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sergedc 22nd April 2012 03:40 AM

USB Cable
Hi All,

I recently purchased Hifi360 HF-D1B, a USB 5.1 sound card (among other functions). I chose this one because I wanted: something with its own power and RCA output (not 3.5mm which I believe to be rubbish).
(HF-D1B) DTS DAC [HF-D1B] - $188.00 : DAC,Audio Amplifier,Hifi Amplifier,Tube Amplifier,Hlly Audio, Hlly Electronics

I use it for movies with multi channels. There are 2 ways I can use it:
- USB: Allows me to play directly the AAC multi channel format. So if someone rip a BR (usually DTS-HD) to AAC 448kbps, I can directly output each of the channels to the RCA plugs, then to my amp.
- Optical: Optical does not support multi channel, so I have to encode the AAC 448 kbps into AC3 640 kbps. The HF-D1B then decodes the DD5.1 signal.

I need some help in gueting things right:
1. I have 2 concerns about using optical:
- When converting from AAC 448 kbps to AC3 640 kbps, am I possibly losing quality? Moreover, by the time people start encoding BR in AAC 640, I will surely be loosing in quality by converting to AC3 640 kbps.
- My USB to optical devise is a Creative X-Fi 5.1 (old model, not the new one called "pro": the old model does not allow bit perfect transfer) which is not the best out there.
2. As a result my preferred chose is USB. The HF-D1B is 7.5 meters away from the laptop (I use a projector, so the laptop need to be next to the projector). I currently use an USB extension cable (A male - A female) rated: 24/28 AWG. It strongly deteriorates the sound. I know I should not use such a long cable, but I really have no chose. I want to upgrade the extension cable and would love to have your views on which metrics are important.
- I understand that when a cable is rated : 20/28 AWG (like the belkin, link below), the 20 refers to the power and the 28 refers to the signal. Is the deterioration in sound quality that I am facing due to power or signal? Since the HF-D1B is fully powered, I would think that I should only be concerned with the second number (the 28, which refer to the signal). If I am correct, this cable will provide no improvement over the one I currently have.
- If my statement above is wrong, there exist USB expansion cable with their own power, maybe that would help? (link of such a cable below)
- What characteristic should I look at when considering the USB cable? AWG? Oxygen free copper?
- Would it be better to use 1 long cable from the HF-D1B straight to the computer rather than using an extension cable? Or it makes no difference?
- Would using a USB to RJ45 to USB solution help? (see link below)
- If all of the above are very bad ideas, could I build a cable myself? If so, could you give advise on which cable to go for.

Belkin: Belkin USB Active Extension Cable - USB extension cable - 4 pin USB Type A (M) - 4 pin USB Type A (F) - 16.4 ft - active cable (signal regeneration) 16FT USB ACTIVE EXTENSION CBL USB-A/A 20/28AWG Manufacturer Part Number F3U130-16: Office
USB cable with own Power (sorry, no english here):
USB to RJ45 Tech-top Technology Ltd

Needless to say, I can not consider an AudioQuest coffee 5m (700 USD) because: 5m would still be a bit short for me, and I am looking for a much cheaper solution.

I will post a review of the HF-D1B later. Currently using shitty cables and still figuring out how to get the most of it.

Cheers all,

sergedc 23rd April 2012 07:30 AM

Hi again,

I read a bit more and understand that long RCA might be a better chose than long USB. However, for me it would be more troublesome (the HF-D1B would then be 8m away from the FM radio wall plug...). Also, it is difficult to find a 8m RCA cables of quality similar to my current 1.5m ones.

Could someone explain me why long USB is so bad? It is not only about jitter. When I use my current extention cable it sounds way less good. Worst was when I used a USB hub.

While long USB is bad, there surely is one of the option I listed in the original post that is less bad (active extension, powered cable, RJ45 converter). If I stay with USB, I want to make sure I select the best option. Any advise?


SoNic_real_one 23rd April 2012 10:47 AM

First of all you said "Optical does not support multi channel". That is false, optical doesn't need to support nothing, decoding is a function of the processor inside.

AAC format is garbage put out by Apple (for iPod, iPad, iPhone). The multichannel formats that are allowed by standard to be on DVD, BR are "AC3" (called also "DolbyDigital") and "DTS" (with several variations for HD sound). Those formats are decoded by any digital receiver. I won't go in legality of the files that you use, but if you make you OWN backups, there is no reason to transcode the sound that is already recorded in DD or DTS to AAC. ACC is not decoded nativelly by any receivers, works primarily on Mac computers. Do your backups in the native format: DD (AC3) or DTS.

USB is the worst connection that you can have in audio world. Use digital out from your card on motherboard if you have one.
Your Creative X-Fi (you didn't say the exact model, I assume is the Sound Blaster X-Fi Surround 5.1) has the ability to send out the to an external decoder the Dolby Digital or DTS signals. There is not an issue about "bitperfect". Get the latest drivers.

sergedc 23rd April 2012 11:44 AM

Hi SoNic,

Thank you for your answer. If you rip BR, not DVD, the source is DTS-HD (which is lossless, as oppose to DTS/DD). Encoding the DTS-HD into AAC will give you a higer quality than AC3/DD at similar bitrate.
Moreover, when playing a BR, I want to send the DTS-HD (lossless) sound to the dac (the HF-D1B), not compress it into AC3 on the fly before sending.

When I output DD using outpical output, the decoder of my amp has problems: it starts ok, but then it looks like it cannot decode fast enough and the sound gets broken. Or myabe it is a problem with my ffdshow config (because I had the same problem with another amp a few years back).

I know UBS is the worst, but surelly one cable is less bad than the other..... any view on which one? or which characteristics are important for USB audio?

With regards to legalitty: I download rips of movies I own in my own country (which I had to leave for work reason), so I think this is ok.


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