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FAQ - Frequently Asked Questions Print

What does SEAS mean?

Seas – Scandinavian Electro Acoustic Systems

Does SEAS produce speakers in Norway?

Yes. All drivers are assembled in a place called Rygge, close to the city of Moss in Norway, 60 km south of Oslo.

How long has SEAS existed?

Since 1950.

T/S and the connection to the resonance frequency?

Qms, Qes and thus Qts are proportional with fo, and Vas is inversely proportional with fo squared.

fo depends on two basic parameters, the total moving mass and the stiffness of the spider and surround combined. The mass is rather well defined and constant, but the stiffness may vary for different reasons.

In order to show what this means in practical terms to-day, we have measured fo in an L18RNX/P H1224-08 fresh from production.


RMS Sinewave
 Fo  36.3Hz  36.6Hz  35.2Hz 


Then we exercised the drive unit for 60 seconds with a 20 Hz sinewave at plus and minus 10mm cone amplitude, and measured again.


RMS Sinewave
 Fo  34.4Hz 
 33.0Hz      32.6Hz



Why are the Waterfall plots gone?

We decided to remove the waterfall plot from the datasheets several years ago. The reason at that time was to allocate more space on the data sheet to other specifications.
 There are many ways to present and measure how the energy is stored and distributed in the driver. Most of these measurements require a lot of individual consideration, and might not be useful for comparing tweeters. We are although open for our customers requirement, and continuously consider what measurement to publish on this internet site.

Quality control

All our drivers are carefully inspected and tested before they're shipped. We are using the comprehensive test equipment from Klippel in Germany. Both frequency response and impedance measurements are stored digitally at Seas.

What’s the difference between a dust cap and a phase plug?

Why use a phase plug?

    •    Reduced moving mass
    •    No gluing or other interaction with the cone
    •    Better cooling of the voice coil
    •    No cavity resonances
    •    More consistent high frequency response

Why use a dust cap?

    •    Avoid air leakage and “chuffing” noise
    •    Larger cone area
    •    Conceal a small voice coil with a big dust cap
    •    Cosmetical reasons


brochure seas 2013

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