Harman Kardon 230A basic upgrades/restoration

[tlann]

Hey all — I have a Harman Kardon 230A from the “minimalist” HK era, and it sounds sweet. Very warm but still nicely defined. So I should caveat what I’m about to ask by saying that I already am quite pleased with the amp. But I recently hooked it up to my Klipsch Heresys, and the sound is so good that it got me thinking — are there any straightforward, relatively quick restoration measures I could do that would make the amp even better?

I know, I know, if it ain’t broke…but I ask this because I remember how surprised I was when my father and I replaced the two can caps in my Dynaco SCA-35. It was easy and quick to do, but the impact on the sound was very noticeable. Might there be an equivalent here? Unfortunately, I don’t have the time to do a full restoration, so I’m just curious about exploring isolated jobs that would enhance performance. Basically: is there a go-to first step that you’d recommend when it comes to restoring or improving an HK 230a?

 

[rickl]

I haven't worked on a 230A but I have done a few 330 series receivers.

you may be interested in reading doug's thread on your model

dlucy's guide to Harman Kardon minimalist series 230A, 330, 330A, 330B B-1, 330B B-2, and 330C

The third era of solid state stereo receivers from Harman Kardon centered around the 330A and 330B and the clones made by Roland and Soundcraftman: This thread is a guide to those models, their specs, and pointers to schematics and restoration threads for each. If you have additional...

audiokarma.org

maybe similar 330 family updates can be applied to your 230A. There are a few 230A threads on AK that you should read.

I'd be careful and be sure to use a DBT and go at it easy.

And comparing a Dynaco kit to your HK isn't really a fair comparison. One was built by a hobbyist with the cheapest parts the mfg could find and one was not. However, both are pretty old and a few updates may improve the SQ. I'd personally just enjoy the HK but I do restos for a shop 'full time'.

 

[dlucy]

Replacing all the electrolytic caps is the biggest step forward, in terms of keeping it running and helping to restore its great original sound.

If you don’t want to do that, just replace all the electrolytic caps in the signal path. That should be about of all the electrolytic caps. That’s the second best thing you can do, just behind the above recommendation of all the ecaps.

The only other “big” improvement would be replacing the small signal transistors in the audio signal path in the preamp and power amp stages with low noise modern devices. That will reduce the background noise somewhat.

 

[dlucy]

Replacing the transistors would only involve eight: the 2sa644 and 2sc828 at TR 401-404 and at TR501-502,TR601-602. Cheap, too, at about $0.12 each for KSA992 and KSC1845.