Warnings and safety precautions!
All vacuum tube circuits operate at dangerous voltage levels, including this project. The dual triodes used in this project and other vacuum tube amplifiers operate at over 300 volts. Accidental contact with an energized circuit of this nature can be fatal.
Working on, testing, and adjusting live tube circuits requires extreme safety. In general, be cautious and have a safety plan in place! Remember, safety first, always!
The return of vinyl records in the digital age is proof of the superior quality of analog sound. Any properly designed vacuum tube phono preamp has the capability to reproduce a warm, rich sound that digital formats struggle to replicate. Similarly, the M65 project introduces a level of harmonics to the sound, offering a smooth and natural listening experience that many find more musical and appealing. Finally, the M32 tube phono preamp project reproduces the nostalgic warmth of music for the vinyl listening experience.
The M65 moving magnet phono cartridge preamplifier project focuses on achieving high-quality audio reproduction from vinyl records. Based on the Shure Model M65 Stereo Conversion Preamplifier.
Maintaining the original RIAA equalization circuit ensures that the prototype remains true to its design for accurate sound reproduction. If a modification is made to the original design, it would also affect the following: choice of dual triodes and magnetic phono cartridges.
The 12AX7 matched pair is known for its ability to provide ample gain and superior audio quality. On the other hand, the 5965/12AU7 pair, while requiring more gain to reach optimal levels, is praised for its cleaner audio quality.
The Audio-Technica AT-VM95C/H and the Ortofon Omega 1e are both excellent choices within the same price range and offer comparable output voltages. While the Audio-Technica may deliver a flatter sound, the Ortofon is noted for its enhanced high-frequency response.
Finally, the performance of the prototype will vary depending on the vinyl record being played, making each listening experience unique to the user and their setup. Overall, it is a subjective conclusion that is completely dependent on the listener.
Here's the link for the M65 data sheet: pubs.shure.com/guide/M65/en-US