Akarakrit Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Friday, April 7, 2017

JBL Graphic Controller Preamplifier & Solid State Energizer Modification

Since 60's, JBL made several audio equipment.

Power amplifier : SE400S, SE408S, SE460, SE400, SE400E, SE401 and SE402

Integrated amplifier : SA600 and SA660

FM Tuner : ST860

And only preamplifier : SG520

All above have great sound and really match with vintage JBL speakers like they've claimed.

But now some components have expired and should be replaced.

Let bring them back to "better" life with high quality components.

SG520 Graphic Controller Preamplifier.

This SG520 just repaired before with standard Japanese components.

So I just replace standard capacitors with Western Electric paper in oil and RIFA electrolyte.

Better look & better sound with long life and high quality components.

Next was SE401 amplifier with Germanium power transistor & interstage transformer !

Top amplifier in picture is SE408S and bottom is SE401.

Indicated for JBL D50S8R (S508) Olympus.

This JBL amplifier was repaired too.

Replace components and treat power supply section.

Audio section with standard components.

After cleaned & replaced.

Seem JBL audio equipment have higher quality than we think before.

That's why some of Japanese guy still using these with their vintage JBL speaker systems.

Cheers if you are JBL fan and find them in reasonable price.


  1. Sir recently I had purchased an Hometheatre via online shopping but neither i had got my product nor the refund. Can you please provide me the currentJBL Customer Care by which I can directly connect to the care executive of the Punjab office

  2. Why did you choose RIFA this time for electrolyte?

    1. Dear Nick,

      I need to using axial type of electrolyte.

      And RIFA is the best when compare with other axial type from Japanese brands.

      Best regards,

    2. Thank you Nattawut, it's the first time you seem to use RIFA on your blog. You used mainly Mundorf, Mallory, Obbligado etc
      So, I'm trying to understand your changes from one brand to another.

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  4. I have a JBL SG520, did anyone interested in it ask me?

  5. All your hard work is much appreciated. Nobody can stop to admire you. Lots of appreciation. Best JBL Studio Monitors in 2018

  6. This comment has been removed by the author.

  7. Thank you for sharing the nice pictures, great work!
    I own a JBL SE-400 myself, that I tried to refurbish, and I'm intrigued with one of the photos. It seems you have replaced the temperature compensating diodes (germanium ones) by 20 ohm resistors? Am I correct? Does it work?
    I have some voltage instability on channel A that I think is related to one of those diodes that I changed.
    Thank you

  8. Great work on the SG520! Thank you for sharing. I am in process of recapping the SG520 I bought in 1969. I've successfully replaced the electrolytics in the power supply. Can you tell me how you were able to access the line amplifier boards for replacing and soldering the new caps? Clearances are very tight. Thank you,
    Ron S.