7AUDIO

These are do-it-yourself (DIY) speakers that we built using granite for the speaker box. External box dimensions 240 x 350 x 280 mm. Internal box dimensions 200 x 310 x 240 mm. Box material 20 mm thick black granite (Nero Assoluto). Weight 35 kg. Enclosure volume 14.9 L. Bass reflex enclosure tuned to 45 Hz. Port length 160 mm

Photograph 1: DIY Granite Speakers with Seas G17REX/P and 27 TFFC Drivers

Speaker Project Summary

Input power 80W. Sensitivity 87.5 dB. Transmission bandwidth 40Hz – 20kHz. Impedance 6 ohm.

Figure 1: Seas Granite Speaker Enclosure Plan

Seas Loudspeaker Drivers

The drivers selected for this loudspeaker system are from Seas who has been producing speaker drivers for over 50 years. The tweeter is the Seas 27 TFFC which has a fabric dome. The Sonolex lightweight fabric dome has high consistency and provides excellent stability against variations in air humidity. The stiff and stable rear chamber allows for a moderately low crossover frequency (~2500kHz). This made the Seas 27 TFFC tweeter the right choice for our granite loudspeaker project.

The woofer we used is the Seas G17REX/P. The woofer consists of a fiber glass cone, a bullet shaped phase plug and a high loss rubber surround. These are carefully matched to each other resulting in smooth frequency response.

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