Twisted USB

[Ogitek]

If you just replace the plug at the very end of the cable, that should be ok.

But if you try to replace a large 24 inch section of cable with untwisted wire, then that is a very different scenario which may impact signal integrity.

What if I cut the original Venton USB in half and put Lemo at one end of one of the pairs? In other words, does the manufacturer have to design the twisting of each cable with certain numbers and design each complete cable or can they just cut their roll of wiring for every one meter and put termination into it?

You can cut to any length and replace the plug.  The twists do NOT have to be "integer" lengths, so to speak.

What have you heard about "Impedance discontinuity"? This thread started because I was reading this physics stack exchange topic. Someone soldered it this way:



And someone answered:

https://electronics.stackexchange.com/questions/430914/a-few-of-my-cables-dont-work-is-it-because-they-werent-shielded-properly

"Some of your cables do not work reliably likely because you have too wide cut-offs near soldering area, which creates impedance discontinuity, which causes reflections and intersymbol interference. USB cables must be tested on TDR (Time-Domain-Reflectometer) to ensure impedance uniformity across soldering joints.".

What does he mean by "wide cut-offs"? Does it means the distance between solders is wide? So you can't use other plugs for USB? If you use a Lemo plug. Why won't it cause impedance discontinuity?

[Andy Chee]

Please refer to my edited image.  The section marked in blue, is what potentially causes an impedance discontinuity.  This section should be kept very short, which unfortunately doesn't provide much wiggle room and makes hand assembly somewhat tedious.

[Ogitek]

Please refer to my edited image.  The section marked in blue, is what potentially causes an impedance discontinuity.  This section should be kept very short, which unfortunately doesn't provide much wiggle room and makes hand assembly somewhat tedious.

(Attachment Link)

I don't get it. Should it be very short so it is enclosed by the shield? or because there is less twisting (but then, twisting can occur one turn every 5 inches so it's negligible)? What else?  And how does it differ to the USB cable soldered to a LEMO plug like the following?

[Andy Chee]

Please refer to my edited image.  The section marked in blue, is what potentially causes an impedance discontinuity.  This section should be kept very short, which unfortunately doesn't provide much wiggle room and makes hand assembly somewhat tedious.

I don't get it. Should it be very short so it is enclosed by the shield? or because there is less twisting (but then, twisting can occur one turn every 5 inches so it's negligible)? What else?  And how does it differ to the USB cable soldered to a LEMO plug like the following?

The LEMO plug is a metal body, so it shields the wires.  Just make sure the shield is connected to the plug body.

If the plug body was plastic, then yes, it needs to be short in order to be enclosed by the shield.

[Ogitek]

Please refer to my edited image.  The section marked in blue, is what potentially causes an impedance discontinuity.  This section should be kept very short, which unfortunately doesn't provide much wiggle room and makes hand assembly somewhat tedious.

I don't get it. Should it be very short so it is enclosed by the shield? or because there is less twisting (but then, twisting can occur one turn every 5 inches so it's negligible)? What else?  And how does it differ to the USB cable soldered to a LEMO plug like the following?

The LEMO plug is a metal body, so it shields the wires.  Just make sure the shield is connected to the plug body.

If the plug body was plastic, then yes, it needs to be short in order to be enclosed by the shield.

Ok thanks. I heard that the termination in the USB 2.0 must be designed to have the same characteristic impedance as the twisted pair.  Have you heard of this? What if they are different?

[voltsandjolts]

You are making this hard for yourself. So many posts.

Looking back at your posts, you've mentioned bio-medical signal amplifiers, baud rates and copying a commercial USB-LEMO (or USB-ODU) data cables you posted pictures of. So, I'm going to guess you have some used medical measurement system which interfaces to a PC via USB, likely at those baud rates you've mentioned (USB-CDC device). The data rates required in this type of system would be modest and it's likely your device (is it a secret what it is?) is using USB-FS (12MHz) and not USB-HS (480MHz). If that is correct, this cable will be easy to make without worrying about imepdance matching and reflections. By way of it's low bit rate and error correction, USB-FS is tolerant of crappy layout and cables.

Because you continue to struggle, I re-iterate my previous post suggesting you use USB breakout boards which are ideal for someone less skilled in the art of custom USB cables. For example, the breakout board shown below, then twist your own wires and solder to your LEMO or ODU connector. Perhaps you could use PTFE wire which is tolerant to overheating during clumsy soldering.

[Andy Chee]

Please refer to my edited image.  The section marked in blue, is what potentially causes an impedance discontinuity.  This section should be kept very short, which unfortunately doesn't provide much wiggle room and makes hand assembly somewhat tedious.

I don't get it. Should it be very short so it is enclosed by the shield? or because there is less twisting (but then, twisting can occur one turn every 5 inches so it's negligible)? What else?  And how does it differ to the USB cable soldered to a LEMO plug like the following?

The LEMO plug is a metal body, so it shields the wires.  Just make sure the shield is connected to the plug body.

If the plug body was plastic, then yes, it needs to be short in order to be enclosed by the shield.

Ok thanks. I heard that the termination in the USB 2.0 must be designed to have the same characteristic impedance as the twisted pair.  Have you heard of this? What if they are different?

The circuit termination is not really in the cable per se.  The circuit termination is on the PCB next to the USB chip of the PC, and on the PCB next to the USB chip inside your device.  Circuit termination could also be within the chip as well.

If impedances are wildly different, you get signal reflections, which may or may not be interpreted as extraneous bits in the serial data, depending on how well error detection & correction does its job.  Too many extraneous bits and you will lose data.  Recall the discussion on the previous page, USB protocol has no speed reduction when encountering bad data. 

[Ogitek]

Thanks for all the information guys. I'm deciding whether to get a $42 cable from China (someone at Ebay told me he can assemble a clone) versus getting the $400 original one. You see, the thing is, the Audiophile equipment Im bidding is untested (I haven't received it yet). I don't want to fry the USB board if I solder a bad cable myself (I dont' know how to solder well). It is confirmed to be USB 2.0 with HS of 480Mbps. If I used the china clone, there may be impedance mismatch that can cause the USB not to work, which may make me think the equipment is not working. So I guess I may just invest in the $400 usb cable. I thought USB cable was just a conductor. Well it is not, it is a transmission system!

[tooki]

You're burying yourself in detail you don't understand, and have created 4 threads about this special cable, without reaching any real conclusion , in part because you aren't listening to what people say.

Yes, impedance matching and discontinuities matter, but the system has to tolerate some because of the physical realities of manufacturing low-cost cables. (USB was designed to be low cost, so it has to allow some tolerances.) The issue in the DIY cables you linked is that the guy wasn't connecting the shield, which is absolutely required.

If the Chinese cable is designed specifically for your device, so that the pinout is definitely correct, go with that. You won't get one cheaper. We'd love to simply verify whether the Chinese cable will be correct, but despite being asked more than once, you refuse to just tell us what the damned piece of equipment is.

If you'd mention the product manufacturer and model that this is supposed to connect to, then people might be able to provide a useful answer.

First of all. I don't have the equipment yet. So I don't know its dimension. You think the one at amazon would work?

https://www.amazon.com/Eonvic-Audio-Zaxcoms-4-pin-Charging/dp/B06XKV73C1?th=1

If yes, then I'd order the $32 at amazon first instead of acquiring the $50 Lemo which can take 4 months (Digikey lead time is 16-25 weeks) to arrive.

How the heck can people tell you whether it’ll work if you refuse to disclose what it needs to be used with?

It’s both frustrating and perplexing to me that people come here for help but refuse to disclose even the most fundamental information, hoarding it like it’s some state secret. You’re far from the first to do this, and I’m sure you won’t be the last, but that doesn’t make it any less perplexing and frustrating.

[magic]

It supposedly is "audiophile equipment", so forking out $400 for cables is the obvious thing to do and frankly a bargain

(Myself, I would surely solder something together and no way it would be worse than the OEM product...)

[Ogitek]

I still don't have the equipment, it is still on the way from a seller in Taiwan. The mail is long.  I'm not even sure the equipment works. In case it doesn't work. I want to get one of 2 remaining items left at Ebay. If I tell you now and some of you empty the shelf. Then I won't have any more left over to get. I'll tell you guys what it is after I received it and it's working.

About the lemo cable clone from China. It would be custom made by Eonvic. However. They won't use branded USB cables. Instead, they may just use generic USB 2.0 cable which may not be up to specs. Has anyone of you own any Eonvic product like this?

https://www.amazon.com/gp/product/B06XKV73C1/ref=ox_sc_act_title_1?smid=A1PUUT3OIOMJ0X&th=1

What generic china USB 2.0 cable do they use?

About the $400 original USB lemo cable. When you go to tire shop and have your flat tire patched. They rotate it and put some small iron to make it balance. So in the case of the original Lemo USB. Maybe they do something similar to it to patch the impedance mismatched by maybe increasing the diameter of the wire at the end or make the insulator thicker?  This is close up picture of the original cable by another Ebay seller of the equipment which includes cable. Do you recognize what kind of cable is that? Maybe even Milspec?

[Ogitek]

I tried zooming in the cable picture above now and seem to make out the words "CMG LL84201 CSA CABLE  COPARTNER FT4". I googled it and the following page comes up.

https://www.ebay.com/itm/374199291173

UTP Patch Cable?  The original $400 USB LEMO didn't even use USB cable but a UTP Patch Cable? What you make of it? They used ODU plug size 0 compatible with the Lemo FGC.0B.

[abeyer]

It supposedly is "audiophile equipment", so forking out $400 for cables is the obvious thing to do and frankly a bargain

True, but creating long meandering threads of psuedo-scientific/engineering blabber without really knowing what you're talking about is also quite on point for audiophoolery.

[coromonadalix]

utp =  un-shielded twisted pairs 

FT4 specification from : https://www.sycor.com/blog/post/csa-ft1-ft2-ft4-ft5-and-ft6
The FT4 certification is one of the most popular as it has one of the toughest tests to pass, given the 70,000 BTU/hour flame. This certifications testing procedure has cables mounted on a vertical tray, which are exposed for 20 minutes to a 70,000 BTU/hour flame. This test is identical to the IEEE 1202 flame test. The FT4 and IEEE 1202 reduced char height requirements make them slightly more difficult to pass than the UL1685 vertical tray version.

The pass or fail criteria for the FT4 certification is the finished wires or cables shall not exhibit charred material beyond a length exceeding 1.5 m (5 ft.) from the lower edge of the burner face when subjected to the test (CSA C22.2 No.38).



for an usb to the lemo,  any good usb cable should have 4 conductors plus a shield, better if it's a foil and shielded braid, you connect the end shield to the lemo casing

and yes this thread      close it 

[Ogitek]

You didn't answer why the original USB Lemo cable shown in the picture uses ethernet cat5 cable (with 4 pair of twisted wires). I read ethernet wire has higher impedance like 100 Ohm). Is this to match the Lemo plug which is 100 Ohm for impedance match. Or is it irrelevant and one can use USB cable or ethernet cable for USB 2.0?

The China cloner is waiting for my payment and I need to know the last critical information above to make the final decision. Thanks.

[voltsandjolts]

The connector in your picture above is not a Lemo.
You've already been told what it is in another one of your moronic threads.

[Gyro]

Surely for an Audiophile cable you should be specifying OFC (Oxygen Free Copper) cable conductors. Gold plated USB connector contacts and shell, and a genuine Lemo connector rather than a Chinese clone?

[tooki]

I still don't have the equipment, it is still on the way from a seller in Taiwan. The mail is long.  I'm not even sure the equipment works. In case it doesn't work. I want to get one of 2 remaining items left at Ebay. If I tell you now and some of you empty the shelf. Then I won't have any more left over to get. I'll tell you guys what it is after I received it and it's working.

LMAO. This isn’t an audiophile forum, and if anything, is generally very skeptical of “audiophile” stuff because stuff so labeled (and people who call themselves that) are frequently quite divorced from objective reality…

About the $400 original USB lemo cable. When you go to tire shop and have your flat tire patched. They rotate it and put some small iron to make it balance. So in the case of the original Lemo USB. Maybe they do something similar to it to patch the impedance mismatched by maybe increasing the diameter of the wire at the end or make the insulator thicker?

LOL no. Again, as I have already explained to you, impedance mismatch was not the problem with the failed cables in that thread you’re giving so much weight to. The problem is that they didn’t connect the shield at all. The shield is essential.

This is close up picture of the original cable by another Ebay seller of the equipment which includes cable. Do you recognize what kind of cable is that? Maybe even Milspec?

That’s a cheap generic USB cable with a LEMO-style plug added to one end. That’s it.

I tried zooming in the cable picture above now and seem to make out the words "CMG LL84201 CSA CABLE  COPARTNER FT4". I googled it and the following page comes up.

https://www.ebay.com/itm/374199291173

UTP Patch Cable?  The original $400 USB LEMO didn't even use USB cable but a UTP Patch Cable? What you make of it? They used ODU plug size 0 compatible with the Lemo FGC.0B.

And if you looked at more search results, you’d find that the same markings are found on a wide variety of cables, including VGA cables and serial cables. So you’re definitely wrong in assuming it means it’s Ethernet cable.

[Ogitek]

The connector in your picture above is not a Lemo.
You've already been told what it is in another one of your moronic threads.

Lemo is compatible to Odu. And since Odu is not a clone of Lemo. I refer to it as Lemo just for sake of discussion. This is in contrast to Lemo clone which are brandless.

Surely for an Audiophile cable you should be specifying OFC (Oxygen Free Copper) cable conductors. Gold plated USB connector contacts and shell, and a genuine Lemo connector rather than a Chinese clone?

You have a point. I'm recording nature's sounds. And don't want to miss a note. What is the impedance of original Lemo vs Lemo clone?

[Gyro]

Surely for an Audiophile cable you should be specifying OFC (Oxygen Free Copper) cable conductors. Gold plated USB connector contacts and shell, and a genuine Lemo connector rather than a Chinese clone?

You have a point. I'm recording nature's sounds. And don't want to miss a note. What is the impedance of original Lemo vs Lemo clone?

   Who knows, it's a Chinese clone!


Edit: Seriously though, I don't think you are going to find an answer here that will satisfy you.

[magic]

Is that original Lemo connector even rated for wave impedance at all?
Anyone has a datasheet or knows the exact part number?

Or is the 'phool vendor using it only because it looks cool, sounds better than micro-USB and requires the sucke, pardon, customers to purchase a custom cable for $400?

Anyway, USB 2.0 can run over all sorts of garbage cables and connectors (this one is probably another testament to USB's robustness), so it shouldn't matter much what particular garbage you use...

[Ogitek]

Is the original connector even rated for wave impedance at all?

Or is the 'phool vendor using it only because it looks cool, sounds better than micro-USB and requires the sucke, pardon, customer to purchase a custom cable for $400?

Anyway, USB 2.0 can run over all sorts of crap cables and connectors (this one is probably another testament to its robustness), so it shouldn't matter much.

I thought USB 2.0 Hi-Speed (480Mbps) can't run over all sorts of crap cables and connectors and it has to change mode to USB 1.1 Full-Speed (12Mbps)? If I'll try to test my USB 2.0 to my external drive via a USB Hub. Where can I see the speed displayed in 480Mbps or 12Mbps?

[Ogitek]

Surely for an Audiophile cable you should be specifying OFC (Oxygen Free Copper) cable conductors. Gold plated USB connector contacts and shell, and a genuine Lemo connector rather than a Chinese clone?

You have a point. I'm recording nature's sounds. And don't want to miss a note. What is the impedance of original Lemo vs Lemo clone?

   Who knows, it's a Chinese clone!


Edit: Seriously though, I don't think you are going to find an answer here that will satisfy you.

Are chinese LEMO clones also made of Nickel and chrome plated? How do I know? I have 2 pcs coming in a week.

[Andy Chee]

You have a point. I'm recording nature's sounds. And don't want to miss a note. What is the impedance of original Lemo vs Lemo clone?

The impedance mismatch in  the USB section of the cable is mostly irrelevant due to the USB protocol's error detection & correction.

Arguably the impedance in the analog cable section of your audio chain is also irrelevant, but given the general vibe of your questions, this is beyond your understanding.

[Ogitek]

Is that original Lemo connector even rated for wave impedance at all?
Anyone has a datasheet or knows the exact part number?

Or is the 'phool vendor using it only because it looks cool, sounds better than micro-USB and requires the sucke, pardon, customers to purchase a custom cable for $400?

Anyway, USB 2.0 can run over all sorts of garbage cables and connectors (this one is probably another testament to USB's robustness), so it shouldn't matter much what particular garbage you use...

The China wire suppliers said he would use UGreen to solder to the Lemo clone. So comparing it to a real LEMO plug. There would be a difference in the data? USB 2.0 has no error correction and so garbages can occur? I don't want the sound of waterfall to have noise that would sound like the cry of a wolf inside it because it will totally destroy the purpose.