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Author Topic: Trs = no phantom power!?! Zoom  (Read 1557 times)

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Offline Elguapo511

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Trs = no phantom power!?! Zoom
« on: November 15, 2019, 12:10:32 AM »
Any reason i cant get a signal when i use a trs and a condensor?

I thought i only needed to not remove them in flight.

Anyone  using phantom power and trs!?

Offline Elguapo511

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Re: Trs = no phantom power!?! Zoom
« Reply #1 on: November 15, 2019, 01:24:12 AM »
Updated the firmware.  No difference.

Offline wvmaine

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Re: Trs = no phantom power!?! Zoom
« Reply #2 on: November 15, 2019, 06:57:31 AM »
TRS connection does not  provide phantom power. Only through an XLR connection can you receive power to your microphone.  Hope this helps.  A lot of this info is well documented. It might take a little reading but you will learn a lot about your machine.
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Offline Gutbucket

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Re: Trs = no phantom power!?! Zoom
« Reply #3 on: November 15, 2019, 10:34:13 AM »
Seems to depend on the model. 

As posted in the other thread-

That is how Zoom F8 operates. TRS = line input with no phantom power option, XLR = mic-level input with switchable phantom.
This was changed on the F8n revision so that either input connection can be line or mic-level, with or without phantom.

Not sure how the H6 operates.
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Offline DSatz

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Re: Trs = no phantom power!?! Zoom
« Reply #4 on: November 22, 2019, 04:14:34 PM »
Maybe there's some context here that I'm unaware of, but a properly wired TRS connector is just as able to handle phantom power (and balanced audio signals) as an XLR-3 connector is. It's got two separate modulation contacts (T = tip, R = ring) and a separate ground contact (S = sleeve), and that's all you need.

The thing is, with a TRS plug it's better if phantom power is shut off while plugging or unplugging, because otherwise there's a moment when the plug is only halfway in where the powering would be applied to the microphone's output circuitry in a way that it probably wasn't designed to handle. XLR plugs are designed with pins 2 and 3 being the same length, so they normally connect and disconnect simultaneously or very nearly so.

--best regards
« Last Edit: November 27, 2019, 08:47:58 AM by DSatz »
music > microphones > a recorder of some sort

Offline Gutbucket

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Re: Trs = no phantom power!?! Zoom
« Reply #5 on: November 22, 2019, 05:14:01 PM »
Always good to keep that in mind.

Thanks for the reminder.

In some Zoom recorder implementations the "TRS/XLR combo" input jacks are wired such that TRS and XLR contacts feed seperate circuit paths, and specific functionality depends on how Zoom has chosen to implement each circuit.  However, as far as I am aware, both are balanced audio inputs.
« Last Edit: November 28, 2019, 10:02:07 PM by Gutbucket »
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Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline EmRR

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Re: Trs = no phantom power!?! Zoom
« Reply #6 on: November 23, 2019, 12:57:23 PM »
The thing is, with a TRS plug it's better if phantom power is shut off while plugging or unplugging, because otherwise there's a moment when the plug is only halfway in where the powering would be applied to only one leg of the circuit and not the other. This forces DC to flow through the microphone's output circuitry in a way that it probably wasn't designed to handle. XLR plugs are designed with pins 2 and 3 being the same length, so they normally connect and disconnect simultaneously or very nearly so.

There's an AES paper about that fault condition called 'The 48 Volt Phantom Menace Returns' from 2009, in which they document peak current flow on the order of several amps from phantom power storage capacitor discharge, which could destroy certain input circuitry.  There are protection schemes that may or may not be employed in commercial circuits, and reports of equipment death are actually rare.    It IS the sort of thing that would pop a ribbon mic immediately. 
« Last Edit: November 24, 2019, 09:06:32 AM by EmRR »
Mics: DPA 4060 w/MPS 6030 PSU/DAD6001/DAD4099, Neumann KM 131, KMR 81i, Oktava MK 012, Sennheiser MKH 105, MKH 20, MKH 30, MKH 40, MKH 800 TWIN, lots of other studio appropriate choices
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Offline DSatz

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Re: Trs = no phantom power!?! Zoom
« Reply #7 on: November 27, 2019, 08:35:04 AM »
I'm no electrical engineer, but what I get from that paper seems true enough--that any preamp or recorder that has transformerless inputs and 48-Volt phantom powering likely uses coupling capacitors to block the DC from entering the preamp's input stage. The value of those capacitors has to be high enough for them to pass low audio frequencies.

Thus when 48 Volts DC is steadily applied to them (case in point: if no microphone is connected), those capacitors can take on enough charge to do some damage if it were suddenly all dumped into unprotected circuitry. The 6.8 kOhm phantom supply resistors aren't positioned to limit that current. The microphone's output circuit might or might not have effective protection for such a case. The cable will help a little--mainly, its capacitance would soften the leading edge of the current rush.

So visualize the moment when a TRS plug is halfway into a TRS socket. The plug's tip is touching the ring contact of the socket, and the plug's ring is touching the sleeve (ground) contact. If phantom powering has been on already, and those capacitors exist and are all charged up, then I think that the microphone's output transistors will receive the full charge from the capacitor on the ring-contact side of the preamp--across them, and not in common mode the way phantom powering is designed to work.

I think the author is right: I don't want that. It's not really a different risk from what I was talking about before, but the risk of damage is greater because the current is coming from those capacitors at the full 48 Volts and very low impedance, rather than 30-something Volts via 6.8 kOhms.

--best regards

P.S.: The two messages above mine have both quoted a message of mine at some length. This is rarely necessary in a threaded discussion board--and since there's a mistake in what I wrote, if I correct it now, it will remain wrong in the quotebacks.

Could people please quote back only what's really necessary to show what they're replying to? For my messages, at least? (I very often post messages and tinker with their text later. Bad habit, I know ...)
« Last Edit: November 30, 2019, 01:00:59 AM by DSatz »
music > microphones > a recorder of some sort

Offline Thechase

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Re: Trs = no phantom power!?! Zoom
« Reply #8 on: December 12, 2019, 04:38:09 PM »
Any reason i cant get a signal when i use a trs and a condensor?

I thought i only needed to not remove them in flight.

Anyone  using phantom power and trs!?



Get the Rode VXLR+ TRS to XLR adapter which not only lets use plug into a XLR port for phantom power, but also "step" the power from 12 to 48V down to the 3.5V your TRS mic needs.
« Last Edit: December 12, 2019, 04:57:26 PM by Thechase »

Offline Gutbucket

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Re: Trs = no phantom power!?! Zoom
« Reply #9 on: December 12, 2019, 07:05:26 PM »
^ That Rode adapter works if you are using electret mics that operate on lower voltage "plug-in-power" (PIP) and use a 3.5mm (1/8") mini-plug TRS connection.

It will not work for microphones that operate on phantom power (Phantom is 12-48V and of a different configuration) with a larger 1/4" TRS connection.
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

 

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