FAQ: Audio Tip: how to reduce AC IFE noise for $0.99CAD
Nov 30, 2013, 12:11 am
#1
Original Poster
Join Date: Mar 2004
Location: YVR
Posts: 11
Audio Tip: how to reduce AC IFE noise for $0.99CAD
Hi anonymous seat mates,
Yes, it's only my sixth post ever, but I lurk a lot. I think '14 is year 8 or 9 of E50k for me so I'm no rookie.
However, it took this noob that many years to solve the IFE headphone output noise problem (i'm embarassed to say I have a degree in EE/communications systems). It even took me over a year to remember to post this so others could stop suffering - sorry!
Anyways, this is the $0.99CAD SHIPPED solution:
http://www.ebay.ca/itm/gib-35mm-MF-S...-/171123169680
Short version:
It's an inline potentiometer (volume control) for your plug-in headphones. Plug it in before your headphones, turn up the volume on the IFE, turn down the volume using this wheel. Noise gone - enjoy.
Technical discussion:
The AC IFEs, particularly in J, are terrible for conducted noise. In J pods the brilliant designer put the AC outlet right next to the headphone jack. The engineer responsible should have their degree taken away or at least be taught a lesson in electricity with a taser.
As a result we, the audiophile air traveller, are screwed. You have the IFE trying to output a movie soundtrack, and power cables running next to the audio lines dumping noise onto your audio output. You plug in your headphones and, because we own proper isolated or noise-cancelling headphones, we're able to turn down the volume on the IFE so as not to blast our ears out. ie. I'm always at the very 1st bar of volume. But we hear ALL the noise. The signal to noise ratio (SNR... as if we needed another acronym on this site) is like 10:1.
Of course we can jack up the amplitude (volume) on the IFE output and cut the SNR way down to 1000:1 (I won't get into db here) or so because the noise itself is steady. Problem is we now become deaf from the jacked up volume in our sound-proofed headphones.
Enter the 99cent potentiometer. You can now use this to attenuate (reduce the volume) of the 1000:1 SNR headphone jack which will also reduce the level of the noise. And voila, decent sound quality.
To those scientists and engineers out there I'm sorry, I didn't have the courage to dig out my carry-on oscilloscope and take actual measurements in J.
Anyways, hope this helps someone out, and if you see someone else plug in an inline volume, give them a thumbs up and mention this thread! ^
PS. Maybe you're wondering what headphones this "audiophile" uses on flights. Answer: Depending on my mood and length of the flight, Shure SE215, Etymotic HF3, or TDK BA200 IEMs (in-ear monitors). Some day, a Westone 3.
Yes, it's only my sixth post ever, but I lurk a lot. I think '14 is year 8 or 9 of E50k for me so I'm no rookie.
However, it took this noob that many years to solve the IFE headphone output noise problem (i'm embarassed to say I have a degree in EE/communications systems). It even took me over a year to remember to post this so others could stop suffering - sorry!
Anyways, this is the $0.99CAD SHIPPED solution:
http://www.ebay.ca/itm/gib-35mm-MF-S...-/171123169680
Short version:
It's an inline potentiometer (volume control) for your plug-in headphones. Plug it in before your headphones, turn up the volume on the IFE, turn down the volume using this wheel. Noise gone - enjoy.
Technical discussion:
The AC IFEs, particularly in J, are terrible for conducted noise. In J pods the brilliant designer put the AC outlet right next to the headphone jack. The engineer responsible should have their degree taken away or at least be taught a lesson in electricity with a taser.
As a result we, the audiophile air traveller, are screwed. You have the IFE trying to output a movie soundtrack, and power cables running next to the audio lines dumping noise onto your audio output. You plug in your headphones and, because we own proper isolated or noise-cancelling headphones, we're able to turn down the volume on the IFE so as not to blast our ears out. ie. I'm always at the very 1st bar of volume. But we hear ALL the noise. The signal to noise ratio (SNR... as if we needed another acronym on this site) is like 10:1.
Of course we can jack up the amplitude (volume) on the IFE output and cut the SNR way down to 1000:1 (I won't get into db here) or so because the noise itself is steady. Problem is we now become deaf from the jacked up volume in our sound-proofed headphones.
Enter the 99cent potentiometer. You can now use this to attenuate (reduce the volume) of the 1000:1 SNR headphone jack which will also reduce the level of the noise. And voila, decent sound quality.
To those scientists and engineers out there I'm sorry, I didn't have the courage to dig out my carry-on oscilloscope and take actual measurements in J.
Anyways, hope this helps someone out, and if you see someone else plug in an inline volume, give them a thumbs up and mention this thread! ^
PS. Maybe you're wondering what headphones this "audiophile" uses on flights. Answer: Depending on my mood and length of the flight, Shure SE215, Etymotic HF3, or TDK BA200 IEMs (in-ear monitors). Some day, a Westone 3.
Nov 30, 2013, 4:40 am
#2
Join Date: Nov 2001
Location: Ontario, Canada
Programs: AC*SE MM, Hilton Gold, Marriott Gold, IHG Plat Amb
Posts: 3,439
Thanks for posting this explanation and especially the link. I'll be ordering one as soon as I remember my eBay sign-in details! I figured out the cause of the noise a while back (and I'm only a Chemical Engineer!) and on every flight I'm reminded that I still haven't done anything about it. I use Bose QC15s and they've got a switch for high/low output. Using the high setting attenuates the signal enough to reduce the buzz significantly but it still doesn't eliminate it.
And another point about the placement of the outlets - we were on a UA flight in F with their pod product and besides a much better IFE system (with no ads) the plugs for headphones etc were all sensibly placed up high where you could see them. Much, much better pod design. And no buzz that I can recall.
And another point about the placement of the outlets - we were on a UA flight in F with their pod product and besides a much better IFE system (with no ads) the plugs for headphones etc were all sensibly placed up high where you could see them. Much, much better pod design. And no buzz that I can recall.
Nov 30, 2013, 11:09 am
#7
Original Poster
Join Date: Mar 2004
Location: YVR
Posts: 11
This tip will work in ANY headphone jack that has induced noise, including the regular AC IFE, UA jacks, etc.
Now that I think of it, there was one time this didn't work: It was on an LH A340 where the noise was somehow coming from the IFE itself and would go up in volume with the sound. That really sucked. But IIRC, in that particular seat, the noise improved if I stood up out of my seat.
Given the choice between that seat and a middle seat, I chose to go to bed...
Now that I think of it, there was one time this didn't work: It was on an LH A340 where the noise was somehow coming from the IFE itself and would go up in volume with the sound. That really sucked. But IIRC, in that particular seat, the noise improved if I stood up out of my seat.
Given the choice between that seat and a middle seat, I chose to go to bed...
Dec 9, 2013, 11:08 am
#14
Original Poster
Join Date: Mar 2004
Location: YVR
Posts: 11
Those who appreciate irony will find humour in the fact that I, the OP, left BOTH my inline volume controls at home last week. Of course that is when my upgrade to J went through!
Luckily it was because I was using some new Sennheiser MM450X which are pretty high impedance already (ie. you need to crank the volume to drive them anyways).
Luckily it was because I was using some new Sennheiser MM450X which are pretty high impedance already (ie. you need to crank the volume to drive them anyways).