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Old 6th February 2007, 11:04 PM   #1
LEAP is offline LEAP  Sweden
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Default HK Citation Nineteen

Anything can be inproved, right?

I just got a hold of a HK citation 19, in very good condition from a friend.

The first thing i did was to to hook it up to my test bench and played it for a couple of minutes, before gutting it (it really seemed to have great power behind it's presentation). It worked great by the way. It might just be me, but isn't it more fun to tear something working apart. Just for the fun of it!

It is clear that someone has been here before me and changed a couple of input connectors and such. However, i felt that i needed a project in the cold swedish winter. Therefore i felt the need to investigate how far you could push a design from 1978-ish.

I now turn to you, a body of weel educated, very smart DIY-ers to help me along the way to make this ancient design really sing.

So far i have gutted one side of the power supply (left to be exact). I just couldn't stand the fact that the wires were not perfect length to the transformer. (i have a problem, i know!)

My thoughts are:

-change powersupply caps
-change all signal caps, as well as all decoupling caps on the amplifier boards (all caps to be exact)
-change wire looms to greater diameter wire... and input signal wire to pure silver wire
-maybe change a whole lot more if you guys think it is neccessary, maybe i need to change output power transistors...
- maybe i should change the lot... all the components on the amplifier boards, powersupply... any thoughts?

i really need help from you guys to decide what this amp could be worth if it would be MAX out. What else should i think about? Does anybody know of any good tweaks? Does the tweaks applyed to the Citation Sixteen (16) apply to this one? How far do you think i could take it? Money is always an object, but i am ready to make an investment if the result is substansial.

Thankfull for any help i can get!

cheers, andy from sweden
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Old 1st March 2007, 04:32 AM   #2
gni is offline gni  United States
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caps, resistors, make sure all solder joints are good, clean pots.
This is a good old amp ready for many more years of service.
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Old 1st March 2007, 01:46 PM   #3
LEAP is offline LEAP  Sweden
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Hey gni!

Thanks for you're input. I also think that this little (not so little in reality) amp is a real gem. Therefore i have decided to take it to the next level.

I have now decided to re-wire the whole thing with lower gauge wire. Starting with the power supply. I decided to keep all the different voltage taps. This way, if, heaven forbid , i have to change continents, i can bring this baby with me.

I have removed both amplifier boards from the heat-sink in the back of the amplifier. This way i have access to all the soldering joints. I was thinking about changing the amplifier board caps to something exotic like: stargate's, rubycon ZA's or alike. But i am having a really hard time finding caps with these values at 63V. I am going to have look harder in this area.

Of course, i am planning to change all the connectors to hi-grade types (WBT or similar).

On thing i did was to remove all the circuit boards and cables associated with the Power LED's on the front panel. I don't need them, so I just cut it out of the amp.

I was wondering if someone has a circuit-diagram of this bad-boy. It would be deeply appreciated!

Keep you updated on the progress.

cheers / andy
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Old 23rd May 2007, 01:47 AM   #4
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Default schematic

I found the link for the Citation Nineteen schematic:
http://manuals.harman.com/hk/Service Manual/Citation Nineteen sm.pdf

Did you get around to doing any upgrades? Also, what size are the power caps? 10,000uf 75 or 85 volt? Thanks.

D
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Old 23rd May 2007, 02:18 AM   #5
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I love this amplifier, one of my friends dads has one, and I have been ebay shopping for one for years.

i have been looking for a schematic for the 19 for YEARS, and your link appears to be dead.

Perhaps you could rework it like Pass Labs did with the Citation 12, and make the Mosfet 19, which would be awesome.

Personally, I don't think I could ever dismantle a Citation 19, I just love it too much the way it is. however I would have no objection towards making one from stratch.....

let us know how it goes

-Moose
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Old 23rd May 2007, 03:27 AM   #6
djk is offline djk
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"your link appears to be dead"

Don't click on it.

Cut and paste the whole link in, it still works.
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Old 23rd May 2007, 01:02 PM   #7
LEAP is offline LEAP  Sweden
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Default Slowly but surely getting there

Due to the fact that i am in the middle of a move, my work on the citation 19 has been somewhat neglected.

However, i did manage to get ahold of a fresh copy of the schematics off eBay. A gentleman in Pensylvania sold me a high-resolution PDF-copy. It was here (Sweden) in less than a week for the mere sum of 9 USD w/ shipping.

General changes:
I have been able to make some progress though. Like i said earlier. I re-wrired the whole thing. Mainly focusing on the mains wireing, making sure all the wireing is tightly twisted to reduce interference. I chose 1,5mm2 stranded mains wire for low inpedence. I also removed the mains thermal breaker that is located on the heatsink. I felt that this was redundant and i really wanted to get rid of all that (3 feet or so) extra mains wire that run up and down the amp. I then replaced the rather crummy (european) power connector with a Neutrik PowerCon for low impedence connection. I also replaced the stock RCA connectors with Neutrik RCA connectors, and in the process i also removed the stereo/mono switch. Again, i felt that this was redundant since i am only going to use this amp as a stereo amp and i didn't want the left side of the signal passing through that crappy switch. Of course the input wires were updated to high grade 22 guage silverplated copper wire soldered directly to the input boards and cutting out the plastic connector.

Component changes:
First of all, i took a step back and started to evaluate the components already inside this baby. Starting from the top. There are two rather hefty transformers inside and i saw no reason changing these. Then we have the rectifiers. Although there might be reason to change these now after such a long time in use, i felt that i would leave them for a potential future upgrade. Then we have the four beer cans in the back. The mains caps. These were original General Electric 10.000uF, 75V (85V peak). This caused some headake i might say. If they would have been intact, i might have opted for keeping them since they are of "computer grade." But, since two of them had been changed to generic stock caps by a previous owner i felt that i had to re-do the whole thing. So i started the tedious process of finding new caps. And let me tell you, it was no easy task. Finding caps with 75V rating today is a futile task. So i started looking for 100V types, and there were some that looked interesting but i felt i wanted to beef-up the power supply at the same time. So i went back to the schematics and started measuring the secondary voltages. Turns out that the secondary AC voltage is no more that 40V and the DC voltage after rectifier is no more than ~55V. Great! This means that a 63V cap will work. So i finally got what i wanted, and i bought 4x 47.000uF, 63V RIFA caps from Elfa.se. These are great caps of "computer grade" and they are very low ESR. However, i failed to realise two things. First of all the physical since of these caps are so enourmus that i can barely get them in the casing of the amp, i might even have to leave the bottom cover open so they won't short circuit. This i can live with if it improves the sound. Secondly, it is now impossible to start the amp du to the fact that the start-up current is so great that i keep blowing the fuse. This is where i am at right now in the re-build. First i am going to try to mount a bigger fuse, and if this doesn't work i will need to put in a slow-start circuit for the mains. I'll keep you updated on the progress.

I have deliberately chosen not to do any changes to the signal boards at this time. I want to be sure that i can get the power supply up and running to my liking and then i wan to take it for a test ride before i contine with more changes.

It has also crossed my mind to re-build the whole thing actually. I have a friend that have a metal machining shop and i have talked to him about milling a new chassis out from solid aluminium. That could be cool looking thing. And i also thought about making my own version of the Pass Citation 12, but for the 19 that is. But we'll see baou that. First i want to take this bad boy for a spin.

Let me know if you come to any interesting conclusions.

Cheers, anders
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Old 24th May 2007, 11:15 PM   #8
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Default Re: Slowly but surely getting there

Quote:
Originally posted by LEAP
Starting from the top. There are two rather hefty transformers inside and i saw no reason changing these.
The transformers are one of the reasons this amp sounds good even now. It helps it to rise above the mass production compromises. I'd buy one just for the transformers.

Mike.
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Old 25th May 2007, 01:15 AM   #9
djk is offline djk
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"The transformers are one of the reasons this amp sounds good even now"

I have six new power transformers if someone wants to build a new rig.

"I have deliberately chosen not to do any changes to the signal boards at this time"

Tack some .1uF film caps across the electrolytics at the input, and in the feedback loop. It will sound quite a bit better.
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Old 25th May 2007, 01:16 PM   #10
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Default Citation 16 question

Hi, I am new to the forum. I have a Citation 16. The way they are wired, would it seem unreasonable to try to connect it to a mixer that also has a 3 prong plug that is connected to a computer that also has a 3 prong plug.
In the manual, it says that it wants to be the only 3 prong plug on the block or lift other grounds.
I have had this amp sitting around for about 12 years. Now my speakers are blown I think it could be nasty sounds coming out of computer fed buy weak onkyo receiver. I was going to try the citation feeding a pair of extra speakers and mathing sub.
I realize this would not be the best aplication for the Citation.
Any thoughts, and anybody near Philadelphia want to take a great Citation off my hands. The amp was last used driving 4ohm pair of aucoustic research 90 speakers. And it did it very well.
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