients that need a little time to settle out when switching modes of operation like that.

IME/IMO - Don
 

jadis

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Apr 28, 2010
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The switch changes the bias condition of the output tubes. I'd expect a pop, and agree with those who say it should only be changed with the amp off. If the headphones are driven from the output and/or disconnect the speakers that will eliminate the pop, but I would wait a minute or so for the amp to settle before switching the speakers back on. A lot of tube amps (no idea about this particular one) have LF transients that need a little time to settle out when switching modes of operation like that.

IME/IMO - Don

Thanks, Don.
 

DonH50

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Jun 22, 2010
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NP. I have had a few amps over the years (SS and tube) that allowed one to change state, e.g. from A to AB, from triode to pentode, etc. Even AC vs. DC coupled. I think every one said to do it only when the amplifier was off. Made sense to me...

If this amp does not say such a thing, or rather if it says you can switch states while playing, then I would ask the manufacturer about it as some sort of soft-switch circuit may have gone bad. If it warns against switching or says nothing I would assume they did not plan on switching while operating.
 

jadis

Well-Known Member
Apr 28, 2010
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NP. I have had a few amps over the years (SS and tube) that allowed one to change state, e.g. from A to AB, from triode to pentode, etc. Even AC vs. DC coupled. I think every one said to do it only when the amplifier was off. Made sense to me...

If this amp does not say such a thing, or rather if it says you can switch states while playing, then I would ask the manufacturer about it as some sort of soft-switch circuit may have gone bad. If it warns against switching or says nothing I would assume they did not plan on switching while operating.

Thanks again for the advice, Don. Will relay to my friend.
 

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