gofar99 Messages: 1950 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi and welcome to the forum. I looked at the listed designs and tend to like the one by lonewolf as it was good with 32 ohm phones. The hybrid one is fine as well, especially since it will be easier to build. All are transformer-less designs. There seems to be an aversion to using transformers in headphone amps. I suspect that it is because so many builders have used poor quality ones and the sound is just so-so. IMHO if you use a 99cent transformer, you will get 99 cent sound, the same goes for capacitors. They aren't clean either. For fun about 6 months ago I designed and built a headphone amp with transformers. I don't recall if I posted the design or not at that time. The transformers I used are not normally designed for the purpose but worked extremely well. I used some Edcor low power matching transformers. In a push-pull design using a single 6J6 per channel. The results were quite excellent. The output was about 400mw and can drive 32 ohm phones easily. The nominal output impedance of the transformer is 75 and 150 ohms, but when loaded with 32 ohms or more still provides an excellent match for the tubes. Cost was reasonable for the components and layout is uncritical.
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I looked at the listed designs and tend to like the one by lonewolf as it was good with 32 ohm phones. The hybrid one is fine as well, especially since it will be easier to build. All are transformer-less designs. There seems to be an aversion to using transformers in headphone amps. I suspect that it is because so many builders have used poor quality ones and the sound is just so-so. IMHO if you use a 99cent transformer, you will get 99 cent sound, the same goes for capacitors. They aren't clean either. For fun about 6 months ago I designed and built a headphone amp with transformers. I don't recall if I posted the design or not at that time. The transformers I used are not normally designed for the purpose but worked extremely well. I used some Edcor low power matching transformers. In a push-pull design using a single 6J6 per channel. The results were quite excellent. The output was about 400mw and can drive 32 ohm phones easily. The nominal output impedance of the transformer is 75 and 150 ohms, but when loaded with 32 ohms or more still provides an excellent match for the tubes. Cost was reasonable for the components and layout is uncritical. 
