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The Starving Student Millett Hybrid - PCB
The Starving Student Millett Hybrid PCB is the latest refinement of Pete Millett's Do It Yourself (DIY) Starving Student headphone amplifier. Just like the original Starving Student design, the Starving Student Millett Hybrid incorporates a hybrid single-ended vacuum tube gain stage combined with a solid state output stage. Forums user Dsavitsk has taken the original circuit and applied it in an ingeneous way to a simple PCB with a clever case design. There were two main issues solved in applying this PCB, with many benefits, not the least of which is retaining the original's inexpensive cost to build. First, the MOSFET output stage develops a tremendous amount of heat. Therefore, heat sinking requirements are paramount. Second, while the Starving Student follows the Millett Hybrid family tradition of using low-voltage power, in the case of the SSMH this "low" voltage is 48VDC. That's enough to a little uncomfortable if contacted in the right conditions. So, totally enclosing all the voltage components was another feature developed in the design.
Please note also that in keeping with the "Starving Student" theme, there is no relay-delay on the SSMH as there is on the Millet MAX/MiniMAX family of amps. There is measureable DC at the headphone jack before the tubes have warmed up. We strongly encourage you to disconnect your headphones from the SSMH upon start-up and prior to turning it off. When this simple procedure is followed, the SSMH should give you and your headphones many hours of listening pleasure.
Like the original Starving Student, the Power Supply is an inexpensive, VoIP (Voice over Internet Protocol) telephone power supply - the Cisco PSA18U-480C, rated for 48VDC at 0.38A from a 120-240VAC input. These supplies are plentiful and can be found almost anywhere that VoIP technology is sold. In addition, the power supplies are widely available in surplus outlets and on ebay (search for "Cisco PSA18U"). This supply is more than adequate for the Starving Student PCB using all options, including the tube LED's.