| SP98-09 Copyright 2009 © Troels Gravesen |
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| Ole L. came by
with these cabs including a pair of D2904/9800 alu domes
and 18W/8531-G00 midbass drivers. He'd bought the cabs
for 125 EUR (the piano lacquer alone had been four times
as much). With a tilted and chamfered upper front it was time to revise the old SP98 crossover and who knows what has happened since then in terms of crossover design and overall voicing. |
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The total volume of the
cabs are close to 43 liter making the 18W produce an F3
of almost 30 Hz! Hearing the 18W in a too large cabinet,
I couldn't help thinking of the unfortunate 2.5 clone. It
goes immensely deep and as long as we do not crank up
volume, everything goes well. Playing a bit louder the
bass becomes boomy and un-precise. Should someone still
be thinking of building the 2.5 clone, take a look at
this construction and build something significantly
better. Yes, it's a bit more expensive, but I think it's
time to bury the clone and get on with our lives. This
speaker is at least twice as efficient, goes just as deep
and has better midrange and treble. Overall it's a
significant improvement. Cabinet dimensions
Cabinet damping: Use 10 mm felt or polyester material on all internal walls. Next you need two rolls of MDM3 or similar. Half the roll is folded and placed at the bottom of the cabinet. The other half is folded and placed behind the 18W driver and towards the top. Download
drawing on bracing here. The Crossover
Crossover Components
Measurements
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