That said; I have one of the first 3 ST-120 kits from Bob Latino. I am using a Dynaco PAT4 preamp (I know it is not valve equipment but Bob's kit makes it sound incredible). My speakers are Heil AMT10B's purchased new in 1974. The driver tubes on the amp are Mullard NOS 12AT7 and the rectifier is a JJ5AR4/GZ34.
The reason that I have joined this forum is to discuss power tubes. Over the last two and a half years I have gone through three sets of KT88's and am now on my fourth set. The first set was JJKT88's which lasted about nine months before catastrophic tube failure. On the second I splurged and purchased Gold Lion reissues which lasted all of two and one half weeks before catastrophic failure. Then I purchased a set of cryogenically treated ElectroHarmonix KT88's that lasted almost eight months before catastrophic failure. These failures make one uptight about the quality control of these manufacturers.
I was bummed about Russian tubes at this point and had read a lot of conflicting information about Chinese products. So to make along story short I took a chance and invested in a set of Penta Labs KT88SC's from Doug's Tubes. They are the sold plate version manufactured by Shuguang which are touted as being Strict Copies of Genalex Gold Lions. I just could not justify $500.00 for the Treasure series or even worse $1300.00 for EAT's.
They have been in the amp for six and a half months now with a little over 300 hours on them, and I must say they are every bit of what I have read about them. Upon installation they biased with no problem and since then I have checked them once a month and have made only one minuscule adjustment. They are steady as a rock, not like the previous sets which required readjustment every three to four weeks.
The sound is quite amazing. On first listen they were every bit as good as the Russian tubes. Now with over 300 hours on them they just seem to get better. The sound stage is open and the experience is like being in the concert hall. The high's are crystal clear, the mids are exceptional, I have been hearing stage noises in the background that I never heard before and can clearly differentiate individual instruments that were just in the "muddle" of sound before. The base response is strong while being clean and not overbearing. The combination of the Penta Labs KT88SC's and Bob's ST-120 kit create an amazing instrument.
Has anyone else experimented with Chinese valves? So far I am very satisfied.