I also inherited dad's Citation I...
And I already own a very unique piece:
I have another BRAND NEW Citation I that's never even been plugged into the wall. Caps might explode now from age, who knows? But the panels, pots, sockets, tubes, switches which get so noisy are all BRAND NEW. The resistors are carbon comps but they are NEW. You can tell the silk-screen panel is pristine, the tube shields have never gotten hot. No smoke discoloration. Actually, really, legitimately new. Not a single scratch on the RCA jacks or wall line plug terminals.
It's still in the original sealed "unopened" box, in the original bag, with the original silica-gel. The box has only been opened from the bottom, the top is still sealed. Original paperwork.
There was a Barzilay console cabinet showroom and they had the Citation I mounted in the showroom floor model because, well, it's got lots of beautiful brushed metal knobs. But they didn't spring for a power amp nobody would see. When they went out of business, I read the ad in Trading Times newspaper (long before the internet) and went over to see what they had, and picked the citation I up for a good price.
I have no clue what to do with it. It's been in my boyhood closet for the last 35+ years. It really belongs in a Harmon museum.
And I already own a very unique piece:
I have another BRAND NEW Citation I that's never even been plugged into the wall. Caps might explode now from age, who knows? But the panels, pots, sockets, tubes, switches which get so noisy are all BRAND NEW. The resistors are carbon comps but they are NEW. You can tell the silk-screen panel is pristine, the tube shields have never gotten hot. No smoke discoloration. Actually, really, legitimately new. Not a single scratch on the RCA jacks or wall line plug terminals.
It's still in the original sealed "unopened" box, in the original bag, with the original silica-gel. The box has only been opened from the bottom, the top is still sealed. Original paperwork.
There was a Barzilay console cabinet showroom and they had the Citation I mounted in the showroom floor model because, well, it's got lots of beautiful brushed metal knobs. But they didn't spring for a power amp nobody would see. When they went out of business, I read the ad in Trading Times newspaper (long before the internet) and went over to see what they had, and picked the citation I up for a good price.
I have no clue what to do with it. It's been in my boyhood closet for the last 35+ years. It really belongs in a Harmon museum.
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"FYI - Johnny Football, Heismann winning QB from Texas A&M, two years ago.
First Frosh winner. He is absolutely the best player I've seen since
I saw Gayle Sayers play."
All I can say is 'wow'!
First Frosh winner. He is absolutely the best player I've seen since
I saw Gayle Sayers play."
All I can say is 'wow'!
Why 72 hours? It seems that is a long time for a tube to "break in" or pre conditioned as you call it. regards.
Better to cook it in an oven, to force a getter flash on a glass to absorb gases than to poison cathodes!
72 hours seems to be how long it takes to cure the cathode coating for most power tubes.
I'm late to the party as usual. I thought I'd add my blog write-ups of some unique mechanical and electrical mods I've done to my latest Citation II.
In addition to my cap-board (I prefer a PCB based power supply to lots of clamps, but that's just personal taste), I added a bias meter modification board, an internal transformer tap and 5-way binding post assembly, and a toggle switch mod to replace the courtesy outlet. I use G10 for my supports for input connectors, output connectors, and switch mounting.
Here's my most recent CitII posts:
Output Transformer Repair:
Sheldon’s World Blog Archive Citation II Amplifier Output Transformer Repair
Input and Output Connector Improvements:
Sheldon’s World Blog Archive Citation II Input/Output Connector Improvements
Bias Meter Modification:
Sheldon’s World Blog Archive Harman Kardon Citation II Bias Meter Modification
Power Switch:
Sheldon’s World Blog Archive A proper switch for a proper amp
I've also designed a replacement bias supply board for someone who bought one of my Citation II amps a decade ago. I've included a picture of the board.
Sheldon
In addition to my cap-board (I prefer a PCB based power supply to lots of clamps, but that's just personal taste), I added a bias meter modification board, an internal transformer tap and 5-way binding post assembly, and a toggle switch mod to replace the courtesy outlet. I use G10 for my supports for input connectors, output connectors, and switch mounting.
Here's my most recent CitII posts:
Output Transformer Repair:
Sheldon’s World Blog Archive Citation II Amplifier Output Transformer Repair
Input and Output Connector Improvements:
Sheldon’s World Blog Archive Citation II Input/Output Connector Improvements
Bias Meter Modification:
Sheldon’s World Blog Archive Harman Kardon Citation II Bias Meter Modification
Power Switch:
Sheldon’s World Blog Archive A proper switch for a proper amp
I've also designed a replacement bias supply board for someone who bought one of my Citation II amps a decade ago. I've included a picture of the board.
Sheldon
Thread's alive!
I made a pcb for the Citation II power supply. It has the doubler rectifiers, doubler caps, PI caps, pre caps, AC fused bias transformer, and bias PS. Ground traces are fat and are doubled up on the back of the board.
No extra holes have to be drilled, and no holes have to be enlarged. It attaches using three existing holes on the bracket.
I made a pcb for the Citation II power supply. It has the doubler rectifiers, doubler caps, PI caps, pre caps, AC fused bias transformer, and bias PS. Ground traces are fat and are doubled up on the back of the board.
No extra holes have to be drilled, and no holes have to be enlarged. It attaches using three existing holes on the bracket.
Attachments
Need PCB
Oh my, did you make extras? I NEED this!
Also, I am following the path that Carvin first navigated, and converting to KT120.
I am also considering a second filament supply, with raised DC, for the first stages. Though Carver says the stock filament supply can handle the additional draw of the KT120, I would like to lower the draw on the stock supply and this could also quiet down the first stages a bit. Modern plate resistors will help get rid of that ocean in the background too. I think mine still has the selenium also; I have to check...it's been on the shelf for a few years now.
Oh my, did you make extras? I NEED this!
Also, I am following the path that Carvin first navigated, and converting to KT120.
I am also considering a second filament supply, with raised DC, for the first stages. Though Carver says the stock filament supply can handle the additional draw of the KT120, I would like to lower the draw on the stock supply and this could also quiet down the first stages a bit. Modern plate resistors will help get rid of that ocean in the background too. I think mine still has the selenium also; I have to check...it's been on the shelf for a few years now.
Just a couple things to consider...
I would think twice about converting to KT-120s. The KT-88s perform VERY well in the amp with less distortion and comparable power output. Take a look at the plate curves on the KT-120 vs. the KT-88 and see what you think. Also, the KT-120 has a grid to ground maximum resistance (with fixed bias) of 51K Ohms instead of the 100K Ohms for the KT-88s. The stock value is 100K, so you can run into issues there. Some KT-120s don't seem to mind 100K but others are not happy at all. Finally, based on years of selling both tubes I have found the Genalex reissue KT-88 to be more reliable than the KT-120.
If you do go to KT-120s I'd recommend you DO add the extra transformer. A stock Citation II at 120 volts or so with KT-88 output tubes will draw about 9.7 amps of heater current. KT-120s will add about 1.2 amps more to that for a total of about 10.9 amps. The original blueprints I have for the Cit II power transformer specs out the 6.3 volt windings at 5 amps each - so you'd be working those windings pretty hard. I'm not sure you want to do that to a 55 to 60 year old transformer!
We've run into a number of cases where the original power transformer's bias winding has gone intermittent - which has caused tube damage that can get expensive. Apparently H-K was going to bring out a center tap from the bias winding but changed their minds at some point. The result was that the bias winding ended up with a solder joint in the bias secondary winding - and in the 50+ years of use the solder joint starts to fail and become intermittent. This proved to be quite difficult to diagnose as you might imagine! A replacement transformer for the bias supply is the least expensive repair for the issue, and you may find a bit lower noise as an extra benefit. The best news was once the transformer was replaced the unexplained tube failures stopped.
You mentioned changing the plate resistors. Up to about 6-7 years ago we used to try to save those resistors whenever we could. The larger wattage resistors were excellent quality Corning-made wirewounds, wound on a glass substrate. But now many of those resistors are literally disintegrating from age, heat, etc., and replacing them is a must. I recommend replacing ALL the old resistors in the amp at this point, including the AC balance pots. Most of the time if you take apart those old pots they are corroded and nasty inside.
If you are careful you can disassemble the dual bias pots and give them a good cleaning and they'll work for a long while, especially since they aren't subject to very much use/wear.. Just watch for damaged or cracked carbon elements when you have them apart.
Finally - Bob Carver is a real nice guy - and very smart! We've had a number of opportunities to talk/write to each other over the years, and he's been very kind and complimentary to me. Having said that I'd just like to mention that you'll probably want to carefully consider applying the Citation II mods he recommends.
I hope that was some help for you. Good luck with your project!
Update on my Citation II with pcb cap board I designed. With KT90's from Mr. McShane I am getting 64 watts per channel both channels driven into 8 ohms at 120V AC input. I measured B+ at 80ma idle per tube at 444vdc. Under load, B+ only sags to 421 vdc at 120V AC input. These KT90's can really swing as I measure 411 vdc at the plate under full load both channels driven.
Quiet, very, very quiet! And sounds fabulous.
I may have had to extend one or two existing wires to install the PCB. All the rest are more or less 'plug and play'.
While I'm not interested in providing a bunch of support other than a BOM and general guidelines to install, if you are experienced in this sort of thing and want a board, PM me.
I used DesignSpark PCB (free) to design this.
Quiet, very, very quiet! And sounds fabulous.
I may have had to extend one or two existing wires to install the PCB. All the rest are more or less 'plug and play'.
While I'm not interested in providing a bunch of support other than a BOM and general guidelines to install, if you are experienced in this sort of thing and want a board, PM me.
I used DesignSpark PCB (free) to design this.
