{"id":1302,"date":"2011-12-28T20:10:01","date_gmt":"2011-12-28T20:10:01","guid":{"rendered":"http:\/\/www.audioexcite.com\/?page_id=1302"},"modified":"2015-05-17T11:41:59","modified_gmt":"2015-05-17T11:41:59","slug":"seas-h1207-l12rcyp","status":"publish","type":"page","link":"https:\/\/www.audioexcite.com\/?page_id=1302","title":{"rendered":"SEAS H1207 L12RCY\/P"},"content":{"rendered":"

Overview:<\/span><\/h3>\n

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\"\"<\/a>The L12RCY\/P is a mid-woofer from the Seas Prestige series. It uses a stiff and light aluminium cone coupled to a low loss rubber surround and it shows no sign of the familiar 500-1500 Hz cone edge resonance and distortion associated with soft cones. The extremely stiff and light cone gives bass precision and a nice midrange detail.<\/p>\n

High temperature voice coil wound on an aluminium voice coil former gives high power handling capacity.<\/p>\n

Bullet shaped phase plug reduces compression due to temperature variations in the voice coil, avoids resonance problems which would occur in the volume between the dust cap and the pole piece and increases the long term power handling capacity.<\/p>\n

An extra-large magnet provides high efficiency and low Q.<\/p>\n

This driver is a very nice small mid-woofers and even though it\u2019s not a SEAS Excel W12CY001 it can be called\u00a0 \u201cExcel light\u201d giving almost 75% of the Excel:s performance, but at a third of the Excel:s price.<\/p>\n

For its size it has great woofer capabilities and has an overall smooth frequency response characteristic up to the cone break-up at 9.2kHz. This cone break-up needs to be taken special care of with a special notch filter in the cross-over filter design. Failure to take care of the cone break-up results in a driver unit with a very fatiguing sound and that \u201crings like a bell\u201d.<\/p>\n

This loudspeaker driver unit needs to be crossed over low in frequency in order to keep the odd order harmonics distortion at bay. I recommend a cross-over <2500Hz.<\/p>\n

SEAS spec sheet: H1207 – L12RCY\/P <\/a><\/p>\n

T\/S Parameters:<\/span><\/h3>\n

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\"\"<\/a>T\/S parametrs are measured both when the driver unit are cold and when warmed up with a 1 hour stress stimulus\u00a0 at 5.66V (4W\/8\u03a9). The warmed up driver units are rested for 2-3 minutes before they are measured.<\/p>\n

Impedance:<\/span><\/h3>\n

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\"\"<\/a>Free air impedance measurement \u201ccold\u201d driver units:<\/p>\n

Sample 1 = Green<\/p>\n

Sample 2 = Blue<\/p>\n

The samples are an almost perfect match between each other and they have a very smooth impedance response curve with no signs of any resonances besides the cone break-up at 9.2kHz.<\/p>\n

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\"\"<\/a>Free air impedance measurement \u201chot\u201d driver units:<\/p>\n

Sample 1 = Green<\/p>\n

Sample 2 = Blue<\/p>\n

The Fs is lowered by 4-5Hz, but otherwise they have the same smooth response curve as the \u201ccold\u201d driver units.<\/p>\n

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Frequency:<\/span><\/h3>\n

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Frequency measurement conditions:<\/strong><\/p>\n

The mid-woofer is measured mounted in a 8 liter Dayton Audio enclosure (PartsExpress part #302-701) baffle with the following conditions:<\/p>\n

Baffle size (WxH):<\/strong> 19,05\u00d730,48cm (7,5\u2033x12\u2033)<\/p>\n

Driver position:<\/strong> Mounted on center-line with driver unit center 10cm from bottom of the baffle.<\/p>\n

Mic position:<\/strong> 1m distance, 12.2cm above driver unit center (tweeter-axis)<\/p>\n

Smoothing:<\/strong> No smoothing applied.<\/p>\n

\"\"<\/a>0deg tweeter-axis
\nSample 1 = Blue
\nSample 2 = Red<\/p>\n

Nice consistency between the two driver unit samples. Downwards sloping frequency response from 2kHz. Heavy cone break-ups at 9.2kHz, 13.8kHz and above. The cone break-up at 9.2kHz needs to be corrected for with a notch-filter in the cross-over.<\/p>\n

\"\"<\/a>0deg = Blue
\n15deg = Red
\n22.5deg = Green<\/p>\n

\"\"<\/a>0deg = Blue
\n30deg = Red
\n45deg = Green<\/p>\n

Distortion:<\/span><\/h3>\n

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Measurement setup:<\/strong><\/p>\n