Over the years, our talented team of techs has worked on a number of note-worthy preamps, from classic 1073s to coveted 312s. But recently, a piece of recording history came into the Tech Shop. This week, Vintage King Audio Technician Scott Krause has been hard at work restoring four TAB/Telefunken V76 preamps and four of the rare V78 preamps:

“The V76s are not like any other preamps that I've ever seen. I mean, these things weigh like 10 pounds—there's so much iron in them. The craftsmanship in the build of all the V series preamps is mechanically and electronically engineered to a degree I don't see in any other pro audio gear that comes through the Tech Shop. They are beautiful pieces. Mechanically, the build is as clean as the sound is pure. With the frequency mod, these preamps expand past 30 kHz, which helps give them a rich, high-quality sound. It’s much more open than you get with other preamps. 

The sound of these pres is in the transformers, the coils, and the dual pentodes used in the amplifier circuits. Rather than triodes, pentodes have a design characteristic of controlling constant current going through them, lessening current flow anomalies, which gives the signals analog cleaner information, and less oscillations or distortion, creating a more vibrant and pure, less colored sound.”

TAB/Telefunken V7X Preamps

The V7x family of tube preamps has a long and complex history dating all the way back to 1928 when Telefunken created the V41 tube preamplifier, which went on to become the industry-standard preamp for German broadcast.

In the early 1950s, stations began seeking a more high-fidelity option after a leap in audio technology. In response, Telefunken released the V72, a V41 preamp circuit outfitted with modern glass tubes (along with a few other modifications).

It didn’t take long for studio engineers and producers to discover the V72, which quickly became a must-have preamp. Owned by many of the world’s most famous studios, the V72 earned a reputation for its rich, beautiful sound, and became a staple on drums, vocals, bass, and more. Used on countless classic tracks throughout the 50s and 60s, the V72 helped define the sound of an era.

Over the years, Telefunken released a number of variations of the legendary V72 preamp, each featuring slightly different components.

TAB/Telefunken V76 Preamp

Also known as the “King Daddy of mic pres,” the V76 was designed and manufactured by TAB in 1956. Essentially a pair of V72s in series, the V76 is capable of 76 dB of gain, (hence the name). 

The V76 has a shelf EQ at 80 Hz and 300 Hz, or a combination of the two. There are also built-in cutoffs at 40 Hz and 15 kHz (these can be bypassed to realize frequency response from 10 Hz to 35 kHz, but it is arguable if this mod is desirable or not.). 

The gain circuit combines variable feedback and input attenuation to provide low noise across the gain range. The higher gain is thanks to an E83F pentode and a trio of EF804 tubes, instead of the pair found in the V72.

TAB/Telefunken V78 Preamp

The V78 is also very similar to the V72, but with 70 dB of adjustable gain. Made by both Siemens and TAB, these units are much rarer than the V72 and often have a mod to include a gain control on the faceplate. Often used as a talkback amp, its circuitry differs enough from the V72 that it offers a unique tone and is usually modded for use as a mic pre.

According to Scott, restoring these legendary preamps has been a long and detailed process.

“It’s a beast. These things have all discrete components—three transformers and three chokes each—which makes them really heavy. Plus, everything is fully compartmentalized to reduce mechanical noise.

It’s all put together in sections. Anything that touches in there, whether it’s a coil or a transformer, is isolated with some kind of shock absorption. But over the years, it all starts to decay. One day, you pick it up and it just rattles around like a bag of bones.

So it requires a complete disassembly just to get to these shock absorbers and rebuild the circuit, which is going to take some time. But I think that design has a lot to do with why these things sound so clean. None of that mechanical noise gets into the circuit because of the care they took when putting these things together.”

Want to learn more about the TAB/Telefunken V7x family of preamps? Check out our Pro Audio Hall of Fame!