Are all tubes glass or are some metal? I noticed allot of older amps have tubes in metal jackets and wondered why.
metal tube covers
Hi-I just purchased a used Jolida 1501 RC at a great price. When I switched out the tubes, I was amazed at how much better the sound got. However, I see the tubes are wrapped in metal covers. Do I need to use these? What's the purpose? Does the sound improve w/o the metal covers. Thanks.