Picked up a Harman Kardon Citation Twelve Power Amplifier Today

[richiem46]

I went to an Estate sale today and picked up a Harman Kardon Citation Twelve Power Amplifier on a whim for $40. I was unfamiliar with the model but it was in great shape cosmetically so I fugured for $40 I had not much to loose. When I got it home I put it on the DBT and there were no issues. The owner assembled it from a kit and did a nice job. Based on all of the components on sale in the garage he was an avid tinkerer/hobbyist. I checked the bias and it was spot on and the DC offset was several millivolts on one channel and about 40MV on the other. Tomorrow I will listen to it to see how it sounds in use.

Based on what I see and have read I will replace all of the small electrolytics on the main board and perhaps replacing the differential pair of 2N5087 transistors on the channel with the higher DC offset in an attempt to inprove the offset. The 2N5087's are still available so I will probably order around 20 or so and pick out the closest matching pair.

Here are some photos of the Citation Twelve:

 

[blademan13]

Great deal for $40, especially in that condition. I quite often listen to a restored Citation 11/12 combo through a pair of Rectilinear III’s. Very easy to listen to and enjoyable in this application. Heck of an amp in its day and is still quite capable.

 

[richiem46]

Tonight I connected the Citation to the pre-amp outputs on the AU-919 I just finished restoring and listened to it for a while. I must say I was quite impressed with how the Citation sounded, very clear midtones and highs. It was a bit lacking in the Bass unless I turned it the volume up but that no doubt was influenced by the tone of the AU-919 pre-amp. With a re-cap I bet the Citation will be quite a nice power amplifier!

 

[richiem46]

This week I got back to working on The Citation Amplifier. I cleaned it up a bit and then replaced the four main Filter capacitors which were 6000UF/50V with 15,000UF 63V capacitors. I somewhat large increase but other solid state amps I have worked on started with larger filter caps so I opted for the large increase goven the Citation was an early solid-state offering. I also replaced the two full-wave bridge rectifiers with 25A 200V units to provide additional headroom to support the larger Filter caps.

I also replaced the 50UF 50V electrolytics with 100UF 63V electrolytics and the two 250UF 6V electyrolytics with 220UF 35V electrolytics. I left the two 250UF 15V electrolytics C1 and C2 in place as I do not have a suitable replacement on-hand and the existing caps have an unusual physical configuration. I am attaching a picture of C1 to illustrate this point.

 

[richiem46]

Here are some pictures of the upgrades that I performed on the Citation:




View of the new bridge rectifiers and new main filter capacitors.




Top view of the Citation after cap replacement.




Here are the components I replaced. The main filter capacitors tested okay, around 7200MF with an ESR around .015. The 50UF caps tested around 65UF with ESR readings around 1.5 which indicated they had seen better days.

The original owner of the Citation performed all of the engineering modifications HK recommended. He also re-traced most of the copper traces on the circuit board with solid copper wire which you can see in the photo below. I noticed the copper foil was very sensitive to heat and lifted off the board with just normal soldering heat applied. Perhaps that is why he chose to do this.

 

[richiem46]

After the re-cap I put the Citation on the dim blub tester and it behaved appropriately so I then set the bias per the manual and measured the DC offset. The bias dialed right in and the DC offset was about 8-12 MV on each channel which was good.

I then hooked up some speakers to the CItation and deove it with the Pre-amp section of a Marants 2270 receiver. I have to say I am VERY inpressed with the sound of the Citation after the re-cap. The bass is really solid and the soundstage is good. The highs are chrisp and clear, not fatiguing to listen to.

Not bad for a $40 investment I must say!

 

[slater529]

Nice work!

 

[dlucy]

That's an outstanding deal... and restoration. I really like my HK Twelve and it has done duty as a stand in for many other amps as they were restored or switched out or similar.

My Twelve has the Nelson Pass updates done. That's something yo know about, even if you never choose to go that route. https://www.passdiy.com/pdf/citation.pdf

 

[Roadrash]

If you can get your hands on a Kenwood Basic C1 or C2 pre amp they pair very nicely with the Citation amps. I've got a C1 with my Citation 22 and a C2 with my Citation 16 and both are just really nice to listen to, and much better than the Onkyo P306RS that I had tried with them.