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Old May 5th, 2012, 10:17 AM   #46
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Re: Output levels of Sennheiser G3 receiver

It is not damaging to the DR-100mkII which is supplying the phantom power. But it IS DAMAGING to the receiver. The output circuit of most audio equipment is NOT protected against phantom power voltages and you run a VERY HIGH risk of damage to the source device. You MUST NOT feed phantom voltage back into the output circuit of equipment that isn't prepared for it.

There are several ways of working around this problem. You could start at the recorder and disable (or switch) the phantom power to the inputs separately. Or you could beef up the wireless receiver with higher voltage output capacitors to withstand 48V. Or easiest (IMHO) is to simply make a DC-blocking cable to interconnect the two. It is probably easiest to do and doesn't require hacking either the recorder or receiver.
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Old May 5th, 2012, 05:12 PM   #47
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Re: Output levels of Sennheiser G3 receiver

The DC-blocking cable is definitely the route I want to go, Richard. I've been looking all around for a place that would carry such a cable (adapter?) but can't seem to find one. Is the only option to make one? Also, does it matter that the 3.5mm to XLR cable that comes with the G3 kit (the CL 100) is unbalanced?
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Old May 6th, 2012, 12:31 PM   #48
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Re: Output levels of Sennheiser G3 receiver

If your going to modify the Sennheiser cable you'll need a 'new' XLR connector, the ones that I've seen are of a molded-on design and can't be altered. New XLR connectors are cheap though... about $ 2.50USD
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Old May 6th, 2012, 02:24 PM   #49
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Re: Output levels of Sennheiser G3 receiver

There's no need for a special DC blocking cable.
The Sennheiser receivers, together with all modern audio devices properly DESIGNED to connect to microphone XLR inputs won't be damaged nor affected by phantom power.

However it may be damaged if it's connected to the XLR input while the phantom power is turned on. The same warning goes for the condenser mics too.
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Old May 6th, 2012, 03:33 PM   #50
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Re: Output levels of Sennheiser G3 receiver

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Originally Posted by Zoran Vincic View Post
The Sennheiser receivers, together with all modern audio devices properly DESIGNED to connect to microphone XLR inputs won't be damaged nor affected by phantom power.
Do you have an authoritative reference source for that statement? I have heard too many horror stories of equipment that was either temporarily rendered inoperable or permanently damaged from feeding P48 back into the output that was never designed for such high voltages.
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Old May 6th, 2012, 07:19 PM   #51
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Re: Output levels of Sennheiser G3 receiver

Reading my previous post I see that I made an error, I should have emphasized the word "properly".

I'm no Eric Cartmann but everytime a G2/G3 receiver I worked with was fed with phantom power, nothing happened. I know that it would be more exciting if I said turned the pp on and then bam, fire, smoke everywhere, run for your lives...

But it was more like oh, left the PP on again...oh well, let me turn it off and continue to work as if nothing happened...dull, isn't it?

If you wan't to be on a safe side, just read the manual first. One would think that if a device could/would be damaged by PP there would be a warning in the manual. In nice, big, bold letters with plenty of exclamation marks.

Feel free to correct me if I'm wrong but I'm pretty sure that the G3 portable receiver's manual doesn't even mention phantom power at all...
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Old May 6th, 2012, 08:55 PM   #52
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Re: Output levels of Sennheiser G3 receiver

I frequently run my G3 and an NTG-3 through a Sound Devices Mixpre. The phantom power on the mixpre is either on or off for both channels. G3 is still alive and well.
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Old May 6th, 2012, 10:29 PM   #53
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Re: Output levels of Sennheiser G3 receiver

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Originally Posted by Zoran Vincic View Post
But it was more like oh, left the PP on again...oh well, let me turn it off and continue to work as if nothing happened...dull, isn't it?
That's great that is doesn't explode into a million bits, but the situation I'm dealing with is that I want to use it while phantom power is on. It seems there isn't a quick "Hey, just buy this cable" kind of solution.
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Old May 7th, 2012, 06:25 AM   #54
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Re: Output levels of Sennheiser G3 receiver

As I said earlier, you're free to use it with PP engaged and without a special cable of any kind.
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Old May 7th, 2012, 10:39 AM   #55
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Re: Output levels of Sennheiser G3 receiver

Fair enough. But won't it introduce a bunch of "hum" and battery drain?
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Old May 7th, 2012, 01:14 PM   #56
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Re: Output levels of Sennheiser G3 receiver

You might get the odd crack when you stick the plug in, but I've never had hum. Phantom power is current limited, so extra battery drain isn't really a problem. Some weird things can happen - some Soundcraft mixers, that maybe are providing your camera an audio feed, react oddly if phantom is present - the LEDs suddenly going up to full - but no impact on the sound.
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Old May 8th, 2012, 09:34 AM   #57
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Re: Output levels of Sennheiser G3 receiver

Quote:
Originally Posted by Rick Reineke View Post
NO! ... The G2/3 has an unbalanced configuration and has been known to cause excessive noise and drain the recorder's batteries faster than you can say "how come my new batteries are dead already".
Only the 100 series pocket receivers are unbalanced - the mains receivers and G1/G2 500 series and 2000 series pocket receivers are all balanced.


Quote:
Originally Posted by Richard Crowley View Post
You can put a DC-blocking capacitor in the XLR connector to keep the P48 from back-feeding into the receiver output circuit. I would recommend also putting a clamp diode to prevent the turn-on/charging impulse current from getting through to the receiver output circuitry. I can draw you a diagram if you think that is what you want to do. It should not be too difficult to solder these components inside the XLR connector shell.
This is the best option.
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Old May 8th, 2012, 09:38 AM   #58
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Re: Output levels of Sennheiser G3 receiver

Quote:
Originally Posted by Zoran Vincic View Post
There's no need for a special DC blocking cable.
The Sennheiser receivers, together with all modern audio devices properly DESIGNED to connect to microphone XLR inputs won't be damaged nor affected by phantom power.

However it may be damaged if it's connected to the XLR input while the phantom power is turned on. The same warning goes for the condenser mics too.
Yes - the evolution receivers are protected against phantom power, except the first batch of G2 receivers.

But - I would not like to unbalance phantom power when you also want to use the phantom for another mic.

But - why don't you plug the receiver into a line input rather than a mic.input? It's the better option, anyway.
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Old May 8th, 2012, 09:59 AM   #59
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Re: Output levels of Sennheiser G3 receiver

It's actually better to connect it to a mic input as the receiver doesn't really output a line level signal even when the output is boosted to + 12dB.
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Old May 8th, 2012, 11:11 AM   #60
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Re: Output levels of Sennheiser G3 receiver

If it's not outputting a high enough signal to drive a line-level input properly when the output adjustment is on one of the top settings, you're probably under-modulating at the transmitter. Set the transmitter's audio input sensitivity higher.
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