At your risk. Please take all safety precautions. A fuse should always be connected in series with any battery. Protect your precious ears.
The amplifier operates in class A (electrons flowing all the time) and it has the characteristic sweet smooth sound.
After listening with the Pleiades 2N3055 amplifier for a few days..,
The sound is very nice without an output transformer but there is no impedance mismatch and efficiency is low. Battery drains very quickly as quiescent current is 200mA.
The transformer described on previous post was then made and connected but it did not sound as good with the 2N3055. Possible reason that bias was not readjusted or that quiescent current is larger.
But if does sound very good with the BD139 which has an operating point of 9V 40mA. It is currently supplied by an exhausted 12V battery which gives 9V (not a good practice for the battery).
It sounds nice with the linoleum Pleiades Auratone 5C type speaker. And it sounds much louder and with more bass with the open baffle Zeiss Ikon typ:31-06 speaker.
It sounds loud, clear and smooth around many rooms.
This power amplifier is made as follows:
(Always use a protective suitable fuse in series with battery)
Battery plus after fuse is connected to collector.
Battery minus is connected to output transformer primary.
Other side of transformer primary is connected to emmiter.
Speaker is connected to secondary of transformer.
Signal is connected to emmiter and base through a series variable resistor connected to base.
Biasing resistor (red violet orange gold) is from collector to base.
Signal path:
Dionna Warwick compilation CD, Arista - Sony CD Walkman 300Ω line out - Pleiades BD139 - Pleiades ferrite output transfor with air gap - various speakers - reverberant small room
No comments:
Post a Comment