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Figure-3: The effect of termination (and lack of same) on a 1-kHz square wave. The un-terminated "spike" indicates transformer ringing that produces a 7dB boost at 50kHz. |
Output termination rounds out the options. Many people, accidentally or not, run Neve modules un-terminated, the resulting sound can be brighter due to transformer ringing. (See Figure-3.) By placing the option on the front panel, users can run either way and not have to futz with resistors or ever have to go to the rear panel for anything other than Input, Output, Insert and Power connections. This also changes the overload characteristic of the output amp.
The rise time (vertical excursion) represents high frequency response while Time (lower frequencies) are represented horizontally. The effect of sample rate on bandwidth and filtering is easily seen when a square wave runs through the conversion process. Note how doubling the sample rate reduces the ringing caused by anti aliasing filters. Analog Tape Emulation is more difficult to capture in a single image, but at the bottom, the high frequencies have been slowed down a bit while helping the mids and lows…
WIDTH CONTROL
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Figure-4: How Digitization Affects Square Waves (click image). |
What you never see is the effect digitizing has on square waves, Figure-4 does just that via HEDD 192. Notice how much more sedate the "ringing" is at higher sampling rates. Also see how Tape Emulation affects the wave. Again, like the MP-2NV, saturation is a dynamic process that can not be depicted in print. Tape saturates at high frequencies because of the record EQ boost and at low frequencies due to head limitations. That's two different idiosyncrasies plus low frequency head bumps, a complex bit of DSP.
All tests were monitored on modified Fostex NF-1A powered monitors as well as the Yamaha NS-10m. Gear comparisons via Studio Technologies STUDIO COMM. All sources were adjusted to within 0.01dB through the Studio Comm using the NTI Minilyzer.
Square waves make it easy to see, in one "snapshot," how both high and low frequencies are affected. A square wave consists of all odd harmonics - essentially sine waves ripped through a fuzzbox, clipped symmetrically top and bottom. Asymmetrical clipping generates even harmonics.
FINAL STAGE
HEDD 192 is Crane Song's second-generation stereo digital converter, adding higher sample rates as well as tape emulation (the original version featured only vacuum tube emulation). Next to an LA-2A, HEDD is the most simple digital signal processor you'll ever use and the most powerful analog emulation you or your clients will ever hear. It should sell itself!
While there are plenty of Neve variations - from repackaged modules to new - the MP-2NV is a completely new product from Great River whose two other preamps are radically different designs. Pick your fave flave. Time travel is not yet possible, but the MP-2NV has features that enhance what was already a good thing, almost like being back in the sixties. There is plenty of gain and surprisingly low noise for delicate acoustic work even when using a ribbon mic.
Both the MP-2NV and HEDD 192 provide their own brand of sonic airbag protection for drums and other transient instruments without sacrificing detail when used "under normal conditions." Combined, these two products enhance the recording process by providing a remarkable level of sonic versatility; two sonic crayons that can paint a whole rainbow. Sessions will be more fun, life will be easier and each product will provide reliable service for years to come.
Eddie finally wired his garage for sound and video. What's next? A surfboard and some hot wax perhaps?
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Reprinted with
permission from Eddie Ciletti, Tangible
Technology, 2001
October modifications © 2000 by Eddie Ciletti, All Rights Reserved
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