Re: Output levels of Sennheiser G3 receiver
 

Reviving an old thread here, but is it okay to have phantom power on when the G3 receiver is plugged into my DR-100mkII?

I ask because I also want to run a shotgun and it seems to be the only way to do both at the same time.

Re: Output levels of Sennheiser G3 receiver
 

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".
If your mic has an internal battery option, use that. If not, use an external PP supply. It may be possible to modify the G3's cable or add an iso transformer that does not pass PP, though I haven't experimented since I don't have that problem. Maybe Richard can come up with a cheap and easy remedy for that.

Re: Output levels of Sennheiser G3 receiver
 

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.

Re: Output levels of Sennheiser G3 receiver
 

I could solder the XLR adapter that came with the G3 kit, yes? Unfortunately, I don't know my way too well around circuitry, but I can't help but feel there is an easy solution I'm not considering.

The Tascam is a music recording device, but surely it can't the first time someone has wanted to do this? I've been scouring Google incessantly with no luck. Would there be some specialty store that sells it?

Re: Output levels of Sennheiser G3 receiver
 

With phantom power, it's rarely actually damaging to engage the phantom when not needed, although it's possible that it could cause issues mentioned (noise and battery drain). Personally I would just experiment and see if it was tolerable before I started soldering custom cables to block the phantom power. But that's more of a seat of the pants approach than a "proper" solution.

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.

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?

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

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.

Re: Output levels of Sennheiser G3 receiver
 

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.

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...

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.

Re: Output levels of Sennheiser G3 receiver
 

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.

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.

Re: Output levels of Sennheiser G3 receiver
 

Fair enough. But won't it introduce a bunch of "hum" and battery drain?

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.

Re: Output levels of Sennheiser G3 receiver
 

Only the 100 series pocket receivers are unbalanced - the mains receivers and G1/G2 500 series and 2000 series pocket receivers are all balanced.


This is the best option.

Re: Output levels of Sennheiser G3 receiver
 

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.

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.

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.

Re: Output levels of Sennheiser G3 receiver
 

Re: Output levels of Sennheiser G3 receiver
>> If the system is gain staged properly, a +4dB (ref level) line level signal can be achieved.
That said, some devices (like Canon XL and HD cams ) have inherently lower than 'normal' input gain available, and 'line level' is probably just padded down to the mic pre anyway, so running mic level is not a huge issue in that scenario.
--------------
Thanks John, I should have specified the G2/3 100 series portable receiver.

Re: Output levels of Sennheiser G3 receiver
 

NB: The G3 portable receiver is diversity - the G2 is not.

The 100 series is unbalanced output - the 500/2000 series has a balanced output.

Re: Output levels of Sennheiser G3 receiver
 

I still maintain that the g3 does not put out a pro line level signal. Yes it will produce a maximum signal level of about +4dBu. But true line level has nominal level of +4dBu, and a maximum level of about +20dBu. It's about 16dB short.

Yesterday I was running a g3 into a Sony ex-1r line input, and the signal never got past about a third to half the meter range on the camera. The transmitter was being fed from a Mixpre and properly adjusted so the transmitter peaked when the Mixpre peaked.


As far as phantom power, I have "accidentally" applied phantom to my g3 for long periods of time, and didn't notice any problems at all.

My understanding is that decades ago, most preamp designs were hand designed one off things that may not have been designed to survive adverse conditions (e.g. unexpected phantom). So worrying about phantom damage made more sense in the past. But preamp design has evolved, engineers have gotten more specialized, and generally tolerance for failure has gone way down. Everything is designed to minimize warranty claims, which are now a huge part of the manufacturer cost as integrated designs have decreased the actual product cost.

And the process of building everything overseas now means there's much more pressure on manufacturers to get their designs reliable the first time, whereas in the past they could tweak designs more iteratively. Audio equipment has only been generally available to ordinary people in our lifetimes and there has been quite a bit of evolution in designs over its short history on this planet. In short, it's best to avoid unnecessary phantom power, but if your time is worth anything you'd probably spend more chasing DC blocking cables than a repair would cost if you did actually damage something.