Sansui SP-3500/SP-5500: Weak bass
Four points:
1) After the passage of these many years, the doped cloth half roll suspension on the 14" woofer (W-114) used in these speakers contracts rigor mortis, meaning the suspension stiffens up. I typically find their free air resonance, which should be around 40 Hz, to have risen to 75Hz, or higher. This gives rise to weaker bass than when new and excessive boominess.
2) The approximately 1.3 cu ft. net enclosure volume in the SP-3500 is too small for the 14" woofer, even when it was new. In order to achieve a "proper" modern woofer alignment, the enclosure needs to have about 3.5 cu ft. net. I think the SP-5500 has a slightly bigger box, but probably is still substantially too small.
Maybe somebody with time, skill, tools, and a flair for adventure, who owns a set SP-3500 speakers would be willing to cut the backs off their speakers and extend the box depth by the 10" required for them to achieve that volume and report back with the results. Of course, the ports would have to be re tuned at the same time. If someone actually wanted to do this, I would be wiling to work out, and provide, the port dimensions required for correctly re tuning the cabinets.
3) The W-114 woofer is rated for 50 Watts, even though it has an aluminum coil former. The reason for the low power rating is that it only has about 2mm of coil overhang outside of the magnet pole pieces, thus having very limited linear displacement capacity.
4) These speakers will have their best bass performance with an amplifier that has minimal damping, rather than the high damping associated with most modern amplifiers. Not coincidentally, Sansui amplifiers of the mid to late 1960s had low damping.
TG
