Finishing up Amp #2

The rear faceplate came this week. Special Thanks goes to BNP Lasers. They look awesome and I can't say enough about their customer service. I would recommend them to anyone building an amp. This is the front faceplate. It took me about 2 weeks to create. If you notice they do go to eleven.

Here is the rear faceplate.

You plug the Tremolo Foot switch which is a stomp switch into this jack. It turns the tremolo on and off.

The line-out circuitry is post Output Transformer. So it contains all of the great sound of this amp. The line-out is controlled by the line-out switch. With the switch in the middle or off position the line out circuity is completely removed from the output signal path. With the line-out switch up the line out circuitry is activated. In this position you must have a speaker connected. In this mode you can be playing through this amp and take the line out into the input on a PA system or a bigger power amp.

Finally with the switch down, it adds a 25 watt 8 ohm resistor to the output so that you can use the line-out to feed into the PA or power amp without a speaker connected to this amp. The resistor prevents damage to the output transformer since it provides the same load as a speaker would.

Below is a line-out level control that will vary the level of the line-out circuit.

Here is the Tube Based (12au7) Active Effects Loop. On the left is the Send level control. The circuit basically is two preamp(s). The 12au7 tube has two channels so one half of the tube controls the SEND and the other half of the tube controls the RETURN. The send level and return level controls allow you to use any pedals. You can adjust the SEND level so that the Input of the pedal is just right. You can also vary the level coming out of the pedal train so that the amp sees the correct level. I used a patch cord from SEND to RETURN and the circuit actually adds more amplification to the 18 watt that the normal gain stage. Thus you get even more distortion at Eleven!

The downside with so much functionality on the back panel is the lack of real-estate. I had to sacrifice a speaker output. To compensate I'll add additional jacks to the speaker cabs to allow them to be daisy chained together. The Attenuate switch in the middle position eliminated the attenuation circuitry from the output signal path. There are three positions, Quiet, Off, and Medium. The Quiet and Medium positions use the attenuation modules on the top of the amp to reduce the power level of the amp (loudness). I'm still creating all of the modules (8 in all).

See the previous posts for more info on the power levels.

The Tube based effects circuitry can be completely removed from the signal path using a Push/Pull switch on the RETURN level knob. Pushed in the effects loop is removed/disabled.

Pulled out the loop is activated.

Pulled out (ON)

Pushed in (Off)

Full rear view