Kursun
05-06-2013, 08:11 AM
I’m 62 years old. I have been a music and hi-fi addict since the age of 6.
I have never been a headphone man. I just don’t like listening through the headphones.
But I do have two headphones:
Philips SBC HP 1000 and AKG K701.
I like the Philips HP 1000 a lot. Its sound is very good for its price. It is a pity it’s discontinued.
I had found the AKG K701 quite bright and had listened to it only for “dim” sounding recordings.
Lately I thought of selling the AKGs as second hand but before doing that I thought of giving it a second chance…
I had been listening top my headphones through my HT receiver. I decided to buy or build a headphone amplifier before deciding to sell my AKG K701s.
I thought,
Headphone diaphragms produce much less distortion than loudspeakers as they have to move much less air mass than speakers. Because of this fact they show the deficiencies of the driving amplifier much more than speakers.
Headphones require milliwatts to produce their maximum output. Unfortunately 99.9 % of the amplifiers we use at home are class B/AB designs. Class B/AB designs produce their highest distortion (especially crossover type distortion) in this milliwatts range…
This information is probably elementary stuff for hard core headphone listeners. It’s a pity that I had thought of such things after so many years. As I said I was ignorant… Well I have never been a headphone man…
In the end I bought parts from e-bay to build a class a headphone amplifier originally designed by good old John Linsley Hood. Actually my first pre-amplifier I had built many, many years ago was also a John Linsley Hood design published in Wireless World. Unfortunately the semiconductors in those days were much too noisy…
If you write “JHL class A headphone amplifier” in e-bay you’ll see many such kits. (BTW I don’t know why it is spelled JHL and not JLH) My kit has Nichicon filter capacitors and Alps potentiometer.
Last week I finished the project. My first listening material was “Randy Crawford & Joe Sample - Live (2012)” album. Though a live recording the sound quality is first rate. And I love to listen to Steve Gadd on drums…
Pictures of the project:
Top: http://img20.imageshack.us/img20/6798/image00001tn.jpg
Back: http://img690.imageshack.us/img690/1941/image00002cse.jpg
Front: http://img507.imageshack.us/img507/1816/image00003kh.jpg
On the chassis though there is no magnetic shield between the r-core power transformer and the circuit board there is no hum on the output. The circuit is very quiet too.
What is the difference compared to listening through the HT receiver's headphone output?
There is more and better controlled bass. The midrange has more immediacy of a live feed. Output from the HT receiver’s headphone output has slightly more distortion in the midrange reminding you that this is a recording. The differences are slight but important.
I’m completely satisfied. The results I got is slightly better than what I expected to get. I have decided not to sell the AKG K701s and keep them for critical listening.
Rest in peace John Linsley Hood.
I have never been a headphone man. I just don’t like listening through the headphones.
But I do have two headphones:
Philips SBC HP 1000 and AKG K701.
I like the Philips HP 1000 a lot. Its sound is very good for its price. It is a pity it’s discontinued.
I had found the AKG K701 quite bright and had listened to it only for “dim” sounding recordings.
Lately I thought of selling the AKGs as second hand but before doing that I thought of giving it a second chance…
I had been listening top my headphones through my HT receiver. I decided to buy or build a headphone amplifier before deciding to sell my AKG K701s.
I thought,
Headphone diaphragms produce much less distortion than loudspeakers as they have to move much less air mass than speakers. Because of this fact they show the deficiencies of the driving amplifier much more than speakers.
Headphones require milliwatts to produce their maximum output. Unfortunately 99.9 % of the amplifiers we use at home are class B/AB designs. Class B/AB designs produce their highest distortion (especially crossover type distortion) in this milliwatts range…
This information is probably elementary stuff for hard core headphone listeners. It’s a pity that I had thought of such things after so many years. As I said I was ignorant… Well I have never been a headphone man…
In the end I bought parts from e-bay to build a class a headphone amplifier originally designed by good old John Linsley Hood. Actually my first pre-amplifier I had built many, many years ago was also a John Linsley Hood design published in Wireless World. Unfortunately the semiconductors in those days were much too noisy…
If you write “JHL class A headphone amplifier” in e-bay you’ll see many such kits. (BTW I don’t know why it is spelled JHL and not JLH) My kit has Nichicon filter capacitors and Alps potentiometer.
Last week I finished the project. My first listening material was “Randy Crawford & Joe Sample - Live (2012)” album. Though a live recording the sound quality is first rate. And I love to listen to Steve Gadd on drums…
Pictures of the project:
Top: http://img20.imageshack.us/img20/6798/image00001tn.jpg
Back: http://img690.imageshack.us/img690/1941/image00002cse.jpg
Front: http://img507.imageshack.us/img507/1816/image00003kh.jpg
On the chassis though there is no magnetic shield between the r-core power transformer and the circuit board there is no hum on the output. The circuit is very quiet too.
What is the difference compared to listening through the HT receiver's headphone output?
There is more and better controlled bass. The midrange has more immediacy of a live feed. Output from the HT receiver’s headphone output has slightly more distortion in the midrange reminding you that this is a recording. The differences are slight but important.
I’m completely satisfied. The results I got is slightly better than what I expected to get. I have decided not to sell the AKG K701s and keep them for critical listening.
Rest in peace John Linsley Hood.