Monday, January 5, 2009

Fender Champion 600 Input Voicing Mod Pt 2

Here's a graph showing the frequency response for the Input Voicing Mod. The measurement is taken at the amplifier output with a 4 ohm resistive load.

The top curve is the stock "High" input and the bottom curve is the stock "Low" input. The middle curve shows the response of the "Low" input with the mod installed. Notice that the modded "Low" input is within 1dB of the "High" input for the high frequencies but the lows are rolled off significantly.

I didn't include the modded "High" input response on the graph because it is so close to the unmodded "High" response that it's almost indistinguishable. I would swear I hear a subtle difference between the modded and unmodded "High" input. This may be because the tone generator used for the frequency sweep is non inductive and doesn't react to the input impedance the way a pickup does. Or I may be crazy. If you do this mod yourself, let me know what you hear.


Anonymous said...

My trouble was: not enough treble through the high input. The amp was sounding a bit dark. I did the mod with a Mallory 0.01uF cap. A true improvement of treble on the high input. A lot of added treble in the low input. I love this mod. It's the only one I will perform. Guitar: 1976 Fender Stratocaster.


Anonymous said...

Of course the mod effects the HIGH input too (extra trebleboost). Why? When just the HIGH input is used in the original version, the two 68k resistors work in parallel mode with an over all value of approx. 33k. In the modded version (HIGH input) now there is also the new cap parallel to the 2 resistors... that's it.
Regarding the LOW input it is like akavalve said before.