DI box without phantom protection

[g1]

back to my phantom curiosity, I would be tempted to activate that on my sound card but I think it's not a good idea.

Check if there are capacitors between XLR and IC that drives XLR. If not, don't test phantom.

[ricci]

Check if there are capacitors between XLR and IC that drives XLR. If not, don't test phantom.

Both pin 1 and pin 3 male are connected to a resistor R in series with a capacitor C. For pin 2 I have not found where it goes for sure because I did everything quite quickly.

[ricci]

I looked more carefully and pin 1 is connected to the Ground Lift switch, pin 2 i didn't understand what it is for and pin 3 is the one connected to the small cab sim circuit.

I also discovered that the mixer of the place where we do jam is a Behringer Xenix 1222 usb which has always kept the phantom power on for all the XLR inputs.

In the ohotos, pins (1,2) and (6,7) are of the same op amp.

[g1]

With both pins 2 and 3 of xlr cap coupled, you are safe from phantom power.

[ricci]

Ok very good, so a capacitor is enough to block the phantom DC component. At this point I don't understand why Mooer customer service replied that the product is not protected from phantom power. I could explain it to myself or why the phantom power is not blocked entirely or why did they answer me without thinking about the product.

[The Dude]

Yes, the caps will block phantom power. It's quite possible that you talked to someone at Mooer customer service that was not a tech and had no idea what you were talking about. In that case, they would give the "safe" answer.

[g1]

I do recall there was a rack preamp model that we had to upgrade them all because the blocking caps where not rated for sufficient voltage. So you might want to check that just to be sure.

[ricci]

C21 and C22 are the capacitors in question, visible in the upper part of the first photo that I have attached but how to understand what maximum voltage they can withstand?

https://music-electronics-forum.com/...etch?id=958395

[Enzo]

Just my opinion, but in this modern era I cannot imagine someone making a product intended to connect to mic inputs on a mixer not making it safe from phantom.

[g1]

C21 and C22 are not electrolytic type so no problem.

[ricci]

C21 and C22 are not electrolytic type so no problem.

Do they have to be electrolytic to be protective? So there is no protection? E in what sense do you say no problem?

[Enzo]

If they are not electrolytic then they don't have a polarity, so you don't need to worry about [polarity

One main job of a cap is to block DC voltage. No it need not be electrolytic to do so.

[ricci]

Just my opinion, but in this modern era I cannot imagine someone making a product intended to connect to mic inputs on a mixer not making it safe from phantom.

Also because anyone can go to the mixer and press the phantom button. But in this case could only the DI box be damaged or also the pedals in series at di box?

[g1]

Do they have to be electrolytic to be protective? So there is no protection? E in what sense do you say no problem?

You are safe and the unit is protected from phantom.

[ricci]

You are safe and the unit is protected from phantom.

This is comforting news, ok better this way, tnx bro !