Experiments of the DAC kind

[NRG]

LOL. Gone back to hIX. Sounds more natural with greater depth.

[NRG]

Flippin heck time flys! Just bringing my old thread up to date. I’ve been using my TDA/RPi2 happily since my last post in 2015. Recently I was made aware of the Allo Kali reclocker for the RPi so went ahead and bought one.

The Kali reclocks the I2S to provide more precise timing and provide correct timing for 44.1khz based material. The RPi master clock runs at 19.2Mhz and is therefore not directly divisible by 44.1khz. The Kali internally buffers the I2S from the RPi and outputs a very low jitter I2S signal at the correct frequency.

Installation is straight forward as it simply plugs on top of the RPi, the output pins are in the same location as the RPi itself. Power is fed to the Kali directly which in turn passes power to the RPi. There is an option to power the RPi separately if you think it will make a difference. I made up a short 9cm cable from a USB lead for the connection to the DAC board. No software mods are required to support the Kali.

To say I’m pleased would be an understatement, the reclocking has made a noticeable improvement. Detail and texture (voices, instruments etc) have improved but it’s the improvement in musical engagement and satisfaction that is the biggest gain for me. Highly recommend.

Installed


In use, signal locked at 176.4Khz

[Gazjam]

Good work Sir...

[Jimbo]

Allo are doing some great stuff so not surprised you got a good result.

[NRG]

I’ve revisited the squeezelite upsampling settings and switched to picoreplayer as I was getting fed up with Max2play not responding and having to have a subscription so as to use a plugin to protect the file system. Picoreplayer runs totally in memory so SD card corruption should not happen.

Reading Archimago’s blog I found a post about digital filters and impulse filter settings for squeezelite http://archimago.blogspot.com/2017/1...igital_23.html

And thought I’d give it a go, I messed about with the suggested settings in the post and ended up with the following as it sounded best to my ears and in fact was much better than the hIX setting I was using previously, in fact I’m quite taken aback there is such a difference.

The setting I have settled on is vX::4:20

Translating: very high quality, upsample to the max rate of 176400 for my 44100 material, -4db reduction in volume to avoid sample clipping during the upsampling process, use 20 bit accuracy. This can also be set to 28 bit but I’m not 100% certain it makes a difference...more time is needed.

There are three other user defined settings for passband-end in %, stopband-start and phase response, omitting them sets them to their defaults IE: 91.3% of 44.1khz/2 or 20.13khz, 100% of 44.1khz/2 or 22.05khz and 50 or linear response.

I thought I couldn’t improve on what I had before but these new settings are a bit of a revaluation to me and I’m going to try some more combinations to if it can get better still.

[NRG]

To wrap this chapter up, I’ve been playing with Archimago’s ‘Goldilock’ settings for squeezelite ending up with the following: vX::4:20:93:100:45

It’s a slight tweak to his Goldilock settings but just seems to hit the spot in a better way for me and my DAC. Blog post here: http://archimago.blogspot.com/2018/0...l-filters.html