I received this little two tube preamp http://www.gikfun.com/electronic-diy-kits-c-7/6j1-tube-preamplifier-board-20-stereo-multiple-diy-kit-p-730.html

It comes with 9 470uF caps. The symbol on the board for them is a circle, with white strips across one of the legs. Does anyone know if that indicates the positive leg of the capacitor?

Also, I don't read Chinese characters. Which set of RCA plugs are the input? No word back from GikFun to these questions yet.

There is no schematic posted to work out the details myself.


Updated - added a picture of the labelsenter image description here

Updated - added a picture showing two of capacitor pins that both connect to the RCA plugs common plane -enter image description here and to the common pins of the AC input jack.

Ah ha! Found an e-bay listing that confirms Tony Stewart Sunnyskyguy's answer. Thank you! enter image description here

  • 2
    \$\begingroup\$ Establish if most of them share the same ground terminal (maybe a large copper plane). \$\endgroup\$
    – Andy aka
    Commented Jan 13, 2021 at 17:48
  • \$\begingroup\$ Tubes? I can barely remember those obsolete old things. Why use them today? \$\endgroup\$
    – Audioguru
    Commented Jan 13, 2021 at 17:50
  • 2
    \$\begingroup\$ My earliest impression with great tube designs in 60's were super low noise and crisp wide bandwidth with lots of kick \$\endgroup\$ Commented Jan 13, 2021 at 17:51
  • \$\begingroup\$ Just a general comment those Chinese 6j1 amplifiers are kind of a waste of time.... They misuse the tube and aren't really good at doing much of anything. Read a book and make a simple tube amplifier out of audio tubes and a real output transformer... It'll sound way better than whatever that thing does. \$\endgroup\$
    – MadHatter
    Commented Jan 17, 2021 at 13:56

1 Answer 1


Google says
Input + Output
输入 + 输出

Stripe is -VE

  • \$\begingroup\$ Thank you, will try to confirm if any negatives connect to what appear to be the RCA plug negatives as a check. Going to need a magnifying class to read the symbols! \$\endgroup\$
    – CrossRoads
    Commented Jan 13, 2021 at 18:01
  • \$\begingroup\$ 别客气。 我也不懂中文。 Bié kèqì. Wǒ yě bù dǒng zhōngwén. \$\endgroup\$ Commented Jan 13, 2021 at 18:02
  • \$\begingroup\$ Then a photo then Zoom it \$\endgroup\$ Commented Jan 13, 2021 at 18:03
  • \$\begingroup\$ Ok, so the terminals near the screw would appear to be the Inputs. \$\endgroup\$
    – CrossRoads
    Commented Jan 13, 2021 at 19:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.