OTOMON Laboratory　(音門ラボ)/Product details page

This is special order made tube manufactured by master Tossie of Valve World. Power tube is transmission tube 808, drive tube is 6L6, directly coupling.

Valve world is very famous tube amplifier maker in Japan in 80s, unfortunately it was closed now. Their product is not only have good quality, but it has very great design. From now, I will introduce some products of them that I have data in hand. This is one of the great tube amplifier designed for 845 tube. 845 tube is considered as king of tube with plate volt up to over 1000V, plate current is about 80mA.

This amplifer use a very powerful tube 6L6 as drive tube 808 in class A2. 808 is transmission tube. Its sound is even better than 300B. Instead of running at high B+ volt and low current, it works in class A2 mode, low B+ volt and high current. The big problem is that if you let tube work in class A2, the grid of power tube will have current and it is more difficult to drive than let tube work in class A1.

Shishido resolve this problem by using a strong interstage transformer and drive tube with (+) volt bias. This is very good solution but it is not easy to find a strong transformer as well as price for it is very high.

Mr Tossie used a powerful tube to directly drive output tube. 808 is working at its best at bias 30V, at that bias, grid current is about 20mA, and the best matching drive tube in this case is using EL-34 or 6L6.

Pre-stage is 5693, pentode connection. Power tube can be change between 811 and 808 without any modification.

Specification:

Output 12W+21W　
Response frequency　10Hz～21KHz(±2dB)
Damping factor　2.8

Power consumtion　200W
Size:　570x325x230
Weight 31Kg