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Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter
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Old 21st May 2019, 12:40 PM   #4931
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by soundcheck View Post
@palmito
Interesting that potentially good solutions just get forgotten.
Or maybe Ian had his reasons !?!?
As palmito's post demonstrated, they did not get forgotten. Ian along with others came up with interesting solutions to the same problem. Clocks perform better when isolated from vibration.

His floating pcb on an elastic band was taken further by other experimenters who found suspension with dental floss to be superior. Where possible I use both approaches.

His rubber grommet mounting was also effective. It prompted me for example to set the standoffs in 2cm hole filled with silicone as a cheap but effective proxy.
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Old 21st May 2019, 01:00 PM   #4932
wlowes is offline wlowes  Canada
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Originally Posted by soundcheck View Post
That's why I'm not a big fan of hooking up 4+ power supplies to a HAT tower.
If 4+ PS sound better then 2 it'll just show that there's a weakness on the HAT. That should trigger the designer to look after it.

The same applies to attaching Farrads of capacity to a (or any) power rail.
As long as nobody understands what's actually going on all this here remains a wild fishing exercise and will keep us tweakers busy until EOL.
Everyone has their priorities. But if you are suggesting that buying advanced ethernet cable (or any cable) should be a priority over perfecting PS or clocks, then be clear that priority is not driven by sound quality.

I agree that cables make a difference, and in the case of IC, power and speaker cables I build my own to my satisfaction dirt cheap, but that is another topic. In the case of ethernet cable I can't help thinking that gagabit spec'd cable will get the bits to the Pi with sufficient accuracy. Sure there may be noise from the cable, but it is connected to the Pi which is an open board computer generating all kinds of noise. So I chose to put the ethernet cable, the Pi and all its digital friends in a Faraday cage separate from the DAC and analogue outputs. Might not be perfect, but it was cheaper than buying an exotic cable, and it works for me.

Similar approach with the supercaps. 10+ years experience taught me that sound improvements GregS hears can be duplicated in my system. So when he said that the Uptone Audio supercap supply delivered top performance, it got me thinking. So I checked out their site and realized they use Nesscaps. I happen to have a bunch of these things that also cost me nothing, so why not emulate the Uptone approach and see if there was anything to it. My experience was identical to review after review, so I reported it here in case anyone wanted to try it. I see speculation on this site as to what may cause the improvement. But speculation without scientific proof is not well received here for good reason. I'll leave it to the engineers to figure it out. In the mean time I will enjoy great sound at low cost and be content.

Last edited by wlowes; 21st May 2019 at 01:04 PM.
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Old 21st May 2019, 02:42 PM   #4933
soundcheck is offline soundcheck  Germany
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I'm not questioning that you or anybody else experience differences. I do too.

What I'am saying is you can't answer the "Why? What's causing it?" question.
And that leads to endless and very expensive trial and error projects.


Yep. Greg is the fishing master. I'd agree.
But he's simply following a basic recipe that's known for years.
He obviously brought the device and part swapping tactics to different, close to IMO insane, levels.

Of course I do understand the background behind all this.

1. Most people want quick results
2. People lack skills to approach a subject like an engineer would do
3. Even if you'd have the knowledge people lack measurement equipment
4. Most designers stick to textbook designs, they need to accept compromises - and that's where the tweakers job start.
5. What the designers can't measure won't be addressed.
6. What the competition is lacking, doesn't have to be done either.
7. ...


All that is not what I'd call satisfactory.

Anyhow.
Most of our systems sound great. And that's what counts.

Enjoy.

PS:
Advise: Just go wireless with a PI3B+ and turn the PI USB stack off altogether, which saves about 40% on the power side and thousands of interrupts per minute. Go for the easy wins first!"

Last edited by soundcheck; 21st May 2019 at 02:47 PM.
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Old 21st May 2019, 03:16 PM   #4934
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by soundcheck View Post
PS:
Advise: Just go wireless with a PI3B+ and turn the PI USB stack off altogether, which saves about 40% on the power side and thousands of interrupts per minute. Go for the easy wins first!"
I like these suggestions. Not sure how to turn off USB, but I am sure I can find it.
I did go down the path for years of reducing CPU overhead. First with Win98 where I met Greg & others as we pruned the OS to the min. Then with Alix, later with BBB with realtime mods and all kinds of Linux scripts to shut down processes and reduce OS overhead. At some point I felt that the FIFO/isolators were finally good enough that the processor was enough out of the equation to ignore. Sounds like I should revisit that assumption. Not sure these are the easiest endeavors. I can build a linear PS from scratch in an hour. It takes me that long to recall how navigate Linux command line.
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Old 21st May 2019, 03:21 PM   #4935
soundcheck is offline soundcheck  Germany
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No need for Linux commandline work.

Try this.
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Old 21st May 2019, 04:26 PM   #4936
wlowes is offline wlowes  Canada
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Great stuff. I will try it!
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