Harman Kardon Citation IV Modification

After finish modified Harman Kardon Citation I.

http://mellowgroovy.blogspot.com/2016/07/citation-i-real-sound.html

I've read Jeff Day's blog about Harman Kardon Citation IV that he mention about

phono preamplifier section is very good like in Citation I.

One day, my friend asked me about Citation IV that he kept in his storage room

and want to upgrade it like Citation I that I've modified before.

Same front cover layout like Citation I.

Use 6 of 12AX7 tubes, 1 and half tube for phono stage in each channel.

Bottom side (Channel B) before modified.

Almost coupling capacitor use Good-All paper capacitors.

Some capacitors has changed by repairing shop before.

Using Selenium rectifiers both high voltage and filament voltage like others in their era.

Wirewound and high power carbon resistor in rectifier section.

Top view (channel A) before modified.

0.5W carbon resistors for loading cartridge in front of phono will replace with 2W rating later.

Almost parts for modification.

Channel A after modification.

All coupling capacitors replaced with Arizona capacitor "Blue Cactus" except last capacitor

using Western Electric film 2.097uF.

Channel B after modification.

Diodes still using Ultrafast soft recovery for high voltage and Silicon type for filament.

IRC GS-3 Metal glaze resistor for stable high voltage too.

And finally use Western Electric film capacitors for decoupling all high voltages.

First impression sounding just more relax than Citation I and also transparent.

You will find IV in cheaper price than I, but quality still in same range.

Cheer!!!