gofar99 Messages: 1955 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi Everyone, I just finished up a tube based headphone amplifier. The project was sent to diyaudioprojects.com for posting when Gio gets it massaged for use there. (allow a few days please). Anyhow the amplifier part is simple but the power supply a little more complicated. An easy and fairly cheap (probably under $150 if you are frugal) project that has really nice sound. Very quiet, full range and can drive nearly any phones. Best matches are with 32 to 300 ohms. Others may work ok depending on their sensitivity and impedance. The schematic is attached. The power transformer is about $15 from Edcor and the outputs are about $18.
gofar99 Messages: 1955 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
hi Wayne, Thanks for the kind words. The full project covers how to build the amplifier and some considerations that might not be obvious from the schematic. Is there a place that such projects can be posted. Even though this is a short one, it is about 5 pages long.
gofar99 Messages: 1955 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Thanks for reminding me, I had a senior moment. Just don't tell my spouse. Anyhow, this project and one for building a pair of class A valve mono blocks using EL84 are in the group build section.
Excellent contribution. Thank you. I'm learning more these days on how to get better audio from my sources of music, and you are helping in that regard.
Thank you for sharing, Bruce! To my understanding, the mobile phones or iPods nowadays are already equipped with an amplifier for the earphones. I am thinking of getting a better headphone in near future for my music needs, so I wonder if I also should get amplifier like this to boost the experience.
gofar99 Messages: 1955 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi, Maybe. I would select the phones and try them first without an external amp. There is a fair probability they will work fine. The biggest difference between internal and external phone amps is generally the output power. Since most phones are fine with just a few milliwatts this is a good thing and an external amp is not needed. Now moving on to an external DAC and phone amp ...then there may be some benefits. Externals can have more processing power and better components so the sound can be better. To a large extent it depends on the source material. If all you have is MP3s then the external DAC will not do much. If your source is high resolution stuff then you could notice significant benefits. All my phones are various models of Sennheisers. I don't find it necessary to use an external amp or DAC with the stuff I listen to. YMMV.
Reading this, I just wish that I had skills that match yours gofar. Too bad that I dropped Physics just after high school. Just out of curiosity, how much would this cost now?
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Anyhow, this project and one for building a pair of class A valve mono blocks using EL84 are in the group build section. 
