One of my favorite tubes for its sweetness with a very involving midrange and overall detailed sound. Very good treble with a great delicacy, tight low end, this rectifier is very dynamic and fast compared to the RCA or Brimar which tends to be harsh for the first and somewhat dark for the second. Good imaging and depth and wide sound-stage are a bonus.
I used two chokes for hum free DC and calculated the cells for the following time constants 12,18,26 and 40 milliseconds assuming it will provide good recover on transients.
Parts were chosen for reliability and " une fois n'est pas coutume " I did not use electrolytic except heaters and 6463 cathode decoupling (Philips LL, nasty good and reliable). Over the usual F&T caps I preferred top quality Siemens paper foil and very low ESR ICAR polypropylene.
Resistors are Sprague Koolohm and AB carbon composition. Heaters are LC filtered for hum free on my 104dB speakers.
Special Yamamoto sockets are used to hold the A710 B4 base along with any other UX4 type 10 triodes.
Point to point wiring, star grounding and short leads. Once finished amp is compact but heavy, weighing about 45 pounds (ca. 20 kg).
What a thrill when I listened to this amp for the first time. Like in my memory...gold!
The A710 is a superlative triode, a tube for hedonists. I guess the magic is in the very small details I usually do not hear with other amps. Main drawback, poor records are even poorer.
Amplifier fed with regular thoriated type 10 by Visseaux too. Second best choice when you can source a pair.
and some good sounding Philco VT25A
Needless to say that driver tube choice is part of the final sound. Gave a try to various 6463 brands and the winner is Telefunken without contest. Clear, clean, neutral and very dynamic.
The men at Ulm plant knew how to make top quality tubes.
it would be nothing without good vinyl's or CD's
tiny listening room in my house attic
