Transcendent Sound       Vacuum Tube OTL Audio Amp Kits

The full range speaker is a high performer.  But unfortunately, at three cubic feet, is too big for many installations.  By reducing the low frequency cutoff slightly, it can be substantially reduced in size.  It has been shrunk down to a 0.75 cubic foot enclosure.  This small size still gives it an F3 of 83 Hz, which is still quite good.

The speaker used is again the Tang Band W8-1772.  The enclosure measures 17 inches tall by 10 inches wide and 12 inches deep.  The port is 3 inches in diameter and 4 inches long.  No stuffing or lining is used in the cabinet.  The driver needs all of the available box volume.  Small enclosures are very sensitive to cabinet changes.  The attenuation circuit of the full rage model is still necessary.  While the larger box needed the L-pad set at the 3 o:clock position, the small box version requires more attenuation and the control was set at the 12 o:clock position.  This is because the speaker is functioning differently in the smaller enclosure.  Set to wherever it sounds best to you.       

The L-pad is 16 ohms, at 50 watt.  Use the left and center terminals of the L-pad as viewed from the rear.  Do not follow the instructions that come with it.  The inductor is an air core, 0.5 mH, unit with 18 AWG wire.

The speaker sounds almost like the full size model with the exception that the larger box has a slightly more resonant character to the sound and deeper bass, which is to be expected.  The small front panel reduces diffraction effects and makes the speaker sound a bit more open.  The grill (Parts Express 296-107) is still necessary to minimizes beaming.  It was glued to the speaker frame itself with a bit of silicone.  Shrinking the box down will allow it to be used in many more installations.  The bass is perfectly adequate as is without a subwoofer for most musical material.  Of course, a sub can be added if desired.

Small Enclosure Single Driver Speaker