Analog Obsession: David Blackmer and the dbx 160
By Will Shanks
I recently acquired a private collection of old Ampex tape-machine parts from a gentleman who had a service business in the '60s and '70s. Among this collection were a few other oddities, including a UREI model 200 frequency plotter, and a less-than-pro looking tabletop compressor called the dbx 160. I did not think much of it at the time, as it appeared to be in disrepair. A friend spotted it among the Sanford and Son-style storefront I had set up in my garage, and thought it to be the first compressor ever made by dbx. This got me interested, and sparked some nostalgic feelings for my very first compressor, which was the later rackmount dbx 160X. I did some research and saw that the 160 was not only quite valuable, but still considered a studio staple by many. I packed up the unit and sent it to serviceman extraordinaire David Kulka for a full service. What I got back was a beautifully working unit, and a bit of a surprise at how useful I found it.
The Father of the VCA
Originally founded by David Blackmer in 1971, dbx (shorthand for "decibel expansion") was the birthplace of many groundbreaking and enduring technologies and designs. Originally employed as a device to restore transient loss due to the negative side effects of magnetic recording, Blackmer’s patented VCA (Voltage-Controlled Amplifier) and RMS (Root Mean Square) detection technology soon found a home in many audio products such as compressors, noise-reduction devices, and subharmonic synthesizers, which have made the dbx brand one of the most recognized in the audio production world. Blackmer’s patented VCA designs even found heavy use in many audio products not necessarily sporting the dbx brand. Like Bill Putnam, Blackmer eventually sold his company to a larger entity, but the products and technologies he designed during this era endure to this day as a working testimony to his brilliance.
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| The one that started it all: the dbx 160 “VU” |
Birth of a Legend
Of all the dbx designs, Blackmer’s first compressor design is one of the most enduring, and has spawned the greatest number of iterative products for dbx, even to this day. The dbx 160 has been a staple in studios since its inception. “VU” is the common nickname for this widely regarded first-generation tool, famous for its simple control set and firm compression characteristics. A bit of a one-trick pony, the dbx 160 produces a sound unlike earlier compressor technologies, and exhibits hard knee compression characteristics with subtle program dependencies different from an LA-2A or 1176.
The solid-state, transformerless design set new standards for performance and affordability, and for better or for worse brought the decline of older compressor topologies. It really ushered in a new wave audio technology, and was one component in the birth of home recording, along with the original Teac 4-track recorders and other “pro-sumer” devices of its era.
Sonically, the 160 is in a league of its own and has a distinct ability to grab virtually every transient thrown its way.
Variations
The original dbx 160 unit is still considered the very best in a long line of VCA compressors that continues to this day. Unlike later monolithic IC units, the VU uses a series of components for gain reduction, and therefore has unique nonlinearities not found in its later cousins—giving it a sonic distinction and a higher value. On a purely speculative note, the product was probably also popular in the era because of those fabulously '70s wood sides. The wood sides could of course be removed for a single or dual rack kit, not unlike the LA-3A. Tragically, many of those wood sides were discarded in the process, which tends to devalue the original unit—but I digress.
In addition to the 160, the 161 was a lower cost, yet functionally identical, version which offered unbalanced -10 RCA connections and was likely targeted at the home recordist. Happily, the 161 can be converted to a +4 input and output with relative ease if so desired. There was also the 162, a two-channel version of the 160, which favored stereo use. Similar to the UREI 1178, the 162 was not very practical for using the individual channels on separate sources due to the lack of separate controls.
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| Original dbx 160 advertisement |
In Use
With its simple control set including Threshold, a continuously variable (1:1 to ∞:1) Compression (Ratio) and Output Gain, the dbx 160 can be seen as functionally very similar the LA-2A. There are also two LED threshold indicators which continually present a “Below” and “Above” state of the compression threshold, as well the Input/Output/Gain Change VU meter for which the unit is famous. Sonically, the 160 is in a league of its own and has a distinct ability to grab virtually every transient thrown its way, and can tame the dynamic range of even the most wildly fluctuating performance. The gain reduction metering can be deceptive (as is the case with many vintage compressors), and is likely doing a lot more than the eye can detect with the meter—therefore please proceed with caution. On the other hand, destroying tracks with the 160 may be exactly what you want to do. But be warned that while certainly unique, the “over-the-top” compression characteristics in this device are not necessarily always musical. The dbx 160 is probably most famous for taming kick, snare, and other percussion sources. Some folks swear it is the best electric bass compressor ever made. The later dbx 160X was my first compressor for several years, and of course I used mine on everything.
Enduring Technology
Since the introduction of the VCA as a gain reduction element, it has become the de facto basis for modern compressor design. A few other manufacturers and products that use VCAs for gain reduction in no particular order: Neve 88R consoles including the 88R series, SSL consoles and rackmount compressors, the RNC Really Nice Compressor, the Empirical Labs Distressor, the Alesis 3630 (gasp!), the Valley People Gain Brain and Dynamite, and the Focusrite Red compressor. Long live the Blackmer legacy!
Additional links of interest about the late David Blackmer, his family’s businesses, and his VCA technology:
http://mixonline.com/mag/audio_memoriam_david_blackmer/
http://blackmersound.com/
http://www.earthworksaudio.com/
http://www.thatcorp.com/vcahist.html