Restored by Alter Ego Appearance 

The Technics 1520 has long been regarded as one of the prized tape decks. Impeccable consideration to the points only the most meticulous of audiophiles would understand.  Below is a description of this one of a kind rebuild written by the creator himself.

Hello fellow tape lovers. I hope you enjoy the below detail on the past 8 months of my hard work. - Alex Dorin

METAL LETTERING 

I'd been gestating this idea for a long time, ever since I got my first laser. The laser just isn’t top shelf. It isn’t the best. Raised metal lettering was clearly the choice. But applying it in practice turned out to be quite difficult. First, the letters must be firmly fixed to the surface, and secondly, they must shine, that is, they must be polished. In addition, they should not lose luster over time. The search for the alloy was tedious and time-consuming because each option had to be tested practically. I purposely exposed the metal lettering to sun, snow, rain, degreasers, anti-freeze and multiple different cleaning agents before finding the right alloy’s.  

Of the base metals available for such a restoration, stainless steel, nickel, titanium and a soft alloy containing silver performed well. Of the yellow metals, aluminum bronze showed itself to be excellent, namely C64200 from a local manufacturer right here in Brooklyn, NY (In general, almost everything used to make this device is made in the USA). The alloy contains aluminum, which immediately after processing forms a thin and durable layer of aluminum oxide on the surface, protecting against corrosion. After Polishing the lettering shines and will last forever.

The next test was making the letters and affixing them to the surface. Of course, I decisively rejected the idea of gluing it to a painted surface due to insufficient strength of adhesion, not to mention, during the baking process degradation of the adhesion is almost certain. This means that the letters must be attached to metal, painted, and then stripped of the paint for polishing. It’s difficult, but I wasn’t looking for easy ways, I was looking for what produced the best results. I began to think about how to actually cut and attach the letters. Naturally, there was some waste and experimentation; and, of course, it also took a lot of time. The metal had to be rolled out into sheet metal because such an alloy is simply not available anywhere in sheet form. After convincing my wife that I couldn’t live without the 160MM FLAT Ultra Series X-Drive Electric Rolling Mill I got to work. The optimal thickness turned out to be 0.35mm.

After this, the panel is processed with another laser, which does not burn through the metal, but removes any remaining adhesive. Then the panel is processed for painting and a powder coat is applied. After this, a mask is made from a special film using a laser, applied to the painted panel, and the letters are cleaned and polished. 

TAPE COUNTER

While meticulously studying the Technics RS-series circuits, I noticed one detail that I didn’t really like. A red LED is installed in the head block, which acts as a stroboscope to control the speed of the tape. It is supplied with power at a frequency of 64Hz for 9.5sm/sec, 128Hz for 19sm/sec and 256Hz for 38sm/sec. These frequencies are located clearly within the audio band. The measured voltage drop across the red LED was 2.2 Volts and connecting block are wires with a signal level of only a few millivolts from the reproducing heads. Unable to come to terms with this, I decided to remove this circuit, but what should I replace the stroboscope with? There was only one conclusion: read the tape speed from the counter. Experiments began.

First I tried an optical encoder wheel mounted on a 3mm axle, on which the wheel for the meter belts were previously mounted. The idea was bad, since the optical encoder wheel had to be rotated using a belt. In addition, the complexity of installing the reading sensor and the complexity of subsequent maintenance forced me to move on.

The only correct solution was to mount the counter wheel located under the head block directly on the existing ready-made optical encoder. I came across an Allen Bradely 38mm, which was difficult but could be roughly put in place. Then SolidWorks, with whom I have been on friendly terms with for a long time, came into play. Of course, for accuracy, everything had to be digitized, and not with a ruler, but with a 3D scanner. Diplomacy came into play and I asked for a 3D scanner as a birthday present from my beloved wife. I immediately got to work and digitized everything. I took 3-4 months. Then I started designing, and it was also hard work. I removed the housing from the encoder and removed the connector. After that everything fell into place. In the Technics RS-series panel at the bottom of the head block there is a conical niche that would be stupid not to use. I designed the encoder mounting in such a way that it is easy to remove and install, as well as centered.

From my MR-1 from Langmuir Systems CNC machine what you see in the photos was being made right in front of my eyes.. The encoder snapped into place like it was original.

Now I had to make a new wheel for the encoder. The choice fell on titanium 6al-4v. Aerospace grade, non-magnetic, stainless, durable and lightweight! That's where its merits ended. It is Insanely difficult to process, to put it mildly. Broken cutters, damaged workpieces, wasted time. This is only a fraction of the price per part. In the end, I still won. I CNC milled with the most expensive cutters slowly under a flow of coolant and lubricant. Then I centered it, then polished it.

A little about the diameter. The diameter of the original wheel is exactly 45mm. For this, I bow to the engineers of Matsushita Electric (Panasonic). My wheel diameter is 45.48mm. Fits perfectly. With this diameter and the number of pulses per revolution equal to 600, the tape travels 95.25mm in one second at a speed of 3.75 and rotates the encoder 240 degrees, which corresponds to 400 pulses. Thus we have 4 pulses per 1/100th of a second at the slowest speed. And 2500 microseconds between pulses. Next is math.

For other speeds, we multiply the number of pulses and divide the time between pulses. Now the question is where to send these signals. Without a microsecond of doubt I chose Teensy 4.0.  C++ helped me program it. Teensy 4.0 is capable of reading up to 2 million pulses per second using interrupt routine without additional cpu overclocking. More than enough. In simple terms, if you accelerate the tape recorder to such a speed, the coils will begin to work like propellers and the device, having accelerated on the runway, will smoothly take off from the ground and begin to confidently gain altitude like a fighter jet.

COUNTER SCREEN

Probably the only part from China is the counter screen. I designed a separate aluminum block for it instead of the old plastic.

HEADS

97% head life. Slight relapp and polish was all that was necessary. For an additional price we are happy to install brand new Flux Magnetic Heads. 

 VU Meters

I dismantled the original VU meters down to the bolts, took out the mechanism with the pointer and installed it on a specially designed aluminum base. Utilizing For VU meters backgrounds I used LED screens. Why? My customers demand the best, they are meticulous. As such I wanted a way to allow them to adapt this restoration into their existing systems. (*Next machine will have McIntosh, D’Agostino and more) To begin with, I drew six modes, including a mode for setting zero. Power supply for the meter and screens from a separate source.

ELECTRONICS & CAPACITORS

A little more about electronics. All electrolytic capacitors have been replaced with new Nichicon FG(Fine Gold) series. At the same time, I selected each pair for the left and right channels with a difference of no more than 0.2%. Of course I cleaned all the boards and connectors; replacing the connectors on the back wall with gold-plated connectors. Along the way, I changed almost all the bolts; and of course the bearings. 

BACK

Back panel made of acrylic sheet. Acrylic, according to the results of my experiments, protects the insides from dust the best. There hasn't been a speck of dust in my 1520 for two years. The graphics on the back cover are laser, no paint. The fiber laser mode is chosen in such a way that the material foams at the microscopic level. Black acrylic, when processed in this way, forms a contrasting and very durable graphic.

SIDE PANELS

The side panels were made from American white oak. But before that, I dried it well in an oven at 250F for 12 hours, then immersed it in a vacuum chamber and filled it to the top with Cactus Juice with black pigment. I pumped out the air and kept it under vacuum for 7 days. Then I wrapped it in aluminum foil and baked it in the oven for 7 hours. The wood darkened, became very heavy and became resistant to moisture. Processed on a CNC machine and polished to a high shine, feels like silk. I installed protective aluminum ends on the top and bottom of the panel, which I painted to match the color of the machine. The legs are also aluminum, very durable.

KNOBS, SWITCHES, BUTTONS

It took me a long time to choose the material for the metal parts of the front panel. The requirements are the same: corrosion resistant, white. I chose white bronze. Annoyingly, this metal can only be purchased in the form of cubes measuring approximately 12mm x 12mm x 12mm. I used graphite for injection molds. The shapes were cut out on a new CNC machine, the results are perfect. The metal for each part was cast into a graphite mold and then processed.

STATE OF THE ART EQUIPMENT, COST & END RESULT

My clients do NOT want replica's - they want a show stopper not one of their friends can purchase and the FEEL that only tape brings. They want real artisan craftsmanship.

This level of restoration takes technical knowledge of multiple programming languages and softwares like C++; design & 3D modeling softwares such as Fusion360, Lightburn, Solidworks, SolidCAM, and others. It takes incredibly expensive CNC machines, powered coating stations with air compression, 100,000 volts spray gun and related accessories, ovens to bake, metal manipulation and wood working skills and experience. If you want the next best alternative, for only pennies less that mine you can buy a plastic front Tascam BR-20 or Technics. Up to you. 

Thank you for reading. This is my passion and my life's work. I don't view myself as merely a technician but combination of technician and artist. What you see before you is my pursuit of audio perfection; the scrutiny placed on every detail and every piece of this 1520 is, for me, happiness. If you want to feel sound and own a truly one of kind tape recorder, this is the one for you. You certainly won't see another person on the planet with a replica. 

**Schedule your private test drive at the Reel to Reel Haven Showroom. Tape deck comes with following.
- One year warranty (*Warranty only machine related malfunctions. No protection for shipping or user related errors, Alter Ego Appearance reserves the right to inspect customer complaint)
- Master Tape Copy of Jazz/Blues Royalty Catherine Russell
- Master Tape Copy of Kishi Bashi
- One 1/4 Inch SM911 recording Tape by Recording the Masters 
- Custom NAB adapters 
- Custom Reels (2)