Can My Amp Be Damaged by Phantom Power to DI?

[dug dog]

The title pretty much says it all.

This topic came up in discussion of the Boss GT10B floorboard in which a TB'er reported that he was advised by Roland support that his GT10B should NOT be subjected to phantom power through the DI connection. He was not told what type of damage could actually be done, just that he shouldn't do it.

This info caused me some anxiety, as I like the idea of using the GT straight to the PA, but can't always be sure that it won't somehow get a shot of phantom power. Then I started to wonder about my amp's DI if connected in the same manner.

Who can shine some light on this?

[BassGreaser]

i had a Carvin head blown due to the sound guy hitting the phantom power on the board that was running to the Carvin's DI out..

[prd004]

All the more reason for a dedicated DI. I know this doesn't answer your question specifcly, but if you want to send your rigs signal to the board, I reccomend a mic. As a sound guy I NEVER use the DI on the amp, dedicated DI box, mic, or both but never the built in DI.

[Bob C]

Yes, it can harm your amp. My Demeter HBP-1's owner's manual warns not to run the XLR out with phantom power.

Just make sure communicate with the sound person at every show you do, before powering up.

[dug dog]

So long as you can trust the sound person, you'd be OK. Personally, I'm still concerned about the possibility of an accident destroying an expensive piece of gear.

At least I'm now aware of the potential for disaster. It would never have occurred to me that a device meant to be used direct to FOH would not be protected against phantom power.

[trowaclown]

Originally Posted by dug dog

It would never have occurred to me that a device meant to be used direct to FOH would not be protected against phantom power.

That will depend on the product I guess. My Genz Benz Shuttle 3.0 head's DI out is fully protected against phantom power, according to the manual. But it does seem strange for a product to be designed with DI out, but not designed to be protected against phantom power, it's like a severe design flaw/disaster waiting to happen.

[prd004]

Originally Posted by dug dog

So long as you can trust the sound person, you'd be OK. Personally, I'm still concerned about the possibility of an accident destroying an expensive piece of gear.

At least I'm now aware of the potential for disaster. It would never have occurred to me that a device meant to be used direct to FOH would not be protected against phantom power.

Ummm, been playing gigs for close to twenty years and maybe, maybe have encountered ten to fifteen sound men who knew what they were doing and I could trust, big red flag! Read your owners manual, contact the manufacturer, whatever you have to do, so you know what you can and can't do with your amp. Relying on someone else's knowlege is a BIG mistake!

Then buy a DI box! You can get one for next to nothing, and you can get VERY good ones under $200.

[Bassflute]

Originally Posted by trowaclown

That will depend on the product I guess. My Genz Benz Shuttle 3.0 head's DI out is fully protected against phantom power, according to the manual. But it does seem strange for a product to be designed with DI out, but not designed to be protected against phantom power, it's like a severe design flaw/disaster waiting to happen.

Originally Posted by dug dog

So long as you can trust the sound person, you'd be OK. Personally, I'm still concerned about the possibility of an accident destroying an expensive piece of gear.

At least I'm now aware of the potential for disaster. It would never have occurred to me that a device meant to be used direct to FOH would not be protected against phantom power.

that they would continue to build DI's incapable of handling that...that is so stupid and shortsighted.

Originally Posted by prd004

Ummm, been playing gigs for close to twenty years and maybe, maybe have encountered ten to fifteen sound men who knew what they were doing and I could trust, big red flag! Read your owners manual, contact the manufacturer, whatever you have to do, so you know what you can and can't do with your amp. Relying on someone else's knowlege is a BIG mistake!

Then buy a DI box! You can get one for next to nothing, and you can get VERY good ones under $200.

and give up complete and total control of your sound out front.

Here's my favourite DI:

C 414 XLS

Then I have control...they can still tweak it a bit, but they can't completely kill it. And it REQUIRES phantom power!



Cheers,
Cameron

[erigod23]

I'm skeptical about this. Smaller and low-end boards have global phantom power. Surely an amp's dedicated Line out can withstand that small amout of current.

[mikeddd]

Aren't there "DI Isolation Boxes" or something like that? I also have a Demeter HBP-1 and as has been said, the manual specifically warns against phantom power. On a side note, I find it ridiculous that a $900 preamp with it's own built-in DI is not protected against phantom power.

[billfitzmaurice]

Originally Posted by dug dog

Who can shine some light on this?

A well designed DI is capacitor isolated and won't be bothered in the least by phantom power. But unless the amp manual states that it's OK to connect it to a phantom assume that it's not capacitor isolated.

On a side note, I find it ridiculous that a $900 preamp with it's own built-in DI is not protected against phantom power.

+1, especially when you consider the cost of isolation capacitors might come in at 90 cents.

[MNAirHead]

When designing my wireless/ampless/IEM setup.. I kind of surveyed the field for months.

Overall get some type of DI that isoloates

About 1/2 roadies I know (they sell them selves as sound engineers) think phantom makes it louder... many boards will do it accross the board... many sound engineers do not spend the time to put all controls back to zero before they start.

[Roger Davis]

Hi

I'm a DB man but have just seen this while logging on. I've had my concerns about phantom when it's not needed wrecking an amp. I contacted my amp makers (no names!) and they said that the amp is designed to take unwanted PP into the DI out but they've heard of some worrying incidents so best not to. So make of that what you will. I've had a 1m length of XLR male to female that I can put in the DI to board line. It has had one of the cores cut (can't remember which one but I'm sure someone can help you with this) so PP won't go up to the amp. Never had worries since.

[electracoyote]

I always talk to the sound person before he does anything to mic or run DI from my amp. I tell him how my DI works (Markbass CMD151P), that I can control its output so he can tell me if he needs more or less, that it's a pre-EQ signal, and under no circumstance is he to use phantom power. It's interesting, once the sound person knows YOU know a thing or two about your signal going to the board, they usually appreciate it and you get a good mix and avoid the risk of damaging your equipment.

[Passinwind]

Originally Posted by electracoyote

I always talk to the sound person before he does anything to mic or run DI from my amp. I tell him how my DI works (Markbass CMD151P), that I can control its output so he can tell me if he needs more or less, that it's a pre-EQ signal, and under no circumstance is he to use phantom power.

What happens when the board has global phantom and the overhead mikes are condensers?

[electracoyote]

Originally Posted by Passinwind

What happens when the board has global phantom and the overhead mikes are condensers?

When I say to the sound person "no phantom power please," that naturally includes a global phantom board. I would hope they are smart enough to make that connection.

[Passinwind]

Originally Posted by electracoyote

When I say to the sound person "no phantom power please," that naturally includes a global phantom board. I would hope they are smart enough to make that connection.

And do what?

Luckily, it's been years since I had to use a Mackie 1604VLZ. But in that case, I would've said fine, my DI or a mike on your rig? IMHO it's completely inexcusable to build a DI that won't tolerate phantom.

[electracoyote]

Originally Posted by Passinwind

And do what?

I'm not sure I follow your logic. If the sound person realizes they are running a global phantom powered board, and I tell them point blank not to run phantom power to my DI, they should then mic my cabinet and not connect a phantom powered cable to my DI.

[Passinwind]

Originally Posted by electracoyote

I'm not sure I follow your logic. If the sound person realizes they are running a global phantom powered board, and I tell them point blank not to run phantom power to my DI, they should then mic my cabinet and not connect a phantom powered cable to my DI.

Or just give you a DI that is properly engineered, no?

Anyhow, we're on the same page, but that wasn't immediately obvious to me. Thanks for the clarification.

[jasonbraatz]

It is inexcusable to build a DI into a head that is harmed by phantom power. I can't believe it still happens.