class a elektor headphone amp

Tekko · 26th January 2006, 06:32 PM

Does anyone know this amplifier ?

I got it with a heatsink a few years ago and was told that it was an elektor class a headphone amp that could also deliver around 10 watts into 8 ohms.

Anyone recognice it ?

lineup · 26th January 2006, 07:20 PM

Class A, discrete 10 Watt in 8 Ohm.
I do not remember this Elektor headphone amplifier.

What are those 4 ouput transistors?
BD139/BD140?

Nisbeth · 26th January 2006, 07:36 PM

A headphone-amp that provides 10W output? That's a little unnecessary. Why don't you email elektor with the PCB-number and see if they can help you?

/U.

dx.master · 26th January 2006, 07:51 PM

I have build this Headphone amp too.
And somewhere i have the orignal article ...

But 10W is to mutch for this headsinks ...

peranders · 26th January 2006, 07:54 PM

I remember this amp. 10 W with these transistors is a bit weak but if the supply voltage was +- 15 volts it's possible to get a couple of watts from the amp. Beware of the thin traces from the output.

Why do you ask?

I have the article somewhere in my collection. If you could tell me when it was published it would help me.

jacco vermeulen · 26th January 2006, 08:03 PM

Elektor did that design in 2 versions, the first one was part of their 80s discrete modular preamplifier design.
Second version was identical but doubled output devices, also BD139/140.
Bias was 0.1 amps.
I still have both articles.

Tekko · 26th January 2006, 10:21 PM

I soldered those trannies on today, the originals were fried/stolen a few years ago, i still have the heatsink that came with the amp when i got it from a forum member of a swedish hifi forum.

It originally used BD139/140, the ones there now is similar ones but are drivers from a broken poweramp.

It was the previous owner that said the thing could deliver around 10 watts in 8 ohms while it operated in class A driving 32ohm headphones.

I believe its either the 1983 mag 4 headphone amp, the mag 7 1984 mini crescendo, the mag 1 1986 AXL amp, the mag 9 1986 or the mag 10 1986 mini stereoamp.

Board number EPS83022-7 if it helps.

jacco vermeulen · 26th January 2006, 10:28 PM

It does nearly 10 watts in class AB.
With 4 BD139/140 per channel i managed to get 2 watts in class A and keep the devices alive.
Sound on a K1000 isn't bad

The board number stands for 1983
I can post a picture of the 2 device version i built, same as yours.
I used it on efficient loudspeakers, amazing what such a little amplifier can do.

Tekko · 26th January 2006, 10:34 PM

I find the sound suprisingly good with just a cd-rom drive as source.

My output transistors are: 2SD669A ond its complement 2SB649.

If anyone have the issue with this amp, i´d like a scan of the info sheet and schematic.

Tekko · 26th January 2006, 11:04 PM

Maybe i should add that i run it with a pc power supply, also i have it hooked up to a pair of old 4 ohm speakers.

26th January 2006, 06:32 PM	#1
Tekko diyAudio Member Join Date: Jan 2005	class a elektor headphone amp Does anyone know this amplifier ? I got it with a heatsink a few years ago and was told that it was an elektor class a headphone amp that could also deliver around 10 watts into 8 ohms. Anyone recognice it ?

26th January 2006, 07:20 PM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	Class A, discrete 10 Watt in 8 Ohm. I do not remember this Elektor headphone amplifier. What are those 4 ouput transistors? BD139/BD140? __________________ lineup

26th January 2006, 07:54 PM	#5
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	I remember this amp. 10 W with these transistors is a bit weak but if the supply voltage was +- 15 volts it's possible to get a couple of watts from the amp. Beware of the thin traces from the output. Why do you ask? I have the article somewhere in my collection. If you could tell me when it was published it would help me. __________________ /Per-Anders (my first name) or P-A as my friends call me

26th January 2006, 08:03 PM	#6
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Elektor did that design in 2 versions, the first one was part of their 80s discrete modular preamplifier design. Second version was identical but doubled output devices, also BD139/140. Bias was 0.1 amps. I still have both articles. __________________ Looks like Sponge Bob has killed another thread.

26th January 2006, 10:28 PM	#8
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	It does nearly 10 watts in class AB. With 4 BD139/140 per channel i managed to get 2 watts in class A and keep the devices alive. Sound on a K1000 isn't bad The board number stands for 1983 I can post a picture of the 2 device version i built, same as yours. I used it on efficient loudspeakers, amazing what such a little amplifier can do. __________________ Looks like Sponge Bob has killed another thread.

26th January 2006, 07:36 PM	#3
Nisbeth diyAudio Member Join Date: Jan 2001 Location: Denmark	A headphone-amp that provides 10W output? That's a little unnecessary. Why don't you email elektor with the PCB-number and see if they can help you? /U.

26th January 2006, 07:51 PM	#4
dx.master diyAudio Member Join Date: Jul 2004 Location: Hessen, Germany	I have build this Headphone amp too. And somewhere i have the orignal article ... But 10W is to mutch for this headsinks ...

26th January 2006, 10:21 PM	#7
Tekko diyAudio Member Join Date: Jan 2005	I soldered those trannies on today, the originals were fried/stolen a few years ago, i still have the heatsink that came with the amp when i got it from a forum member of a swedish hifi forum. It originally used BD139/140, the ones there now is similar ones but are drivers from a broken poweramp. It was the previous owner that said the thing could deliver around 10 watts in 8 ohms while it operated in class A driving 32ohm headphones. I believe its either the 1983 mag 4 headphone amp, the mag 7 1984 mini crescendo, the mag 1 1986 AXL amp, the mag 9 1986 or the mag 10 1986 mini stereoamp. Board number EPS83022-7 if it helps.

26th January 2006, 10:34 PM	#9
Tekko diyAudio Member Join Date: Jan 2005	I find the sound suprisingly good with just a cd-rom drive as source. My output transistors are: 2SD669A ond its complement 2SB649. If anyone have the issue with this amp, i´d like a scan of the info sheet and schematic.

26th January 2006, 11:04 PM	#10
Tekko diyAudio Member Join Date: Jan 2005	Maybe i should add that i run it with a pc power supply, also i have it hooked up to a pair of old 4 ohm speakers.

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