One transistor amplifier from record player cartridge to loudspeaker?

At your own risk.


By taking inspiration from the books at the reference and the fabulous Dansette Bermuda vintage record player which uses one UL84 electron tube from crystal cartridge to loudspeaker...It sounds so alive. It was used by Mike Oldfield when he was a kid [BBC]. He must have learned a lot from such an immediate reproduction to just one point source loudspeaker.


It may be possible to use a good quality crystal or ceramic cartridge driving a small JFET. At the drain is connected an 800Ω loudspeaker such as Philips AD5046N. The other terminal of the voice coil is connected to battery + through a few milliampere fuse. Or using a step down impotence transformer. See also the Pleiades 2N3053. The 2N3053 is very suitable for a line out output of low impedance and it works very well if we include a series variable resistor to base which can be used as a volume control. The Pleiadss 2N3053 with the Philips AD5046N even with just 8mA quiescent current can sound amazing and fill a room and even much more area with a so natural sound. For a crystal cartridge we need a JFET for its high input impedance property. It might be possible to connect a bipolar transistor such as RCA 2N3053 by using a high impedance series input circuit. More experiments needed.


Piezoelectric cartridges are constant displacement ttansucers for constant voltage output like condenser mocroohine capsules. Moving coil ttansucers are constant velocity for constant voltage output. Therefore most of the RIAA EQ is there.


So just a Pleiades amplifier possibly a few resistors and a battery. Using a fuse in series with the battery is very important for safety.


References:


Mike Oldfield Tubular Bells documentary - BBC - YouTube


Transistor audio amplifier manual - Clive Sinclair - page 6 - Bernard's radio manuals (full of transistor amplifiers where the load is the voice coil itself)


Audio Amolifiers - J. R. Davies - page 41 - Data Publications (it contains the brilliant K. Jones circuit where the voice coil itself is the collector load).


Semiconductors Handbook Volume 2 - page 100 - Piblishers De Muiderkring NV Bussum Netherlands (many class A one transistor circuits including at keystone with the voice coil the collector load itself and bias from collector to base)