There's a little extra room in the Paradyne layout around the 7L7 tube that can be used for tweaks/mods to adjust the performance of the circuit. When I delivered the prototype to Doc B., I included a minor EQ to bump up the bass response and tip up the treble ever so slightly, which is something I knew he'd appreciate. I will cover here how to fit this mod if you'd like to try it!
1. There is either a red or a white wire running from the center pin of the RCA jack to terminal 2U. Heat up this joint, remove that wire, and attach it to 1L.
2. Insert a 3.32K resistor and 3300pF capacitor between 1L and 2L. Solder 1L and 2L.
3. Heat up the solder joint at 2U and slip one lead of a 0.47uF capacitor through that terminal. Attach the other end to 7U.
4. Heat up the solder joint at 3U, slip one end of a 22.1K resistor through 3U, attach and solder the other end of this resistor to 7U. If 3U will not accept more connections, the end of this resistor can be carefully wrapped once around the tinned bus wire going from 3L to the loctal socket.
This mod costs about 1.5dB of gain and stretches the -3dB bandwidth points to 6Hz and 165kHz. Here are some links to the parts I would recommend using for this:
0.47uF Capacitor
3300pF Capacitor
3.32K Resistor
22.1K Resistor
1. There is either a red or a white wire running from the center pin of the RCA jack to terminal 2U. Heat up this joint, remove that wire, and attach it to 1L.
2. Insert a 3.32K resistor and 3300pF capacitor between 1L and 2L. Solder 1L and 2L.
3. Heat up the solder joint at 2U and slip one lead of a 0.47uF capacitor through that terminal. Attach the other end to 7U.
4. Heat up the solder joint at 3U, slip one end of a 22.1K resistor through 3U, attach and solder the other end of this resistor to 7U. If 3U will not accept more connections, the end of this resistor can be carefully wrapped once around the tinned bus wire going from 3L to the loctal socket.
This mod costs about 1.5dB of gain and stretches the -3dB bandwidth points to 6Hz and 165kHz. Here are some links to the parts I would recommend using for this:
0.47uF Capacitor
3300pF Capacitor
3.32K Resistor
22.1K Resistor
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