I purchased this 6J1 amplifier from eBay. The seller was located in China. Below is a my experinces building the preamp. I have not had a chance to give it a full test. I will update this post once I have had that chance.
It took a little over an hour and a half to finish building the kit. The board seemed a little tight for installing everything. The board itself runs on 12AC and from what I can gather it takes the 12AC and runs it through a voltage doubler which then gives the "B+" voltage.The tubes are 6J1's and obviously have 6volt filaments that run in series. I can not find a lot of info on the 6J1. Link to Data Sheet .
There is not a lot of instructions. Most everything is in chines and so I cannot read it. I was able to follow down the parts list and figure out what everything was and where everything went. I used a multimeter to check the resistors before installing them because the colors were not easy to interrupt. Overall this is a neat little preamp and an easy build.
The box with a flash light for scale.
These are the instruction.
Here is the initial unpopulated board and the bag of parts.
Below is the finished kit.