At Grimm Audio we are dedicated to update our products frequently. Our motto is “Driven to Improve”. In Japan this philosophy is called “Kaizen”, which means a continuous cycle of improvements, literally change for better. The LS1 is a clear example of Kaizen. The basic design is unchanged since its incarnation in 2010: the mechanical design, the driver choices, the acoustics. But we kept improving elements all the time, and if you put a modern LS1 next to the original the sound quality difference is staggering.
The LS1 update we present to you now consists of two parts. First we improved the sample rate converter on the digital input. We selected a higher performance chip with lower distortion and higher resolution. A small but pleasantly audible improvement.
The second step took us much longer, and is more fundamental. Every LS1 that leaves the factory is hand calibrated by tuning a series of equalizers in its DSP chip. We measure every LS1 in the same test jig with a high performance measurement microphone of Microtech Gefell. The operator then manually tunes the DSP eq’s in such a way that variations between drivers are ironed out and a response close to a neutral straight line is achieved (we do not believe in “voicing” toward a certain sound color). During this laborious tuning process a lot of experience is applied. We know for instance that high Q filters should be avoided, and we aim to minimize the amount of eq’s in general.
Last year we had a software development intern, Simon Jaasma, who spent his graduation project on a “Computer Aided Calibration” tool to enhance this process. He developed an algorithm that simulates thousands of possible EQ combinations to achieve the ‘target curve’ with the smallest amount of EQ’s and the least extreme settings. The algorithm takes the acoustic sum of tweeter and woofer into account and aims for an “acoustic optimal 4th order Linkwitz-Riley crossover” between the two. During the whole process an operator evaluates intermediate results and directs the algorithm. We believe that this hybrid “computer & human” approach offers the best of both worlds and leads to a supreme result.
After his graduation, we employed Simon and he optimized the user interface of his software. It has recently been put into daily use in our production chain, to great effect. Computer Aided Calibration is not only a time saviour but often presents surprisingly minimalistic eq settings with a better curve matching than even our most experienced operator would manually achieve. The sound quality improvement is worth all the effort.
