A world class reproduction sound system with just a few components

At your risk. All safety precautions should be followed with any voltage or current.


A fuse should be always be connected in series with a battery.


All needed is:


A good source of music signal. It may be a Walkman CD player.


One BD139 transistor


A heat sink


The Pleiades BD139 one transistor schematic


One bias resistor


A 12V battery in series with fuse


A potentiometer for volume control in series with base circuit.


A big, heavy output transformer of primary inductance say 100mH and secondary inductance 25mH. 25mH works well for a 12Ω speaker. For a lower impedance speaker a correspondingly lower secondary inductance should be used.


A world class baffle sensitive fullrange speaker.





Even an operating point of 10V 50mA will sound loud, amazing, broadband, natural, dynamic, big.


This is just a power dissipation of 1/2 watt. Mighty power output should be about 250mW sending to the cleaners almost any amplifier regardless of power output.


Such loudness can be achieved that one has to move to another room when for example a sax (Carlos Jobim albums) is playing loud similarly to having a real saxophone playing in a small room.


A Zeiss Ikon typ:31-06 baffle speaker is used.


See also:
https://euroelectron.blogspot.com/2019/05/zeis-ikon-typ31-06-baffle-fullrange.html

The best comparison for electron tube or transistor?

See previous post:
https://euroelectron.blogspot.com/2019/06/how-does-dl33-sound-like.html


There is not much point in comparing an amplifier with 2 electron tubes and one with say 14 transistors with negative feedback etc and trying to decide that electron tube will sound best. Of course it will. The point may be comparing an amplifier with just one electron tube to one with just one transistor, both in class A (electrons flowing all the time) both with no negative feedback, using the same transformer core etc.  Same device power dissipation.

How does the DL33 sound like?

At your risk. All safety precautions should be followed for any voltage or current.


Operating point used is 70V, 12mA.


Output transformer is a Sowter SK05s.


Amazing smooth sound. Big bass. Amazing mid and treble. Very smooth sound on very low noise ambience.


A schematic similar to Pleiades V6 is used but pull up grid bias is with a 10MΩ resistor from filament centre tap to grid. A 1:7 turn ratio input transformer is used. Electron tube is triode connected ie grid 2 connected to anode.


For some strange reason the one transistor Pleiades BD139 at operating point 10V 50mA sounds about 3 times louder. Not as smooth but could the grainess be from the CD player?


Perhaps electron tube bias should be changed to cathode resistor bias. Grid leak must be preventing  overload created harmonics due to the change in bias ie amplification by the grid rectification effect affecting DC grid bias. Progressive overload can be part of the loudness of sound, see Russel O. Hamm.


Would the best comparison for an electron tube vs transistor be one active device amps with no feedback fed with the best live signal? For example musicians playing in another room and sound picked up be a world class mic? A Pleiades filter added in the signal path if needed for flat frequency response from producer's  brain to listers brain. [Lowe, Morgan]


References:


Tubes vs Transistors (vs op amps), Is there an audible difference? - Russel O. Hamm - JAES


Sound Picture Recording and Reproducing Characteristcs - D. P. Lowe, K. F. Morgan - Journal of the society of Motion Picture Engineers

Playing with DL33

At your risk. All safety precautions must be followed at any voltage or current.


Grid potential measured with respect to filament when filament is connected to battery through safety fuse. No anode potential supplied.

-2.8V
-0.3V center tap of filament
-1.5V

The first pico pico pico Watt is the most important

The limit of zero power.


The infinitesimally small power.


This was thought while browsing through the datasheet of the DL33 electron tube with filament for use in battery operated equipment.


The infinitesimally small power.


This is what analog electronics is about. A class A amplifier (electrons flowing all the time).


Amplifiers approaching in resolution the granularity of matter.


The size of an electron.


Not very unlike modulated molecules on vinyl records. The wavelength of modulation inside a record groove being so small as to be comparable to the size of the wavelength of light.


How would a direct heated DL33 electron tube operating in class A sound like with an output of 250mW?

How would DL33 or DL35 electron tube sound as a class A power amplifier?

With a high quality transformer.
Electron tube possibly triode connected.


Direct filament cathode. Only 1.4V at 100mA for heating (thermoemision of electrons).


See next posts for how it sounds.

A linoleum panel speaker baffle plays the double role...

of separating front and back wave of a drive unit and


an efficient bass reverberation absorber improving the acoustics of a room by converting low frequency vibration to hear. The large electro we area behaves like a giant woofer antenna receiving bass frequency content and sympathetically vibrating while absorbing such vibration. Ie not reradiating it.


An amazing advantage is its great mid frequency clarity with lack of boxiness coloration and the amazing easiness of construction. Just opening a hole on a nice colored sheet of linoleum.


A safe way to hang from ceiling is one support option. A floor supported mounting frame another etc.