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JunktionFET

My new headphone amp

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Some of you may not know, but I am an audio enthusiast/hobbyist. I used to work for Cary Audio, a well known company in Cary (heh, go figure) that produces some of the world's finest and most expensive high-end audio gear, with an emphasis on tubes. For a while now a friend of mine and I have considered producing a line of high-end amplifiers and loudspeakers--actually we've been toying with the idea since we were in high school. I feel that we are moving closer to this becoming a reality.

Though my audio interests are primarily centered around sound reproduction from speakers, I have recently become more interested in headphone high-fi as well. At present I own three pairs of headphones. My collection consists of Beyerdynamic DT-660s, DT-990 PROs, and some AKG K501s. Though the DT-660s are generally happy when driven directly with portable gear (like a portable CD player or MP3 player), the other two are higher impedance and portable gear sometimes just doesn't have the voltage swing necessary to drive them.

My friend, who is an unbelievable analog engineer, designed a very nice sounding headphone amplifier for use with my high-impedance studio headphones. The circuit is designed to be semi-portable... something I can bring to work or on a trip out of town. This weekend we assembled the unit and packed it all into the smallest enclosure possible. I'll get more pics of it online later including some interior shots.

The circuit uses no ICs (chips), it is all discrete. It uses a single ended input stage and a class A push-pull output. Because it is intended as a somewhat portable amp, I could not make the whole thing single-ended because it would just generate too much heat. This design consumes far less power and the single ended input circuit adds a lot of the warmth and smoothness I prefer. The circuit is rounded out with some NOS vintage Roederstein and expensive Rubycon Blackgate capacitors.

It sounds very "airy"--there is a warmth in the upper midrange that very faithfully reveals the room surrounding each instrument/sound/voice. Very fine detail is clearly audible, but the clarity does not come with any edge or fatigue. It is actually addictive--I sat for hours listening last night, well beyond my normal bedtime.

Here are some pictures of it on the work bench. Pictured with it is my trusty old modified Marantz CD67SE. I removed the Marantz HDAM modules completely, all the audio coupling capacitors, and replaced the stock opamps with much better sounding chips. Anyway--

Portableamp1.jpg

Portableamp2.jpg

Portableamp3.jpg

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cool. my brother would probably buy some of those from you. he's obsessed with high-end headphones. there are a few local guitar amp makers that produce some really awesome guitar amps too. the last time i was at fat sound in cary i think they carried a few including the doctor z. a friend of mine has one of those amps and it sounds amazing.

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