|I happened to own Electra Print 300b monoblocks (2 300b per side) and what I assume is UltraPath Line amp - preamp with 6j5 signal tubes and 5v4gt rectifier tube. Very nice amps and preamp - keeper. |
link to pictures below:
picasa album - click to open
Amplifier and matching preamplifier sounds fantastic and I couldn't be happier, however. I am a bit worry with limited information about this particular amp. From what I gathered and read about Jack Elliano’s Direct Reactance Drive Amplifiers and his products is that most of his work is custom and that he usually builds around specific tube(s). Circuitry is tweaked and optimized for that specific tube(s) and that's how my dilemma began. Simply speaking, I have no idea what 300B tubes are used in this amp and if I can swap those with other new production tubes or something more vintage like Svetlana Winged C ? These tubes resemble in construction cheap, Chinese imitations of WE 300B tube but have no markings other then "300B" right in the middle of the glass.
Another concerning issue was mentioned in Enjoy the Music review article of similar amp. Here is small fragment from that review, describing that nitty gritty problem:
" The Electraprint has one problem. Not with the sound and normal operation, but with the biasing. Because of its setup, biasing is done by moving a connector on a variable resistor and then measuring the voltage drop change across a 10 ohm resistor. Problem with this is found inside the chassis where it is difficult to reach unless the amplifier is turned over. Therefore it is difficult to do with the amplifier in the system. Second, the variable resistor also controls the voltage to the driver tube and the two interrelate. Thus as you change the output tube bias the driver tube voltage changes. "
If anybody has any info about these amps (and preamplifier), tips, etc. please share your thoughts.
(BTW other tubes used in these amps are small radio 6an4. Also, I emailed these questions to Electra Print, Jack Elliano but was referred to circuit page on their website. Unfortunately, I am not that advance and it really did not help me in any way)
Thanks in advance