Triode's USB 24/192 plug in - sound quality impressions

[JohnSwenson]

The way EDO works when selecting the 192 digital out will use less memory and will result in less processing going on. (please note that this output will do all sample rates up to and including 192, not JUST 192). What Triode has done here COULD have been done with the original S/PDIF driver (and IS done in TT3.0). Triode has just chosen to bundle the changes in the way the driver is used with the new driver, as far as I can tell there is nothing different in the new driver other than support for 192. The differences are all in the way the driver is used.

Are these differences going to affect sound? Maybe. First off it depends very much on how sensitive a DAC is to whats going on with the input. Some are quite sensitive to jitter in the input, noise, reflections etc. Others are fairly insensitive to this. (I have yet to find a DAC that is COMPLETELY insensitive to what's happening on the input) (all this of course is assuming the the bits are all getting across without errors)

I don't think anybody has a complete definitive explanation of what's going on, but there are some speculations. My theory is that most of the changes to the S/PDIF signal are coming about because of ground plane noise. There is a perception amoungst a lot of people that a ground plane is a large equipotential (same voltage everywhere) system, this is far from the truth. The impedance of a ground plane is NOT zero, its not a lot, but it is still there. A digital system like the Touch has all kinds of high frequency currents flowing all over the place through the ground plane, the impedance of the plane is enough to cause voltage differences to develope on the plane due to those currents flowing through it. Everything on the board is going to be affected by this noise to some degree. Digital logic IS affected by it, but in most cases it's not great enough to cause any issues. Where it becomes an issue are things like the local oscillators, the recloking flop, DAC chip etc. For S/PDIF output, the two most critical parts are the local oscilators and the reclocking flop. This noise can cause increased jitter on the clock and is also directly injected as noise onto the output.

I have actually measured this ground plane noise. I built a simple device that detects and amplifies the noise and sends it to a spectrum analyzer. I can actually see changes in this ground plane noise with changes in what is going on in the Touch. I'm in the process of building a much more sensitive ground plane analyzer, sometime this summer I hope to have it up and running and can do some better tests.

Of course then you have to do correlations between this ground plane noise and what changes this makes in SOUND at the output of a DAC. That is a whole different kettle of fish. This is going to be hampered by the way that different DACs will deal differently with any changes.

So the upshot is that yes I have actually measured real electrical changes in the Touch due to these types of changes, these changes have the possibility that they may cause audible changes, whether they do has not been determined. If they due cause an affect, that affect will almost certainly be different or non-existent for different DACs.

Can I personally hear the difference? On some DACs yes and on some no. On the ones that I can hear the difference it's not a huge night and day difference.

John S.

[Dave1972]

Can I personally hear the difference? On some DACs yes and on some no. On the ones that I can hear the difference it's not a huge night and day difference.

John S.

At least that's a more sober assessment than the guy who stated that going from the incredible sound of the Touch +App back to the stock Touch was like listening to a transistor radio.

[jksbt]

FWIW--one of the more obvious differences in SQ (in addition to those I noticed with EDO) was soundcheck's advice to cause FLAC decoding to be done on the LMS instead of the sbt. It doesn't require the TT3.0. This improvement was very clear and required a simple setting change to the file types menu in LMS settings.

[Dave1972]

FWIW--one of the more obvious differences in SQ (in addition to those I noticed with EDO) was soundcheck's advice to cause FLAC decoding to be done on the LMS instead of the sbt. It doesn't require the TT3.0. This improvement was very clear and required a simple setting change to the file types menu in LMS settings.

Have you tested that double-blind?

Performance-wise, I am finding my Touch running the Tiny server is performing very well. It's currently loaded with just short of 5000 tracks and Memory Used is at 73% so still plenty of headroom. Before installing the app I would generally get stutters at the end and/or beginning of songs with more than about 4500 tracks loaded. I'll keep moving more tracks onto it to see how it copes. May be a coincidence as the Touch can be temperamental anyway.

[jksbt]

Double blind testing...nope. Maybe double ear testing though. ) Just kidding.

I have checked it many times and I feel confident I can hear the difference. I don't mean to claim that you or anyone else will. I believe I heard more detail and more articulated sound. But, again, this is on my system with my ears. YMMV.

[tonyptony]

- it does not start an effects jive_alsa process (it is assumed users don't want to hear the effects processing)
- it bypasses the alsa plug layer and uses the spdif output "TXRX" directly, simplifying the amout of processing required between jive_alsa and the spdif output driver

Does anyone know if Inguz uses the alsa plugin layer or the jive_alsa process? It would be unfortunate if this interesting new app is not able to run with Inguz in line. I'll have to try it out and see.

[Triode]

Does anyone know if Inguz uses the alsa plugin layer or the jive_alsa process? It would be unfortunate if this interesting new app is not able to run with Inguz in line. I'll have to try it out and see.

Inguz is all server side and this is all done on the Touch player so don't see why they can't coexist.

[bobertuk]

Does anyone know if Inguz uses the alsa plugin layer or the jive_alsa process? It would be unfortunate if this interesting new app is not able to run with Inguz in line. I'll have to try it out and see.

I've been using Phil Leighs 'custom-convert.conf' for Inguz which uses 'sox' to upsample all 44.1k audio to 96k. I modified his 'custom-convert.conf' to upsample everything to 192k and everything is working well.

Inguz is upsampling to 24/192k and my DAC is receiving audio as 24/192k. So in short - yes, Inguz works with Triodes EDO app.

Bob

[tonyptony]

Thanks Triode and Bob!

[Dave1972]

Double blind testing...nope. Maybe double ear testing though. ) Just kidding.

I have checked it many times and I feel confident I can hear the difference. I don't mean to claim that you or anyone else will. I believe I heard more detail and more articulated sound. But, again, this is on my system with my ears. YMMV.

If I had a quid for every time I heard someone say "No, I haven't tested it double-blind because I'm confident I can hear the difference" I'd have £11. Sorry, make that £12 now! I'm not claiming there is no difference - just that I don't even trust my OWN ears against the placebo effect, never mind other people's. No one is immune to it. NO one, I tells yer, mmmwhahahaha!