I think your switch pops aren't due to a big cap on your passive vRef. There is a time constant associated with charging capacitors but that happens when you power the circuit up, not when you mechanically bypass the input/output. Your switch pops could have several causes but the solutions are often straightforward:
You may know all this, I'm just speedrunning simple solutions.
There are times when a buffered vRef is beneficial. For instance, in high gain circuits a buffered vRef does help by providing a highly stable voltage source and can reduce noise. Sometimes it it even requires more than one vRef decoupling cap placed at different points on the physical PCB layout.
Or when you have many taps on vRef throughout a circuit (like dozens of ICs and/or transistors). In that case a buffered vRef can help or using multiple vRef sources for different parts of the circuit.
Another instance is when you have multiple taps on vRef through very small resistors. I'm thinking of OTA designs where the bias voltages are tied to the source through small values (like 1k or so). Since those resistors are small they can create an undesirable load. Buffering that source eliminates that problem usually.
Anyway, to be more specific if you are going to use a buffer, just stick with the TL071 and use a small series resistor as suggested. I'm betting that's just as good and a lot cheaper than any OPA IC.
You might check some of the threads on this subject over on the diystompboxes forum, too. There have been several over the years and I'm sure some have better technical explanations.
- Check for leaky coupling caps at the input and output. If DC is present at either replace the cap.
- Use appropriate sized pull down resistors at input/output. At input this is generally 1M and output a minimum of 10k.
- Add series resistance to the input and output. Usually 1k to 10k at the input and 100R to 1k at the output is enough.
You may know all this, I'm just speedrunning simple solutions.
There are times when a buffered vRef is beneficial. For instance, in high gain circuits a buffered vRef does help by providing a highly stable voltage source and can reduce noise. Sometimes it it even requires more than one vRef decoupling cap placed at different points on the physical PCB layout.
Or when you have many taps on vRef throughout a circuit (like dozens of ICs and/or transistors). In that case a buffered vRef can help or using multiple vRef sources for different parts of the circuit.
Another instance is when you have multiple taps on vRef through very small resistors. I'm thinking of OTA designs where the bias voltages are tied to the source through small values (like 1k or so). Since those resistors are small they can create an undesirable load. Buffering that source eliminates that problem usually.
Anyway, to be more specific if you are going to use a buffer, just stick with the TL071 and use a small series resistor as suggested. I'm betting that's just as good and a lot cheaper than any OPA IC.
You might check some of the threads on this subject over on the diystompboxes forum, too. There have been several over the years and I'm sure some have better technical explanations.
