After reading comments and reviews I decided to seek out the Penta Labs KT88SC only to find out that its no longer available. It was made by Shuguang specifically for Penta Labs. However, the deal between Penta and Shuguang ended for some reason. Fast forward a bit and now Ruby Tubes and also TheTubeStore have picked up the ball and struck deals with Shuguang for that same special construction tube. This particular version has three getters, two side and one top. I ended up with the Ruby KT88V-STR From Doug's Tubes because its the same exact construction as the Penta KT88SC.
I was able to make a direct comparison of the two power tube types by simply unplugging the KT120s and plugging in the KT88s, reset the bias to 0.50mv and listen. I now have about 30-40 hours on the new tubes. The first thing I can say is that, contrary to what I have read, this KT88 goes just as deep in the bass as the KT120. I found the bass to be equally deep and significantly better defined! I guess 'tighter' would be the word? At first, the KT120s sound like they are producing more bass but in actuality their bass is a little muddy and less defined when directly compared to the KT88V-STR. Moving on to the midrange and treble, (which is where I was looking for change) I found the midrange more forward and the treble more extended. Both positives in my system. I like these KT88s. The KT120s are now relegated to back-up duty.
What I plan to do in a couple months is revert back to the KT120s just to make sure that I'm not 'fooling' myself
![Rolling Eyes](https://2img.net/i/fa/i/smiles/icon_rolleyes.gif)
BTW, I just started rolling some 6CG7s in the nine pin locations using proper adapters. Pretty interesting. Will report on that experience but first need to make sure these new KT88s are fully burned in. That's all for now.
Regards,
Wayne