The Kuartlotron - keantoken's simple error-correction superbuffer

R9 is the DC trim. You may be sending ~1uA of DC through your cart (if I assume correctly that is what you're doing). Either that or your BC560 has ~250Hfe. Or possibly it is running at double it's intended current (could happen if you don't use Fairchild transistors). To adjust R9 all you need is a DMM.

Why is it recommended to use the Fairchild transistors? What is wrong with the ON Semi ones?
 
Here is my buffer from Keantoken the board is from Project16
I use unmatched ON Semi transistors , my offset is 0.1-0.2 mv.
i put total 3,7ΜΩ resistors for R12 .
i use 10uf cap before the buffer and 10ΚΩ and 50ΚΩ pot.Super quiet...
 

Attachments

  • IMGP0051.JPG
    IMGP0051.JPG
    123.6 KB · Views: 864
  • IMGP0055.JPG
    IMGP0055.JPG
    202 KB · Views: 853
  • IMGP0052.JPG
    IMGP0052.JPG
    124.6 KB · Views: 857
  • Kuartlotron - All.png
    Kuartlotron - All.png
    39 KB · Views: 845
Last edited:
Hi Keantoken
I use ON Semi
I need to make changes for better results?

The Kuartlotron webpage schematic gives instructions for changing resistors to accommodate Vbe. There is also a possibility it could be unstable, but I haven't seen it so far. You may get acceptable results without any changes, although your input transistors will probably be running low bias.
 
The Kuartlotron webpage schematic gives instructions for changing resistors to accommodate Vbe. There is also a possibility it could be unstable, but I haven't seen it so far. You may get acceptable results without any changes, although your input transistors will probably be running low bias.
Thanks Kean
i will decrease the R1 nad R2 to 52Ω or 47Ω....and i will readjust the R5 trim ...
When i change the 15pf to mica cap i put 5pf the only available , the sound change for the best ,sound completely clean...now
the 25mv on multimeter are the output from my amplifier Golmund clone 9.2.
with SuperBuffer after my DAC AK4490.
 

Attachments

  • IMGP0071.JPG
    IMGP0071.JPG
    196.2 KB · Views: 847
  • IMGP0077.JPG
    IMGP0077.JPG
    155.3 KB · Views: 712
Last edited:
Yesterday i had make some tests with Buffer after the dac 4490 Discrete (the Dac has 0.1Ω output impedance) i put on buffer 100ΚΩ without any pot just the buffer
at the high levels volume via foobar understand some correction of THD if that makes any sense.
 

Attachments

  • IMGP0083.JPG
    IMGP0083.JPG
    145.5 KB · Views: 666
  • IMGP0080.JPG
    IMGP0080.JPG
    153.6 KB · Views: 666
Um no...

I'm reporting I don't have any harshness because Keantoken noted higher voltage can come across with a harsher sound. I'm only at 12.5v.

I'm currently playing around with a shuntreg kit I assembled and tried a couple of 'non-recommended' voltages to power the Kuart.

+/-14.3V sounds too in-your-face, too forward-sounding for my liking, though it did bring drive, flow and much better retrieval of lower level details. But the airiness for which I so loved the Kuart was lost.

Toning it down to +/-13V restored the earlier laidback presentation (with the LM317/337 PSU), while retaining much of the new-found liveliness, drive, flow, and better resolution, but more importantly, restoring the airiness.

I haven't got down to checking if the transistors are overheating, or if the DC offsets have gone up, but the sound is definitely more likable than before. Unfortunately with my existing transformer 13V is the lowest the shuntreg can provide. I also need to re-do the TP adjustment (of half Vcc).
 
Last edited:
I'm currently playing around with a shuntreg kit I assembled and tried a couple of 'non-recommended' voltages to power the Kuart.

Higher voltages will increase potential thermal mismatch and possibly cause thermal distortion. Furthermore the bias chain is made for +-10V so if you go much higher you won't be able to dial in TP. If you like the sound at a higher voltage, try deliberately putting TP 2V high or low.