Harman Kardon 730 and A-402 - PHONO stage differences?

[dlucy]

There's a great question just asked: the HK 730 and HK A-402 power amp stages are very similar; the Harman Kardon 730 receiver's PHONO stage, when recapped, is awesome; is the PHONO stage in the HK A-402 integrated amp the same as the one in the 730?

Let's take a look:

The HK 730 PHONO stage (from the Harman Kardon 730 service manual):



The HK A-402 PHONO stage (from the Harman Kardon A-402 service manual):



Answer: yep, those are nearly identical. Same design, same semiconductors, mostly-same passives... just minor value differences.

I'd say "if you like the sound of the PHONO stage in the 730, then you'll find the PHONO stage of the A-402 to be (effectively) identical". That said, the TONE section of the two units are different, so the overall units will sound a little different.

 

[Skywatcher]

That also means that neither are RIAA compliant. That is where the "mod" comes in changing a few cap values.

 

[Skywatcher]

You had me curious so I checked the Wards 450 (GEN-6959A) schematic (SAMS MHF-191) and bingo, it is the same.

 

[jheu02]

There's that great thread on modding the phono stage for better RIAA curve, so that’s what I did for the two 402s I rebuilt. One of them I put socket pins for the input caps so I could try out different ones there…Silmic, cerafine, UKL film, etc.

 

[dlucy]

The thread with HK 730 phono stage mods https://audiokarma.org/forums/index.php?threads/modding-the-harman-kardon-730-phono-stage.769186/