How can I take sounds from PC through Phantom XLR connector

[kgallen]

12 hours ago, Keith_ said:

Yes, but I am wondering how those Senn receivers are protected from the 48V if it appears on every channel.

Because they are balanced outputs wired with balanced cables. Phantom thus not an issue. However, use those inputs singled-ended and wham you have 48V across your source device. 

Edited March 7, 2022 by kgallen

[paulears]

The cheap ones from Thomann are less then ten quid - link here.

I discovered that feeding the output of Soundcraft mixers into another mixer that had phantom turned on didn't do any damage - due to the differential outputs, but it did leak into the LED metering and every output LED ladder lit up!

[sandall]

9 hours ago, paulears said:

I discovered that feeding the output of Soundcraft mixers into another mixer that had phantom turned on didn't do any damage - due to the differential outputs, but it did leak into the LED metering and every output LED ladder lit up!

Happened to me once (this was feeding a video camera with permanent phantom)  - A DI box & some bodging leads solved the problem, but it was quite alarming at the time!!

[PaulL]

After following this advice I did some reading and found that Klark Teknik PRO DI DI 10P would do the job for me:-

https://www.gear4music.com/PA-DJ-and-Lighting/Klark-Teknik-DI-10P-Passive-DI-Box/2H4C?_gl=1*re4dgg*_ga*NDkwMTI5NDE2LjE2NDY1ODM3OTk.*_up*MQ..

Unit arrived yesterday and tested - just the job.

Thanks again Stuart

[sunray]

13 hours ago, sleah said:

Denon do an almost identical rx/tx set that use 2.4Ghz, which is probably what you've used. Don't think they are bluetooth though - just 2.4Ghz digital, bit like Line6. The unit above is a kind of add on to the range that does bluetooth.

I could be wrong... 🤔

Yes apologies, thinking on the number 202 rings a bell

Edited March 8, 2022 by sunray
In fact I hope I remember as: DN202WR & DN202WT

[sunray]

13 hours ago, kgallen said:

Because they are balanced outputs wired with balanced cables. Phantom thus not an issue. However, use those inputs singled-ended and wham you have 48V across your source device. 

Nothing to do with it at all.

You still have 48V across electronic outputs whether balanced or unbalanced, In fact the Trantecs with both simply use one leg of the balanced signal for the unbalanced jack.

The only protection from phantom power is capacitors.

Edited March 8, 2022 by sunray

[Bazz339]

On 3/7/2022 at 9:04 AM, Keith_ said:

Yes, but I am wondering how those Senn receivers are protected from the 48V if it appears on every channel. I agree a transformer is ideal to block DC, but I have used a pair of 64V electrolytics in the path as recommended on  https://www.soundservices.co.uk/circuits-wiring-connecting-terminology-repairs/  (phantom power and radio mic receivers). Perhaps Paul would like to point you to a suitable mono transformer box.

It would be a pretty poor job if something that has an XLR mic Level output on it and intended to be plugged into a mic level input on a mixing deskwas not designed to cope with 48V phantom power and to be honest I have never given it any thought. 

These are pretty versatile low price readily available stereo DI boxes. It would be best to make sure there are no 3.5mm jacks to MXRL cables around or indeed jack or phono to MXLR adaptors. You will need a 3.5mm stereo jack to 2 X 6.35 mm standard mono jacks. 

 

Edited March 8, 2022 by Bazz339

[themadhippy]

Quote

It would be a pretty poor job if something that has an XLR mic Level output on it and intended to be plugged into a mic level input on a mixing deskwas not designed to cope with 48V phantom power and to be honest I have never given it any thought

Some ribbon mics,especially older models don't like it up em

[kgallen]

10 hours ago, sunray said:

You still have 48V across electronic outputs whether balanced or unbalanced, In fact the Trantecs with both simply use one leg of the balanced signal for the unbalanced jack.

The only protection from phantom power is capacitors.

@sunray makes a valid point. Slightly off topic but at least one of my Sennheiser EW500G2 receivers doesn't have the blocking caps in the output stage. Seems to be a change on a later PCB design to introduce them. I don't know how to tell from the outside which has them, I guess the serial number will be the key, but I don't know where the change occurs.

[sunray]

This is the output stage of a TOA WT3800 (happened to be the first RX manual I found). As can be seen  if one follows backwards from pin2 of XLR; swittch set to 'mic', R103 (10K), C104 (16V), R10 (47R).

I'm not saying all RX's are exactly the same, but the few I've had dealings with have all been relatively similar.

 

Edited March 8, 2022 by sunray
Going further; when set to 'line', Q15 & Q16 sit directly across the balanced lies to ground

[sunray]

16 minutes ago, themadhippy said:

Some ribbon mics,especially older models don't like it up em

Again I'd expect ribbon mics to be totally tolerant. The 2 I've worked on (Lustraphone C1962ish & Reslo supplied for new school system 1966) are completely floating across the ballanced line and isolated from ground.

Both have happily been used on global phantom powered desks. I can't imagine others being different unless the mic contains a pre-amp but then it will require power of somesort - not a device I've encountered.

[Jivemaster]

Phantom power is typically 48vDC, microphones are typically milli volts. Feeding 48v into a circuit that is built for a millivolt will likely kill something. The best way round the problem is to use a properly chosen transformer DI box.

[J Pearce]

Quite a few misconceptions flying around up there. 

Many vintage ribbon mics are NOT tolerant of phantom voltage. In theory in a correctly wired mic the transformer stage should block it, but there is much evidence of damage to ribbon mics from phantom - this is likely down to patching through jackfields and the momentary misconnections that creates, or down to miswired mics or mics using old wiring systems. Most modern ribbon mics are tolerant (some indeed use it to run a FET based gain stage). Check first.

Most plain balanced dynamic microphones are tolerant of phantom - the audio is across the coil, phantom has the same potential on both sides of the coil so no current flows. It'd have to be doing something odd to not be tolerant.

Most mic inputs will be phantom tolerant (so they don't blow themselves up when their own phantom power is on). Some cheaper or older units may not be.

Most balanced line outputs on professional kit will be phantom tolerant - though it's always good to check, and if in doubt turn off phantom and/or use an isolator (either transformer or active).

As well as capacitors you can also block phantom with a transformer stage (audio is measured across the winding, phantom has the same potential on both sides of the winding so no current flows). I'd guess that some differential op-amp inputs are also tolerant, but don't quote me on it - it'd depend on the specific implementation.

We'll leave the endless discussion on phantom sharing on splits for another day shall we?

[sunray]

8 minutes ago, J Pearce said:

Many vintage ribbon mics are NOT tolerant of phantom voltage. In theory in a correctly wired mic the transformer stage should block it, but there is much evidence of damage to ribbon mics from phantom - this is likely down to patching through jackfields and the momentary misconnections that creates, or down to miswired mics or mics using old wiring systems. Most modern ribbon mics are tolerant (some indeed use it to run a FET based gain stage). Check first.

 

Thank you for that, I freely admit it has come as a massive surprise to me. As I previousely mentioned the only couple I've had any dealings with, both very elderly, are completely isolated from the earth connexion and have happily coexisted on global phantom desks.

I know it's silly but I assumed that would have been the case across the board, Although I would have put a meter on it if I encounter another.

[J Pearce]

If it's wired as a transformer based output, across pins 2 and 3, and you're not using a jackfield - you should be fine. There are lots of 'converted' ribbon mics out there that were originally high impedance unbalanced, or on DIN/Tuschel connectors that haven't been converted to fully follow the now standard XLR wiring convention.