Roundtone v.4 is built as an extension of the original concept of Roundtone v.3. The sound is the same, the interface has been improved, some parameters have been grouped differently to better mimic the interface of a real tape machine.

It includes several tape formulae, that affect the response in relationship to dynamics and settings. A new Bias control gives a lot of control on the response thropugh each one of the available tape formulae.

The overall concept includes a tape machine and a delay network. The tape machine is in the feedback loop of the delay so, if the delay is used with some feedback, every single pass is through the tape and the sound evolves with repetitions.

Description of the controls (left to right, top to bottom):

  • Power switch. Bypasses the whole device.
  • Gain knob. This is a cut/boost control on the input signal. It is placed on the tape machine, so also affects the gain for every feedback pass.
  • Speed knob. A new feature, includes several old parameters and its effect is extended with more detail. This control affects the rotational speed of the reels, from a max of 30 ips (inches per second) down to almost zero. The range from 30 down to 7.5 ips mimics the classic settings of real machines. The lower range is added for special effects and sound design. Speed of tape affects the response of the medium in several ways. Due to the interaction between tape heads and magnetic medium, frequency response, frequency band extension, signal/noise ratio, wow and flutter behaviour and more details are affected.
  • Internal level meters. These meters show internal working levels, separately for left and right channels, and are useful to manage tape saturation and delay feedback.
  • Mix knob. Mixes the output of the tape machine with the dry incoming signal. Note that, while the signal passing through the machine is naturally saturated, dry signal isn’t so a strong feedback configuration could give uncostrained increasing output levels if some dry signal is mixed in. Zero setting means 100% dry while max setting means 100% through machine. (NOTE: this control affects ping-pong delay modes – see below).
  • Output Volume. A cut/boost gain stage at the output of the machine.
  • Machine tape strip menu. Assigns the instance to a “tape machine”, so that some parameters are moved together from any one of the grouped units. (Currently disabled).
  • Tape formula tape strip menu. Select which tape formula is being used. Several physical parameters have been grouped in useful configurations to give the greatest versatily with the less possible overlapping.
  • Bias screw. Every tape formula has a magnetic response that changes with working levels. The classic way of setting the tape to its best range is to add a “bias” signal to audio to get the best possible linearity and signal/noise ratio. While this is not an issue in a digital model, abusing the Bias setting can be extremely useful, so Roundtone v.4 includes this Bias control to set tape’s working conditions. The center position is the most neutral one (like on a well maintained tape machine). Low positions affect dynamics and lowest working levels, while high positions affect higher working levels. Effect of Bias is strongly related to the tape formula which is being used. Background noise and working levels have been separated in the model, so even very low Bias settings are interesting without adding excessive levels of background noise.
  • B-Exp knob and meter. The lower section includes both working parameters for the tape machine and external features like the delay section. B-Exp recreates the behaviour of a noise-reduction system used for consumer tape units (to-tape section). It includes an unique style of dynamic filtering that, abused as an enhancer is often useful on the highest frequency range. The knob sets an internal threshold, best results are achieved when it is set to get the most possible movement from the meter.
  • Wow and Flange knobs and menus. This section contains interacting controls and affects several details of the sound of the tape machine. Wow (and flutter) is related to imperfections in tape movement (motor speed, tape oscillations and vibrations) and affects pitch response, frequency modulation and overall sound quality. Flange is strictly related to Wow (and flutter) and adds some effects due to the use of a couple of tape machines in parallel, with their natural differences in tape speed, phase, etc. Two options are currently included for Wow (and flutter). The first one includes the real behaviour of the motor. The second one adds more effect from tape vibration. Wow (and flutter) are obviously related to tape speed. Two options are available for Flange. The first one emulates two machines in parallel, while the second option sends the output from each one to a different (left/right) channel. (NOTE: this control affects ping-pong delay modes – see below).
  • Delay section. This is a simple and extremely powerful delay network around the tape machine. Includes very simple controls and options. Delay knob sets the duration of the delay. If the Synch button is on, delay time is automatically linked to host’s tempo setting and changes, without any discontinuity. The active button in the “division” group on the right, from 1 to 1/8, set the ratio between host’s tempo and synch’d delay time. NOTE: division settings are referred to a total duration of 4 beats, so 1/4 is on the beat. The Feedback knob sets the amount of signal sent back from the output of the delay network back to the tape machine. Note how the tape machine is in the feedback loop, so strong feedback configurations can output controlled (in level, thanks to natural saturation) and evolving (thanks to repeated passes through tape) sound. Also note how mixing dry signal to tape signal (by the Mix knob) includes sonme un-costrained dry signal and so affects the behaviour of the feedback network. Three configurations are available for the delay network. The first one is a straight delay (left to left, right to right channel). Second and third one are “Ping-Pong” configurations one starting from the Left channel and one starting from the Right channel. NOTE: Ping-Pong configurations are affected by Mix and Flange controls and modes, because of how the networks are builts (tape machine in the feedback loop). Set Mix to 100% (full wet) and Flange to first mode for a full Ping-Pong stereo delay. The last button in the Delay section is for “Send” mode. When active, this control removes the straight signal from the output so only delayed repetitions are generated. This is useful when Roundtone is inserted in a send configuration (parallel channel).
  • Noise section. Background noise has been separated for better control. Tape noise is not just useful to get a “vintage” feeling. The right amount of “good” noise can improve the overall sound of a track. The Noise knob controls the level of background noise. Two modes are currently available. The first one is static (normal behaviour) while the second option is dinamically ducked (attenuated) by the audio signal.
  • Manual control on reels movement (“Don’t Touch”). This is a mean to abuse the tape machine and get effects from subtle enhancement to special effects to chorused and bi-phonic sound. By directly dragging the reels with the mouse, some level of manual “braking” on the reels is achieved. As opposite to using the Speed knob, that corresponds to changing tape’s speed before the sound goes to tape and then using the same speed for playback, braking corresponds to slowing playback speed down _after_ the sound has been recorded to tape. The net effect is a static (as opposed to periodically modulated) pitch shift. This shifted signal can be sent to feedback, mixed to dry signal, modulated by automation, etc. for a wide range of simple but powerful effects.

Roundtone is designed to behave without discontinuities, so everything, including tape speed, can be automated. By combining automation for several parameters at the same time, complex special effects can be achieved, like tape stopping and more.