Who would have thought, what is old is new again! People are rediscovering the wonders of vinyl and tube based audio equipment.
Unfortunately a lot of the newer tube or solid state pre-amplifiers do not include a phono stage. If you want to integrate turntables from the 60’s, 70,s and 80’s into your system you will require a phono stage to amplify the signal before input into a pre-amplifier. A lot of my customers buy this phono stage to replace an older phono stage they may already have.
Offered for sale is a 12AX7 tube based phono stage fully populated PCB. This circuit will handle either MM or MC cartridges.
This is hi-end circuit is based upon years of tube circuit development and refinement. After all tubes have been around since the 30’s and for the most part remain unchanged in design.
The circuit uses four 12AX7 tubes(Tubes not included) in a 2 stage amplification circuit. We do not include tubes with this PCB. 12AX7 tubes are readily available from other suppliers. Most people like to choose their favorite sounding tube anyway. We keep our prices down by not including tubes that will probably be swapped out anyway.
The circuit has 2 sets DIP switches. This allows you to select either MM or MC cartridges. When selecting MC, the switches allow you to further match the impedance of the MC cartridge (150 ohm to 2.7k). Don’t worry we provide a chart detailing these settings.
The RIAA circuit based negative feedback design provides low noise and wide range frequency extension. For the MC side of the circuit a ground grid design is used for maximum sound quality.
Quality parts are used throughout including: AB and Dale carbon resistors, Franeh, Elna, and Rifa capacitors. The board itself is double sided and gold plated. The board is 2.4mm thick. The dimensions are: 220mm (l) x 155mm (w). Very solid build indeed!
This PCB is just one piece of the parts you will need to build a working phono stage. You will need a transformer, power regulator circuit and of course the smaller bits and pieces like RCA plugs, switch and wire. The transformer (R80-31), power regulator (LSDY), and RCA plugs we sell as well. I recommend the tube based power regulator in keeping with the tube based phono stage. We also sell a chassis that you can mount the system in and includes a lot of the finishing parts.
Of course we provide a circuit wiring schematic with the PCB for those who understand that sort of thing. BUT this phono stage does not require an electrical engineering degree to build. If you have some experience with kit building you should be fine with this project. Keep in mind you are dealing with high voltages!
(1) Lite LSDY Power Regulator
(2) Lite 115V/230V Hi-Fi Grade 100W R-Core Transformer (R80-31)