isolation transformers and Mic's

[killivolt]

I still have no time anymore. However, I need to solve my Microphone issue.

Question, Can I put a isolation transformer in line with my Electorate phantom powered Mic.

If so, can I ground it on the Mic side of the circuit without damaging the mic.

All I need to do is mute it. Maybe to switch the Phantom power off and on would be better but I don't want the pop when it comes back on ?

Any suggestions.

kv

 

[duffy]

>>Question, Can I put a isolation transformer in line with my Electorate phantom powered Mic.

No, unfortunately it will block it. "Phantom" power is a DC offset on an AC signal. If you put a transformer in it, you will block the DC. If you put the DC on the other side of the transformer, you could saturate the core. The way to do this is to put the DC to the microphone, then use a series capacitor to block the DC from the transformer. If you use a separate supply, there should be no problem grounding the mic.

If all you need is mute with no pop, a simple way to do it would be with an L pad.

 

[Nigel Goodwin]

I still have no time anymore. However, I need to solve my Microphone issue.

No idea what you're on about?.

Question, Can I put a isolation transformer in line with my Electorate phantom powered Mic.

No you can't.

I suggest you tell us what your problem is?.

 

[killivolt]

I thought I did ?

No idea what you're on about?.



No you can't.

I suggest you tell us what your problem is?.

Ok, so what part of (I need to mute the mic) not stated in the about above ?

I'm just looking for simple yes or no. You have done that.

And I'm guessing putting a series capacitor to block the phantom power would work ? or am I somehow missing this and adding a dc circuit to mute is needed ?



kv

 

[duffy]

A series capacitor will block the DC phantom power and turn the mic off, yes.

But it might not block the pop. Blocking the pop from a microphone is more tricky than most people give it credit for, especially when it's phantom-powered like that. That's why I suggested an L pad. Sounds like overkill, but in a professional studio they pot the mics up and down for this reason.

If you try the cap, put it in series with the mic (forget the isolation transformer for now), and switch a resistor in parallel with the cap. I can't tell you the exact value of the resistor, start with maybe a 220Ω resistor and a 10µf cap and see how that works. You will be balancing the current requirements of the mic against the charge time of the cap.

 

[killivolt]

A series capacitor will block the DC phantom power and turn the mic off, yes.

But it might not block the pop. Blocking the pop from a microphone is more tricky than most people give it credit for, especially when it's phantom-powered like that. That's why I suggested an L pad. Sounds like overkill, but in a professional studio they pot the mics up and down for this reason.

If you try the cap, put it in series with the mic (forget the isolation transformer for now), and switch a resistor in parallel with the cap. I can't tell you the exact value of the resistor, start with maybe a 220Ω resistor and a 10µf cap and see how that works. You will be balancing the current requirements of the mic against the charge time of the cap.

So, then the application will pass voltage when the switch and the resistor are in circuit? If I am able to get the basic spec on the mic dynamics and Impedance would this get me closer to a working solution ?

kv

 

[duffy]

Yes, powered through the resistor. Yes, the mic impedance would be a big help - it's difficult to measure, and some of those phantom power systems work at surprisingly high voltages, like 24V or even 48V.

 

[killivolt]

I also have one more Idea for my problem. I have a Clearone XAP 800 it has Balanced (input) but ( line output) I am attempting to use a (line to mic converter) which I can switch with a L Pad circuit on the output side of things.

I intend to have a series Parallel line running across all the Student Desk's using a DC powered Relay to switch the L Pad. 2 Mics, 2 L pads 1 relay.

The Parallel Switching line will be about 30 feet long. I plan to switch the neutral side of the line.

kv

I am however worried about the coil inducing chatter or EMI to the line.

Maybe it's better to L pad each work station ? Forget the relay.