The end of the line for Type 2260 Investigator
By Peter Sims
22 Feb 2011
February 2011 saw a sad spectacle as the last distinctively-shaped Type 2260 Investigator™ sound level meter left the Brüel & Kjær production line. Here's its unique story, from inception to retirement.
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After almost 17 years of faithful service that saw it travel into space and appear on the BBC, ‘Investigator’ has finally come to the end of its natural life. Stocks of model-specific rubber buttons were allowed to run out, leaving it to be superseded – as all great things are – by the new generation Sound Level Meter Type 2250/2270. Here, to mark its passing and welcome in the new blood, we look back at the stormy development surrounding the iconic design, and celebrate the unique technological advances it brought.
Development
Investigator was conceived in difficult times following a change in the ownership of Brüel & Kjær, and the change in company culture that followed. Reflecting this, when it came to replacing the aging Type 2231 Sound Level Meter in the early 1990s, a new procedure was followed. Previously, top-level sound level meters had been developed by a small team of dedicated engineers and technicians who were experts in all aspects of their design, including market research, industrial design, standardisation, applications, hardware and software – all of which were manifested in the project manager, Peter Hedegaard.
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| Enlarge image | | Type 2260 Investigator brought a revolutionary combination of portability and functionality |
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Peter’s grand new concept would take modularity, processing power and ease-of-use to new heights by taking advantage of the quickening pace of technological development, and to implement his vision he called on a large design team. Veterans from many teams were co-opted into the project, with each having responsibility for a different area of the design, and with each stamping their mark on Investigator.
Team discussions were loud and emotions were frequently high, with the result that the management of the project changed more than once, but finally the various threads were combined into one cohesive package. Industrial designer Steve McGugan, who had worked on the Type 2236, was called in to sculpt the new model’s streamlined design that would limit its interference in the sound field.
Technology
The result of all of the wrangling was a set of unique, market-leading capabilities. Unlike previous iterations, Investigator digitised all signals as they came into the body of the instrument, allowing simultaneous measurement of all relevant time and frequency weightings and parallel measurement of spectra in 1/1-octave or 1/3-octave bands. This feature was marketed as Multi-D where the ‘D’ stood for dimensional. Before Investigator, sound level meters only had a single detector where you had to select time and frequency weighting, a peak detector and serial analysis of spectra. Meanwhile a general-purpose microprocessor took care of everything else like running the menu-driven interface with its digital LCD screen – which bought the unit squarely into the 1990s.
| "NASA took an Investigator into orbit to measure the sound level inside the International Space Station" |
In keeping with the 1990s theme, the CPU ran on a low-power DOS system that allowed PC-like data management just as the popular ‘palm top’ computers of the period did, interfacing with dedicated Windows® PC reporting software. Combined with the capability to log events onto a large and reliable internal CF card, the Investigator became a true toolbox. Suddenly, you could measure all of the weightings simultaneously, so there was no longer a danger of coming home only to discover that you had set it to the wrong weighting when you made the measurement.
As well as the revolutionary real-time analysis, the new dual-channel architecture meant Investigator could provide a wide dynamic range in a stacked configuration, or use the two channels for sound intensity and building acoustic measurements – opening up a wide range of applications. Suddenly, sound direction and sound power could be calculated in the world’s first hand-held sound intensity system.
Future proofing
Just as the exponential progress of technology had intensified the race to develop up-to-date equipment, it had also created a new challenge for Brüel & Kjær – to develop up-to-date software. As with most technological developments there was enormous pressure to get Investigator to the market quickly, so that early models were shipped only with basic analyzer software. The idea was that later software modules could be added as they were needed, and indeed developed – while in the meantime the customers had a fully-functioning Type 1 Sound Level Meter that they could then build on by buying more modules.
The high investment required for the software development came as a surprise, but it was an inevitable wake-up call that heralded the age where software would become king. In fact it was only when the programmers began to develop new modules that the true strength of Investigator’s design came to be realised, as they found they were able to hone its performance and versatility to never foreseen levels.
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Each module was released as a software download (or on CF cards in the early years) that could easily be added to the other existing ones, as the on-board memory was sufficient to store them all. With the ability to perform simultaneous, multi-dimensional (Multi-D) multi-tasking, Investigator became even more versatile with each successive software release. When the last new module was released in 2001 Investigator could count Noise Profile, Building Acoustics, Room Acoustics, Sound Intensity and finally FFT Analysis among its capabilities.
Even the future gets old
Despite its dramatically improved user-interface, Type 2260 was still a little way off the modern intuitive intelligence that is designed into current sound level meters. Described by one of its fondest champions as “gruff and stringent”, Investigator was a very capable tool – just as long as you turned your mind to its own intricacies. Its design from the point of view of highly-skilled engineers was less considerate of the user, stemming as it did from a time when the ethos of the whole industry was more ‘the product does this, now go and use it’ than ‘how can we help you to do your job?’
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| Enlarge image | | Type 2260 Investigator checking sound levels on the International Space Station. Image courtesy of NASA. |
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Ultimately it would take the user-centric revolution that came with the age of the internet and smartphones to teach the world the value of true user-friendliness, and so it was that when the time came to develop a replacement at the turn of the century, a blank-sheet approach was taken that put user demands as the primary design concern. Dubbed the ‘Handyman project’, the improved consultation process lead to the award-winning Type 2250, and later Investigator’s true heir – Type 2270 – leading the field of top-end sound level meters.
Fact file
- Investigator was released in May 1994
- Over 7000 Type 2260 Investigators were made
- It appeared on the BBC’s ‘Fame Academy’ programme in 2003, measuring the frequency of Paris Campbell-Edwards’ voice – at 1.775 kHz, where host Claudia Winkleman said of Investigator: “This is a strange machine, please don’t make me explain it, it’s got a very large manual.”
- Every Investigator had an optical interface to future-proof it, but it never came into use
- Investigator was the first and last Brüel & Kjær sound level meter to have a name
- Its immediate replacement, Type 2250, won the 2004 Danish Design Prize, and the German red dot design award: product design 2005
- Its predecessor, Type 2231, had external modules to re-programme it for different applications
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