Yesterday I received and assembled my GCV-300B amp kit, it took me about 4 hours and it was not too difficult. The amp is built using point to point and terminal strips which is not really my favorite construction but for a circuit that's this simple and for something that's not going to be hauled around to gigs, it's fine.
The kit comes with all of the tube sockets and transformers mounted to the chassis. It comes with a Hammond mains transformer and One electron outputs. The only control is the on/off switch. On the back there are two RCA jacks and a set of banana/binding post connectors, that's it! The layout is clean and nicely done using a Hammond chassis.
Inside of the chassis all but one of the terminal strips came mounted in place with machine screws. All the wire and enough to build another amp is included as are all the components. Everything seems to be quite high quality and it still seems like this guy isn't making a whole lot of money on an amp kit. My kit came with JAN 12AT7's and Electro Harmonix 300B's, good stuff. The tube sockets are ceramic on the 9 pin and high quality plastic on the 4 pin. AC cord is also included.
Gabe uses a DC bias scheme on the 300b filaments and it's really noise free when the amp is idling. There is a hum balance pot on the back of the amp that you adjust after it's had a chance to warm up for a while. The hum is noticeable when you first turn on the amp but it fades quickly as it warms up and after a few minutes it's gone.
The instructions are nicely done with only a few errors but the illustrations are quite good and they give you some great tips on how to arrange the components as you build the amp. Wiring the heaters is the first step an that makes sense because they need to be twisted and placed close to the chassis.
How does it sound? VERY VERY VERY impressive! I'm playing the amp through my Altec Iconic speakers and it sounds incredibly good! The imaging, reverb tails etc are very clear. So far my amp has about four hours of use on it and most people say that it takes about 1-200 hours for the 300b tube to really sound it's best. The sound is not muddy or wooly at all and in that respect it defies common thoughts about what a tube amp sounds like. It's quite revealing and relentless when it comes to hearing edits and things like that in the recording. For instance, I was listening to Pink Floyd "The Wall" and I never noticed before tonight how the song "Mother" doesn't really end all that smoothy. You hear the noise floor drop away sort of oddly.
The amp is also louder and more powerful than I expected, it pushes the old Altecs very easily with plenty of level in a moderately large room.
I did a lot of looking around before getting this kit on the way and now that it's done I'm thinking that I'd like to build one of his tube preamps, I'm satisfied. This is a budget amp and it's not filled with hype or fancy parts it's very basic but sound quality is not sacrificed at least not when compared to what I'm used to hearing. It would take a very expensive amp to beat this thing by any amount.
No matter how you cut it the 300b's are not cheap but this amp kit was money well spent.