Table of Contents
Advertisement
Optional Gain Reducing Resistors
This section describes an optional step. Should you desire, at the same time that the tone
controls are turned off, you can decrease the gain of the high-level stage. This increases
the Signal to Noise Ratio of the preamp. I'll present the arguments for and against, but
you'll have to decide.
Note: gain reducing resistors are not included in this kit! The resistors that are included
in the kit are the 4.7 Meg-Ohm "no-click" resistors. Their installation is described on
Installing the Treble No-Click Resistors, on page 16.
Add the Gain Reducing Resistors
If you never run the volume control past 11 O'clock, and
You don't mind that the gain with the tone control off will be less than the gain
with the tone control on.
These resistors aren't needed. The modification works perfectly well without them.
Installing them gives you the opportunity to customize your preamp a bit more to your
personal preferences. Note that if you routinely max out the volume control on your
PAT-4, this step is not recommended.
Should you decide that you want to reduce the gain of the preamp for the reasons
described above, you'll have to decide how much gain reduction you want. Page 18 has a
table of the resistor values and their resulting gain reductions.
To install the gain reducing resistors, follow these steps, referring to Figure 5.
1. Form the leads of one of the resistors so that its ends can solder to the indicated
terminals on the upper portion of the switch. One lead goes onto the already
soldered upper BASS 1 wire. Refer to Figure 5 for the location of the second lead
of the upper resistor.
2. Form the leads of the second resistor so that its ends can solder to the indicated
terminals on the lower portion of the switch. One lead goes onto the already
soldered lower BASS 3 wire. Refer to Figure 5 for the location of the second lead
of the lower resistor.
The Tone Control Switch is now ready for installation.
Disassembling the PAT-4 Preamp
Disconnect your PAT-4 from your music system. Make sure that the power cord is out,
and has been out for at least 1 minute before starting this section.
Here are the steps to disassemble the PAT-4 preamp to the extent you'll need to in order
to gain access to remove the Filter switch and replace it with the Tone Control Switch.
1. Remove the 4 sheet metal screws (two on each side) that hold the cover of the
chassis in place.
2. Lift the cover off the chassis.
3. Center all the rotary controls. This will make it easier to put the knobs back at the
right orientation. They must be removed to remove the front panel.
Page 13 of 20
Advertisement
Table of Contents
