Tube-Tech EQ 1A Full Range Equalizer

The Tube-tech EQ 1A is an all-tube based, mono equalizer, which provides a sweet, musical EQ that offers creative sound-shaping with minimal tweaking. It provides the exactly results you'd expect from a world-class EQ, and does it effortlessly. A mastering version of the EQ 1A, the EQ 1M is available with stepped rotary switches for accuracy and parameter recall.


Tube-Tech EQ 1A Full Range Equalizer, First Take:
One-channel, all-tube based parametric equalizer
High- and low-cut filters
25kHz cut for anti-aliasing filters
High- and low-cut shelving EQ sections and three overlapping bands

All-Tube Based Parametric EQ

The EQ 1A has seven EQ sections that can be switched in and out, including high- and low-cut, high and low shelving, and three overlapping bands ranging from 40Hz to 20kHz. Except for the power supply, the EQ unit is all-tube based. Both the input and output stages have fully floating transformers for superior electronic isolation, which results in noise-free, ground-loop immune operation. All voltages (with the exception of the anode voltage at the output stage) are DC stabilized, since any variation in the DC energy when combined with the musical signal would cause distortion. Put simply, the EQ 1A's DC-stabilized circuits keep the EQ bands free of any unwanted artifacts. EQ is smooth and distortion-free.

High- and Low-Cut Filters

The cut filters are designed with unity gain amplifiers. This is significant since they don't load down the source or draw any current. Therefore, they drive the load as if it were a perfect voltage source. They also eliminate distortion due to overload, crosstalk, and other electromagnetic interference. The low- and high-cut sections include a frequency switch with a choice of six frequencies, a slope switch and an in/out switch. Both the low- and hi-cut filters offer a choice of six frequencies.

25kHz High-Cut for Anti-Aliasing Filters

Of particular interest is the 25kHz high cut setting. Its purpose is to roll off the digital artifacts that can be heard when recording to digital systems when using their onboard converters. As you may know, design engineers use the anti-aliasing filters in digital converters to dump "garbage" (digital artifacts) above the audible spectrum (above 20kHz). In use, the 25kHz cut appears to have very little effect on the high-frequency content, however, its effect is very audible when it comes to removing the effects of those artifacts.

High and Low Shelving EQ

The shelving and bell filters (for the three overlapping bands) are designed around two tube operational amplifiers. Tubes can be operated in the overload region without adding objectionable distortion they way op amps and solid state amplifiers do. Due to this extra headroom, although subjective, tubes sound louder and have a better signal-to-noise ratio than transistor amplifiers. This is why the EQ 1A sounds so musical and smooth, even when you boost frequencies in the extreme. The EQ 1A also offers six frequencies of shelving in both low and high sections, and the same 6dB or 12dB slope per octave, and ±15dB of gain. The three bands of bell-type EQ offer 36 overlapping frequencies (12 per band), +/-20 dB of gain and variable bandwidth.


About Tube-Tech

For over twenty years, Tube Tech has been one of the most prominent names in all-tube signal processing equipment. You'll find their gear in the best recording and mastering studios around the world. The company's founder, John Petersen is an electrical engineer who was factory trained at Solid State Logic, EMT, Studer, Sony, Neumann, and NTP Electonik (digital audio routers). He also designed tape recorder playback/recording amps for Lyrec tape recorders (found in the studios of the legendary Joe Meek and Vangelis). His first design under the name of Tube-Tech was an all-tube equalizer based on the legendary Pultec EQP 1A. Petersen continued to design and manufacture a number of innovative all-tube outboard processors including preamps, multiband compressors and summing amps. Thanks to John's dedication to high-quality analog sound you'll see Tube-Tech gear in the racks of pro audio legends such as multi Grammy Award winner Al Schmitt, (Frank Sinatra, Steely Dan, Toto, Quincy Jones, Natalie Cole, Diana Krall), Grammy winner Joe Chiccarelli, (Elton John, Beck, U2, Tori Amos, Counting Crows, Offspring), engineer Russ Long (Sixpence None The Richer, Wilco, Dolly Parton, Allison Moorer), producer-engineer Tony Shepperd (Elton John, Madonna, Kenny Loggins, Barbra Streisand, Lionel Richie, and Whitney Houston), and many more.