NIRVANA sound crew chief, Dave Stevens, describes the computer controlled system used on the 1993/94 tour. This article was originally published in Live Sound International, Jan/Feb 1994

At least once during every show, someone invariably asks what the computers at the mix position are for. Even last year, computers were not common in the touring sound business, except for traditional business uses. And while computer control of sound systems remains in its infancy, the technology is now readily available, from multiple sources, for truly functional, flexible methods of controlling large sound systems via computer.

On the current Nirvana tour, Seattle based Proshow USA is providing computer and DSP control for a house speaker system comprised of 32 Proshow/Electro-Voice MT4 enclosures and 6 Proshow/EV MT2 enclosures. An Apple Powerbook 160 and Macintosh SE/30 are being utilized as well as an Acer 730, '486 SL notebook, to control the Nirvana FOH system.

Redefinition Revisited

The TOA Saori re-defined digital sound processing in the late 80s and remains among the most advanced DSP devices available. On the Nirvana tour, the TOA Saori is configured as a stereo digital 1/3 octave EQ and stereo 4 way crossover/controller, with three delay group setting per bandpass. The advanced Saori DSP also has the capability to be used as a notch filter as well, although the notch filters are not used on this tour. 
Using a PC interface allows any operator to access all Saori control panel parameters directly from the PC. The only disadvantage is that the front panel controls are not active when the Saori is controlled by the PC. In planning this system, all involved considered this a minor inconvenience a small price to pay for the enhanced flexibility.

The Saori will store eight pre-sets on board and the Saori control program runs on the Acer notebook (or any other Intel/DOS based PC). The control program also allows for storage of settings for as many programs as disk space will allow. Dozens of pre-sets will fit on a single 3 1/2" diskette.

Each night a few pre-sets are loaded into the Saori and the system is compared using a few different settings, depending on existing venue conditions. The preset options also make the support act mixer very happy by allowing storage of several custom programmed EQ curves for that mixers' artist.

Reason #1

Still, the primary reason for using the Saori was the way it made the system sound. In September, 1992, extensive A-B comparisons were held in the Proshow shop. Other devices that were tested include an EV MTX4, modified by Proshow, a BSS FDS340, and a Yamaha D2040. But based on Proshow's experience with the Saori in large scale sport stadium installations the Saori was in an advantaged position, even before testing began. 
At the same time, measurements were taken by Dave Carlson of EV and John Murray of TOA, in the R&D lab of EV in Buchanan, MI. Settings were analyzed and optimum settings were found. They were a mix between the anechoic chamber settings (driver phase alignment) and real world listening tests (EQ contouring).

The ability to align components in the enclosure made a noticeable improvement in the vocal intelligibility. The 20 bit D/A converters seemed to make the system sound more "open" than with other devices, with cleaner, better defined high end. There was also greater separation between the various bandpass outputs.

After a few months use in touring applications (including some regional Nirvana shows) John Murray again was dispatched, this time with a TEF 20 analyzer. Another day was spent further optimizing the Saori for the MT4 system. These tests focused on phase alignment within the MT4 enclosure and optimizing the gain structure of the Saori within the system. The current Saori settings were finalized during these tests.

Dynamics Control and Input Management

Mixing an act of this intensity requires a bit different approach to mixing, according to FOH assistant Allan Bagley. Bagley and Nirvana house mixer Craig Overbay, use an extensive array of dynamics processing to keep the mix in the pocket. The dynamics rack consists of four channels of Aphex 612 noise gates, one each on kick drum, snare top, rack tom and floor tom.

Four channels of BSS DPR 404 comp/limiter, one each on kick drum, snare top and one each on bass DI and bass mic. One channel of BSS DPR 504 noise gate is used on snare bottom. The rack also includes eight channels of DBX 903 compressors.

One on cello DI, and one each of the two acoustic guitar and five electric guitar inputs. Of the five electric guitar inputs, three are from Kurt Cobain's guitar, a Sennheiser MD409 and Shure SM57, along with a Countryman Type 85 DI. The other two are from rhythm guitar player Pat Smear, consisting of an EV ND408A and Shure SM57. A dbx 160XT is used on Kurt Cobain's vocal and spare vocal, in line with a Klark Teknik DN300 on each channel. BSS DPR 402 comps are used on drummer Dave Grohl's mic, as well as bass player Krist Novoselic's vocal mic.

Garage FX For Great Halls

The front of house effects rack sports a greater amount of processing than one might expect for an act of this type, to truly represent the band's seemingly raw, yet larger than life polished sound. Two Lexicon digital delay lines are used for the lead vocal delay, for effects and repeats. Each is panned hard for a true stereo delay. A Lexicon Model 97 Super Prime Time is used as a vocal doubler, in the one-input, two-output mode.

The primary vocal reverb is a Lexicon PCM70, on the Concert Hall program. An additional PCM70 is used on the kick drum, with the Small Hall program. Two Lexicon LXP 1 are used on the drums as well, one on the snare, with a gated reverb, and one on the toms in a plate setting. Two Yamaha SPX900 are also used. One is used for electric guitars as an autopanner. The other is used as a utility reverb, generally for cello and acoustic guitars, with the program depending on the instrument and song.

With the exception of the delay lines, which are not MIDI compatible, all the multi effects program changes and and some of the parameter changes are controlled by a Lexicon MRC, MIDI controller. The entire show is mixed on a nearly virgin Yamaha PM4000-60.

While the music may be a more stripped down approach to rock and roll, the dynamics of and music of the act require a studio quality mix from the house PA. Bagley explained the most difficult part was getting vocal intelligibility and separation in the mix, without mixing at excessive levels.

Bagley added that the guitar sound needed to be mixed with the vocal mic settings at normal gain and that the stage volume leakage must be taken into account in the guitar tone. Due to the amount of leakage into the downstage vocal mics and drum vocal mic, a different approach had to be used.

Conventional dynamic cardioid mics did not offer the off axis rejection that is required for this show. It's differoid design allows for greater gain before feedback, something very critical for this show. The CM310A also has outstanding off axis rejection, keeping stage volume bleed to a minimum.

Bagley and Overbay, as well as longtime Nirvana monitor mixer Ian Beveridge, feel these are the key to a good sounding Nirvana show. For over a year, Nirvana has used the Crown CM310A for all stage vocal mics, carrying at least six at all times, even for network or MTV television tapings.

Maximizing the Macrotechs

Another powerful computer based tool, the Crown IQ 2000 is being used as a network control/monitoring system for the Crown powered Nirvana house system of 10 Crown MA 1200, 10 Crown MA2400 and 8 Crown MA5000vz, ach with a Crown IQ PIP module.

The mix position Macintosh SE/30 runs the IQ Mac via the IQ buss. Currently, the tour is using version 1.4, but a beta copy of version 2.0 is being tour tested as well. Version 1.4 includes multi level security protection for the system. With this feature, unauthorized persons can't access the amplifier control software. Each user is assigned an access level. System engineers have almost complete access to the system, except for configuring the IQ system. The front of house mixers and techs have complete access to the IQ system. Support act mixers have only monitoring access.

Window on the Gain

During the performance, a status window showing each amps I/O level and the emulated thermal capacity of each amp is displayed on the Mac. By dividing the system into zones on the IQ system, each enclosure's components can be muted or attenuated from the mix position. Typically, the on stage near fill and off stage near fill are adjusted by this method.

Another vital monitoring feature is the use of alert dialog boxes displayed by the Mac. This feature can be enabled on any amp or combination of amps. The alerts are triggered after a time period and condition set by the user of the program. (Assuming they have the proper access level) Bagley has the IQ alert boxes set to warn of extreme level or thermal conditions and to alert the IOC condition of each amp.

A small database within the IQ software stores the model, location and application of each amp. This information is displayed in the alert dialog box, enabling almost instant troubleshooting. This near real time monitoring tool has saved more than a few transducers.

The use of sequenced scenes is another tool that the tour employs. IQ Mac ver 1.4 has a sequenced scene playlist which allows configurations to be saved and recalled on demand or played back in sequence. Scenes can also be added to the menu directly. In fact, a scene called "All Mute" and a scene called "All Unmute" have been added to the IQ menu by Stevens and Bagley.

Instead of walking backstage to check each amp by turning up each channel with pink noise as a source, scenes are stored that have all channels muted, except for the active channel. These scenes are then added to the sequence list and are then played back at 50% level. The result is the component check takes less time, and is more convenient to execute. This sequence plays 46 scenes. It took about three shows to fully implement this utility.

Monitors to Die For

The two must have, no substitutes, pieces of gear for the Nirvana tour were the EV DeltaMax DML1152 enclosures and the tc Electronics tc1128 tc6032 EQ system, speced by Nirvana monitor mixer Ian Beveridge. Due to the exacting standards of the act and the on stage SPL, there was no room for compromise. Beveridge explained that, prior to to using the DML1152, it was rather difficult to get the monitor volume over the stage volume and house PA volume, especially in large, reverberant rooms.

The DML is a small enclosure, never specifically designed for floor monitor use. The monitor system is basically a series of small PA enclosures, laid on their sides, with a block of wood, to compensate for the angle of the box. We also have the ability to hang the DML under the stage or overhead. Thus far, we have not had the need to do either.

The DMLs are powered by Crown MA24x6 with PIP AMC modules in the amps, as crossover/controller. Using the vented box enclosure settings on the AMC cards, the DML can be tuned to produce a great amount of low end. This is especially good for a very large drum sound. It would take a much larger conventional floor monitor to achieve these results.

Going Remote

Beveridge specified the remote tc1128 EQ system to make the monitor system equalization simpler, less time consuming and rock solid consistent. Beveridge and monitor assistant Tom Pfaeffle take the remote on stage and tune each mix. Different EQ adjustments can then be made at each position, and compared on the spot to decide which curve will work best at any given show.

Using the CM310A, the EQ curves and response aren't what they would be for a typical dynamic cardioid. Due to the response characteristics of the differioid mic, a vocalist with irregular mic technique or who prefer to sing off the mic, will not be able to achieve their accustomed results.

Vocal mics are a sensitive area with vocalists and mixers alike. First we try to convince them to use the differoids, but some are still set on using the dynamic cardioid they use all the time. To compensate for this, each support act is allowed to store monitor EQ presets, tailored for the vocal mic they prefer. Monitor EQ changes of this type, with conventional graphic EQ's, would be impractical in this situation. The system's programmability nearly always results in support act satisfaction.

Let's Do More

The tour clearly benefited from this technology. Sonically the consistency and ease of operation reduced the grind of one night big system set up. Based on these successes, and as the technology progresses, Nirvana intends to incorporate even more advanced computer control options into their performance.

© 1994, Dave Stevens, Dave Stevens/Seattle Ltd.