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The Terecorder Saga

Updated: Nov 27, 2023

It's the 1950s. America is emerging from WWII with newfound joy and vigor. Rock n' roll is born and new technology is booming. Searching for a way to record and broadcast his radio show, Bing Crosby meets Jack Mullin, a U.S. Marine eager to show off to some "souvenirs" he took from a Nazi radio station during the war. One such souvenir peaked Bing's interest: a device that could record audio with greater fidelity and duration than anything seen before. It was called magnetic tape. By reverse-engineering this new technology, Bing and Mullin founded the Ampex Corporation, the multi-track tape machine was born, and the recording industry would never be the same.

Across the pond, Japan is also undergoing its own emergence. Eager to put the horrors of the war behind them and redefine Japanese excellence, engineers at the Akai Electric Company manage to import an Ampex 600, Ampex's first consumer reel-to-reel deck. They tear it apart, piece by piece, in an attempt to reproduce this mythical machine for the Japanese market. The result is the Terecorder 900, Akai's first production tape recorder. It bears a striking resemblance to the Ampex 600 on the inside and outside, including its bulletproof construction.

Skip ahead 67 years. In 2023, analog tape recorders have almost all fallen into disrepair and obsolescence. Most of their mechanical parts have failed, but the meticulously engineered audio circuitry still remains. This leads many savvy producers & engineers to scavenge the old preamplifiers and channel strips from these old tape machines. As a result, Ampex 600's are pushing $1,000 online, rarely in working order. I find myself driving on mountain road, with a sea of pine trees whizzing past. I'm on my way to Idyllwild to pick up, unbeknownst to me, a very special Terecorder 900. In the middle of the forest, I meet a bearded, friendly man who hands me this handsome little box, almost resembling an old suitcase. It wouldn't become clear what I had until I got home.

My goal was to take the preamplifier section and build it into a rack mount enclosure as a vacuum tube microphone preamp. Cosmetically, the tape machine was in good shape. Electronically, it was a different story. It would not pass signal and the filter caps were so far gone that it sounded like wall voltage was going straight to the machine's sad little internal 4 ohm speaker. I knew I'd be rebuilding the entire amp, but this wasn't a great start. The other capacitors were also oil PCB caps, which are bad news. Thankfully none were leaking, so no hazmat team sealing off my apartment, for now. I also began noticing a number of peculiarities with my particular Terecorder: for one thing, this had a real, bonafide VU meter, unlike the indicator bulb on all the ones I'd seen online. "Matsushita Electronic Co." was printed on the VU meter face.

Then, the bombshell. The power transformer primary read, "100V," meaning this tape machine was manufactured for Japanese AC power. Somehow, this unit had been imported all the way from Japan and ignorantly run on North American 120V AC. That explains the ailing components. Thankfully, the amplifier truly came alive as I rebuilt each section and gave it the correct supply voltage. Some components were interfering with the frequency response, which I knew I had to be a stickler about. It took time, but I eventually got a relatively flat response curve. There's a strange bump around 140Hz, which I'm guessing is some kind of resonance caused by a component in the circuit. I added an XLR jack, mic input transformer, and a big, clicky 48V phantom power button that lights up when pressed. I'm utterly beguiled with how over-engineered this amp is, so I figured that engaging power to your condenser mic should feel like dropping the landing gear on your fighter jet for an aircraft carrier landing. Totally worth it.

Eventually it was time to plug a mic in and see what happened. The first thing that struck me was the sheer amount of gain. With a Shure SM57, the dial barely reached 3 before the meter reached +0 VU. With a Neumann U87Ai, it was closer to 2. I frequently found myself stepping back from the mic while talking. What a splendid suprise! The Terecorder preamp must be pushing 80dB of gain, putting it right up there with the Neve 1073 and its contemporaries. Unlike the Ampex 600 upon which it's based, the Terecorder 900 has a +4dBu line level input. So naturally, I had to plug a synthesizer into it. Both the Minimoog and TB-303 sounded absolutely glistening. I could sense the 6AU6 tubes smoothing out some of the sharp transient information from the signal. When folks search for tube "character," "warmth," "sparkle," or whatever, THIS is what they're looking for. I can see myself using this on so many sources, especially mics like the U87 and C414 that can be too harsh for my taste. Overdrive/saturation is also spectacular. It brings to mind the immediate, yet pleasant saturation on old SSL, Neve, and API consoles. I hope to put it good to use on a tracking session for a client tomorrow morning. Mission accomplished!

UPDATE 11/27/23:

The Terecorder has some odd, Japanese-style 1/4" input jacks that went bad, so I replaced them with modern Neutrik equivalents. While I was in there, I substituted a few tubes, including adding a pair of 7543s. The 7543 is little known, but is a low noise preamp tube used in the Sony C800G large-diaphragm condenser microphone.

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