Instructions for optimization of cartridge loading and preamplifier gain

NOTE: Before starting, unplug the power supply and allow 30 minutes for capacitors to discharge.

1. Remove the cover of the preamplifier by taking out two philips screws on the left and right side of the preamplifier:
2. Identify sockets for load and gain resistors: resistors R11 and R12 set cartridge loading and R21, R22, R101 and R102 set the preamplifier gain.
3. Use the Load Settings Table to determine required load setting resistors (R11, R12) based on the cartridge specifications. NOTE: no resistors are required for the 47 kohm load, however, we find that many cartridges with 47 kohm requirement actually perform better with 23 kohm load. As a general rule of thumb, load resistance 10 times the coil resistance offers the best results. We also provide 10 kohm loading option, which is rarely made available in competing products. This is particularly noticable when the sound appears to be on the bright side. As a general rule, lower load resistance will result in lower noise operation and greater immunity to environmental effects (noise pickup, hum, etc.).
4. Use the Gain Settings Table to determine required gain resistors (R21, R22, R101 nad R102) base on the cartridge requirements. As a rule of thumb, MM cartridges will require 40dB of gain, High Output MC (HOMC) cartridges require 40-55dB of gain and Low Output MC cartridges require 55-65dB. NOTE: Any combinaton of gain and loading is possible. However, in order to maximize performance, increase immunity to noise and hum and lower the noise, feneral rule is to use maximum gain that still provides adequate output.
5. All resistors needed to set any combination of load and gain are included with the preamplifier. They come pre-cut and pre-formed, ready for installation.
6. There are 22 resistors, 7 values:
   • 2 pcs: 47.5kohm
   • 2 pcs: 13kohm
   • 2 pcs: 1kohm
   • 2 pcs: 100ohm
   • 2 pcs: 200ohm
   • 6 pcs: 47.5ohm
   • 6 pcs: 22.1ohm
   • 2 pcs: 10ohm
7. Resistor values are color coded as follows (first four rings define value, last one is always brown denoting 1% tolerance):

   47.5 kohm: Yellow, Purple, Green, Red, Brown
   

   47.5 ohm: Yellow, Purple, Green, Gold, Brown
   

   22.1 ohm: Red, Red, Brown, Gold, Brown
   

   13 kohm: Brown, Orange, Black, Red, Brown
   

   1 kohm: Brown, Black, Black, Brown, Brown
   

   200 ohm: Red, Black, Black, Black, Brown
   

   100 ohm: Brown, Black, Black, Black, Brown
   

   10 ohm: Brown, Black, Black, Gold, Brown
   

8. Identify the required values and insert into the corresponding sockets. By using tweezers or nose pliers, resistor leads should be firmly pushed into the sockets until they botom out, after about 1/8" (3mm). You will feel socket contacts scraping resistor leads, creating an air tight contact seal.

   The picture below shows the preamplifier board with all six resistors installed. Depending on a specific cartridge, there may be 0, 2, 4, or all 6 resistors required. The illustration below shows the example of optimized parameters for the Denon DL‑103 MC cartridge.

   
9. Once the required resistors are installed, the cover can be replaced and preamplifier is ready to use.