Doing Things Wrong

Silvertone 1457 Guitar & Amp (3/5)

The attenuator circuit for both the 1457 and 1472 amps

The LPad is the first stage and does most of the work, the fixed second stage can be switched in for even more quiet. The 50 watt LPad should be sufficient for at least a 20 watt amp. The capacitors suppress audible pops from the switches.

For the circuit above, the 1457 amp is nominally 5 watts at 4 ohms, while the 1472 is 10 watts at 8 ohms. The idea is to bleed off power while maintaining a constant impedance to the amp. This lets you get nice natural tube distortion without the neighbors calling the police. For these small amps, heat dissipation is not a problem.

Each circuit has two options for the fixed second stage, one for 12db and one for 20db - choose one. The values of the fixed resistors depend on the impedance of the speaker. For simplicity, just omit the second stage, it is not necessary, I was just experimenting.

 1 2 3 4 5  

Not sure what possessed me at the time, but I built this with A250 tone pots and B500 volume pots, and the B pots are doing their usual on/off switch behavior - no change until almost zero, then cut off completely. After my most recent testing, I have concluded that B pots have no place in a guitar at all. I probably did this because I have just two A500 pots in the parts bin, one mini and one full sized. A few days ago I ordered a lot of them, when they come in, I will swap these out. In the meantime, the B's will do, especially at full volume, so I can check this thing out.