API 2510 and 2520 opamp upgrades
Scott Liebers is a recording engineer,
Luthier and former and broadcast engineer at KNOW, the Public Radio affiliate
here in the Twin Cities. (His responsibilities included maintaining the
recording equipment as well as mixing live bands for their all-music channel,
The Current.) Reliability is a major issue in an on-air facility, so when
Scott started having issues with a six-year-old API Legacy, he went outside
the box for a solution.
His problems started with the 2510 opamps
used in the 550L EQ's, three per module. (In most applications, the 2510
is used as a buffer amp running on ± 28 volt rails.) Op amps that
die within the five-year warranty period are replaced free, but after that
they're $75 each plus the old one sent in as proof of ownership. Initially
he planned to repair the opamps, which are potted and not easily disassembled
without further damage, so he eventually sought out a local design and
packaging guru to design a replacement.
Scott felt that the potting compound did
not dissipate heat causing the transistors to eventually cook themselves
to death. (The console is on 24/7.) The new design uses two boards instead
of one, has chemical fuses on larger heat-sink- mounted output transistors,
and while still using surface mount parts, it's now serviceable. See
Replacement opamps are $65 each in lots
of 5, $75 each for single purchase.
Scott and Eddie