I'm going to eliminate the whole speaker compensation circuit in my new setup. I'm going from 8" two-ways to a biamp with subwoofers. At that time I will modify the muting circuit.
I'll probably build a better version of this preamp eventually. I'll make it a more integrated design. This preamp is designed so you can swap stuff in and out on the fly. It's a glorified prototype. It has on board jumpers like you'd find in a computer to change some of the parameters (like voltage gain). Some of the boards have been swapped out three times already. I learned a whole lot designing and building it. I could make one that's a little better with essentially the same parts.
I still have one more case just like the one that this is built in. It's in a PA amplifier case, MUZAK brand, like you might find driving a bunch of transformer driven ceiling speakers in a public place. The case is very robust, much more rigid (and heavy) than typical consumer electronics metal cases. I sanded the front and back panels and spray painted them with Eastwood Chassis Black (designed for spraying auto parts like control arms etc) through a small gravity feed spray gun with a six inch fan. The Chassis Black Eastwood Extreme Chassis Black Satin Undercoating matches the color and patina of typical consumer electronics products perfectly. I used nice knurled aluminum knobs (the most expensive parts) so it looks understated and high end. It looks nice!
I still have one more case just like the one that this is built in. It's in a PA amplifier case, MUZAK brand, like you might find driving a bunch of transformer driven ceiling speakers in a public place. The case is very robust, much more rigid (and heavy) than typical consumer electronics metal cases. I sanded the front and back panels and spray painted them with Eastwood Chassis Black (designed for spraying auto parts like control arms etc) through a small gravity feed spray gun with a six inch fan. The Chassis Black Eastwood Extreme Chassis Black Satin Undercoating matches the color and patina of typical consumer electronics products perfectly. I used nice knurled aluminum knobs (the most expensive parts) so it looks understated and high end. It looks nice!