Pleiades 2N3053 operating with 6V, 3V, 1.5V

Signal path, setup:


(From Russia with Love - John Barry, The Best of, CD) - Sony CD Walkman line out - Pleiades 2N3053 (the usual 4K7 from bridged mono line out to base, and 100K variable resistor from collector to base) - PHILPS AD5046N directly connected to collector or Beyer DT 770 at low battery supply


What a transistor!


It operates in class A (electrons flowing all the time) with great sound at even 1.5V. All that is needed to do is changing the value of the biasing resistor for max sound or quality by rotating the rheostat pot, reducing the bias resistor.


Firstly the usual 12V battery was changed to a 6V. Sound was less and distorted. By reducing the bias resistor the sound was again clear and of course of less volume that the 12V case.


Then 2x AAA batteries (Sanyo eneloop) were connected ie 2.6V. Again the bias resistor had to be reduced for optimum performance. At that point Ic was about 1mA.


Then just 1 AAA battery was connected ie 1.3 V. Again the bias resistor was reduced and the sound was quieter but great. (Ic=0.5, Rcb=8KΩ). As of writing this the phenomenal PHILIPS AD 5046N still can be heard in a room and outside of it. This is of course the remarkable property of our ear brain mechanism.


It was then decided (still with 1 AAA battery) to connect hi Z headphones instead of the 800Ω speaker. The 2 600Ω Beyer drivers were connected in parallel (mono) for simulating the 300Ω of Sennheiser HD580.


The sound was amazing with unbelievable bass (due to the (limit of) 0Hz direct coupled response). It was loud.


This hints to have means of variably reducing Vb when we wish to reduce the volume. This has the following advantages. 1. Very low class A power consumption. 2. The sound is always good as the transistor is generously driven. So the sound is full and loud but without disturbing neighbours for example.


A Pleiades 2N3053 in stereo is certainly possible for driving Sennheiser HD580 headphones and operating for plenty of hours with just 1 AA battery. (Caution: All precautions should be exercised for keeping the input signal down to protect hearing and fuses for the protection or safety of batteries, the experimenter and the headphones).


This setup especially with a speaker should be great for recording vocals in tune since pitch perception depends on acoustic intensity and not only frequency (Stevens). See next euroelectron post.


The Pleiades 2N3053 schematic can be seen in the reference and is open source as everything else Pleiades.


Reference:


http://euroelectron.blogspot.gr/2018/03/madonnas-voice-coming-from-point-source.html


Sound and Hearing - Stevens, Warshofsky - Time Life Science Series