Ty for the reply. When engaging half drive I get a loud snap sound. Different on other channel. I understand that there's always a little popping sound. Been that way for years.Those LDR's were supposed to have taken care of that. This just recently started. I've been troubleshooting my *** off. With certain power tubes , its acts as normal. And it only does it when the presence is turned all the way down. Three years ago I did some repairs to it and re capped it along with putting in two new LDR's but popping remained. Oh well . I changed that 6.8 ohm resistor ( with a carbon film)in the switching matrix circuit because the one that came with it (carbon) read 13. Out of curiosity I re installed the old one because after all of the repairs and upgrades, the amp just really never sounded the same. Better before. The newer one read exactly 6.8 and is a carbon film. It seems like that's when this started when putting old one back in. I put newer one back in and problem is still there. Slight hum when Deep and Modern modes ( no half )engaged with level turned down. I have also noticed that the choke is really making a loud buzzing noise. Have to stop fan to hear it. Don't know symptoms of a choke going bad. What's puzzling is that all through the years I've tube rolled and never had this problem. I hope you can understand this. Sounds a bit confusing after I read the whole thing. Thanks for your time! And please let me know if you need any more info. Thanks again, Jim
