I am about to dig into a stack of three CA-1589s and I've been collating through the recommended mods and fixes. In the interest of sharing what I've read (and getting needed insights from Those More Knowledgable), here are what seem to be the most common mods. Please feel free to pipe in with correction, corroboration, etc.
-Add a 30dB “U” or "H" pad before 600 Ohm input
-Disconnect jumpers for LO 600 Ohm input
-Place a 680 Ohm resistor across output terminals
-Add variable attack and release controls. "Attack" replaces R-21 with a +/- 50K linear pot in series with a +/- 22K resistor. "Release" adds a +/- 2M linear pot in series with a +/- 200k resistor, both in parallel with C-5
-Change the coupling caps between the 12AX7 and 12AU7 to 0.0022 versus stock 0.001
-Add 1 mfd of filtering at the B+ branch point that supplies the 12AX7 and the 6AU6's
-Replace input 500K linear pots with a dual 50K log
-Add anode balance: 100k or 250k 1W linear taper pot between R7 and R8
Again, I'd love to hear from anyone with real-world experience with these units. Thanks in advance!
-Add a 30dB “U” or "H" pad before 600 Ohm input
-Disconnect jumpers for LO 600 Ohm input
-Place a 680 Ohm resistor across output terminals
-Add variable attack and release controls. "Attack" replaces R-21 with a +/- 50K linear pot in series with a +/- 22K resistor. "Release" adds a +/- 2M linear pot in series with a +/- 200k resistor, both in parallel with C-5
-Change the coupling caps between the 12AX7 and 12AU7 to 0.0022 versus stock 0.001
-Add 1 mfd of filtering at the B+ branch point that supplies the 12AX7 and the 6AU6's
-Replace input 500K linear pots with a dual 50K log
-Add anode balance: 100k or 250k 1W linear taper pot between R7 and R8
Again, I'd love to hear from anyone with real-world experience with these units. Thanks in advance!
