The Dan Armstrong Orange Squeezer compressor has become a staple among the DIY community. Original units plugged straight into the guitar, with no external controls except for an on/off switch. This layout has the level control offboard, but the bias is a 10k trimpot, but could easily be wired offboard as well. And you should be able to squeeze it into a 1590A. (See what I did there? :D)
Here are a few mods if you want to use it on bass. Some say stock is best, others say to uses these substitutions. As always, YMMV.
• Swap the output cap from 4.7µ to 1µ (between the 390k and 1.5k resistors, below the IC)
• Swap bleeder cap from 4.7µ to 10µ (cap connected to the 1N34 diode)
• Reduce the feedback resistor from 220k to 200k (between Q2 and the IC)
