So... does 48v/PP melt the XLR outs of the Helix or not?

BahamaDada

BahamaDada

Roadie
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247
Hey folks,

I need reinsurance. Maybe just an opinion.

If we go by the Helix manual it says to never connect the XLR out to a device that has 48v engaged (Like my Scarlett 2i2 does all the time), yet when I google the issue there are a hell lot of threads (mostly on the official forum) debating that. Some ppl had their Helix on a PP serving device for weeks and nothing happened. For others it's just worse than the 2012 Maya apocalypse.

You guys are knowledged (I guess?) and have some experience. What's the truth here? I mean, yes, basically I should do what the official manual tells me, but it seems that ymmv in this situation.

(Definetly going to get a XLR phantom blocker down the line.)
 
I’m not aware of any actual damage that can happen physically. My understanding was just that you can get extra noise and it might make things sound a bit weird until you kill phantom power on that line. I hope I’m not wrong about that. I feel like we’d see A LOT of fried Helix around if they could be damaged that way.
 
pipelineaudio said:
I ended up buying a pair of phantom power blockers...totally lame to have to do this for a > 1000$ device
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That would be my next step, too, as I wrote in the initial post. Saw something like the Triton Phantom Blocker für 40€ here in Europe. Kinda sucks to buy this for an already 1500€ device like the Helix, but in the end better safe than sorry. Especially bc my Helix is way outside warranty.
EOengineer said:
I’m not aware of any actual damage that can happen physically. My understanding was just that you can get extra noise and it might make things sound a bit weird until you kill phantom power on that line. I hope I’m not wrong about that. I feel like we’d see A LOT of fried Helix around if they could be damaged that way.
Click to expand...
Yeah, I suppose we would see more. Or maybe it just doesn't happen that often. I mean, most mixers these days have a per channel 48v switch. Only 1 venue we played had a mixer so old, that it was a global 48v. F*cker (sound guy we did not know) came after our set and told us he accidently had 48v globally on.

My main issue is at home with the Scarlett (as I stated above). I'd like to use Input 1 XLR for the Helix (XLR out into the 2i2 XLR in) and Input 2 XLR for my condenser mic. And the latter of course needs 48v. Now the 2i2 has a global 48v and this whole setup should be permanently cabled up. Right now I unplug the Helix XLR when I activate 48v at the 2i2. A workaround, but I am a lazy f*** and I just know someday I forget to do it.

When the only issue is noice, then I won't have an issue with that. If it's noisy it gets a phantom blocker (see other quote), but if I don't need to shell out extra money I am glad, too.
 
Is there a 1/4” on the helix? XLR to 1/4” cable. AFAIK phantom power will not send to 1/4”. Maybe I’m wrong but this may be a solution.
 
Ok read your manual. You should just connect TRS. The manual shows exactly this example with a guitar and condenser mic. It doesn’t specifically say TRS bypasses 48v, but I’m betting it does on the combo jack.
 
Bruce said:
Is there a 1/4” on the helix? XLR to 1/4” cable. AFAIK phantom power will not send to 1/4”. Maybe I’m wrong but this may be a solution.
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I have no experience with this kind of cable, but this morning I tried the Helix with a single 1/4''-1/4'' into the 2i2. Did not sound good at all unfortunatelly - no matter if it was LINE or INSTRUMENT. Way more ground noise and stuff. Went back to XLR-XLR afterwards (Helix XLR Out is set to MIC) and it was alrighty then.
 
I did some reading. This is a snippet from pg 15, user manual for the 2i2:

1. Inputs 1 & 2 – “Combo” input sockets - connect microphones, instruments (e.g., guitar), or
line level signals here. Combo sockets accept both XLR and ¼” (6.35 mm) jacks. Microphones
connect using XLR plugs: instruments and line level signals should be connected via ¼” (6.35
mm) jack plugs of either TS or TRS type. The preamp gain is appropriate for microphones
when an XLR plug is inserted, and for higher level signals when a jack plug is inserted. Do not
connect anything other than a microphone - e.g., the output of a sound module or FX unit - via
an XLR plug, as the signal level will overload the preamp, resulting in distortion; , if phantom
power is enabled, you may damage your equipment.
Click to expand...

It clearly states not to use an XLR plug input for anything other than a microphone, and the rest of the sentence would confirm that only the XLR is carrying the 48v. What I would do, which I think Bruce was getting at, is run an XLR to TRS type cable from the helix to 2i2 (disengage instrument button on 2i2). Still keeps everything balanced and bypasses the 48v. Apparently the 1/4" outs of the helix are not balanced so TRS to TRS cable wouldn't do any good.
Send a message to Focusrite if you're still hesitant. They can confirm and/or give some helpful info.
 
FuzzyAce said:
I did some reading. This is a snippet from pg 15, user manual for the 2i2:



It clearly states not to use an XLR plug input for anything other than a microphone, and the rest of the sentence would confirm that only the XLR is carrying the 48v. What I would do, which I think Bruce was getting at, is run an XLR to TRS type cable from the helix to 2i2 (disengage instrument button on 2i2). Still keeps everything balanced and bypasses the 48v. Apparently the 1/4" outs of the helix are not balanced so TRS to TRS cable wouldn't do any good.
Send a message to Focusrite if you're still hesitant. They can confirm and/or give some helpful info.
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The XLR to TRS could be a good compromise.

About that "Only connect mics to XLR" part: Does this hold true, when you set the XLR Out of the Helix to MIC? Then it should just act as a device with MIC level input.

Might shoot the Scarlett ppl a mail and post the answer.
 
48v will exceed the maximum voltage rating of just about any non-power electronic device.
A good design will always have DC coupling caps on the audio path to prevent DC bias shift, but the caps are NOT there to prevent high voltage from destroying the output of your device, that's 100% a user (sound man) mistake.
Yes a phantom power blocker is a good solution if you play in unknown venues.
 
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So I just ended a chat with Focusrite support and this is basically what Focusrite suggested:
"While mic level via XLR is ideal for long cable runs to a stage box or mixing desk in a live environment, it isn't necessary for a short run to an audio interface"
"I suggest using one of the 1/4" outputs set the line level"
"If you want the lowest possible noise, don't use a standard unbalanced guitar 1/4" TS jack, use a balanced 1/4" TRS cable instead. They look almost identical except for the extra black ring on the connector. This extra conductor is used to eliminate noise."

So I'll order a TRS 1/4 and maybe be good.

Still I feel a bit unsafe about 48v at gigs. Sound guys are weird and inexperienced sometimes.
 
Xlr to TRS into Helix 1/4 outputs are still affected by phantom power. No damage, just signal degradation
 
XLR output from helix to TRS 1/4" balanced input of 2i2. No 48v involved.
Only the XLR (mic only) of the 2i2 has 48v when phantom applied. Many interfaces offer line input/mic input option for XLR input -- but not the 2i2. Only the 1/4" portion is line or instrument input.
 
BahamaDada said:
So I just ended a chat with Focusrite support and this is basically what Focusrite suggested:
"While mic level via XLR is ideal for long cable runs to a stage box or mixing desk in a live environment, it isn't necessary for a short run to an audio interface" [...]
Click to expand...
Their statement is a bit problematic. I.e. laptops are excellent noise sources, a short unbalanced cable is all it takes to pick it up.
 
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