Pleiades 2N3055 one transistor amplifier with vocal exhibition switch updates

A fuse should always be used in series with a battery for fire hazard prevention.



This time Vicky listened to the one transistor amplifier operating in class A ( electrons flowing all the time).


Signal path:


Idlewild-Travis - YouTube - iPad mini headphones out one channel - various coupling capacitors from 4.7μF to 100μF - Pleiades 2N3055 with 12V lead acid battery at various states of discharge - Pleiades linoleum Auratone 5C type speaker - bedroom as listening room - our ears or brain


She was impressed at the clarity and smoothness of voice. Especially when the coupling capacitor was only 4.7μF.
She commented how well at 4.7μF every nuisance of vocal is revealed.
At 100μF the full orchestra sounds but max level has to be lower or more apparent distortion cones in. At 4.7μF voice is beautifully and loudly projected.
The above suggests the inclusion of a 4.7μF or 100μF voice-fullbandwidth examination switch.


We did not particularly like inbetween values of C such as:
10μF Elna starget before ROHS
15μF film Philips


Vicky commented that the best sound was at the beginning of the listening tests.


Possible reasons:


The 1AH 12V battery going below 9.4V. With fresh battery the sound was clearer but less interesting or smooth possibly because of too much speaker DC offset as well as less distortion.


The exhausted battery sounded worse that half exhausted.


Transistor running hotter.


Brain getting used to the nice sound.


At higher quiescent collector current speaker membrane equilibrium passion is more shifted. Ie elastic restoring force higher and higher membrane resonant frequency? (At lower bias sound perception is more deep).


So bias controlling quiescent current must be very important to the sound and optimum sound quality with given battery voltage.


There is also interaction of transistor input impedance which is low, with series resistor volume control and coupling capacitor reducing bass response as potentiometer is moved further clockwise which may be a good thing, like a loudness control compensating human ear equal loudness curves.