Pleiades 2N2146 single Germanium transistor class A power amplifier

 At your risk.

It worked but there was some lack of treble. If memory is correct there is an earlier post on this.

Pleiades amplifiers stand on a Pile of failed experiments

Borrowing an idea from ribbon microphones to low voltage single ended zero feedback power amplifiers in class A

 At your risk.

The impedance of a ribbon could be for example 0.2 ohms.

It is stepped by an internal to the microphone signal transformer to typically 25 ohms or 200 ohms etc.

If we use a MOSFET for a power amplifier we may choose by suitable bias an operating point of 1A at 1.5V. This could mean an output impedance of 1.5 ohms. We have high current but little voltage in order to drive an 8 Ohm loudspeaker.

But if we can also see things upside down we may use a step up transformer instead of a step down transformer as used on electron tube high impedance amplifiers.

So just a few turns for the primary like on a ribbon microphone. And more turns of less thick wire for the output.

Will it work?

The transformer will be fun to make winding few turns for both windings really. Even the secondary can be of the order of only two hundred turns even if using an air gap to avoid DC saturation on a single ended class A power amplifier.

The power supply could be easy too, just for example a D type 1.5V battery in series with a suitable protective fuse. Just one battery will save from the expense to buy may good quality Bulgin battery holders.

Today at Pleiades labs were found a few IRFS540, IRF222, BUZ54A MOSFETS.

Will it work or sound great?

Girls Just Wonna Have Fun - Cyndi Lauper

 

At your risk.

It was heard today on Easy 97.2 MHz FM radio in Athens, Hellas.

It sounds amazing played on the piano too. Key is F sharp major, so you have all those nice black keys.

The bass code is very interesting, like good Bach's music.

For example from 3:22.

Bass F# with A# C# F#

Bass B with A# D# F# ie B major 7th

Bass C# with A# C# F#

Bass F# with A# C# F#

Bass B with A# D# F#

Bass C# with A# C# D# F#

Bass F# with A# C# F#

(this is from memory there may be mistakes as it was figured out on the piano about an hour ago).

It stands alone very well as only bass and melody played together on the piano, bass which is of course only one note at the time played with left hand and melody which is also one note at the time played with right hand. the intervals are so interesting and out of the ordinary. it is a worthy addition  to the Melody Book.

This music is very close to the Bach instruction to his students figured bass code found at the appendix of the Bach's biography by Spitta.

It is likely that in a few centuries people of the future may regard such songs as the classical music of the 20th century, it may be already happening.

It is interesting to note again that in music bass or melody are by definition one note at the time, just one note.

Nobody can hurt you if you do not want it too. Κανεις δεν μπορεί να σου κάνει κακό αν δεν το θες και εσύ.

At your risk. Με δική σας ευθύνη.

By Lambros.  Λάμπρος.

Lambros had given me the book of philosopher Epictetus called Enchiridion, manual of living. Ο Λάμπρος μου είχε δώσει το βιβλίο του φιλοσόφου Επίκτητου με τίτλο Εγχειρίδιον.

Delay on voice is very important

 At your risk.

For example.

A Woman in Love - Barbara Streisand

The Year of the Cat - Al Stewart

Listening carefully one can realize that together with the direct signal of the vocal there is a delayed in time version added.

This can be done in many ways.

An echo chamber does it automatically as it takes time for sound to travel from the speaker to the microphone inside the sound reflective room.

By the way cylindrical pipes like for example drain pipes standing on floor can make the reverberation sweeter possibly due to diffusion scattering of the ways. If memory is correct having seen photos on the Abbey Road book, the echo chamber i think has such or similar scattering structures.

 

How to create an airgap in an output transformer for single ended power amplifiers?

 At your risk.

The Es can be stacked together. The Is are stacked together.

For example Scotch invisible tape can be placed on top of the Es before placing next to them the Is.

When there is DC current flowing in the winding of a transformer, an airgap can prevent magnetic saturation and even increase incremental inductance/

Further reading.

Magnetic Circuits - M.I.T. 

AI

The classic old MIT textbook on this topic is Magnetic Circuits and Transformers: A First Course for Power and Communication Engineers, written by members of the staff of the Department of Electrical Engineering at the Massachusetts Institute of Technology