http://lamkins-guitar.com/music/article/lectrosonics-is400
David Lamkins picked up his first guitar a long time ago. As best he can recall the year was 1967: the year of the Summer of Love. Four decades later David has conjured up an amalgam of folk, rock and jazz solo guitar music for the occasional intimate Portland audience.
location: Portland, OR USA

Facets: Lectrosonics, digital, review, technology, @musings info
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Lectrosonics IS-400 Wireless System Review

Today I "owned" a $1,200 wireless system for a few hours.

I picked up a Lectrosonics IS-400 system from local pro-audio shop Cascade Media the first thing this morning. The deal was that I'd have the package until Monday morning at which point I was to either return it or they'd charge my card. After checking specs and reading whitepapers on the Lectrosonics site, I was convinced that they really have something with the technology behind this unit. I was fully prepared to call up Cascade Media and tell them to post the charge against my card if the unit was as good as anticipated.

Briefly summarized, this package transmits a 24-bit linear audio signal without companding or pre-/de-emphasis. For those of you not so technically inclined, that's good. Those two technologies are necessary for transmitting an audio signal over an analog FM link to overcome the inherently limited dynamic range of FM transmission within a fixed (by regulation) bandwidth. The IS-400 digitizes the audio and essentially runs the digital signal over the analog link through a pair of purpose-built modems. At the receiver, the reconstructed digital signal is converted back to audio.

The system has a bandwidth flat to 1 dB from 30Hz to 20 KHz and a dynamic range of somewhere around 107 dB. I couldn't find a sampling rate mentioned on the manufacturer's site, but one reviewer said that it's 88.2 KHz (twice the sampling rate of a CD).

The transmitter is in a compact machined aluminum housing. There is a locking connector, an attached battery door and belt clip, an on-off switch and power indicator, and two bi-color LEDs and a rotary control for matching levels. None of controls are subject to inadvertent operation. The transmitter includes a buffered instrument cable with high-quality connectors. The transmitter is said to run for six hours on an alkaline 9V battery or thirteen hours on a lithium 9V battery. The antenna is a permanently-attached flexible stainless-steel cable.

The receiver is in a folded metal enclosure. The face of the receiver has an LCD display, a push/turn menu navigation control and a power button which doubles as the menu exit button. The receiver runs on a tip-negative DC source at anywhere from 8 to 18 volts. It can be powered by any pedalboard supply which has about 200 ma to spare. The IS-400 package includes a compact wall wart for the receiver. The back of the receiver has dual BNC connectors for the included antennas. Audio is output via both a 1/4" jack and an XLR connector. Each output is independently adjustable for level and polarity.

Setup of the system was easy. Turn on the receiver, leave the transmitter off, and select "auto-tune" from the menu. The receiver scans its 256 channels, picks a clear channel, and displays a two-digit hexadecimal number. Set that number into the two recessed channel-select switches on the transmitter and you're ready to go.

I spent a couple hours putting the IS-400 through its paces. The good news is that - once the end-to-end levels were matched - I really couldn't detect any undesirable effect upon the guitar's tonality or dynamics. The bad news is that the noise floor was high enough to bother me. I spent quite a bit of time experimenting with gain staging at the transmitter and receiver. When I cranked the transmitter gain high enough so that peaks where hitting the transmitter's limiter, I could still hear hiss on the output. Lowering the transmitter gain (to avoid hitting the limiter) and raising the receiver gain made the hiss worse.

Based upon what I've read of the system design, my guess is that the noise originates in the transmitter's preamp. This is essentially the same transmitter that Lectrosonics uses in their wireless mic products. The only apparent difference is the extended low-frequency response of the transmitter in the IS-400 package. I suspect that Lectrosonics could mitigate the noise if they created an instrument transmitter specifically tailored for the higher (relative to microphones) output of a guitar rather than buffering and padding the guitar output to match a mic-level preamp input.

The IS-400 is a pro package all the way. If you play with a pick and don't use lots of gain (or are comfortable with using a noise gate) I think you'd be delighted with the performance of this package. I play with a huge range of dynamics, apparently. I want to hear every nuance from the slightest brush of a fingertip against a muted string all the way up to popping a string against the fingerboard; the IS-400 can't cover that much dynamic range, but neither can any other wireless system.

January 12 2007 01:38:08 GMT