amroc pro

Before using amroc or amroc pro, it is helpful to understand standing waves, how they depend on room size, and how they affect acoustics. Read my article about room modes for an introduction to these topics.

What is amroc pro?

Both amroc and amroc pro are online room mode calculators designed to help you understand, visualize, and analyze standing waves (room modes).

• amroc is free and calculates modes quickly in your browser, but is limited to rectangular rooms.
• amroc pro uses the "Finite Element Method" (FEM) to calculate modes for rooms of any shape. These calculations are complex and require significant processing power, so they are performed on my server using openCFS.

Main Acoustic Use Cases

Room mode calculators are used to address low-frequency issues in rooms or other enclosed spaces. The most critical factors influencing these modes are the volume's size and shape.

With amroc and amroc pro, you can experiment with these factors to see how they affect mode distribution. For example, you can:

• Enter the dimensions and shape of an existing room where you are experiencing acoustic issues. Look for mode clusters that may amplify certain frequencies, or "holes" in the spectrum where no modes support a frequency band.
• Identify which modes are responsible for "nulls" where low frequencies disappear. Use this to optimize your listening or speaker positions.
• Experiment with different dimensions for a new room to find the ideal proportions before construction begins.
• Calculate modes for other enclosures, such as speaker cabinets.

Examples

How to use amroc pro

The process consists of three phases: modeling the room, verifying the 3D model, and calculating the room modes.

The Modeling Phase

Quick steps:

1. Shape the floor plan
2. Set the room height
3. Click the 3D button

To add new corners, move the mouse to the desired position along a wall. Once a new handle appears, click and drag it.

To delete a corner, select it with a click and press the delete key. A minimum of three corners is required to maintain a valid room shape.

Modeling Angled Ceilings or Floors

While this modeling method is efficient, it has some limitations regarding arbitrary shapes.

Note that you can use the 2D view to shape any cross-section of your room. It doesn't have to be the floor; you can shape a side wall and use the "height" field to define the room's width.

Additional modeling features will be added over time to support more complex geometries.

Once modeling is complete, click the 3D button.

The Visualization Phase

After clicking the 3D button, the 3D view of your model will appear. Rotate the model by clicking and dragging. Pan the view by right-clicking or holding the Ctrl key while dragging.

Purchase Full Mode Calculation

Analyzing only the first 5 modes is often insufficient, as acoustic problems usually extend to higher frequencies.

The Payment Process

To start the payment just follow the dark blue buttons. In order:

1. -> 3D
2. Calculate 5 free modes
3. Calculate x modes for $$$

The payment process is simple and supports providers such as Credit Card, PayPal, and Google Pay.

Please note: I do not get access to your credit card details or account passwords during this process.

How the Number of Modes is Determined

The frequency at which modes become "dense enough" depends on room volume and reverberation time. Therefore, calculating up to a fixed frequency (e.g., 200 Hz) is not always appropriate.

A full calculation provides all modes up to approximately the Schroeder frequency. Currently, the FEM server calculates a specific number of modes rather than an exact frequency range.

First, the room volume is calculated and the reverberation time is estimated. Using these parameters, the Schroeder frequency and the number of modes are calculated:

To estimate the reverberation time, I use two reference points — a small studio and the Wiener Musikverein — and interpolate based on your room's volume.

Note: I plan to allow users to set these variables manually. However, since improper settings could lead to extremely long calculation times, I am first implementing safeguards in the background.

Any other questions?

Please contact me so I know I have to improve this documentation!