[LAU] Berlin Linux Audio meeting @ c-base 2018-10-09

Ralf Mardorf ralf.mardorf at alice-dsl.net
Sat Oct 6 19:00:01 CEST 2018

On Sat, 6 Oct 2018 17:15:19 +0200, Fons Adriaensen wrote:
>On Sat, Oct 06, 2018 at 05:10:53PM +0200, Ralf Mardorf wrote:
>> On Fri, 05 Oct 2018 13:47:58 +0100, Chris Cannam wrote:  
>> >A full-size jack is 6.3mm, not 6.5mm. So the image is of everyone
>> >turning up and then spending their time trying to jam oversized
>> >jacks into undersized sockets. An excellent joke, I thought, if
>> >wilfully obscure.  
>> Unfortunately my aged caliper gauge is damaged and not good for
>> measuring inner diameter. However, it's good to measure outside
>> diameters. At least one of my Neutrik jacks has got a measured
>> outside diameter of 6.35 mm, while one of my elCheapo's has got an
>> outside diameter of 6.3 mm and there's still much clearance, if I
>> connect the 6.35 mm Neutrik to different sockets. I can't say for
>> sure, but the inner diameter of a socket might even reach be around
>> 6.9 mm, which would likely be enough space to join with a 6.5 mm
>> jack. OTOH data sheets from at least two vendors mention an inner
>> diameter of 6.4 mm, for the sockets, too small for 6.5 mm jacks.
>> Anyway, I own a lot of cables with 6.3 mm jacks, that can't be used
>> with a lot of 6.3 mm sockets or they at least don't ensure a safe
>> connection, especially not for "mobile" instruments, such as
>> guitars ;).  
>AFAIK, these are 1/4 inch jacks, which translates to 6.35 mm.

The data sheet of the Neutrik that I measured with 6.35 mm, mentions
6.29 mm. The data sheets for the 6.4 mm sockets mention that they are
made to fit to 6.35 mm jacks. All that jacks and sockets are sold as
6.3 mm. I don't know how much allowance above or below nominal size it
tolerated. A few 6.3 mm jacks of some elCheapo patch cables I own are
too short. I also noticed such an issue for some kettle plugs and USB
connectors. Sometimes the covers, especially of moulded jacks, do not
allow to plug some jacks into the sockets, resp. they don't fit good.
I guess around 6.9 mm is not really reached by some sockets, but
perhaps some do reach 6.55 mm :D. In the 80s they sold MIDI cables with
much thicker pins, than those of averaged DIN jacks. In short, there is
some tolerance. If 6.5 mm jacks would existed, they perhaps would fit
into at least some "6.3" mm sockets.

Btw. instead of crimping a telephone cable again and again or replacing
it by a new cable, I removed the RJ jack and soldered the cable to the
telephone. RJ as well as TAE jacks and sockets are a PITA for usage
with gear that gets moved. I never had an issue with RJ jacks and
sockets for LAN, since I don't walk around with my PC, router etc., but
I do with my wired telephones. I know, wired telephones are weird ;).

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