ARC LS25 mkII tube change

GeneJazz · 12th October 2010, 07:11 PM

I am thinking of replacing the 2 6H30 tubes. Is this swap and play or do I need to adjust the 2 trimmers on the board? The manual says nothing about this.

GeneJazz · 15th October 2010, 03:56 PM

No one knows? I imagine I am supposed to measure someplace and set the trimmer to a specific voltage...

Zen Mod · 15th October 2010, 04:18 PM

just plug & play

trimpot is for Jfets operation

GeneJazz · 15th October 2010, 04:31 PM

Quote:

Originally Posted by Zen Mod

just plug & play

trimpot is for Jfets operation

Thanks for your response.

Can you tell me how to make sure the trimmers are adjusted correctly? I assume I am supposed to measure some location on the board and check for a specific voltage?

I got the preamp 2nd hand so want to make sure everything is good.

Zen Mod · 15th October 2010, 05:09 PM

just check +/20V points

re- set with pot if needed

but - if nobody didn't tweak them , they're probably fine

GeneJazz · 15th October 2010, 05:20 PM

Quote:

Originally Posted by Zen Mod

just check +/20V points

re- set with pot if needed

but - if nobody didn't tweak them , they're probably fine

Thanks so much! Exactly what I needed.

The previous owner told me John Rutan of Audio Connection did the tube change couple of years ago. And perhaps he messed with the trimmers...

I want to make sure.

GeneJazz · 18th October 2010, 04:09 PM

Did a voltage check throughout the amp. All looks good. I had to tweak one of the trimmers a very small amount.

The preamp sounds great to my ears.

12th October 2010, 07:11 PM	#1
GeneJazz diyAudio Member Join Date: Oct 2010 Location: NYC	ARC LS25 mkII tube change I am thinking of replacing the 2 6H30 tubes. Is this swap and play or do I need to adjust the 2 trimmers on the board? The manual says nothing about this.

15th October 2010, 04:18 PM	#3
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	just plug & play trimpot is for Jfets operation __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

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15th October 2010, 03:56 PM	#2
GeneJazz diyAudio Member Join Date: Oct 2010 Location: NYC	No one knows? I imagine I am supposed to measure someplace and set the trimmer to a specific voltage...

18th October 2010, 04:09 PM	#7
GeneJazz diyAudio Member Join Date: Oct 2010 Location: NYC	Did a voltage check throughout the amp. All looks good. I had to tweak one of the trimmers a very small amount. The preamp sounds great to my ears.