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#45979 - 08/13/17 02:18 AM What's it for?
artie505 Online


Registered: 08/04/09
I occasionally see cables like this one, and I"m wondering what the barrel-like appurtenance is and what it contributes to the cable's functionality?

I"ve seen some cables with only one...at the external end, and others with one at each end (even if they were different), and I've seen them most often on camera cables.

Thanks.
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#45981 - 08/13/17 05:52 AM Re: What's it for? [Re: artie505]
MacManiac Offline
Moderator

Registered: 08/04/09
Loc: Paradise....on the central Ore...
It's called a Choke
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#45982 - 08/13/17 06:54 AM Re: What's it for? [Re: MacManiac]
artie505 Online


Registered: 08/04/09
Thanks for the explanation of the nature of the beast, but, at the least:
  1. Does a choke improve a functional cable,
  2. make an otherwise non-functional cable functional,
  3. decrease or increase manufacturing costs (Are they so unusual because they're a victim of cost cutting?),
  4. do something that's beyond my ability to think of?
  5. At which end of a cable is a choke [most] desirable, and why?
  6. Is using them overkill in any/some/all instances?
  7. Why their particular presence on camera cables?
And anything else that I might have missed.
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#45983 - 08/13/17 11:37 AM Re: What's it for? [Re: artie505]
joemikeb Online
Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
  1. Yes it can improve the performance of a functional cable
  2. No it cannot make an otherwise non-functional cable functional. However it could potentially raise the performance level from not-acceptable to acceptable in a specific situation.
  3. Yes it increases manufacturing costs
  4. ❓That is for you to say
  5. ❓Good question and one I am unequipped to answer. Years ago my preference was for cables with a choke on both ends.
  6. Using them could be overkill when dealing with a low bandwidth signal or a data signal that by its very nature is relatively insensitive to electrical noise. But overkill isn't necessarily bad just perhaps a tad bit more expensive. In the specific case of photography might NOT be overkill if you are a pro/semi-pro/prosumer and will be going to be going over the images with a jeweler's loupe looking for electrical noises, submitting the work to be judged by experts, or blowing the images up to very large sizes.
  7. Because...
    1. electrical noise that would have no effect on most data might appear as minute "faults" in hyper-critical examination of photographic images
    2. including a choke in the cable is a really inexpensive enhancement that can help make the consumer believe they are getting a superior product.
In years past chokes on cables were more common but greatly improved design and manufacturing of cables, newer data transmission protocols, better electrical noise suppression in electronic devices in general, faster processors capable of more sophisticated error correction and detection, improved software algorithms has made them less necessary with the possible exception of item 7.b.

FWIW Currently I only have two cables with a choke — a Thunderbolt 1 that came in the box with an OWC Thunderbay mini RAID enclosure and a USB 3 cable that came with an OWC drive enclosure. If I had a choice between a cable with a choke and one without I would use the one with a choke. Would I pay more to get the cable with a choke? Not unless I encountered a demonstrated need for it.
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#45984 - 08/14/17 10:18 AM Re: What's it for? [Re: artie505]
Ira L Offline


Registered: 08/13/09
Loc: California
I see 3 of them (not all in use; one for power, one for USB and one for serial connectivity) hanging off the back of my Epson scanner.
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#45985 - 08/15/17 12:03 AM Re: What's it for? [Re: Ira L]
artie505 Online


Registered: 08/04/09
Originally Posted By: Ira L
I see 3 of them (not all in use; one for power, one for USB and one for serial connectivity) hanging off the back of my Epson scanner.

I wonder if it's because your scanner is an old one, because a choke is more appropriate with a scanner than with other devices, or because...?
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#45986 - 08/15/17 12:22 AM Re: What's it for? [Re: joemikeb]
artie505 Online


Registered: 08/04/09
Thanks for the detailed response.

Originally Posted By: artie
Does a choke...do something that's beyond my ability to think of?

Originally Posted By: joemikeb
❓That is for you to say

Now, there's a Catch-22 for you. grin

Originally Posted By: joemikeb
FWIW Currently I only have two cables with a choke — a Thunderbolt 1 that came in the box with an OWC Thunderbay mini RAID enclosure and a USB 3 cable that came with an OWC drive enclosure.

The only cables with chokes I've run across also came from OWC, but they use them inconsistently; they've neither been a "given", nor have I been able to discern a pattern to their use.

It leaves me wondering if they're doing us a favor or if they just bought a cheap job-lot of the things?
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#45992 - 08/15/17 05:52 AM Re: What's it for? [Re: artie505]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Opinions will differ, so I'll toss my 2c into the ring. Okay maybe 3c, this is a long post...

1. Does a choke improve a functional cable
2. make an otherwise non-functional cable functional
It can. The purpose of a choke is twofold. It can (A) prevent interference to the accessory it's attached to, and/or (B) prevent the accessory from interfering with other equipment. It works a bit like a surge-suppressor, but is two-way. The accessory may use a "noisy" power supply in its enclosure, and that may cause hashing lines to appear on your monitor (or nearby television) as an example. Or when your laser printer kicks on (and makes the light in your room dim VERY briefly) it may cause your webcam's audio to POP loudly. Adding a choke to one of the cables in the mix can block this interference, or at least limit it. I've seen surges cause gear to reboot or freeze, sometimes consistently, sometimes intermittently, as a result of interference from other accessories, because CPUs that aren't properly protected can do really weird things when they get "blipped". Chokes are very good at stopping weird digital noise from coming out of cheap external speakers when you set your cell phone down on the table near their power or audio cables.

3. decrease or increase manufacturing costs
everything adds cost, but it may be the cheapest short-term solution. There may be arguments that hardening the accessory against interference, or adding internal filtering on it to prevent it from CAUSING interference may be cheaper than the cost of the choke. It's just a matter of counting beans. If you've already got your design sent and 100,000 of them manufactured, and they're being sent to another facility to assemble and package, and the UL/CE cert people tell you that you can't sell it due to too high of emissions, and the cable is coming from another source, it will DEFINITELY be cheaper to tell your cable source to change to a cable that has a choke in it for another 15 cents/unit rather than scrap or fix your existing stock, redesign your accessory, and reconfigure your manufacturing system. (though Revision 2 will likely incorporate changes that make the choke unnecessary to pass certs, and save them 10 of those 15 cents)

Also consider placement. A lot more things have chokes than you are aware of. MOST consumer electronics have them inside their enclosure instead of in the cord. Cheaper gear skips that to save manufacturing costs, and only bundle them with the more expensive cord that has the choke in it when selling in a country that requires lower emissions.


4. do something that's beyond my ability to think of?
I've reused chokes for other things, but most people won't have much luck there. It takes about 9 of them to make a decent balun for ham radio. I've also seen them mitigate the effects of a nearby lightning strike when placed on the AC line cord. (though it appears to be DC, lightning IS a pulse, having many of the qualities of an AC source, and thus can be blocked or limited by a choke)

5. At which end of a cable is a choke [most] desirable, and why?
Interference needs to be stopped as close to the source as possible, or as close to the sensitive equipment as possible. Any unnecessary wire in between the source and the choke will function as an antenna to radiate the signal into the air. Any unnecessary wire between the accessory and the choke will also function as an antenna, to receive and channel the interference into the accessory. Which is worse depends on the design of what's receiving it. Some gear is very sensitive to interference over its power wires and other equipment is more sensitive to radiated RF interference through the air. In general, you want the choke as close to the accessory as possible in either case. That's why you tend to see them right near the connector to the accessory. This unfortunately often creates a stress point in the 1" or so of cable between the choke and the connector. The original black powerbooks had a recall on their adapters for this reason. (http://www.cnn.com/2001/TECH/ptech/07/09/apple.recall.idg/) I had one of these and it stopped working. I tore it apart and found the shielding wires in the 1" section of cord had been SHREDDED by the concentrated stress and fell onto the table like a pile of steel wool clippings.

6. Is using them overkill in any/some/all instances?
It's about as much overkill as say a dust mask. Is it overkill for me to wear one when I'm outside? Probably. But not if I live in Beijing! So it's only overkill if you don't actually need it, and everyone's need is different. If your accessory is very noisy and you have other sensitive equipment, OR if your accessory is sensitive and you have other noisy equipment, then you need it. Better to have and not need, than to need and not have!

7. Why their particular presence on camera cables?
Cameras are very sensitive pieces of equipment. That CCD contains millions of sensitive sensors. If even ONE of them gets majorly interfered with, you're likely to see it. And if interference has any kind of a repeating pattern (think "digital noise") then it's pretty much guaranteed to show up on an image as a moire pattern of some sort or other, even if the interference is VERY small.

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#45993 - 08/15/17 06:42 AM Re: What's it for? [Re: Virtual1]
artie505 Online


Registered: 08/04/09
Thanks! (That's got to be at least 5 or 10 cents worth. wink )

So, pulling all the threads together, when's the last time you ran across a computer peripheral (not a camera with which a choke can clearly be an asset) with which a choke was a necessity for either reason 2. (A) or (B), which, paraphrasing my original question, leaves me wondering whether OWC is shipping cables with chokes because we need them or because someone else doesn't?
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#45997 - 08/15/17 09:40 AM Re: What's it [Re: artie505]
joemikeb Online
Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
Originally Posted By: artie505
So, pulling all the threads together, when's the last time you ran across a computer peripheral (not a camera with which a choke can clearly be an asset) with which a choke was a necessity for either reason 2. (A) or (B), which, paraphrasing my original question, leaves me wondering whether OWC is shipping cables with chokes because we need them or because someone else doesn't?

I can think of several reasons OWC may have a predeliction for cables with chokes...
  • Chokes on cables are cheaper than the design and manufacture of highly rf proofed electronics
  • Cost is a high design priority
  • It is a cost effective means of adding value to the finished product
  • Chokes provide the end product with a bit more “bang for the buck”
  • Chokes provide an additional performance margin
  • The manufacturer in China throws the cables with chokes in at the same price to OWC
I will say I have a LOT of OWC drive enclosures, and other peripherals and their performance has been uniformly met or exceeded my expectations so I don’t care what their reason for providing cables with chokes.
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#46003 - 08/16/17 01:24 AM Re: What's it [Re: joemikeb]
artie505 Online


Registered: 08/04/09
Originally Posted By: joemikeb
I will say I have a LOT of OWC drive enclosures, and other peripherals and their performance has been uniformly met or exceeded my expectations so I don’t care what their reason for providing cables with chokes.

Can't argue with that!
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#46007 - 08/16/17 05:10 AM Re: What's it [Re: joemikeb]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Originally Posted By: joemikeb
will say I have a LOT of OWC drive enclosures, and other peripherals and their performance has been uniformly met or exceeded my expectations so I don’t care what their reason for providing cables with chokes.

I'll give that a "me too". OWC has a perfect track record with me for quality products and outstanding customer and technical support. When I've needed to talk with an engineer, I've gotten to talk with an engineer. All the rest of my technical questions were handled easily by their technical support line. (no small feat for some of my question!)

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