The Synth Project Episode 47: Noise Generator Module - Part 1

[@shunbuambaladagobe3217]

thank you for sharing your synth build experiences! I have a question: how do you come up with your selection of opamps? I notice that you use quite common types in your builds, but I fail to understand the aspects you consider for your actual choices. E.g., why did you choose a 5534 Opamp for the first amplification stage, and not for example another LM358 half or a TL071?

[@eleneasy]

It all depends on the kind of necessities. The LM358 is a general purpose op-amp with a good bandwidth that allows for quick response times (high slew rate). When I need a very high input impedance I use a TL072 or TL074, depending on how many op-amps I need. The TLxx op-amps have JFET transistors on the input side, which provide a very high input impedance. They also have a very good slew rate, which makes them as fast as the LM358 in terms of response time. Finally, I use the 5534 when I need a very low noise op-amp. This IC, in fact, although providing a similar slew rate as the TLxx or the LM358, it also provides a very small noise figure, around 3.5nV per square root of the frequency. In rare cases, I also use the LM7332 which works like the LM358 but with a higher output current, around 60 mA.