Topping E30: another DAC for linux/RPi

The Topping brand has put out various well received budget Chi-fi units over the last few years, and of interest to me, with various USB enabled DACs such as the D90, D50s and so forth. The most recent addition as of Q2 2020, the Topping E30 is a hi-res DAC with an all metal case, requiring 5v ~1A via by a 2.1mm barrel jack. The E30 has traditional inputs and outputs: toslink/coax and USB digital input and RCA out and crucially for me, without the bloat of a headphone amp or bluetooth receiver- a pure DAC.



How does it work with Linux and a RPi music server running forked-daapd.

Poor sound with Dell onboard Conexant CX20641 / HDA intel soundcard

Some Dell machines have a soundcard that is essentially wired up differently to how some software expects. This can be evident when using the line-out of the machine to go into speakers and finding that there is very poor bass output but can manifest itself in other soundcard jacks not behaving as expected. This is observed during enforced homeschooling on an old Dell Optiplex 390 running Fedora 32.

Verifying the soundcard is using a similar troublesome chipset:

$ dmesg | grep snd_hda_codec_conexant [ 19.026492] snd_hda_codec_conexant hdaudioC0D2: CX20641: BIOS auto-probing. $ lspci -v -d 8086:1c20 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04) DeviceName: Onboard Audio Subsystem: Dell Device 04f5 Flags: bus master, fast devsel, latency 0, IRQ 36 Memory at e4c30000 (64-bit, non-prefetchable) [size=16K] Capabilities: Kernel driver in use: snd_hda_intel Kernel modules: snd_hda_intel

New Fedora, new VMplayer startup problems

With older machines we have the risk of unsupported software hitting compatib ility problems with each OS upgrade. A recent example of this is running vmplayer 12.5.9 on Fedora 30 which ran fine on Fedo ra 26 .. 28 albiet needing a couple of tweaks

But what's the new problems on Fedora 30 and what are the workarounds?

VMWare Horizon >4.8 on linux fails to start: undefined symbols

VMWare Horizon 4.8 works well with Fedora but when your service forces you to move to a later version you will find Horizon client 4.9 and above to fail to start. What to do?

An easy way to remove duplicate files

After years of backing up files from various harddrives and various folders into new harddrivers and additional various folders, we inevitably get a duplicate music, video and photo files - here are 2 tools that can help clean up: fdupes and exiftool

Migrating an old disk to larger disk

The need for more storage is a never ending process but the processes for migrating your old disks to new has never been easier withe collective experience over the years.

But there can still be gotchas if we've been repeating our process of migrating old to new for many many years - one of these gotchas is when you are moving a disk that has its first sector startig at 63 instead of say 2048. What do we do then?

The Remastered Aeron - What was once Old is New again

The original Herman Miller Aeron has been in the wild since 1994 and has been widely successful in both corporate and domestic office settings. In 2017, after nearly 23 years, Herman Miller released a revamped update, calling it the Remastered Aeron and ended production of the original Aeron later the same year.


^{(c) Herman Miller}

But aside from the revamped looks, weight and features how does the Remastered Aeron sit and feel in the real world?

Linux cgroups Resource Constraints

Linux cgroups (control groups) have been around for a long time providing varioius functions for resource management and the ability to segregate workloads with their own constraints. cgroups have provided the basis for container engines such as docker that has become so aggressively adopted in enterprises over the last few years.

cgroups are enabled on all contemporary linuxes with systemd being the API to manage them; the system will manage various cgroups organised in:

• slices - see systemd-cgls where we will typically see system services under the system slice users services, including the segregation for user sessions in another. Encapsulates scopes and services.
• scopes - parent for a logical grouping of units/services which can be managed (killed/stop/resource managed)
• services - logical grouping that provides a service, such as the sshd, that are usual started based on configuration in unit files

But how can cgroup and resource controls be useful for a developer?

VMware Player 12.x with 4.18.x kernels / Fedora 28

A Fedora 26 to Fedora 28 upgrade (with its 4.18.x kernel) broke VMware Player 12.5.7. However upgrading to the newer (14.x or 15.x) versions didn't work so how to fix?

Fedora 28: fixing mpv and libOpenCl.so.1: no version info and hardware acceleration

One of the great benefits of Linux is that it can run on a whole host of legacy components and still perform well. Re-purposing an old Dell E520 with a 32bit Intel Core2 Duo cpu, a PCI via vt6321a based IDE raid card, for Fedora 28 install was straight forward until we started to look at hardware accelerated mpv for watching movies files: libOpenCL.so.1: no version information available (required by /lib/libavfilter.so...

Fedora: bonding over ethernet and wifi devices finally works

Bonding network interfaces for a laptop is a useful feature allowing you to keep the same IP as you switch between a ethernet or wifi connection. However when I last tried this with Fedora26/network manager 1.8 this wasn't a s success.


With the Fedora 28 release with network manager 1.10.10, it is now possibe to create a bond over an ethernet and wifi device

Backing up an RPi SD and shrinking the disk image

There are numerous tutorials on how to resize/shrinking media but they typically advise using gparted for the task; whilst gparted is a great tool, it can fail with obscure error messages when trying to shrink partitions. This is how we can do this the old fashioned way.

RPi and iTunes <-> IOS app for music

After finally setting up Kodi to use a DAC mounted on Raspberry Pi for controlling/serving my music controlled by an IOS device, I re-discovered that IOS devices, via the Apple iTunes remote, can control remote iTunes.

But how's that help?

Kodi and DACs from a RPI to an amplifier

There are a number of options to connect a Raspberry Pi to an stereo amplier but one option is to use a DAC hat card such as an IQAudio DAC with RCA jacks. With the hardware in place it's all about the software to library/index/serve your music and to provide a pleasant user experience to select/queue/control your music - this typically means to control your music via a IOS-based smartphone/tablet.

What's preventing spindown of disks on RPI?

I have a RPi3 with an external USB hardddisk attached which appeared to be not to be spinning down although the setup (via hdparm was correct. But how to determine what was the cause of activity to the disk?

Nikkor 24mm f/2.8 AI-S Disassembly

The Nikkor 24mm f/2.8 AI-S is a lens from the late 70s but shares its optical formula with its predecesors (pre-AI and AI) and successor (AF-D). The AI-S is also quite common and as such appears on ebay frequently in various conditions.



The 24mm f/2.8 AI-S lens is reasonably simple to disassemble and teardown with the only complication being the CRC unit at the rear.

ffmpeg and Nvidia GTX hardware encoding

ffmpeg video processing on an old linux/machine, like a i7 860, running Fedora26 can be painful if you only rely on the CPU. With a recent Nvidia card supporting NVENC (GeForce 6/7/8/10.x) ffmpeg can be compiled directly to support these cards.

Another Well Regarded Legacy: Nikkor 28mm f/2.8 AI-S

The 28mm f/2.8 AI-S is a well regarded lens from the early 1980s that is still available new today. But what's the point of this compared to, say a 24-70mm f/2.8 zoom? And how does it fair for use as a walk-about or an environmental portrait lenses at/near wide open (f/2.8..f/5.6) apertures?


^{28mm f/2.8 AI-S}

How to distinguish AI and AI-S lenses

The old time manual Nikkors from circa 1977 had the designation of an AI lens and then sometime leading into 1981 the AI-S lenses replaced the AI; both AI and AI-S lenses will fit onto all modern day Nikon F-mount bodies with no issues and the lens are functionally identical.

With the release of the AI-S lenses however, there were some subtle changes external to the lens: the primary reason for AI-S was to use enable cameras to use program or shutter priority modes - this was important for the upcoming release of cameras with this function at the time and the AI-S lenses were designed to facilitate this. With this said, the lenses that had a AI and then an AI-S counterpart were typically optically identical.



But why does this matter to be able to distinguish between an AI vs AI-S lens, if the optical formulas were the same?

Going Long: Nikkor 200mm f/4 AI

A 200mm can be a useful focal length in the bag, albiet a less frequently used length. However the modern and autofocusing xx-200mm zooms are heavy and expensive and therefore options to satisfy the 200mm can be better sourced from the legacy Nikkor AI/AIS catalog.