'Analog Dinosaur' succumbs to the joys of FBA : enter Raspberry Pi 2/IQ-Audio DAC+!!

[killie99]

got volumio working so thought I'd try picoreplayer. Flashed a new card and it shows up in my lms as picore but I'm getting no sound. Sound level is set as 100% in lms and if I switch to my Logitech touch everything I'd fine. Anyone any idea what could be up?

[Desmo]

got volumio working so thought I'd try picoreplayer. Flashed a new card and it shows up in my lms as picore but I'm getting no sound. Sound level is set as 100% in lms and if I switch to my Logitech touch everything I'd fine. Anyone any idea what could be up?

Nope, not a clue. I had exactly the same experience but with Volumio - everything looked fine I could see it on the network etc but no sound. Switched to Rune Audio, and It worked! Who knows why....

[killie99]

fixed it, school boy error ..... the sound was set to output from the rpi's analogue port in squeezelite rather than the iqaudio

[NRG]

piCorePlayer doesn't seem to upsample by default but there are an array of settings for squeelite to set it up. However, for some reason, its quirky and the settings don't always 'stick'. With a lot of mucking about I've managed to force it into submission.

Here's what I did:
In Upsample Settings I put in mI then saved it.
Reload the page and add X to the Upsample Settings so: mIX
Save it then reboot.

With the IQAudio DAC+ this forces it to upsample to 192KHz

If you want to keep up sampling to an Integer value for 44.1 material go back to the settings page for squeezelite and type -u (minus u) in the various input box
Save it, then in the max sample rate box type 176400 Save it and reboot.

To check what is actually being o/p ssh into the RPi (user: tc password: nosoup4u) and cut n paste this into the command line:
sudo cat /proc/asound/card1/pcm0p/sub0/hw_params

What ever you do do not be tempted to use 352800 in the max sample rate box, you'll need to re image your SD card

The mIX setting is interesting, the first letter defines how much SOX suppresses alias artefacts from the up sampling process, you can set v h m l or q (Very High, High, Medium, Low and Quick) I think the higher settings take more processing to achieve and may not be the best sounding, h or m seem to work well.

The second letter chooses which type of filtering you use and so far I've found this make a very noticeable change to the sound, you can choose M for minimum phase, I for Intermediate or L for Linear I prefer the intermediate filter, the X ensures the up sampling is done to the highest rate set IE 176400

[Krisbee]

Adrian Smith's (a.k.a. Triode) "Squeeze on Arch" has a pretty good web interface page for setting up resampling, making it as simple as possible:



See : https://github.com/SqueezeOnArch

[NRG]

The settings are all listed here for those interested:

http://manpages.ubuntu.com/manpages/...ezelite.1.html

[Paul Hynes]

Since you're here, mate, could you also outline the design of the SR3DR and in what way it's been designed to improve the sonic performance of the RPi (and IQ-Audio DAC), including how its final iteration will differ again from the current circuit (i.e the one I'll eventually end up using)?

Hi Marco,

The SR3DR power supply is an upgraded version of the SR3 using two high performance discrete component voltage regulators in cascade. I have been using this regulation cascade technique since the 1980s on analogue equipment and since the 1990s on digital audio equipment. There is also additional energy storage capacitance for a more robust dynamic response to load transients. It adds to the cost, but the benefits are considerable. Indeed, your PH head amp and SL1210 use this regulation technique in their power supply system. To achieve the greatest benefit both of the regulators should be designed for fast transient response and settling time to load current change, wide operating bandwidth, and very low noise so that the first regulator in the cascade (the pre-regulator) does not restrict the performance of the second regulator in the cascade (the output or post-regulator).

The benefits are :-

1) A large increase in supply line rejection of mains born interference, which reduces the susceptibility of the equipment being powered to poor mains quality.
2) A large reduction in AC to DC rectification artefacts that can cause interference with sonic information presentation particularly the important low-level information.
3) Improved rejection of load transient return current feed-through back onto the mains reducing interaction with other equipment via the mains.
4) A large reduction in back ground noise within the sound field allowing greater low level information clarity.
5) Improved dynamic load change stability providing a more stable sound stage presentation particularly when the music gets busy and dynamic.

The SR3DR-05 is my first stage of upgrade for the Pi-DAC and it provides a 5 volt supply rail capable of delivering 2.5A continuously and up to 20A transient delivery so there should be no Pi operating dropouts caused by lack of power.

The second stage of Pi power supply upgrade follows the internal regulation upgrade path I used on the Technics SL1210, by replacing on board regulation with higher quality voltage regulators. This provides lower noise regulation with a much wider operating frequency range, which results in lower interaction between the various sections of the Pi motherboard and lower background noise level in the system. With reduced system noise comes better low level information clarity, as less noise is riding on the signals passed on to following stages in the system. The dynamic signal integrity is also improved further as there is less voltage fluctuation on the supply rails to affect the signal processing circuits. Essentially you can expect similar levels of sound quality improvement that your SL1210 regulator upgrades provided.

Regards
Paul

[Marco]

That's brilliant, Paul. Thanks a lot for taking time to outline the design and explain the sonic benefits of your off-board PSU for the RPi, which I'm sure many will find very interesting

The SR3DR certainly tackles some fundamental issues (not solely attributable to the RPi), mainly relating to noise suppression, which require addressing in computer audio sources, in order that they can ultimately sound as musically satisfying as a top-notch CDP or turntable - indeed that is precisely what I've heard with the introduction of the SR3DR in my own RPi set-up, so I very much look forward to 'stage 2', and the further transforming of this humble little device (at still practical cost) into a truly world class music source!

The AoS 'SPPV principle' at its best...

I'll post some pictures of the unit tomorrow, so that members can see just how well 'screwed together' it is, and outline what I perceive as its major sonic benefits, so that folks will understand that it's worth every penny of what you're charging for it

Marco.

[Canetoad]

I hardly think that a PSU that costs about 5 times the cost of the RPi/DAC+ hardware to be good value for money!

[Marco]

What if, Bernie, it succeeds in creating a music streamer that outperforms £4-5k designs from some leading high-end manufacturers, but at a cost FAR less than that? Think why we modify Techies...

I never got into the RPi simply because it was cheap - I got into it because it was bloody good, and I could hear its latent sonic potential, which I knew could be exploited

You cannot judge the RPi/IQ-Audio DAC on price alone - you have to judge it on its inherent sonic prowess.

Marco.