Dear Sirs
Since kid, always had a passion for vinyl. The pleasure of listening to music is something magical. I decided to design a project for my simple (denon 103R). phono stage. Follows the same philosophy of the power amplifier (thread 04-10-2013, "project... power amplifier ").
The circuit is 100% discreet, not using operational amplifiers. Each channel has two stages of amplification. The (RIAA) is passive and is located between the two stages. The first stage gain, have the selection of gains and also correction of the load Cartridge. The second stage amplifier has a gain of approximately 25 dB to compensate for losses (RIAA).
On the input board, I put a socket for a future alteration of the load value. Small signal circuitry is based on discrete circuit, multiple cascode, output stage consists of powered Mos-Fet. Accurate tracking of the RIAA equalization curve is a more difficult task than is generally appreciated. By using extremely high quality components custom made film foil capacitors (dYnamiCap) and better than 1% tolerance Welwyn, Caddock resistors in a passive network. The chassis uses a precision front panel machined of high grade aluminum and custom aluminum for the top and side.
The transformer ( power supply ) sub-enclosure is constructed from machined aluminum plates. Affixed to the top and bottom surface
are closed-cell neoprene damping sheets and mu-metal. The neoprene combines excellent damping and thermal stability, the mu-metal is excellent to isolation of magnetic fields.
I go enclose photos and then inform details of the project.
Cheers
jon
Since kid, always had a passion for vinyl. The pleasure of listening to music is something magical. I decided to design a project for my simple (denon 103R). phono stage. Follows the same philosophy of the power amplifier (thread 04-10-2013, "project... power amplifier ").
The circuit is 100% discreet, not using operational amplifiers. Each channel has two stages of amplification. The (RIAA) is passive and is located between the two stages. The first stage gain, have the selection of gains and also correction of the load Cartridge. The second stage amplifier has a gain of approximately 25 dB to compensate for losses (RIAA).
On the input board, I put a socket for a future alteration of the load value. Small signal circuitry is based on discrete circuit, multiple cascode, output stage consists of powered Mos-Fet. Accurate tracking of the RIAA equalization curve is a more difficult task than is generally appreciated. By using extremely high quality components custom made film foil capacitors (dYnamiCap) and better than 1% tolerance Welwyn, Caddock resistors in a passive network. The chassis uses a precision front panel machined of high grade aluminum and custom aluminum for the top and side.
The transformer ( power supply ) sub-enclosure is constructed from machined aluminum plates. Affixed to the top and bottom surface
are closed-cell neoprene damping sheets and mu-metal. The neoprene combines excellent damping and thermal stability, the mu-metal is excellent to isolation of magnetic fields.
I go enclose photos and then inform details of the project.
Cheers
jon
