Eventide H3000 - "Silence the HUM!"

Achilles Heel

I love the Eventide H3000, but it has one fatal flaw… a horrible and all too typical AC transformer hum. This isn't always the case. H3000's I'm sure, didn't come from the factory with horrible humming transformers. It's just the nature of age, and it's something that slowly is sure to happen to all units in the h3000 lineage that use these old iron core transformers. Progressively, they get worse and worse. See, iron core wound AC power transformers tend to degrade over time due to a variety of factors, leading to the development of a 50 or 60hz hum or buzz. One of the primary causes of this degradation is the aging of the transformer's insulation, usually epoxy resin, which will lead to a decrease in its dielectric strength. This in turn will cause the transformer to draw more current, leading to increased heating of the core and windings, a feedback loop, that further degrades the insulation and exacerbates the hum or buzz. As it gets worse, the mechanical stress on the transformer from the vibrations contributes to the speed of the degradation of the insulation and the development of even stronger hum & buzz. It just keeps going. Every hour that you operate the transformer, the worse it gets, until eventually it is lights out. 😵

A sad, tired, worn out stock A/C transformer, near it's death

When I set out do design a new power-supply for the H3000 that would once and for all eliminate that annoying 60hz hum, I was also hungry. I was in my studio listening to that stock transformer buzzing through the chassis of the h3k. The only thing that would occasionally drown out that annoying rattle was the sound of my stomach growling. I decided to take a break and went out to get my usual quick solve for hunger, donuts and coffee. As I was enjoying my donuts it suddenly dawned on me, the Toroid! I realized that the cure to that hum that was driving me—and everybody else with a vintage h3k in their rack—absolutely mad, was right there in front of my face.

🍩 + ☕️ = 🤐

the formula for silencing an engineers stomach

When I got back to the lab, I started to think on the problem and solution seriously. After consulting the OEM Eventide H3000 service manual, I drew up a quick schematic, and searched through some parts suppliers catalogs looking for suitable transformers. I found one that met the specifications and with little delay ordered the parts and downloaded the manufactures data sheets. Less than an hour later, I had the initial schematic laid out. I took the top of my H3K off, and took out my caliper to take some measurements. It looked like there was just enough room for the new parts to fit in the void that would be left from removing the stock iron-core power transformer.

Anticipation

Every single time in my life as an electronics engineer—when I await the arrival of a new PCB design from a board house—I experience the same level of anticipation. It feels similar to the excitement I felt as a school-boy waiting for the last day of class before summer-vacation. Finally the day came, and the new PCB arrived. I quickly assembled the first "proto-type" and to my ultimate chagrin, it fit like a tailor made suite, and worked just as good.

It's quite an experience to conceive and design something in 2-D on a computer screen, to only days later have it to behold in 3-D 'meat-space' and see it function as you'd expected. It never gets old. I guess I'm in the right line of work?

A Solution

If you'd like to get your hands on one of these replacement power supplies, You can head on over to https://Synthesizer.repair/h3000 where you will find a handy "buy" button.