It would be nice to have for an electric bass guitar or bass synthesizer:
A Pleiades battery powered portable electron tube amplifier with speaker cabinet.
The preamplifier can be a Pleiades V5. (Note: V5 is a two stage battery powered EF183 tube amplifier. The second tube is driven hotter because of the first stage and it should be doing instatenious peak limiting. This is a reason it sounds so good and not clipped. This output with a resistive potential divider can DI drive normal op amp inputs such as Tascam porta 2 and then the sound is great as the op amp is not clipped by the processed waveform).
The power amplifier can be a Pleiades Elektra II.
The speaker can be an full range open back.
This setup is all electron tube and battery powered:
Signal path:
Electric bass - Pleiades V5 - Pleiades Electra II - Full range speaker
An output transformer may be needed to match 600Ω to 8Ω. Or a few higher than 8Ω speakers connected in series.
Alternatively the power amp can be a Pleiades one transistor power amplifier operating too in class A (electrons flowing all the time). This does not need an output transformer as the collector current passes through the voice coil. In a similar way to Pleiades Electra designs, the anode or cathode electron current passes directly through the headphones voice coil.
A darlignton transistor can also be used. Careful biasing again by a higher resistor from collector to base. A Pleiades filter (indicator in parallel with pickup coil) to compensate for the Fletcher Munson curves so as to make the bass sound correct to the listener's mind.
The structure may be just a baffle supporting the speaker and amp.
Open back speakers and baffles are very nice as the bass drop is only 6dB per octave. they sound amazing.
Pleiades concepts and schematics are open source.
Reference:
Audio Amplifiers - edited by J. R. Davies - Data Punlications LTD, London - chapter 7 - 2-Transistor miniature A.F. amplifier - page 41-42
Other posts on euroelectron on Pleiades amplifiers, speakers etc
Tubes vs Transistors - Russel O' Hamm (this amazing paper explains why 60's recordings sound so loud, so dynamic and subjectively uncompressed)
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