Monday, March 19, 2012
I managed to purchase a couple of 807/ATS25 tubes for $7 each and were giving two in excellent condition. Both pairs of tubes test 85% emissions. Matt, an American electronics engineer, volunteered to design an amp around the tubes. Though this project stagnated for years finally it has come to completion.
The bases are made by a local amp builder and are from Australian Spotted Gum. The top and bottom plates are 2mm Al and the colour "Red Delicious". Edcor 30W OPTs and power tranni grace this smart looking amp. The design is SE with no feed back apart from Ultra-linear. The driver tube is 6SN7 and the rectifier tube is a 5Y3. I have a few different 6SN7s and rectifier tubes to roll this amp and another pair of JAN 807s.
The sound appears natural with a little forwardness in the upper-mid and excellent head room. Loud and dynamic passages are handled with no compression or strain. Voice clear, stands out and is natural. Instruments are individually defined. A pleasing sound and a well performing amp.