4.16.2003

 


So, I built my Foreplay pre-amp, and it sounded great with the Magnavox, but with the ST-35 it has WAY too much gain, and I can hear a lot of buzz and hum. It has been suggested:

What you will need to do to start with is lower the overall gain of the FP. There are wads of post on this subject in the archives. and VoltSecond's page in 'Loose Parts' has an excellent section on attenuators. The quickest, cheapest, easiest fix is the Simple Shunt.

Once you get the gain where you like it, you may need to tackle some other issues, such as grounding and noise reduction, but geting the "gain chain" right is the logical first step, IMO.

Jim


Simplified instructions for Simple Shunt for Simple guys like me:

1. Using a 100K resistor instead of a wire, connect right tab of left L-Pad to left inner contact of selector switch.
2. Connect center tab of left L-Pad to A-2.
3. Connect left tab of L-Pad to terminal 14.
4. Using a wire, connect center tab of left L-pad to Right tab of left L-pad.


more:

The Easy Way to make the Stock Foreplay Volume Control into a Shunt Mode Volume Control:

1. Remove the wire connection from the top (right terminal) of the volume pot to the selector switch at the volume pot end.

2. Insert a resistor between the volume pot top (right terminal) and the loose wire going to the selector switch.

This resistor is typically 47.0K (3.3 dB minimum attenuation) to 200K (9.5 dB minimum attenuation) metal film when using a 100K volume pot.
3. Run a short wire from the wiper (middle terminal) to the top (right terminal) of the volume pot.

Using this method (Shunt Mode Easy Way) will reduce the any noise you get when you adjust the volume when compared to (Shunt Mode Pot Typical). I have been told it sounds better this way too. I didn't notice too much of a change with the stock Foreplay pots, but I didn't have a hot rodded Paramour to drive my speakers at that time either.


From VoltSecond's web page

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