A question about this schematic....

[Sender]

I have a question regaurding this schematic. I have some idea of whats going on, but I was just hoping for some answers before I blow up a mic....

http://www.jensentransformers.com/as/as016.pdf

The question is regaurding R1 and C1. It looks like you would only need these if you're using a bi-polar power supply for phantom, correct?

So if I'm running just +48 I elmininate these and go right to the 6k81's, correct?

haha, one more noob question! 6k81 is 6,810 ohms, correct?

 

[Samuel Groner]

The question is regarding R1 and C1. It looks like you would only need these if you're using a bi-polar power supply for phantom, correct?

A bipolar supply has three terminals--positive, negative and ground. The supply shown is actually single supply, "-" is simply ground. Do not omit the R and C, it is a hefty low-pass filter to kill the last bit of hum and noise in the phantom power line.

6k81 is 6810 ohms, correct?

Yep--can be 6k8 as well, don't care about the last digit.

Samuel

 

[Sender]

So do I need to repeat C1 and R1 on every XLR connector I'm wiring phantom for or can I do it once and then just split the out?

 

[walter]

I would think you could omit those components for a single input, if the supply is well filtered, but for multiple inputs you will want to have them for each channel.

 

[Sender]

So this circuit is really the best way to wire phantom?

I guess I should specifiy that I want switches for each channel.

 

[JohnRoberts]

If you're using global phantom power (one on/off for all channels) you can probably get away with one RC for the lot. If switching at each channel repeat. While operators should know not to, if they do switch phantom on/off with audio up, the RC will slow down rate of change and reduce click amplitude.

The 6.81k also suggests 1% tolerance, since you don't want to imbalance the + and - inputs' impedance termination.

JR