Background: I’ve owned several DHT amps over the years (2A3, 300B, and 205D) but I’ve always been desirous of a full-sized 45-based amp since I (briefly) owned a Lampizator Big7 Mk3 DAC with a 45 tube output stage. So, ultimately I sold my Eddie Current Studio B 300B amp and ordered the Shiny Eyes 45 DHT SET amp to supplant it.
Build: The amp is the physical manifestation of the common wisdom that the sound of a great SET amp is 80% the transformers / power implementation and 20% the actual tubes. As you can see, the Shiny Eyes presents a literal cityscape in miniature of Hashimoto iron rising like skyscrapers from the top plate. Specifications from the manual for the technically inclined are as follows:
“This is a high end, low power headphone/speaker amplifier with a 16 ohms HP output and 8 ohms speaker output at max 2W. The amplifier uses all Hashimoto transformers and chokes, and it is assembled on a sturdy 1/8" aluminum chassis made by LandFallSystems, and wrapped in Peruvian walnut front and sides…
The power supply has a powerful 5AR4 or GZ34 tube rectifier, followed by a CLCLC filtering using two Hashimoto chokes, and two 4 poles Mundorf HV+ high fidelity capacitors.
The amplifier was designed to use the 5AR4 rectifier (or equivalent). Using other 5V rectifiers that have the same pin out is possible. However, they will have an effect on the sound by changing the operating points of the 45 tubes, and therefore the power output. The 5AR4 has a nice 10-12 seconds soft start. Using other rectifiers with shorter ramp up will slightly affect the longevity of the audio tubes. Other possible rectifiers are 5U4, 422A.
There are 3 separate DC regulated supplies for the 45s and C3g tubes, an excellent choice for zero hum. The audio section of the amplifier uses the C3g pentodes in triode mode loaded on a Hashimoto interstage transformer and powered by cascade CCS for minimal distortions. The final/power stage is using the 45 self-biased using Mills resistors and Mundorf Mcaps capacitors. The 45 is loaded on a Hashimoto output transformer.
All the small parts are audio grade and tested for the best sound. I used Audio Note Tantalum, Takman Rey, Mills, AMRG, Vishay Milspec and 5W Kiwame for the supply bleeders.
The amplifier is integrated with one RCA input, and the volume control is a stepped attenuator Elma 47 positions by Goldpoint.
The amplifier delivers 2W maximum on 16 ohms, 1W on 32 ohms, and 100mW on 300 ohms headphones.
The amplifier will also deliver maximum 2W on 8 ohms speakers.”
Sonics: The 45 arrived Thursday so I’m only on day 2 of listening and she is still breaking-in sonically, but, similar to Geoff’s statements in an earliest post about the sound signature of his Shiny Eyes 4P1L, the 45 SET presents the most “holographic”, curved soundscape I’ve heard to date. While the 2A3 may have more texture and splash in the treble and the 300B certainly delivers more power and is nominally more linear, there is some (I hate to use such vague terms) musical realism and sweetness across the frequency range to this 45 implementation that resonates with me. I also feel that while other DHTs may deliver more power in the bass, the 45 achieves a perfect balance of power and texture in the sub- and mid-bass for most headphone power needs. I do understand 2-channel listeners may need the added wattage of a 300B or bigger triode implementation like 211s or 845s, but, for headphones, the 2W 45 (and the 1.5W 205D for that matter) is all most head-fiers will ever need. Back to sonics, I was primarily pairing the amp this week with a Raal Immanis combined with 8-ohm ribbon drive interface connected to the 2W speaker taps of the 45. Stage width, depth, imaging, and detail were top tier even by Immanis standards (my baseline being the Immanis driving by the also excellent Raal VM-1a in triode mode). The amp is very clear and clean but has a noticeable second order harmonics emphasis and a slightly laid back feel conducive to long, fatigue-free listening sessions.
Early days, but the Shiny Eyes is so far proving to be a superb headamp.