The box is a small aluminium cigarette size. Tye components are just the 2N3055 power transistor, a 10KΩ bass biasing resistor, and connectors etc. the speaker is the load collector resistor itself.
It operates of course in class A meaning electrons flowing all the time. Distortion tends to 0 as signal tends to 0 and gradually increases at larger signals. Much like the human ear and many systems in nature which are linear for small signals and gradually overload to compress information. Although the output of this example is much less than 1 Watt it sounds lively, dynamic, sweet, warm, natural, treble extended with deep bass and great punch and alive midrange.
It sounds great but it can be improved.
1. The 9V battery has very small capacity. There is a large voltage drop too. Only 7-8V get to the amp. It lasts for a few songs? Perhaps use li-ion batteries in series inside Bulgin battery holder? Further precautions should be taken with li-ion batteries.
2. The cabling should be changes from thin to thicker. It is a power amplifier. Bypassing a wirewrap wire with a crocodile clip cable made a significant difference. How about silver wire?
3. For optimum impedance maching the speaker should be 40Ω?. 8Ω reduces power output and efficiency. Perhaps using a few small full range 8Ω speakers in series. All speakers close so that they behave as a single large membrane. And everything in a Beolit radio type enclosure? A CD player included in the enclosure?
The amplifier may be called Ionas as Ionas was puzzled as to why 2 speakers should be needed for reproduction.
Mono can sound great.
Listening to a portable radio for example.
Setup, signal,path:
Sony Walkman CD player line out - Pleiades Ionas amplifier - Sony APM speaker
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