Originally Posted by Snaxster
...I decided to try swapping an OPA2134PA into my OSD...
...it worked. And now my OSD was socketed. So since I also own some TI NE5532AP, eventually I'll do an A/B comparison between the NE5532AP and the OPA2134PA in my OSD.
Last night, on learning about the practice of stacking op-amps (aka parallel op-amps), I wanted to try it in my newly socketed OSD. Since I had only a few of the expensive Burr Brown op-amps, like the one I had recently swapped into my OSD, and I didn't have the nerve to experiment with them, I stacked two TI NE5532AP instead. Disclaimer
Don't try this at home, folks. Don't try it anywhere. If you do try it in your OSD, it's all you: I am completely not responsible for anything related to your OSD.
I followed advice from the Barber Electronics website
. Orienting two TI NE5532AP op-amps the same way, I pinched the pins of the top chip slightly, so it would sit higher. Then I soldered each pair of pins so as not to obstruct the bottom pins for their insertion into a socket. photo of two NE5532AP stacked
The appearance of the stacked TI NE5532AP installed in the crudely socketed OSD is a bit grotesque. But the arrangement functions perfectly. photo of stacked hacks in the OSD: parallel op-amps in the socket Clearance in the case
When I started to re-seal the OSD case, I saw that the stacked op-amps might be too tall to clear the case back. Luckily, the case back has a sort of scooped design, allowing another 1/8" or so of clearance for the internals.
Had my socketing job been conventional, with the socket soldered directly into the board and lying flush, there would probably be room for three stacked op-amps.
photo of the height of the stacked op-amps installed in the OSD Sound
Compared to the single Burr Brown OPA2134PA, the stacked NE5532AP impart a very different sound to the OSD.
In the OSD, the stacked NE5532AP push the circuit into overdrive much sooner, and sound tougher, with more midrange punch and snarl, and with less bass.
When later I swapped the single OPA2134PA back in, the sonic difference was striking: relaxed, big, open bass; much higher overdrive threshold; midrange that seemed flat; slow and easy response, without the pronounced snarl. Conclusion
For use in the OSD, the single Burr Brown op-amp is for me. It lets me easily find the point just below obvious overdrive, where I can push the OSD into overdrive with my playing dynamics. Also, its retention of my instrument's true bass frequency output is important to me. photo of the Burr Brown op-amp in the OSD