Start Dating fender bassman amp

Dating fender bassman amp

A couple of things in the circuitry were immediately changed in 1965 when the AA165 and AB165 replaced the AA864.

1) Combining the AB165 and AA864 The schematics for this amp is explained below.

The red circles in the schematic below illustrates these changes.

The picture below shows a 1969 transition model amp.

Unfortunately the Bassman was one of the first amps that CBS laid their hands on after buying the company from Leo Fender.

We will further focus mostly on the AB165 vs AA864.

Some things have not changed since the beginning; The Bassman never had reverb or tremolo.

Remove the 0.1u F cap and 47KOhm resistor in the feedback loop and replace with a 820 ohm resistor (which you can make switchable by using the ground switch).

Personally we have experienced good results with a 1.5K which reduces the negative feedback and increases distortion and treble.

From right to left: – Switch the polarity of the two wires coming from the output transformer going to the speaker terminals.

You need to do this only if you change the negative feedback loop to AA864 specs.

We’ll come back to this later in the “blackface chapter” below where we’ll demystify some of the hypes with the popular AA864.