Constructing and Reviewing the SEAS Froy Mk3

October 11 2017, 10:00
The SEAS Froy Mk3, an improved version of the original Froy kit was launched at the end of 2002 by the famous Norwegian speaker company, utilizing drive unit technologies from its Excel product line. Designed by Murray Zeligman, who also designed the original FROY kit, the Froy Mk3 kit uses two W15CY001 woofers and a single T25CF002 "Millennium" tweeter mounted in a D'Appolito configuration. The cabinet is a bass reflex design with the vent placed in the rear. This directs any potential vent noises away from the listener, and allows for minimum baffle area in the front. The port tube is constructed of two MDF boards which also serve as additional bracing for the cabinet. The crossover network is conventional except for a parallel circuit which suppresses the response peak due to the magnesium cone.

On March 2003, Edward T. Dell, Jr., audioXpress founder, published a complete build project for the kit, which he discovered on the Madisound website while searching for details on the THOR speaker (also available online here.) As Ed Dell writes at the time, "The Froy is a small MTM utilizing the SEAS Excel Millennium technology drivers. The specs looked impressive. (...) Its only unusual feature, other than small size, is the 1/2" slot port centered in the rear panel which also adds rigidity to the one-square foot enclosure."

"The 5" mid/woofers use the same type of machined magnesium cones as the larger ones used in the THOR design. SEAS says the rear vent directs any possible port noise away from the listener. The crossover, set at 2200Hz, includes a Zobel (L2 + C2) in parallel with the paralleled mid/woofers. (...) Frequency range is claimed to be 40–25000Hz, with a maximum short term power of 300W and longterm power of 140W and 4Ω impedance."

In the subsequent April 2003 edition, audioXpress published a complete review of the Froy Mk3, with measurements by Joseph D’Appolito, accompanied by a listening evaluation from Dennis Colin. Joseph D’Appolito ran a series of measurements, including impedance, frequency response, polar response, and distortion tests on the Froy Mk3. As Ed Dell writes, "Before I saw Joe’s report I was frankly surprised how close they were in sound profile to the THORs. I noticed a slight edginess in the upper end, which is surprising since they have the same tweeter as the THORs. They
do require stands, which should be 26" high, to lift the tweeters to ear level. They have excellent horizontal dispersion, although like the THORs, the vertical sweet spot is quite narrow. Building this pair was a very great pleasure, as speaker construction always is for me."

The two articles were available online in a previous generation of, but unfortunately, they were not included in the content migration to the current generation of the website. We learned that many forums and magazine still refer to the original articles, and we decided to correct the situation. The PDFs attachments are now back online and the original links are working again.

The Froy MK3 kit as well as other SEAS speaker kits are available for purchase here:

These articles were originally published in audioXpress, March and April 2003.
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Constructing the SEAS Froy Mk. 3
The tiny vented SEAS Froy Mark 3 design turned up on the Madisound website ( while I was searching for details on THOR1. The Froy (Photo 1) is a small MTM utilizing the SEAS Excel Millenni- um technology drivers. The specs looked impressive. The structural drawing (Fig. 1) is from SEAS. Its only unusual feature, other than small size, is the 1⁄2′′ slot port cen- tered in the rear panel which also adds rigidity to the one-square- foot enclosure.
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Testing the SEAS Froy Mk3
According to the SEAS web- site (, the Froy (Mk3) kit is an improved version of the original Froy kit. It uses SEAS’ latest drivers from the EXCEL line. The kit employs two W15CY001 15cm magnesium cone woofers with one EXCEL T25CF002 Millennium tweeter in my MTM configuration. Ed Dell built the two Froy (Mk3) loudspeakers tested here. (March ’03, p. 60)
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