My tube amp sounds darker now.


I'm using Siemens CCAs, and after putting around 100 hours on the tubes, they are almost too dark sounding now. When I first got them, after about 20 hours of use I thought the sound was a hair too bright, so I bought warm cables to offset that, and everything was perfect for awhile. But now I think the sound is too dark, and I'm about to try some different cables again.
I noticed this just after I accidently left my amp on overnight (for 12 hours). This didn't damage the tube / amp did it? Ugh, what gives?
nemesis1218
My tube amp sounds best after it has been on for several hours. Aural memory is very unreliable- listen further and see if your ears adjust before making changes. I've listened to systems I thought incredible, and on later re-asessment I found them bright or forward or rolled off. I only change things when a I notice a pattern or tendency that spans several sessions.
Knghifi has a valid point. Real Siemens are very open and detailed. Can u try different tubes as a test?
You might also want to test the tubes. If they are weak (especially driver tubes), that can easily contribute to darkness in the amp.
Just wanted to add my $0.02 to the conversation. I agree with others who've said something doesn't sound right when you say the Siemens CCAs sound "dark". I just installed four Siemens 1960s vintage, grey plate, silver pin, 6DJ8s in my Manley Chinook. All I can say is WOW. Their reputation is well-deserved. Siemens tubes (genuine) don't sound anything like "dark". If you can return them, that might be an option. Contact Andy at Vintage Tube Services - he stocks Siemens tubes.