Boundary microphones are often chosen for their convenience as they have a low profile and a wide coverage, while requiring minimal setup at the same time. However, not all boundary microphones perform the same and choosing one is difficult as subtle differences in design, polar pattern, and build quality can dramatically affect intelligibility and noise rejection. This article compares several boundary microphones on the lower end of the price range to see how they differ in real-world use. Since there are many tests with repect to drum micing, this article aims at using boundary microphones for the recording of piano and vocals. Read more

I have been using a Raspberry Pi as private Git server for several years to store the different versions of publications and software scripts I write. Recently, I switched from the very simple Gitolite to Gitea. While Gitolite was doing it’s job well and generally did not cause any trouble, I always missed an interface for easy overview and administration of the repositories. Therefore, I’m glad to have Gitea up and running as the software offers all features I was looking for. Read more

The new year begins with the release of the website of Deborah Hödtke, church musician at the cathedral and catholic Diocese of Eichstätt in Bavaria. Being an organist, the website is mainly meant to provide an overview of upcoming and past concerts alongside biographical information. Therefore, I have chosen a layout with a prominent but not disturbing background image which still allows for a good perception of the menu and content. To allow for an easy editing of the content, the content management system (CMS) Contao is employed. Contao proved to be very flexible and highly customizable which is a clear benefit over most other CMSs as it can handle events and an image gallery out-of-the-box and without any third extensions. The website can be found at www.deborahhoedtke.de. Read more

As Advent begins, people start asking others for their wishes regarding Christmas presents. It’s a similar story when it comes to birthdays. To get around these questions, I started an online wish list a few years ago that is accessible by everyone. Updating this initial version of the list required modifying and manually uploading files. Therefore, I recently expanded the wish list into a web application with a simple interface. Users can easily add and delete entries to their wish list, organized into different categories. Each entry can be completed with an online link, while the system itself can handle multiple users. The wish list web application is written in PHP and based on a SQLite database. The code is available on GitHub. Read more

The development and progress in the field of unmanned aerial vehicles (UAVs) also has an impact on many other fields as new applications arise. Near-field antenna measurements, for example, have been traditionally performed in anechoic chambers where the antenna had to come to the measurement system. With the usage of UAVs, a very flexible measurement system can be designed and brought to the antenna under test which enables the measurement of large antennas and also the characterization of mounted antennas in their real operating environment. However, the changed measurement setup entails new components which cause effects that may introduce noise or errors if they are not treated carefully. One key difference of traditional chamber-based measurements and their UAV-based counterparts is the fact that the field probe contains moving parts as the whole UAV including the probe antenna has to be considered as field probe. In our new publication, we investigate the impact of the rotating rotor blades of a UAV on the performance of a field probe. The article has been published in the IEEE Transactions on Instrumentation and Measurement and is available on IEEEXplore. A list of further publications can be found here. Read more

Some weeks ago, when I was doing another audio recording, I asked myself if there is an optimal gain setting for the input of the audio interface and what it might be. In general, we can adjust the input gain to any value and amplify or attenuate the signal later in the post processing. However, we all know that low gain settings destroy our recordings as they contain too much noise which is basically impossible to reduce afterwards. So the optimum I am looking for means an optimal trade-off between high gain and low noise as any amplifier also contributes and increases noise. Read more

Some time ago, when I was looking for long microphone cables, I came across the idea of using network cables with appropriate adapters. This is a neat idea since you can run four audio signals over one network cable with 8 pins + shield. However, soon questions about the audio quality and other drawbacks came up. Therefore, I did some simple measurements on microphone and network cables of different lengths, which are described in the following. Read more

Running multiple servers and (web-)services, sometimes makes it hard to keep track of possible problems and errors. I had the same problem, when I came up with the idea of a centralized online-logfile. Searching the internet revealed tons of logfile applications, also for centralized logfile collection and evaluation. The problem with most of those applications is that they are either not open-source, too advanced and therefore complicated or require an own server instance. I was looking for a simple solution that runs on any webserver and displays log messages that can be reviewed from time to time. And so I sat down and came up with a simple web application, written in PHP and based on a SQLite database. Basically, any application with internet access can add a new entry to the logfile by calling a specific URL. This is especially useful when running Bash scripts performing different tasks, like backups or restarts of devices. The code of the logfile application is available on GitHub. Read more

Recently, I had the chance of comparing different cardioid small diaphragm condenser microphones. Among the test candidates were the Neumann KM 184 and the Haun MBC 440, which are both highly recommended and praised by a wider community. Further, I included a Rode M5 MP into the test to compare the high-quality microphones to a much cheaper one. To enable a real comparison of the microphones, I performed simultaneous recordings of an organ and vocals. The recording setup is described in the following, before the actual recordings are presented and evaluated. The corresponding audio files are also included below. Read more

It was not allowed to celebrate masses on Sundays during the shutdown regarding the COVID-19 pandemic. Therefore, the churches of München-Neuhausen had the idea of recording short masses that could be celebrated at home. I helped with the recording and production of those podcast-style home masses. Read more