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Simple (I hope) cable question

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Folks:

In my study, I have an iMac that I’m using to serve music (Roon and Tidal) via Apple express to remote locations in the house - not critical listening and all is fine.  Except sometimes I want to listen critically to hi res files in my study.  The issue is that my iMac and the audio system in my study are on opposite sides of the room so I need a long (about 16’) USB cord to my study dac (Schiit Bifrost Multibit with gen 5 USB) OR a long set of interconnect cables from my dac to my amp.  Question: Which solution will degrade the signal the least (longer USB or longer RCA interconnect)? 

Thanks,

Mike

 

P.S.  I posted this on AudioAsylum and got conflicting responses almost immediately.  I'm hoping for a less ambiguous result here.  8^)

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Indydan   

I once asked my dealer this question. He said go short on USB, long on the analog interconnects. Apparently, USB (digital in general) degrades faster over long cable runs.

 

I installed a 6 foot USB to DAC, then a 12 foot analog interconnect from DAC to amp. It is not ideal, but it worked just fine. 

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gmgraves   
35 minutes ago, Indydan said:

I once asked my dealer this question. He said go short on USB, long on the analog interconnects. Apparently, USB (digital in general) degrades faster over long cable runs.

 

I installed a 6 foot USB to DAC, then a 12 foot analog interconnect from DAC to amp. It is not ideal, but it worked just fine. 

 

Technically, this is correct. Keep the USB interface as short as practical. Long analog interconnects will do less harm. A 20 foot interconnect is only like 1 dB down at 20 KHz and less in shorter runs. You can't hear that. OTOH, long runs of USB cable invite errors which definitely will make your music sound worse!

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3 hours ago, gmgraves said:

 

Technically, this is correct. Keep the USB interface as short as practical. Long analog interconnects will do less harm. A 20 foot interconnect is only like 1 dB down at 20 KHz and less in shorter runs. You can't hear that. OTOH, long runs of USB cable invite errors which definitely will make your music sound worse!

i would think the type of rca''s would make a difference too....I usually won't buy expensive cables, but my brother gave me some silver rca cables, and I "believe" i did hear a difference.

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mansr   
3 hours ago, gmgraves said:

Technically, this is correct. Keep the USB interface as short as practical. Long analog interconnects will do less harm. A 20 foot interconnect is only like 1 dB down at 20 KHz and less in shorter runs. You can't hear that. OTOH, long runs of USB cable invite errors which definitely will make your music sound worse!

A 20-foot USB cable is non-trivial. However, if it works, there is no degradation of the music signal. Also, two 10-foot cables with a hub in between (even a bus powered one) should work reliably.

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gmgraves   
35 minutes ago, beerandmusic said:

i would think the type of rca''s would make a difference too....I usually won't buy expensive cables, but my brother gave me some silver rca cables, and I "believe" i did hear a difference.

 

You might think that the type of RCAs would make a difference, but they don't. Silver's a better conductor than copper, but over a length of three  feet or less (the normal length of MOST home audio interconnects), I have found that you could use a straightened coat hanger as an interconnect, and you wouldn't hear a difference (as long as the two chassis were grounded together some other way). I don't think I'd recommend it though :)

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esldude   

https://www.monoprice.com/product?p_id=6149

 

These $8.71 plus shipping active USB extenders also work just fine.  This one is 32 ft, there are different lengths.  You'll suffer zero problems at least up to 192 khz and 24 bit files.  I have used a couple longer than this without problems.  I would prefer it to a pair of analog cables.  Though actually either for 16 ft will work fine. 

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gmgraves   
33 minutes ago, mansr said:

A 20-foot USB cable is non-trivial. However, if it works, there is no degradation of the music signal. Also, two 10-foot cables with a hub in between (even a bus powered one) should work reliably.

 

Yes, a 20 ft USB cable is non-trivial. Suspect that it would work reliably, but I hesitate to say that there is no degradation of the music signal. I suspect that the error rate would go through the roof, and error correction would be working overtime. And if the errors force the DAC into interpolation, one can certainly hear it! 

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gmgraves   
8 minutes ago, esldude said:

https://www.monoprice.com/product?p_id=6149

 

These $8.71 plus shipping active USB extenders also work just fine.  This one is 32 ft, there are different lengths.  You'll suffer zero problems at least up to 192 khz and 24 bit files.  I have used a couple longer than this without problems.  I would prefer it to a pair of analog cables.  Though actually either for 16 ft will work fine. 

 

You know, that probably would work fine and the price is certainly reasonable. I wasn't thinking of repeater cables when I made my response. In fact I didn't even know that such a puppy existed! I knew that hubs could extend the range, but they are messy at best. In fact, I think I'll order a couple of these from Monoprice. Thanks for the heads up. 

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rickca   

Well, if you're willing to spend some real money, the best solution is probably an Adnaco USB extender that uses fiber cable.  This has the additional benefit of galvanic isolation.

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26 minutes ago, wwaldmanfan said:

Never tried one myself, but the Corning fiber optic USB cables were quite the rage here for a few weeks. A ten meter one of those with a USB A-to-B jumper might be a solution.

https://www.corning.com/microsites/coc/ocbc/Documents/CNT-009-AEN.pdf

this is VERY interesting, and probably worthy of it's own thread!

 

I wonder if you can use one of these extender cables to eliminate noise from standard usb cables and if they will actually work with DACS???

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mansr   
1 hour ago, gmgraves said:

Yes, a 20 ft USB cable is non-trivial. Suspect that it would work reliably, but I hesitate to say that there is no degradation of the music signal. I suspect that the error rate would go through the roof, and error correction would be working overtime. And if the errors force the DAC into interpolation, one can certainly hear it! 

Either the signal at the far end is within specified parameters, or it is not. If it does meet the spec, there will be no problems regardless of cable length (although actually achieving this for cables longer than about 10 feet is tricky). Errors only start showing up when the received signal is out of spec. At that point, the degradation quickly becomes catastrophic.

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8 hours ago, wwaldmanfan said:

Never tried one myself, but the Corning fiber optic USB cables were quite the rage here for a few weeks. A ten meter one of those with a USB A-to-B jumper might be a solution.

https://www.corning.com/microsites/coc/ocbc/Documents/CNT-009-AEN.pdf

 

Had bad experience with Corning Optical USB, unreliable, too much hassle.

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esldude   

The USB active extenders have a circuit of some sort in the far end of the cable.  It is of course USB powered.  The signal leaving that is fractionally lower than 5 volts (I think for some reason I can't remember they are 4.5 volts).  If you are feeding a USB powered device that might cause trouble (though not always I have found).  If you are simply passing data it has never been an issue in my experience with them.  You can daisy chain them if just passing data.  At that point no USB powered device will work.  Data may or may not work depending upon the device.  If you go past two in series it doesn't work at all.  But one of those puppies even in the 78 ft length will feed a DAC with nary an issue I have seen. 

 

I have never tried feeding an active hub at the end of one and then feeding another extender from that.  It might well work for lengths of 150 feet that way.  Yes ethernet was made for that, but sometimes your gear only has USB. 

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mansr   
5 hours ago, esldude said:

The USB active extenders have a circuit of some sort in the far end of the cable.  It is of course USB powered.  The signal leaving that is fractionally lower than 5 volts (I think for some reason I can't remember they are 4.5 volts).  If you are feeding a USB powered device that might cause trouble (though not always I have found).  If you are simply passing data it has never been an issue in my experience with them.

High-speed USB signalling is only 400 mV, so if the circuitry at the far end doesn't require a full 5 V, a slight drop will be of no consequence.

 

5 hours ago, esldude said:

I have never tried feeding an active hub at the end of one and then feeding another extender from that.  It might well work for lengths of 150 feet that way.  Yes ethernet was made for that, but sometimes your gear only has USB. 

In such cases, an Ethernet based USB extender might be a better option.

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On 9/25/2017 at 2:20 PM, gmgraves said:

 

Yes, a 20 ft USB cable is non-trivial. Suspect that it would work reliably, but I hesitate to say that there is no degradation of the music signal. I suspect that the error rate would go through the roof, and error correction would be working overtime. And if the errors force the DAC into interpolation, one can certainly hear it! 

There is no error correction in isochronous mode which is what USB audio uses. There is a CRC that can be checked at the receiver, but no way to correct or resend.

 

About a year ago I did a whole bunch of tests on actual error rates of different USB cables for USB audio.

 

Real cheap basic cables: errors started showing up after about 5 feet, so 3 ft cables do well but 6ft and longer can cause problems.

 

Good quality but still inexpensive cables do better, they can be good up to about 10 ft.

 

The Supra cable was the only one I had that had no errors over 10ft.

 

I did not try any of the really expensive "audiophile" cables. My guess is they would be worse than the Supra.

 

I have tried the Corning and for me in my system it worked very well. Others have not had this experience

 

John S.

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Icron Ranger USB 2.0 extenders, one or more ports whatever you wish. Single port is USD350 something. USB Cables at either end, and up to 100m of Ethernet wire in between. Solved, using this system for years now, very reliable and transparent, shows up lousy USB fixers or excellent ones, detect USB cable differences, if your ear is tuned enough ;)

 

There's a USB3.0 extender in one cable, 15m cable though.

 

iFi Audio have demonstrated in Japan five 5m USB cables in tandem with their iPurifiers in the system as these devices are extenders as one of their prime functions.

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Em2016   
1 hour ago, JohnSwenson said:

Real cheap basic cables: errors started showing up after about 5 feet, so 3 ft cables do well but 6ft and longer can cause problems.

 

Hey John, did these cheap basic cables that had errors showing up, even include High Speed Certified USB cables?

 

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marce   
1 hour ago, JohnSwenson said:

There is no error correction in isochronous mode which is what USB audio uses. There is a CRC that can be checked at the receiver, but no way to correct or resend.

 

About a year ago I did a whole bunch of tests on actual error rates of different USB cables for USB audio.

 

Real cheap basic cables: errors started showing up after about 5 feet, so 3 ft cables do well but 6ft and longer can cause problems.

 

Good quality but still inexpensive cables do better, they can be good up to about 10 ft.

 

The Supra cable was the only one I had that had no errors over 10ft.

 

I did not try any of the really expensive "audiophile" cables. My guess is they would be worse than the Supra.

 

I have tried the Corning and for me in my system it worked very well. Others have not had this experience

 

John S.

What speed was the USB running at?

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marce   
12 minutes ago, Em2016 said:

 

Hey John, did these cheap basic cables that had errors showing up, even include High Speed Certified USB cables?

 

?

The thing here is distance, you have to take into account the drive strength of the USB transceiver, USB data speed, how the cable was terminated at the far end.

Digital and cables and distance... A remote industrial serial interface I know of can do 200m on basic belll wire, go to a shielded Beldon twisted pair and we got a signal 1km... cheaper cables tend to have higher high frequency attenuation so the waves loos there shape over distance becoming rounded and ISI increases, so if you have to go long use a decent cable, if your only going a few feet any cable will be bit perfect.

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Em2016   
21 minutes ago, marce said:

?

The thing here is distance, you have to take into account the drive strength of the USB transceiver, USB data speed, how the cable was terminated at the far end.

Digital and cables and distance... A remote industrial serial interface I know of can do 200m on basic belll wire, go to a shielded Beldon twisted pair and we got a signal 1km... cheaper cables tend to have higher high frequency attenuation so the waves loos there shape over distance becoming rounded and ISI increases, so if you have to go long use a decent cable, if your only going a few feet any cable will be bit perfect.

 

John mentioned he saw errors with cheap cables over 5ft.

 

But there are High Speed Certified USB cables that are cheap and up to 10ft (Supra not included in this because those aren't cheap).

 

So my question is asking if errors showing up with cables >5ft even included cheap High Speed Certified Cables.

 

Or does High Speed Certified mean error free, regardless of length. 

 

For those that don't know, the Supra USB cables are High Speed Certified for up to 15ft but I'm not asking about those.

 

 

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