mikefatom
Well-known member
Ladies and Gentlemen,
Everyone seem to have made their own version of the classic 312 pre. This is mine and this is what I've been working on during my time off from work. It is nothing mind blowingly new but I wanted to share and get feedback on it
Description/features:
- Straight up basic 312 pre circuit, no fancy build option, but a couple extra features added.
- Relay switchable HPF made up of a simple RC network before the 2520. Simple but very effective for proximity effect bass correction. I tested many options including active circuits but settled on this more subtle effect.
- Minimum signal path from the mic input to the input TX, nothing in between!
- Automatic relay-switched DI input option. The DI signal goes straight to the op-amp. I will start working on an add-on FET DI board for it.
- Relay switched phase reversal done between the op-amp and output TX.
- Relay switched TX output ratio, from 1:2 (normal) to 1:1 (-6db attenuation) to pad the output a bit and give a slight tonal variation. I like that feature, but I am debating changing this to a switchable T-Pad. opinions?
- Phantom power capacitor gets discharged through the indicator LED (when disengaged), to avoid undesirable POPs when plugin in a different condenser mic.
Schematic is HERE.
More info to come...
but for now, it's picture time! Click on the image for more and hi-res pictures.
Comments? thoughts?
Mike
Everyone seem to have made their own version of the classic 312 pre. This is mine and this is what I've been working on during my time off from work. It is nothing mind blowingly new but I wanted to share and get feedback on it
Description/features:
- Straight up basic 312 pre circuit, no fancy build option, but a couple extra features added.
- Relay switchable HPF made up of a simple RC network before the 2520. Simple but very effective for proximity effect bass correction. I tested many options including active circuits but settled on this more subtle effect.
- Minimum signal path from the mic input to the input TX, nothing in between!
- Automatic relay-switched DI input option. The DI signal goes straight to the op-amp. I will start working on an add-on FET DI board for it.
- Relay switched phase reversal done between the op-amp and output TX.
- Relay switched TX output ratio, from 1:2 (normal) to 1:1 (-6db attenuation) to pad the output a bit and give a slight tonal variation. I like that feature, but I am debating changing this to a switchable T-Pad. opinions?
- Phantom power capacitor gets discharged through the indicator LED (when disengaged), to avoid undesirable POPs when plugin in a different condenser mic.
Schematic is HERE.
More info to come...
but for now, it's picture time! Click on the image for more and hi-res pictures.
Comments? thoughts?
Mike