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MIX – Endless Analog CLASP Signal Processor Review

Monday, November 15th, 2010 8:14 am

By Kevin Becka

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.)

D-sub connectors give you the ability to record up to 24 tracks through CLASP.

D-sub connectors give you the ability to record up to 24 tracks through CLASP.

I spent the first day with CLASP in a session recording a six-piece band. Drums were in an iso booth while the rest of the players were taken direct or miked in the large main room. Cue mixes were built from the CLASP outputs, which offer the same listening experience as hearing input on the analog machine: zero latency, before the converters. Levels were set, and the session ran from Pro Tools with CLASP running in the background. After the initial tracks were cut at 30 ips, new Pro Tools playlists were created on all tracks and another pass was run at 15 ips. The difference was remarkable. The bottom end on the kick, low toms and bass was thicker, with more saturation at the top end and, of course, more tape noise. After some discussion, the 30 ips pass was kept and the bass and vocal were auditioned and re-cut at 7.5 ips. This particular singer’s voice benefitted from the lower tape speed, and the bass took on a richness and symbiosis with the kick that was not apparent at the higher speed. Because of the mix of the speeds, the noise wasn’t as intrusive as it was when the entire track was cut at the lower speed.

Another session involved re-cutting drums on an existing track. The CLASP-specific plug-ins and master faders used in the previous session were imported into this day’s session, and I was up and running in no time. Levels were set and I put CLASP into Demo mode to audition tape speeds. As I was listening straight off the uncorrected repro feed from the machine, it necessitated killing the cue feed to the drummer. While the drummer was playing, I could drop out of Record on the analog machine, change tape speeds, engage Record and hear the difference. I can’t say enough about this feature. It lets you audition the “effect” and change levels to tape accordingly. It’s much like changing the settings on an EQ or compressor on the fly.

Once out of repro-only mode, I could sync to the track and re-cut the drums. The drums were first cut at 30 ips, then I created new playlists for the second pass and cut at 15 ips. Just for fun, I then dropped down to 7.5 and did the same. CLASP’s front panel buttons make this a simple operation: Choose the desired speed on CLASP, change the machine’s speed and you’re off.

Once the drums were cut, we started experimenting with the rest of the track—which had been cut directly to Pro Tools a year before. I created an ADT (automatic double tracking) effect on the vocal using the interface. This is similar to how it was done in the 1960s: using a secondary tape machine set at a different speed. I didn’t need a second machine because I re-recorded the vocal to a new track through CLASP at a slower speed. The difference in the head gap created a great double. I tried a few different speeds until I nailed it and moved on.

Another great trick? I took some interesting guitars that unfortunately had a nasty digital edge to them and tamed them down by re-recording them through CLASP. This corrected the edginess, giving the tracks a roundness that was easier to tuck into the mix. This particular technique was an “a ha!” moment for me, seeing the possibility of tweaking the sonics of tracks not previously recorded to analog tape.

The only problem with CLASP is that it’s harder to describe than to use. At first, it’s tough to grasp the concept, but once CLASP is in your session, the wow and wonder of your first encounter with pro audio is revived. During sessions with live musicians, I was easily jumping between tape speeds, auditioning and changing levels to tape based on what I heard, then printing that directly to Pro Tools. It was easy to re-record original digital tracks back through CLASP for color, create ADT, run tests at different tape speeds—all while having a blast. The system quickly reminds you about the beauty of tape’s effect on transients, low frequencies, cymbals, vocals, guitars and more, especially at slower speeds. The workflow was sonically and functionally inspiring because CLASP puts the tape machine behind the curtain, letting the session run just as it would with the DAW alone.

Like other early releases of new technology, CLASP is costly. However, the payoff for home and commercial studios with tape machines in mothballs, or those looking to put their own unique creative stamp on their work, is worth it. And the timing is perfect: The used audio gear market is rife with tape machine bargains from 2-tracks on up. Plus, the arguments that good tape is no longer available or too costly no longer hold water. I bought 10 reels of RMGI 900 2-inch and the formulation is as good or better than any BASF, Ampex or Quantegy tape I’ve used. There was a time when this wasn’t true, but the market has reset itself and there’s plenty of good tape out there from ATR and RMGI. In all my years of writing product reviews, I’ve gotten excited about great products from time to time, but this is something more: It’s a concept whose time has come. If you get a chance, try CLASP for yourself and rediscover your love of sound.

Kevin Becka is the technical editor of Mix.

Endless Analog - Digital Controlled Analog Tape Recording