ARC LS7 preamp channels drop out intermittently

Replace tubes.... I believe that unit can go into protection and mute outputs if there is a problem with the tube.  May want to re-tension tube sockets.   

Given it's age and your belief it has original tubes I would start there 

oddiofyi has it right.

Thanks guys…really appreciate the insight!

Arvin

Get good ones.  I always feed my babies the best !  I would either get a set from ARC or a matched set.

It uses 4 6922 , personally with preamps I like to get matched pairs or quads so channel balance is as tight as possible.  Pose the question here and other forums what the best replacement is.  They probably used Sovtek during the period that was built.    JJ makes a very good sounding 6922 and the Gold Lion 6922 is good too.  The JJ has more meat on the bones and the EH is very good top to bottom, clear .   I like the tone of JJ bettter but that is subjective 

What I would do is get a replacement set (couple matched sets) pronto… like from The Tube Store. If this solves the problem, then go get some from Audio Research (They do extensive testing and I like supporting them)… or Upscale, if you want play with fancy ones… then the first set you purchased become your backup.

This is me… based on my priorities.

I always like having an extra set around. Just in case… they don’t act strange or fail often. But it is great to have a set in case a tube develops a whistle of some other idiosyncrasy.

@oddiofyl ​​@ghdprentice 

Thanks for the tips!

I just ordered 4 Electro-Harmonix 6922 Gold Tip tubes from Upscale. I did go for the Platinum grade, non-cryo versions. I was considering the Gold Lions, but figured I could always go that route if I wanted a more lush, warm sound than what the EH tubes will give. As this will be the first time replacing the tubes for me, I wanted something “close” to the stock sound I’ve grown to love…which, from what I’ve researched, the EH are, but with a touch more warmth and presence in the mid-range. I also did check the tube connections and contacts; all seemed good, but the problem remained.  So, I’m hoping the replacement tubes are all I need…

Will let you guys know how it goes when I get them installed.  Thanks again!

Arvin

Good to hear. Most likely it is the tubes.

Hello all!

Just wanted to close the loop and say the replacement tubes seem to have solved the channel drop-out issues I was having.  As a side benefit, the Electro-Harmonix Gold Tip tubes have a decidedly improved the sound of my system when compared to the stock Sovtek tubes.  These guys definitely have a meatier, weightier mid-range to them, without losing any noticeable detail up high…though, to be fair, I would probably wish for just a tad more “sparkle”/energy up there.  Also, the bass hits harder and faster out of my KEF Blade Two’s than before.  So, all-in-all, what a great repair and upgrade solution!

Thanks for everyone’s help and suggestions…the Audiogon forum community comes through yet again!  

Happy Listening!

Arvin

🎉👏🏝👍

👍

Excellent! Thanks also for the follow up for us all as well! Enjoy the tunes! 

Nice!   With solid state gear I always look at things like connections, maybe swap a cable when there is a problem with tube gear I always look toward tubes and dirty sockets or sockets that don’t grip the pins well

Happy Listening!