Favorite 300B: Sophia vs KR

What`s class A3 and why is it unique/different from traditional class A?

Charles, bear in mind that I'm not the technical brains of the operation nor will we be able to disclose everything about this design since some of it will be kept proprietary until patents are issued. I would not say that the design is necessarily unique from traditional Class A, but it is different in that while the product of the plate power on the output tubes might be the same in both classes (ex. 300B tube), the voltage in an A3 circuit is higher and the current is lower. Since the power is developed by more voltage the result is more lifelike dynamics. This holds true only if the tube can take the increased voltage in A3. Not all can. We could not do this with a 45 or 2A3, but the 300B and EL-34 were rugged enough to take on the increased voltage. Today in an effort to determine if more power could be generated, my partner Jack burned through a number of EL-84's and 7189's that failed the test. We will most likely just stick with the 300B and EL-34 and be satisfied with the 10 -12 watts of power.

What has also been accomplished using this Class A3 circuit is a drop in THD and more importantly IMD. Measurements indicate a lower noise floor as well. This was one of the first things we noticed when swapping out the Coincident amps for our amp in Auntjenof2's.

Clio09,
Thanks for the explanation. Low noise floor is one of the strengths of the Frankenstein. Just for fun I `d like to hear the Franks/Takatsuki (rather than with the Psvane Treasure 300b) compared to your new amp. I say this knowing the vast superiority the Takatsuki provided when I switched tubes(bass,clarity,seperation etc. as these were the same improvements cited by Auntjenof2 with the new amp). Your amplifier sounds like it could be a really great product. Does the increase voltage and power rating affect tube longevity? Thanks again Clio09.The more choices in high quality low power amps available the better IMO.

Charles, the output tubes are biased on the high end, so yes, tube life is likely to suffer somewhat. On the other hand the sonics are improved. Such is the trade off.

Perhaps we can work out a demo for you. If you go to the Electra Fidelity website, complete the contact us form, and send it off I will respond with my phone number so we can chat. We would like as many people as possible to hear this unit. Shows are obviously a good method, but in ones own system is always better. Auntjenof2 just happens to be in the same town which made things easier for him.

Thanks Clio09.