Sounds like one of the 6DJ8 tubes in the line stage went bad.
4 responses Add your response
Thanks for the correct diagnosis. I replaced the existing tubes with a spare set of Sovtek 6922 which I received when purchasing the unit. Some additional questions: when initially turning on the system there was some crackling sound that went away after the first few seconds- is this normal? Also, is there a burn-in period for new tubes and what are the different "musical" attributes of the various tube manufacturers. Thanks again.
The only time I have heard crackling sounds from my LS-25MK1 is when the tubes were shot.... It never does it now.. Make sure the new tubes you buy are fairly well matched or you may get a "ringing" sound when changing the gain level... Burn-in on tubes is usually 48 hours for a fairly decent sound. I would also leave the preamp on the lowest gain setting with no input for 2 hours before listening to new tubes... This lets them start up "slow".