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DIY advice for headphone extension cables sought
Old 14th April 2018
  #1
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🎧 10 years
DIY advice for headphone extension cables sought

I'm going to try a recording session with several musicians playing live in a room, with instrument amps either screened (ie baffles, gobos) or hidden away in adjoining rooms, cupboards etc.

The musicians will hear themselves and one another via headphones, so I want to extend their headphones' distance from the little Behringer MiniAmp 800 https://static.bhphotovideo.com/lit_files/84868.pdf with 4 individual extension cables...probably 3.5 metres each (10-12 feet max) .

The amp has an additional set of phones outputs on the rear (paralleled ?) , but i expect to use only those on the front panel.

As modern headphones don't consume a lot of power (a few milliwatts ?) I'm hoping it will be appropriate to use some twin core mic cable.

Ordinarily mic cable wouldn't be recommended for passing any signal with significant current (eg speakers)...but for the typical low cost studio headphone (eg Sennheiser HD 280/380) I'm hoping to use some of what I have lying around here...is it likely to fit the bill ?

The Behringer amp specs say: Amplifier... Max. output level +21 dBm/ 124mW (100 ohm load); min output impedance 47 ohm.
Phones Out: Min impedance 100 ohm; Max output level +13 dBu @ 100 ohm load

I could go to star quad (which would give 'more copper' ), but is that even necessary ? Thanks for any advice.....
Old 14th April 2018
  #2
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jimjazzdad's Avatar
 
🎧 10 years
I purchased four of these 25' extensions to go with my little ART HeadAMP 4. Cheap as chips and they do the job - no issues. I think that unless you are an audiophool, speakers (that's all headphones really are) simply require wire that is of adequate size for the current involved. As you say, a few milliwatts is easily handled by AWG #24 . Sorry, don't know what that is in metric.
Old 14th April 2018
  #3
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Richard Crowley's Avatar
 
🎧 15 years
Yes, I regularly use ordinary mic cable as headphone extensions. As you say, the power is very low, so the gauge of the conductors is more than adequate for typical headphone connections unless you are approaching kilometers/miles.

I have even made adapters with a male XLR and female TRS at the headphone end, and female XLR and male TRS at the source end. They allow you to use ordinary XLR mic cables (or a snake channel) for headphone circuits.
Old 14th April 2018
  #4
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🎧 10 years
Thanks Jim (and Richard) , that's a great comparison link !

If I didn't have all the connectors and oodles of raw mic cable already lying around, I'd be tempted just to get the ones you have...but a couple of hours of meditative soldering will see me right !

Plus I can mix and match the socket ends, since many headphones come fitted with 1/8" plugs these days, so might as well be ready for them if the musicians bring their own cans to the session, as well as having the 1/4"ers too

I think that mic cable should be just fine, as you say....and Richard's multipurpose XLR adapter ends are a great way to make use of existing mic cables !
Old 14th April 2018
  #5
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tourtelot's Avatar
 
1 Review written
🎧 10 years
Yes to mic cable adapters. I have sent headphone cue feeds down 100s of feet of mic cable (from a little Mackie headphone mixer) and no one has ever complained about level or quality.

Audiophools! Awesome. You know, don't you all, that you can turn the s**ty wiring in your home into more beautifuler music with the addition of a $500 IEC AC cable. It's been proven in some tests you know.

D.
Old 4 weeks ago
  #6
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Scoox's Avatar
 
3 Reviews written
🎧 10 years
Yes, old thread. I'm not sure using a common ground cable is a good idea for headphones. You'd get some crosstalk between the 'hot' wires. Sennheiser cans use two separate individually shielded wires. Even if the shields are connected together at the connector, crosstalk is still prevented over the entire length of the cable because the hot wires are never separated by air or plastic, but the ground shield. Microphone cable seems to work only because, sure, sound comes out of the other end, but it's not ideal and the amount of crosstalk you get is proportional to the length of the cable.
Old 4 weeks ago | Show parent
  #7
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🎧 10 years
Quote:
Originally Posted by Scoox ➡️
….. because, sure, sound comes out of the other end, but it's not ideal and the amount of crosstalk you get is proportional to the length of the cable.
No, signal loss or hum pickup due to local RF or cable capacitance is the possible (and not even likely) result from a long mic cable…not crosstalk. It would have to be shockingly badly designed and assembled cable to produce that !
Old 4 weeks ago | Show parent
  #8
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🎧 5 years
Quote:
Originally Posted by Scoox ➡️
.... but it's not ideal and the amount of crosstalk you get is proportional to the length of the cable.
Hmmm, I'm in the mood to create an experiment:

How about I play/send a mono track out from the DAW to the 'L' channel of the headphone output, and capture the 'R' channel as an unbalanced input into a rec-enabled channel in the DAW?

I'd like to use 2W resistors as stand-ins for the transducer of the headphone. What resistor values and dBu levels would you like to see in this setup?
Old 4 weeks ago
  #9
DGL
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🎧 5 years
Dependant on whether or not you are using 3.5mm jacks/sockets you will probably need to find the thinnest mic cable you can find and will also need to find 3.5mm jacks that have wide enough cable entries, for a 6.35mm plug to 3.5mm socket I used this cable https://www.thomann.de/gb/sommer_cab...blin_white.htm and a cheapo 3.5mm socket but the cable would not fit in the strain relief so I had to trim the insulation at the end to get it to fit, REAN (and possibly others) do have 3.5mm sockets that can accept larger cable (6mm for the larger REAN connector) https://www.thomann.de/gb/rean_nys_240_l.htm .
At the end of the day most cables you get with headphones use simple unshielded 3 core cable so anything really is fine, hell you could probably use 0.5mm² or 0.75mm² 3 core mains cable if it's flexible enough.
Old 4 weeks ago
  #10
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Phil Cibley's Avatar
 
🎧 15 years
Quote:
Originally Posted by studer58 ➡️
I'm going to try a recording session with several musicians playing live in a room, with instrument amps either screened (ie baffles, gobos) or hidden away in adjoining rooms, cupboards etc.

The musicians will hear themselves and one another via headphones, so I want to extend their headphones' distance from the little Behringer MiniAmp 800 https://static.bhphotovideo.com/lit_files/84868.pdf with 4 individual extension cables...probably 3.5 metres each (10-12 feet max) .

The amp has an additional set of phones outputs on the rear (paralleled ?) , but i expect to use only those on the front panel.

As modern headphones don't consume a lot of power (a few milliwatts ?) I'm hoping it will be appropriate to use some twin core mic cable.

Ordinarily mic cable wouldn't be recommended for passing any signal with significant current (eg speakers)...but for the typical low cost studio headphone (eg Sennheiser HD 280/380) I'm hoping to use some of what I have lying around here...is it likely to fit the bill ?

The Behringer amp specs say: Amplifier... Max. output level +21 dBm/ 124mW (100 ohm load); min output impedance 47 ohm.
Phones Out: Min impedance 100 ohm; Max output level +13 dBu @ 100 ohm load

I could go to star quad (which would give 'more copper' ), but is that even necessary ? Thanks for any advice.....
I've used star quad headphone extenders for year with no problems.
A TRS male on one end and a female on the other and you're good to gol
Old 4 weeks ago | Show parent
  #11
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jimjazzdad's Avatar
 
🎧 10 years
Quote:
Originally Posted by DGL ➡️
Dependant on whether or not you are using 3.5mm jacks/sockets you will probably need to find the thinnest mic cable you can find and will also need to find 3.5mm jacks that have wide enough cable entries, for a 6.35mm plug to 3.5mm socket I used this cable https://www.thomann.de/gb/sommer_cab...blin_white.htm and a cheapo 3.5mm socket but the cable would not fit in the strain relief so I had to trim the insulation at the end to get it to fit, REAN (and possibly others) do have 3.5mm sockets that can accept larger cable (6mm for the larger REAN connector) https://www.thomann.de/gb/rean_nys_240_l.htm .
At the end of the day most cables you get with headphones use simple unshielded 3 core cable so anything really is fine, hell you could probably use 0.5mm² or 0.75mm² 3 core mains cable if it's flexible enough.
3.5 mm plugs and jacks are the work of the devil and should only ever be used with evil Apple products like iPhones...oh wait - I don't think even iPhones use them anymore. 1/4" TRS with the good, solid, nickle-plated barrels -e.g. Switchcraft or Rean. Not a big fan of the 'fat' Neutrik 1/4" TRS either...
Old 4 weeks ago | Show parent
  #12
DGL
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🎧 5 years
Quote:
Originally Posted by jimjazzdad ➡️
3.5 mm plugs and jacks are the work of the devil and should only ever be used with evil Apple products like iPhones...oh wait - I don't think even iPhones use them anymore. 1/4" TRS with the good, solid, nickle-plated barrels -e.g. Switchcraft or Rean. Not a big fan of the 'fat' Neutrik 1/4" TRS either...
I only went with a 3.5mm socket one side as it's one less adaptor to lose!
Also OT but some wireless systems used special 3.5mm jacks for the beltpack connectors, fine if they are of a standard type as they are easier to wire than a lot of other beltpack connectors (looking at you Trantec LEMO 4 pin), but TOA and dB Technologies used their own style, the TOA ones are unobtanium (but will accept a thin 3.5mm jack but with no locking, the original cables having a screw on boot over the jack to lock it in) and dB Technologies ones only being available from Thomann.
Old 4 weeks ago | Show parent
  #13
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Scoox's Avatar
 
3 Reviews written
🎧 10 years
Quote:
Originally Posted by studer58 ➡️
No, signal loss or hum pickup due to local RF or cable capacitance is the possible (and not even likely) result from a long mic cable…not crosstalk. It would have to be shockingly badly designed and assembled cable to produce that !
I'm hoping I'm wrong because mic cable is easier and cheaper to source than two-core shielded.

If the signal wires are shielded (even if the shield is shared), external EM sources should not be a problem, unless the shielding doesn't provide 100% coverage (e.g. spiral shield). I can't comment as I've never measured this.

When I said crosstalk I was referring to the fact that the transmission line is effectively a low-pass filter. If the high-cut rolloff is in the region of audible frequencies, it can result in treble attenuation and phase shift, while lower frequencies make it to the far end of the line largely unaltered. See (this):

Quote:
Shielded cables must use insulation with good dielectric properties (i.e., low dielectric constant) to assure that cable capacitances are kept low when a shield is added to the cable. The proximity of two conductors in a cable and the dielectric constant of the insulation between the conductors determine the capacitance measured between the conductors. The addition of a shield around the two conductors introduces two very significant “parasitic” capacitances; those between each conductor and the shield. The conductor to shield capacitances combine with the conductor to conductor capacitance to significantly increase the overall capacitance of the pair.
When each conductor is shielded individually, the conductor-to-conductor capacitance is greatly reduced; this raises the high-pass rolloff. If the rolloff is above the highest frequency you can hear then it's not a problem.

I found this graph which shows the difference between the amp output (red) and the far end of a "figure of 8" parallel conductor cable:



You can see there is some loss of high frequency content above 10 kHz, as well as phase shift—subtle but measurable and I'm sure it can be heard. There's probably a good reason why some headphone manufacturers (e.g. Sennheiser, Audeze) use individually shielded conductors instead of 3-conductor cable.
Old 4 weeks ago
  #14
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kludgeaudio's Avatar
 
I have always used 18/3 SJOOT or SJOOW from the hardware store for this. There may be some lack of separation due to the resistance of the shared ground lead, but I never noticed any real problem in practice. No shielding needed. But I have normally also driven from a very low-Z source too, and never really gone more than about fifty feet.
--scott
Old 4 weeks ago
  #15
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pencilextremist's Avatar
 
9 Reviews written
🎧 5 years
I use a Neutrik AV Adapter, Female 1/4 in Stereo to Female XLR now for all my headphones, it's very handy, a tip I got from mike senior, I hated the REAN version in comparison, I think the Neutrik one is far better made, it was a worthwhile purchase and not too expensive, in the UK you can get them from RS components which saves having to import it from thomann.
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