Siegfried Linkwitz: “An optimum crossover filter topology should be the starting point when the outputs from multiple drivers with different frequency responses and sensitivities need to be combined for a flat acoustic response.” (In “Crossover Topology Issues”)
A new product generation of ASP for LX521.4 was the opportunity to start circuit design with optimum cascaded topology. Furthermore, CAD optimisation in filter design allowes a reduction in filter stages. ASP LX521.4 v2.0
Some basic considerations, see “Crossover Topology Issues” on linkwitzlab.com:
parallel (typical), summing errors:
cascaded plus all-passes (ideal) leads to perfect summing:
- Generally, the cascaded ASP LX521.4 generates the same filter (magnitude) curves as before. Now with improved phase coherence among all channels
- The cascding of the 120Hz high pass relieves the 10cm HiMid driver in the 200Hz region and below.
- Topology theory New edition V2.0 with cascaded circuit topology, same magnitude filter curves, improved phase coherence between all channels.
- Reduced noise levels
- Reduced distortion
- CAD based optimised filter blocks (F,Q,Gain)
- Parallel filter blocks at critical locations reduce noise and distortion further by a factor √2 . Furthermore, it improves inter channel matching by √2
- Shortest feedback loops minimize stray capacitances, stray inductances and external interference pickup.
- Newest Generation, High Performance Audio OpAmps (OPA 1656 etc.)
- Dedicated ground returns.
- Tightly specified 1% capacitors with lowest distortion figures (eg polypropylene dielectric) and 0,1% metal thin film precision audio resistors. This allows 20x better inter-channel matching.
- Balanced signal input for maximum common mode rejection
- 3-step rumble filter for turntable users: off – med – hi.
- Input gain increase by 12dB selectable (install jumper).
- Optimised gain structure in woofer channel.
- Smart power supply decoupling with feed-tru capacitors and large local buffer capacities.
- +/-13V rails, from ultra low noise LDOs with additional CMC filtering, effective up to the MHz range (especially useful for SMPS use and their common mode spikes).
- DIN 5-pole power plug compatible with MeanWell desktop PSU.
- Slim design. Massive 3mm full aluminum case with stainless steel front plate: ca. 44 x 36 x 5,5 cm.
- Dedicated case grounding point (M4 screw).
- Neutrik XLR input and output plugs. XLR-RCA adapter cables are optionally available available in our webshop.
- On request, please specify when ordering: Circuit adapted for the new LoMid driver LINKWITZ 22MG.