ricothetroll
Well-known member
Hi !
I've been asked for a "custom" DPA adapter, from mini-XLR to regular XLR, to connect and power-up a 4061 that's been adapted to mini-XLR.
Doing some researches I found this schematic, to convert the 48V phantom supply to 8.2V :
http://www.4099.fr/fiche-specgraph.php?id=86
It looks like the two 6k8/48V from pin2 and pin3 are combined through R1 and R3, filtered by C3 and then sent to the Zener through current-limiting resistor R2B.
So DC circuit will work for sure, but what about the AC circuit ? It seems to me that the signal coming from the mic (on the left) is shorted to ground through the reverse biased Zener. The only thing I see to prevent that is the virtual series resistor of the Zener, as found on the theorical equivalent schematics. I also doubt this series resistor is very linear to keep distorton low, and has a sufficient value.
I guess they have created a virtual ground on pin3 but why the 30R resistor ? Mic signal, if anything remains, goes through C2.
Is there something I don't see, or is that a dubious schematic ? I'm always looking fo having a better understanding of things.
Best regards.
Eric
I've been asked for a "custom" DPA adapter, from mini-XLR to regular XLR, to connect and power-up a 4061 that's been adapted to mini-XLR.
Doing some researches I found this schematic, to convert the 48V phantom supply to 8.2V :
http://www.4099.fr/fiche-specgraph.php?id=86
It looks like the two 6k8/48V from pin2 and pin3 are combined through R1 and R3, filtered by C3 and then sent to the Zener through current-limiting resistor R2B.
So DC circuit will work for sure, but what about the AC circuit ? It seems to me that the signal coming from the mic (on the left) is shorted to ground through the reverse biased Zener. The only thing I see to prevent that is the virtual series resistor of the Zener, as found on the theorical equivalent schematics. I also doubt this series resistor is very linear to keep distorton low, and has a sufficient value.
I guess they have created a virtual ground on pin3 but why the 30R resistor ? Mic signal, if anything remains, goes through C2.
Is there something I don't see, or is that a dubious schematic ? I'm always looking fo having a better understanding of things.
Best regards.
Eric
