Open Box Tube-Tech SSA-2B Stereo Summing Amplifier Level 1

Yes, you can mix inside the box and get good results, but with the Tube-Tech SSA 2B Stereo Summing Amplifier, you can mix inside a much better box and get stunning results. Where extremely high-quality summing of several signals into two channels is desired (and where isn't it?), the SSA 2B is a top choice.


Tube-Tech SSA 2B Stereo Summing Amplifier, First Take:
Ultra high-quality summing amplifier with very wide frequency response
8 stereo/4mono inputs summed to 2 channels out
Inputs balanced by zero field transformer
Balanced and fully floating outputs

Ultra High-Quality Summing Amplifier

The rackmountable Tube-Tech SSA 2B Stereo summing amplifier features two very low-noise, low-distortion summing amplifiers with a very wide frequency response of 5Hz - 100 kHz. The inputs are transformer balanced and the circuits are symmetrical from input to output. The inputs are also capable of handling extremely high input levels.

8 Stereo/4 Mono Inputs Summed to 2 Outputs

The Tube-Tech SSA 2B summing amplifier has 4 mono input (hard wired to CH1 and CH2) and 8 stereo inputs, which are summed to two outputs. The SSA 2A consists of a summing amplifier at the input, a 23 stepped attenuator with a range of +/- 10 dB and an output stage. Two large VU-meters show the levels on the XLR output sockets. To avoid the distortion introduced by the VU-meters when connected directly to the output XLR sockets, symmetrical configured OP- amps buffer the VU-meters. The summing amplifier is a symmetrical two-stage amplifier, designed around two dual, low impedance, and high transconductance triodes. The input transformer is part of the dual feedback configured as a so-called zero field transformer. The attenuator is a heavy gilded 2 x 23-position switch with steps of +/- 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10dB. The output stage is designed around two dual triodes in push-pull and an output transformer (with a static screen). Both the summing amplifiers and the output amplifiers are symmetrical.

Zero Field Transformer-Balanced Inputs

All inputs on the Tube-Tech summing amplifier are balanced by two zero field transformers (one for each channel). In zero field transformer configurations, the transformer is part of the feedback circuit. There are several benefits to be derived from this: 1. The voltage across the transformer is reduced substantially, whereby a much smaller transformer is needed for the same specification. The reduction is of the same magnitude as the feedback applied. 2. The distortion at low frequencies is reduced substantially. 3. Frequency response in both the low and high range is extended. 4. Phase response in both the low and high range is more linear. The results are better harmonic balance of the instruments and more realistic sound.

Balanced and Fully Floating Outputs

The outputs are balanced and have fully floating transformers with a static screen. Floating a transformer (not referenced to ground) provides maximum electronic isolation for superior noise rejection. The static screens shield the transformer's secondary windings from the primary and prevent RF (radio frequency) electromagnetic noise from getting across. The Tube-Tech amp's Line Input is unbalanced, but an optional transformer is available, which will allow the line in to act as though it's balanced. The power supply and the sidechain circuits of the Tube-Tech SSA-2B summing amplifier are based on a solid-state circuit. With the exception of the output stage all DC voltages are stabilized. This prevents any variation in the DC energy when combined with the musical signal, which would otherwise cause certain types of distortion or hum.


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 amplifiers and gear in the audio 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.