Das knapp 60 km lange und 12–20 km breite Oderbruch erstreckt sich zwischen den Städten Oderberg und Bad Freienwalde im Nordwesten und Lebus im Südosten. Zweitgrößter Zufluss nach der Oder — zugleich größter Nebenfluss der Oder — ist die Warthe, die gut 10 km nach deren Eintritt ins Oderbruch einmündet. Im Westen wird das Oderbruch durch die Hochflächen des Barnim und des Landes Lebus begrenzt, in deren Hanglage sich die Städte Wriezen und Seelow befinden. Die östliche Begrenzung bilden das Neumärkische Hügelland und die Wartheniederung. Unter Ausschluss der Neuenhagener Insel hat das Oderbruch zwischen Reitwein und Hohensaaten eine Gesamtfläche von 920 km². Westlich des Flusses ist es seit Mitte des 18. Jahrhunderts ein Flusspolder, während sich auf den 17 % der Fläche am Ostufer, heute in Polen gelegen, das ursprüngliche Feuchtgebiet erhalten hat. Der Boden des Oderbruchs bildet eine sehr schwach geneigte Ebene und fällt von 14 m im Südosten auf einen Meter Meeresniveau im Nordwesten ab. Der tief gelegene nur 2–6 km breite Teil westlich des Neuenhagener Sporns wird Niederes Oderbruchgenannt.
The Oderbruch, which is almost 60 km long and 12–20 km wide, stretches between the towns of Oderberg and Bad Freienwalde in the northwest and Lebus in the southeast. The second largest tributary after the Oder — at the same time the largest tributary of the Oder — is the Warta, which flows into the Oderbruch a good 10 km after its entrance. In the west, the Oderbruch is bordered by the high plateaus of the Barnim and the Land Lebus, on whose slopes the towns of Wriezen and Seelow are located. The eastern border is formed by the Neumärkische Hügelland and the Wartheniederung. Excluding the Neuenhagen Island, the Oderbruch between Reitwein and Hohensaaten has a total area of 920 km². To the west of the river it has been a river polder since the middle of the 18th century, while on the 17% of the area on the eastern bank, now located in Poland, the original wetland has been preserved. The bottom of the Oderbruch forms a very gently sloping plain, dropping from 14 m in the southeast to one meter sea level in the northwest. The low-lying part west of the Neuenhagen spur, which is only 2-6 km wide, is called Niederes Oderbruch.
What is it?
This tube preamp emulation has been developed Philipp Bulling as a thesis work. Philipp has been offering the plugin in VST format for some time on his own website. He has now moved on to new areas for some time already but didn’t want to let down his users. Hence, DDMF took over the code and will continue to offer the plugin as freeware, with the intent to further improve it and maybe add some more bells and whistles in the future.
The plugin is very unique in the sense that it gives you full control over all aspects of the modelled circuit. All values of all the capacitors, resistors etc. can be tuned by the user. Here is what Philipp had written on the original page.
AbstractSince the sound of an analogue tube amplifier has always exerted a strong fascination, electrical circuits with tubes play a certain role in the world of audio engineering up to now. On the other hand, audio technology becomes more and more digitised. In many cases, digital models emulate real devices in such a way that differences in sound are hardly audible. In this work a model is developed which is able to emulate the typical sound of a tube amplifier on digital devices. Here the main focus is on preamplifiers with triodes, since they have a particular influence to the sound.
Based on the physical properties of real tubes, a tube model is developed first. This mathematical model includes results of theoretical studies as well as analysis of data sheets. The model is then used to implement an entire amplifier circuit. In addition to the tube itself amplifier circuits contain several passive elements. In the domain of digital signal processing the latter are described by finite difference equations, which are solved recursively.
The resulting algorithm is finally implemented as an audio plugin in order to examine its tonal properties. The behavior of the digital model corresponds satisfactorily to real amplifier circuits. Important sound effects of analogue tube amplifiers can also be attested to the digital model.
Diode modelThe first step was to develop a triode model, based on the characteristic curves of real tubes. In theory, the characteristic curve of a vacuum tube is described by Langmuir-Child’s law. However, it was quickly realised that compared to real tubes, this law is not accurate enough. So a new model has been developed. This model describes a triode as a mathematical function. With the model, it is possible to compute the plate voltage (Upc) as a function of the grid voltage (Ugc), depending on the working resistor (Ra) and the supply voltage (Ub).
The following graph shows this function for a 12AU7 triode with Ra = 10k and Ub = 250V: Circuit modelingBased on this model, a plate follower stage was implemented. Cathode biasingIn this circuit, cathode biasing is used to adjust the bias point of the tube. This is realised by a resistor (Rc) and a capacitor (Cc), placed between the cathode and ground. The effect of cathode biasing can then be modeled by a simple first order RC low pass filter, with Ic*Rc being the input of the filter, and the cathode voltage (Uc) being the output.
If the input signal jumps for example from 0 V to 5 V, the cathode voltage follows quite similar to the step response of a RC-low pass filter: Signal limitingThere are two reasons for signal clipping in this circuit. The first one is caused by the tube itself. If there is a high peak at the negative half-wave of the input signal, the tube can’t amplify the signal anymore since the flow of current is completely cut-off. Thus, the positive half-wave of the output is clipped. This effect can be intensified by a more negative bias point.
Here the bias point of an 12AU7 is at around -12 V: The second reason for clipping is caused by grid current. High peaks of the positive half-wave of the input signal make the grid voltage positive compared to the cathode voltage. In this case electrons are attracted by the grid. The grid current causes a voltage drop at the internal resistance of the previous stage, which limits the input signal. The following figure shows the effect. The grid voltage is obtained by shifting down the input signal (Uin) by the cathode voltage (Uc). In the upper picture the maximum grid voltage (Ugc) is ~ 0 V compared to the cathode. Hence, there is no grid current. In the lower picture the input signal has an amplitude of 10 V. At the positive peaks of the input signal the grid voltage rises above 0 V (compared to the cathode). The grid current begins to flow and clips the grid voltage.
Inphonik has announced the release of a free bitcrusher effect plugin for Windows, macOS, GNU/Linux, and iOS.
Meet the PCM2612 Retro Decimator Unit, a bitcrusher effect plug-in with a distinctive legacy. Based on the work we made on the RYM2612 Iconic FM Synthesizer, our tribute emulation of the Sega Genesis sound chip, the 8-bit decimation is inherited from the FM synth’s PCM playback feature, packed in a simple and compact effect unit. Bonus: it’s free!
The effect is available in 64-bit VST/VST3, AU and AAX plugin formats, as a Rack Extension for Reason 10.1 and higher, and as an AUv3/IAA app for iOS.
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