HiFiBerry Digi+ Works Best on RCA...!

[deleted]

Grundgütiger wroteMy suggestion is that Hans Beekhuyzen used the Transformer version of the Digi+ board. He mentioned that he payed 35 Euros which - as for today - is the price for that version. From HiFiBerry's web site: "The output transformer provides a full galvanic isolation between the Raspberry Pi and your DAC on the electrical output". This would explain the difference between the optical and the electric outputs Hans mentioned in his video.

The output transformer is only before RCA because RCA is the only electrical output from Hifiberry Digi. Optical output, as it's OPTICAL, not ELECTRICAL is fully galvanically separated by itself thus it doesn't need any transformer.

zycamaniac

Just my two cents on digital signal, or SPDIF in particular...

In normal cases, where you spent virtually NOTHING on the digital cable (optical or coax), Coax will DEFINITELY sound better. This is due to the huge diameter of the Toslink fiber optics, where internal reflection with such large diameter of cable will cause some of the light pulse to arrive later, some earlier. instead of getting a sharp on/off, you get a slow brightening/dimming effect (to the detector), and this cause the receiver to trigger at unpredictible interval, and thus creating jitter.

Since clock is part of the SPDIF signal, jitter here will just screw everything up.

Coax on the other hand, does not have this problem, at least not as bad.

However, if you plan on spending on a cable that costs much much more than Raspberry Pi (that's what I'm using now), you can get optical cable the works better than most coax cable, plus you also get optical isolation thrown in for free.

My own experiment is that multi-fibered optical works much better, likely due to smaller diameter of each fiber limiting the path that the light can travel, and thus reducing the effect of some signal arriving earlier/later. (I don't think you can eliminate that unless you go single mode, but I don't think we are going to see specialized single mode fiber here anytime soon.)

The more fiber it have in the same 1mm diameter, the better the performance, but the law of diminishing return works here, you will be paying a lot of money for the last bit of improvement. To some, it is utterly stupid, since it is not their setup's weak link, and often a cheap coax will work just fine for them. To others, who might already be spending a pile of money on their system, it could be the cheapest upgrade in their system, which would work out well for them.

BTW, just setup my Raspberry Pi 2 + Digi+ compatible digital output a few days ago... and damn it sounds great... I'll check back and see which sounds best, I currently have 3 ways to connect to my DAC:
Optical
Coax/BNC
USB (This one can do DSD!! yes!)

It should be fun trying them all out. To anyone who want to test different interfaces, quickly listening to a short piece and switch quickly to another usually don't work for me. I usually listen for a while on one, then switch to another for a while, this is where I can pick up the differences.

Beelzebassie

zycamaniac wrote(...)

Sounds like a lot of audiophile bullcrap to me... Provide us with some decent math based on actual measurements.

zycamaniac

Beelzebassie wrote
zycamaniac wrote(...)
Sounds like a lot of audiophile bullcrap to me... Provide us with some decent math based on actual measurements.

I had some tools to measure them a while back, but since I'm not in the business anymore, I didn't kept them. If you want to read more into this, check out how clock signal is embedded into the SPDIF, as well as the ambiguous state in electronics and how it affects operation. In short, the less time it takes for a signal go from 1 to 0 or 0 to 1, the less time it spent in ambiguous state, the less chance of jitter being produced.

If you really want to know, study, I'm not really here to teach you on that. Suffice to say, clock jitter affects final output quality just like turntable jitter affects vinyl's output quality. A lot of it is quite similar yet different. Don't believe it? sure, fine with me.

Beelzebassie

zycamaniac wroteDon't believe it? sure, fine with me.

That was exactly my point; it has nothing to do with 'believe', just math...

Discovery

As the original poster, I would suggest the answer only relates to what I hear with my ears. Jitter does play a part; perhaps maths does too, depending on your point of view. However the ONLY thing that matters to me is the perceived sound quality.

I'm happy to entertain any visitors to allow them to use their own ears to decide...

Corvanzundert

Dear all,

I just switched from an ASUS EEE PC with USB > M2TECH > TENTLABS b-DAC
to a Raspberry Pi2 with a digi+ PRO board, connected to the TENTLABS b-DAC.

Just like you I noticed more bass and also mid response but .. also much less details in the higher frequencies.
My first impression is that I am missing a lot of details.

My first step for improvement was to use an accupack instead of the Raspberry powersupply and that .. sounds better
but still I am missing lots of details.

Playing a Raspberry with a Collibya DAC or an Audiophonics DAC and connect it directly to my monoblocks sounds A LOT BETTER.

Has anyone an idea how this difference can occur ??

I expected the connection through RCA and using the Digi+ PRO board would sound exactly the same ..

Cor van Zundert,
The Netherlands.

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