JISBOS - great headamp !

[juma]

Almost a year ago I bought a pair of Sennheiser HD555 headphones (50 Ohms) and since then I've been searching for appropriate headamp. I've tried diamond buffer and about dozen usual topologies found here and at Headwize.com, but nothing really shined until I gave JISBOS (http://www.diamondstar.de/jisbos/jisbos_design.html ) a try.
Some people mentioned it here but no one really told us how good it is. The design is pretty explicit, it is very stable and it sounds extremely good. The amp is completely noiseless.
The end result is so good that I had to report it here, and I recommend it to anyone who is in search for a unity gain headamp - small power buffer.

Steinchen and Amb (from Headwize), thanks for this great headamp !

I changed an original schematic a bit (parts availability) and this is how it looks:

 

[juma]

I've built it point-to point in the old network switch box.
Pic 1:

 

[juma]

A close-up - yes, it looks untidy, but IMHO p2p is far superior to PCB (3D beats 2D any day in the week), at least in audio - it would be a real challenge to make a PC motherboard p2p 🙂

 

[Zen Mod]

congrats !

with almost same topology - you can try scaled down Pass's F5 .

 

[juma]

congrats !
with almost same topology - you can try scaled down Pass's F5 .

Thanks,
probably I'll do it, if it's unity gain stable; scaled-down F4 (IRF610/9610 on output, Iq=100mA) sounded a bit dull.
Also, F5 has higher OLG => stronger GNFB
JISBOS uses strong Source and Emitter degeneration to minimize GNFB.

Pozdrav !

 

[nelsonvandal]

I've also made one of these point to point. I agree, it sounds better than any monolithic opamp based amp I've heard.

 

[juma]

Yes nelsonvandal, I saw your posts here and on other forums, they've been very informative. What cans are you using now and what headamp ?
I remember that you were occupied with pocket - battery operated version of JISBOS?

 

[juma]

Finally, I found the time to finish the front plate and case work.
Here it is:

 

[ekaerin]

Hi,

Cool. Finally a network switch box with a useful circuit inside.

/ Mattias😀

 

[Onvinyl]

Hi Juma,
What's in front of you HP-amp? With a HD-650, I found a unity-gain amp (that followed both a riaa-amp or a CDP) wasn't sufficient. Switching back to loudspeakers would almost destroy them. Or my ears...
Rüdiger

 

[juma]

Hi Juma,
What's in front of you HP-amp? With a HD-650, I found a unity-gain amp (that followed both a riaa-amp or a CDP) wasn't sufficient. Switching back to loudspeakers would almost destroy them. Or my ears...
Rüdiger

Hi Rüdiger ,
I have HD555 (low Z - 50 Ohms), so unity gain is OK. In front of JISBOS is modified M-Audio SuperDAC 2496 with 1.7 V RMS output.
Mit poti am 11 uhr es ist schon zu laut. 😀

Tschüs!