Voice Coil Focus: Quasi-Alignment Families

This article is another great contribution by Claus Futtrup, this time with direct support from Jeff Candy, the two creators of Speakerbench, the free to use web-based application for low-frequency analysis and design of loudspeakers. Another follow-up article for the Bass Reflex Alignments article series that was published in audioXpress and Voice Coil, this time, the authors discuss the important Quasi-Alignment Families where the fundamental idea is trying to approach a roll-off similar to the Butterworth B4 alignment (a maximally flat response) but compatible with real systems for which the driver Qt will not allow a true B4 alignment.

After seeing many speaker designers returning to trial-and-error approaches that seem to forget the historical work and analytical approach, Lars Risbo decided to explore numerical optimization to synthesize attractive alignments both for reflex and passive radiator box types. This reference article basically expands on Claus Futtrup's "Loudspeaker Bass Reflex Alignments" article series published in audioXpress, and expanded with dedicated articles in Voice Coil.

Speakerbench, the web-based application for loudspeaker design with an emphasis on an advanced transducer model, has been officially available since March 2020. Created by Claus Futtrup and Jeff Candy, the online tool celebrates its fifth anniversary with a significant update that introduces new valuable features, plus comprehensive documentation. Originally intended to support the loudspeaker DIY community, Speakerbench is increasingly recognized by global speaker designers at all levels.

After discussing computation of discrete alignments such as B4, BL4, LR4, IB4, and CD4, this new article in the "Computation of Bass Reflex Alignments" article series explores the real-world situation where it becomes impossible to have a system design that exactly matches a certain driver Qt, normally described as an alignment error (or misalignment). The technique presented allows designers to modify tuning towards a desired target response function.

In the fourth article from Claus Futtrup in his series about the invention, concept, and historical perspective of loudspeaker bass reflex alignments, he explores the Critically Damped Fourth-Order (CD4) bass reflex alignment. This alignment remains one of the least known and hasn't been discussed in literature related to loudspeaker design, even though it allows for interesting output properties. This article was originally published in Voice Coil, August 2024.

The new Genelec 1237A and 1238A Smart Active Monitors (SAM) are tri-amplified systems featuring AutoCal and GLM technologies and powerful Class D amplification. The 1237A and 1238A monitors feature on-board intelligence to automatically tune the frequency response to compensate for acoustical room influences, as well as achieving perfect alignment of levels and distance compensation at the listening position.