Not long bought an old Laney AOR 50, really old amp from the 80's, got a really good deal on it, everything is working great on it apart from when I push the master volume past around 7 it starts to get this strange crackling sound in the background which only happens when i strum the strings, if nothing is being played it is not there, same happens if I push the gain up a fair bit too. It isn't highly noticeable when playing live or anything, but the problem is when it comes to micing up the amp and recording it as when it comes to getting an extremely clean signal this background crackling very much prevents that from happening. Also when cranked the volume sometimes completely drops out, but if I turn the master back it all comes back. Not sure if anybody come give me some advice on this please, do you think this will more than likely age related as the amp is extremely old or just a simple tube replacement etc? thanks!