Endless Analog CLASP Signal Processor Review

May 21, 2010 4:30 PM, By Kevin Becka



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Five years in the making, CLASP (Closed Loop Analog Signal Processor) represents an exponential leap forward in hybrid analog/digital technology. It offers an easy, cost-effective way to integrate analog tape into digital production workflow by literally turning any tape machine into a DAW plug-in processor. CLASP drastically cuts rewind time and tape cost because the tape is only used for momentary throughput. This lets you use the same reel for an entire project and run the reel front to back before rewinding. CLASP even pulls some new analog tricks out of its hat, offering the ability to jump between tape speeds on the fly to audition and then print, even mixing speeds in the same project—something that’s impossible in an all-analog production.

CLASP’s simple front panel provides access to essential system functions and a large countdown display.

CLASP’s simple front panel provides access to essential system functions and a large countdown display.

For this review, CLASP was integrated into an existing studio comprising an SSL 4056 E/G console, a Studer 827 2-inch analog machine and Pro Tools HD2 Accel running on a Mac Pro with 6 GB of RAM, Mac OS 10.5.8 and Pro Tools Version 7.4.2cs4. Conversion was through Apogee Rosetta 800s clocked by an Apogee Big Ben.

CLASP is a well-built, two-rackspace box with a large countdown LCD and five backlit function switches for tape rewind (RTZ), sync mode (SYNC), tape speed auditioning (MON), post-stop recording (POST) and machine speed alignment (IPS). The countdown display indicates the remaining time on the reel and can be set to beep as the reel end approaches.

The back of the unit carries enough D-sub connectors for 24 tracks (12 D-subs), a 15-pin machine control port, XLR sync in/outs and MIDI in/outs. There is no minimum requirement for tape tracks; CLASP will operate using analog machines capable of anything from mono up to 24 tracks and can be daisy-chained for up to 72 tracks. Add an optional optical sensor, and an older machine (without a 15-pin transport control port) can also be used.

The key to understanding CLASP (see the signal flow diagram) stems from its signal flow and how the system time-corrects audio. Analog signals from your mic preamps, console or your DAW are recorded through CLASP to tape, then immediately routed off the playback head into your workstation because the deck runs in repro. Due to the head gap delay between record and playback, CLASP cleverly uses plug-ins to time-correct and re-time stamp the audio. The system is sample-accurate: It doesn’t need SMPTE timecode for sync, so all 24 analog tracks are simultaneously available for recording.

It’s important to understand how CLASP accomplishes access to the Pro Tools software. CLASP uses a USB-MIDI interface and HUI protocol for machine control and track arming. For Pro Tools delay compensation to work with the CLASP hardware, it requires 24 mono master faders in the Pro Tools session, each carrying a CLASP plug-in. I used Apogee converters, which—among others—don’t correctly communicate with Pro Tools Delay Compensation. To fix this timing mismatch, an offset number for the Rosetta’s delay was added into the CLASP Bridge plug-in. (For more on working with Pro Tools delay compensation and third-party converters, go to mixonline.com.) These workarounds are unnecessary for users with Cubase, Nuendo or Logic systems, as CLASP can easily gain access to MIDI Machine Control.

Initial setup was simple. CLASP integrated via the patchbay using TT-to-D-Sub harnesses, plug-ins were loaded into the system and a CLASP-specific session template was created. The 24 master faders used for time correction were hidden via the Show/Hide list, making the session look like any other. Whether the session was from scratch or pre-existing, importing the needed CLASP session components was easy.

Apart from the 24 other plug-ins used in Pro Tools, the CLASP Bridge plug-in is a single instance that can sit on any channel. It offers access to rewind, arming and other essential functions for system operation. I ran a quick one-time setup operation, in which the hardware figures out the difference in time between the record and playback heads and stores it at different speeds. (The system holds setups for up to three machines.)

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