oneoldude
Member
ronv,
Man am I happy I was brought to the woodshed re: my post about your circuit. Best stupid mistake I ever made. Once I got it running in LTS its beauty became apparent. It runs on a single supply and has a Pi filter supplying the MIC bias. Clever!
The pic below shows my intended application. The R on the output of my ckts is a pot that will be in my test box/jig. I will be measuring speakers and feeding to a sound card line-in.
I appreciate your providing the file for LTS. But not only did it not import the OPA but the ECM disappeared as well. I guess I'll have to stick to V sources.
I hope you don't mind a few questions about your circuit.
For my purposes, what fixed gain would you suggest for your circuit and what value pot would be best to least affect the FR with volume changes? You see, I cannot put a pot in the feedback loop of the OPA. Won't fit in the wand.
Given the 10k impedance of the MIC, would it make sense to take the positive side of C1 and move it to the junction of R7 and C3? That way the combined resistance of R1 and R7 will be looking at C1 for a lower f3. But I don't know about any interaction with C3 or the MIC.
Is there any magic re: the 100k values for R4 and R5? Could they be higher or lower for a lower noise contribution?
Thank you for your efforts.
Man am I happy I was brought to the woodshed re: my post about your circuit. Best stupid mistake I ever made. Once I got it running in LTS its beauty became apparent. It runs on a single supply and has a Pi filter supplying the MIC bias. Clever!
The pic below shows my intended application. The R on the output of my ckts is a pot that will be in my test box/jig. I will be measuring speakers and feeding to a sound card line-in.
I appreciate your providing the file for LTS. But not only did it not import the OPA but the ECM disappeared as well. I guess I'll have to stick to V sources.
I hope you don't mind a few questions about your circuit.
For my purposes, what fixed gain would you suggest for your circuit and what value pot would be best to least affect the FR with volume changes? You see, I cannot put a pot in the feedback loop of the OPA. Won't fit in the wand.
Given the 10k impedance of the MIC, would it make sense to take the positive side of C1 and move it to the junction of R7 and C3? That way the combined resistance of R1 and R7 will be looking at C1 for a lower f3. But I don't know about any interaction with C3 or the MIC.
Is there any magic re: the 100k values for R4 and R5? Could they be higher or lower for a lower noise contribution?
Thank you for your efforts.