I have been fielding numerous emails regarding proper discrete opamp installation for my preamps and other modules. I thought I would post a
few bits of information to help make this easier for those who do not know. The tips and techniques specified here are only for 2520 style
opamps that seat in the Mill-Max sockets that I supply.
The Mill-Max sockets are very stiff when they are virgin. So stiff that you may get the feeling you will break something if you keep
pushing on your open or unpotted DOA. A properly seated DOA is very solid and will typically never come out even when the module is
moved/turned around a quite bit.
A simple way to prep your virgin Mill-Max sockets can be accomplished with a small paperclip and a few minutes of time.
Lets start by locating a small paperclip. The wire of a small paperclip will measure about .034" (.86mm) in diameter. The
typical DOA pin is .04" (1mm) in diameter. You definitely want to make sure that the paperclip is a little smaller in
diameter than the DOA pin. The tape is not necessary. It only demonstrates the depth the paperclip will travel in the socket.
That's about .2" (5mm).
You will insert the paperclip until it bottoms out inside the Mill-Max socket. Some significant force may be required. Don't worry. You
will not hurt anything. Don't twist or turn the paperclip. Just insert it straight and then pull it out. Again, the paperclip
will travel down about .2" (5mm).
Once all of the sockets have been loosened up, it is time to install the discrete opamp. It is important to try your best to
push down evenly to prevent bending over the Mill-Max pins on the DOA. Use your fingertips to push on the PCB, NOT ON THE
When the DOA is properly fully seated, you will have approximately 3/16" (4.8mm) between the top of the main PCB and the bottom
of the DOA PCB.
Simple as that! Now, have some fun and enjoy!
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Customers and fans should not refer to Classic Audio Products, Inc. as "Classic API."
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