At your risk. Please take all safety precautions. A suitable fuse should always be in series with a battery for burn injury or fire prevention hazard.
This is the current schematic without RIAA tests or tuning done yet. So the network used may be wrong, it is just used for initial listening test purpose. Tests will be done using a Lipshitz inverse RIAA networks including the ultrasonic time constant, (please see Wikipedia article on RIAA).
At this prototype stage an input transformer is not used. The Stanton 681EEE calibration standard moving (ultra low mass) iron cantilever cartridge is directly connected to the 47K resistor input.
Two 9 V batteries in series with a fuse are used to power this great sounding very low power consumption and low noise preamplifier.
The sound is warm like a good electron tube design with (no source) cathode bypass capacitors capacitors. Warm may well mean with less distortion, no high frequency overtone artifacts added to the music program.
The output transformer is used with the 2 secondaries in series, so the ratio is typically 5:1. 2 Channels can drive the Sennheiser HD-580 2x 300 Ohms headphones to a comfortable level with big deep bass, liquid mid and treble. But all these adjectives may be unreal.
The sound is real, close to reality.
I wrongly thought some cartridges like the Stanton 680 series, Ortofon OM series, some Shure were MM. There are variable magnetic reluctance and give MM a very hard time and possibly MC too. For example the cantilever has neither a magnet or a coil attached to it. The mass is so low that the 681 can track at less than 1g. One day i heard by chance n Stanton 680 and that was it. I could not believe how good, warm (natural) and detailed it sounds. The treble...
From AI overview:
The Stanton 681EEE is a highly regarded moving-iron phono cartridge, historically used as a calibration standard in broadcasting due to its flat frequency response (
) and low distortion. It is often sold with a Vivid Line stylus or original Stereohedron stylus and requires precise setup (tracking force 0.75–1.5g, best around 1.5–2g, typically without the brush).
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