finbase
Well-known member
Hello folks!
Yet another DIY-n00b question, so paternal patience is required…
I'm planning to build one 325 DI for bass (I am a professional bass player), based on Bo Hansen’s schematic. Since I am a beginner, I want to study the 325 thoroughly, until I can really understand what's happening in it, and what the every discrete component and connection actually stands for.
I think I've got a good overall understanding on the circuit this far, but there are a couple things (or actually caps) I don't understand. They're probably crystal clear to you, but I can't find the answer either on the internet or in my books. I’ve tried several hours now, with no success. So I decided to humble myself and ask for help in public… (and since I’m anonymous, there’s not much to lose, is there! )
1) Although this might be VERY simplistic question, I just don't understand how the -10db pad works. I can figure out the component layout, but I don't understand what the parallel RC circuit actually does... What happens to the current flow, voltage etc., what's the physical phenomenon when the pad switch is either on or off? I can understand the resistor, but what that parallel capacitor is supposed to do?? (Why oh why?!?)
2) Similar question: I don't understad what the Capacitor C6 in the Op Amp feedback circuit stands for. If I interpret the circuit right (this is a non-inverting amp, right?), the resistor R3 (47K) and the 47k rev. log potentiometers control the amount of the output amplitude. But that parallel RC circuit (R3 and C6) is confusing again. I don't understand WHY there's that capacitor...
Please, if you have time for this, try to explain what those parallel RC circuits are used for in audio circuits such as preamps. I understand it's usage in oscillators, but in the 325 circuit... I'm clueless!!
The schematic is attached below. (If it’s not permitted, please let me know, I’ll remove it.)
Thank you in advance!!
finbase
(PS. hopefully my English is understandable, I'm not a native)
Yet another DIY-n00b question, so paternal patience is required…
I'm planning to build one 325 DI for bass (I am a professional bass player), based on Bo Hansen’s schematic. Since I am a beginner, I want to study the 325 thoroughly, until I can really understand what's happening in it, and what the every discrete component and connection actually stands for.
I think I've got a good overall understanding on the circuit this far, but there are a couple things (or actually caps) I don't understand. They're probably crystal clear to you, but I can't find the answer either on the internet or in my books. I’ve tried several hours now, with no success. So I decided to humble myself and ask for help in public… (and since I’m anonymous, there’s not much to lose, is there! )
1) Although this might be VERY simplistic question, I just don't understand how the -10db pad works. I can figure out the component layout, but I don't understand what the parallel RC circuit actually does... What happens to the current flow, voltage etc., what's the physical phenomenon when the pad switch is either on or off? I can understand the resistor, but what that parallel capacitor is supposed to do?? (Why oh why?!?)
2) Similar question: I don't understad what the Capacitor C6 in the Op Amp feedback circuit stands for. If I interpret the circuit right (this is a non-inverting amp, right?), the resistor R3 (47K) and the 47k rev. log potentiometers control the amount of the output amplitude. But that parallel RC circuit (R3 and C6) is confusing again. I don't understand WHY there's that capacitor...
Please, if you have time for this, try to explain what those parallel RC circuits are used for in audio circuits such as preamps. I understand it's usage in oscillators, but in the 325 circuit... I'm clueless!!
The schematic is attached below. (If it’s not permitted, please let me know, I’ll remove it.)
Thank you in advance!!
finbase
(PS. hopefully my English is understandable, I'm not a native)