Hifiberry DAC+ Pro - HW mods anybody?

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Odal3

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Joined 2014
Soundcheck - following along with great interest. Thanks for pushing the envelope. Looking forward to hearing more and trying it out myself. I like to dabble on the software side but Kernel changes are way over my head. Will implement the other clues you mentioned until you are ready feeding us more clues.

What's the logic behind the overclock?

Has anyone done any hardware tweaks to the rpi board such as completely eliminating the diode, or other optimizations? Or maybe it doesn't matter if it is turned off in software.

Greg -You maybe have already mentioned it but which linear supplies and chokes do you use?

Illinimdg - I'm in Indianapolis.

Btw: some good arguments why software and kernel logic make an impact: Q&A with John Swenson. Part 3: How bit-perfect software can affect sound | AudioStream
 
sckramer

sckramer

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Joined 2010
Greg Stewart said:
@sckraemer

Really!

I've looked at your settings and there is some overlap, but a key area that Soundcheck addressed is not covered.

I won't steal his thunder, but will let him reveal as he wishes.

And I believe his kernel and binaries will be very significant too.

And finally, truthfully, I am not a good resource to assess your optimizations other than HW... I am very early on my Linux audio optimization learning curve.

Greg in Mississippi
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My point is, I'd be nice if we were all on the same page assessing differences, these are fairly easy/obvious modifications (by me) on the pi side and piCorePlayer (so would like to be filled in on something easy I missed) ... before testing the more interesting kernel/squeezelite changes (good, bad, or nil) that soundcheck is good (or bad at ;) kidding) at!
 
sckramer

sckramer

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Joined 2010
As for networking, I'm sticking to wifi. So I don't have to give a crap about ethernet cables, network switch power, LMS server power etc-- because you really don't have to.

...playing the song from RAM anyway, there is no net traffic.

Tracking down noise sources on a Raspberry Pi | Crazy Audio

Sure you can use a UTP ethernet cable, but don't really trust that.


And think I'm on to something with the piZERO, decoupling the wifi power... with it's stability at ~100mA... all the other pi's are saddled with ethernet/usb you can't truly turn off.

See my hardware section (digi+) same with D+Pro tho: piZERO notes.

Wonderful digi+ improvements! (mostly due to the 3.3V decoupling & linear power)
 
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sckramer

sckramer

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Joined 2010
As for CPU settings... picoreplayer is a little dumb on that & sets all boards the same-- see my notes on that-- turbo=1 is important to not have the clock changing speed constantly, so a slight under clock may be a good thing, it's usually at 99% idle anyway-- no heat or damage worries

Gonna go out on a limb here... piZERO or go home :)
 
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sckramer

sckramer

Member
Joined 2010
sckramer said:
My point is, I'd be nice if we were all on the same page assessing differences, these are fairly easy/obvious modifications (by me) on the pi side and piCorePlayer (so would like to be filled in on something easy I missed) ... before testing the more interesting kernel/squeezelite changes (good, bad, or nil) that soundcheck is good (or bad at ;) kidding) at!
Click to expand...

Edit: this is not just for me (well a little :) keep butting in with my digi+), I bet there are a bunch of people following along... really changing too many things all at once will really confuse the sound quality discussions, and a stable stopping point on the pi side should be in place... for the hifiberry side hw/power changes to be evaluated and adjusted
 
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Odal3

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Joined 2014
sckramer said:
:D pretty nerdy

Hi Odal3, couldn't resist
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:)
Nerdy...yeah... fits me perfectly :zombie: but I would say that most things discussed in all the audio forums kind of is to some degree. The good part is learning and theorizing and then trying it out in the "home lab"/living room is what kind of makes it a fun hobby at least to me.

Btw: thanks for sharing all your tweaks as well. I have been using mpd for a long time but now need to get on the picoreplayer bandwagon.
 
sckramer

sckramer

Member
Joined 2010
soundcheck said:
First things first. ;)

I'm in the middle of getting the kernel project done. That keeps me quite busy.
The learning curve is pretty steep.
Still. All that is as complex as I expected it to be on PCP.
There's nothing like a proper writeup out there. All info is widely spread.
Anyhow I managed by now to get my own crosscompiled 4.1 kernel booted and the core modules loaded. (I'd still need to get the INTEGER.patch and the 384kHz for kernel 4.1 ).
Now I'm working on the Alsa modules which are kept in a different package.
I'm positive though that I'm gonna manage today. I found some related info on the net.

@sckramer
I looked at your tweaks:

1. I also turn off HDMI - but you know that
2. I also turn off the LEDs
3. The streaming buffer is configured with e.g. 40000:500000 - I just stream PCM streams!!
All decoding of flac/mp3 etc. is done on the server.
This I also mentioned a long time ago @squeezebox forums and elsewhere.
You basically stream a full track from a RAM Buffer to the device. That huge buffer
gets bulk loaded within the first seconds of a track.
4. Obviously I also kill all processes that are not required.
5. I also overclock the PI.
Greg mentioned that he prefers the lower rates. I still run below settings on my PI2:
1000 ARM
250 Core
500 SDRAM
OV 2
Force Turbo 1 (renders warranty void! -- by setting a hardcoded warranty bit - Be careful with this one!!!)
GPU_MEM 16

If you guys tell me there's something better -- I'm all ears.

Above settings are not available via PCP webinterface!

6. I also set the DAC params via Alsa. I mentioned that before - and made my recommendation.

7.-26. I do some more. :D

I plan to write-up something as soon as I have my kernel done.

I'm sure - Greg won't spread any info I gave to him -- as he promised. ;)



Cheers
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Thanks! That kernel stuff must be so fun :D

Why don't they just move to 4.4, plenty of people would beta test along the way. Is it really still changing that much in areas it would be effected?

Did you solve the squeezelite running at 384K problem?
 
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Abartels1965

Abartels1965

Member
Joined 2015
drive.google.com/drive/folders/1qUlkQQD3KTTSyUkG5q-V1PFU2DU4brf7
VASILIST said:
Yes theoretically the NDK series have better speqs , special in phase noise area ,

practical the expresso series ... listed beter , more black background , faster and relaxing micro-dynamics , imho its the second better choice after the King series of Crystek ( but cost almost one HAT board ... )

and some more .. the separate voltage regulator for oscillator its really GOOD idea !
Click to expand...

Forgot to mention, you were right, the XpressO TCXO's DO sound better than the NDK SD's!!!

Does somebody know if there's some kind of DIL14 adapter for soldering
on SMT pcb? I would love to try using OCXO's on the DAC+Pro, but need
some sort of adapter which can be soldered on the pads for ExpressO XO's.

Thanks in advance!!!

Alex
 
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