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Terms of Service

Last updated: 27 September 2026

These Terms govern the use of LinFIR (the “Software”) and of the demaudio.com website. They are an agreement between you and DEM Audio, operated by Arnaud Demion in Valais, Switzerland (“DEM Audio”, “we”). By downloading, installing, using or buying a license for the Software, you accept these Terms. If you do not accept them, do not use the Software.

1. The Software

LinFIR is available in two forms:

  • Free version. You can download and use LinFIR at no cost, for personal or commercial work. It includes all features for on-axis measurements and filter design.
  • Advanced Module. A paid license unlocks additional features (off-axis and directivity analysis, spinorama curves, spectrogram, splicing and others, as described on the LinFIR page).

The features in each form may change from one version to the next.

2. License

The Software is licensed to you, not sold. DEM Audio remains the owner of the Software and of all related intellectual property.

  • You may install and use the Software for your own projects, personal or professional.
  • A paid license is a one-time purchase. It is not a subscription and does not expire.
  • It covers every update of the current major version of LinFIR (for example, all 1.x releases). If a new major version (2.0) is released one day, it may require a new or upgrade license; your license keeps working with the versions it covers.
  • A license allows one activation at a time. You can move it to another computer by deactivating it first, from the License tab of the Software.
  • A license is personal to its buyer and may not be shared, resold or transferred without our written consent.

Filters, measurements, projects and any other files you create with the Software are yours.

3. Restrictions

You agree not to:

  • reverse-engineer, decompile or disassemble the Software, except where the law expressly allows it;
  • circumvent, disable or tamper with the license activation;
  • share, publish or resell your license key;
  • redistribute the Software or modified copies of it;
  • use the Software in breach of applicable laws.

4. Purchases and payment

Purchases are processed by Lemon Squeezy, our reseller and Merchant of Record. Lemon Squeezy handles payment, invoicing and applicable taxes (VAT), and its own terms apply to the transaction. Your license key is sent by email right after payment. Prices shown include taxes.

5. Refunds

You can request a refund within 14 days of purchase if you have not activated your license key. Contact us through the contact form with your order number. Once a license has been activated, refunds are at our discretion. This does not affect any mandatory rights you have as a consumer under the law of your country.

6. Updates and support

We regularly publish updates that fix issues or add features, at our discretion. Updates within the same major version are free for everyone, license holders included, as described in section 2. Support is provided by email on a best-effort basis.

7. Measurements and safety

The Software can play test signals (sine sweeps) through your amplifiers and loudspeakers. You are responsible for choosing safe levels, protecting your drivers (for example with the built-in protection high-pass filter) and protecting your hearing and that of the people around you. Filters designed with the Software must be checked before being used on valuable equipment or at high levels.

8. No warranty

The Software is provided “as is”. We work hard to make it accurate, but we do not guarantee that it is free of errors or suitable for a particular purpose. Simulations and predictions shown by the Software are only as good as the measurements and settings you provide.

9. Limitation of liability

To the extent permitted by law, DEM Audio is not liable for indirect or consequential damages arising from the use of, or inability to use, the Software, including damage to equipment, loss of data, profits or business. Our total liability is limited to the amount you paid for your license. Nothing in these Terms limits liability that cannot be limited by law.

10. Privacy

We collect as little data as possible. See our Privacy Policy for details.

11. Changes to these Terms

We may update these Terms. The date at the top of this page shows the latest version. The Terms in force when you bought your license continue to apply to that purchase.

12. Governing law

These Terms are governed by Swiss law. Any dispute will be submitted to the competent courts of the canton of Valais, Switzerland. If you are a consumer, you keep the protection of the mandatory laws of your country of residence and may also bring a claim before the courts of that country.

13. Contact

Arnaud Demion — DEM Audio

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