Ok. Now I've done it. I loved a guy's system I auditioned some speakers with so much that it really piqued my interest in tubes. Been doing alot of reading, which means I still know almost nothing about them.
I figured I would dip my toe into tubes by watching Craigslist for something modest that I could tweek to learn more - that's the way I do things; I'm never happy until I know how it works.
So, I've been haunting Craigslist and found a Harman Kardon Citation II. I was the first to contact the guy (6 minutes after it listed) and picked it up for $100, which I now understand was a good deal - if its not got big problems I suppose.
Now my question... The amp needs tubes and to be checked out. I need to know some advise for next steps and sources for whatever parts it may need (tubes, caps, ???).
Also looking for someone in the Chicagoland area who I sould take it to? I'm looking for someone who will let me do some DIY to learn, but keep me out of trouble by telling me when to let him handle it - and being honest along the way. (yes I have read enough and done enough electrical work to know that I better be careful inside tube amps - 100's of volts)
Suggestions? Or just advise...
I figured I would dip my toe into tubes by watching Craigslist for something modest that I could tweek to learn more - that's the way I do things; I'm never happy until I know how it works.
So, I've been haunting Craigslist and found a Harman Kardon Citation II. I was the first to contact the guy (6 minutes after it listed) and picked it up for $100, which I now understand was a good deal - if its not got big problems I suppose.
Now my question... The amp needs tubes and to be checked out. I need to know some advise for next steps and sources for whatever parts it may need (tubes, caps, ???).
Also looking for someone in the Chicagoland area who I sould take it to? I'm looking for someone who will let me do some DIY to learn, but keep me out of trouble by telling me when to let him handle it - and being honest along the way. (yes I have read enough and done enough electrical work to know that I better be careful inside tube amps - 100's of volts)
Suggestions? Or just advise...
You might want to contact Jim McShane, as he is an expert regarding these amps.
Jim McShane Home Page
jeff
Jim McShane Home Page
jeff
Yeah you got one heck of a great deal on that Citation II. IMO one of the best performing vintage PP amps out there.
You'll need to check it out thoroughly and replace all of the electrolytics in the power supply. There are a number of very hot running wire wound resistors in the audio circuitry - Mills makes a line of suitable non-inductive wire wounds. Coupling caps may be suspect too. Just check everything..
Jim McShane is a great resource for the Citation II and can probably provide everything you'd ever need to whip it into shape. (Information and parts) Here: Jim McShane Home Page
Congratulations - I paid $200 for a basket case over 23yrs ago, you got a comparative steal. Mine needed a total rebuild..
You'll need to check it out thoroughly and replace all of the electrolytics in the power supply. There are a number of very hot running wire wound resistors in the audio circuitry - Mills makes a line of suitable non-inductive wire wounds. Coupling caps may be suspect too. Just check everything..
Jim McShane is a great resource for the Citation II and can probably provide everything you'd ever need to whip it into shape. (Information and parts) Here: Jim McShane Home Page
Congratulations - I paid $200 for a basket case over 23yrs ago, you got a comparative steal. Mine needed a total rebuild..
BB,
The other posters are correct, in more than 1 way. You stole candy from a baby and Jim McShane is THE man, when it comes to tubed H/K Cit. units.
Your good fortune continues, as Jim is metro Chicago based in Orland Park.
A complete, stem to stern, refurbishment (ala McShane) is in order. Once the overhaul is done, you will have a superb sounding piece with the "stones" to handle some pretty difficult speakers. I would not mate it to big Thiels, as those "beasts" dip down to 1 Ω. Also, some horn speakers may not sound good, due to overdamping.
The other posters are correct, in more than 1 way. You stole candy from a baby and Jim McShane is THE man, when it comes to tubed H/K Cit. units.
Your good fortune continues, as Jim is metro Chicago based in Orland Park.
A complete, stem to stern, refurbishment (ala McShane) is in order. Once the overhaul is done, you will have a superb sounding piece with the "stones" to handle some pretty difficult speakers. I would not mate it to big Thiels, as those "beasts" dip down to 1 Ω. Also, some horn speakers may not sound good, due to overdamping.
My dad better have me in his will for his Citation I and II and I. He built the first set from kits which (based on my childhood recollections) the company gave him in return for some writing he did...something about patent rights and how it differed from a traditional "Williamson" circuit.
And about 20 years ago I found another brand-new Citation I, new in the box, never even been plugged in, which I grabbed for the perfect unworn silk-screened faceplate and clean pots at the least. Caps etc. in unknown condition after all these years, all tubes and switches etc. brand new. It was in a "Barzilay" brand stereo cabinet showroom-floor "demonstrator" cabinet just because it had so many nice turned metal knobs. They had opened the box from the bottom, in order to put the amp back in with the original tape across the top (weird), had all the manuals etc. It's still in a closet at dad's house. Must be 30 years old now, still never been plugged in.
And about 20 years ago I found another brand-new Citation I, new in the box, never even been plugged in, which I grabbed for the perfect unworn silk-screened faceplate and clean pots at the least. Caps etc. in unknown condition after all these years, all tubes and switches etc. brand new. It was in a "Barzilay" brand stereo cabinet showroom-floor "demonstrator" cabinet just because it had so many nice turned metal knobs. They had opened the box from the bottom, in order to put the amp back in with the original tape across the top (weird), had all the manuals etc. It's still in a closet at dad's house. Must be 30 years old now, still never been plugged in.
Kevin is too modest to mention that he's also written up a short note about upgrading the Citation II. Take a look here:
http://www.kta-hifi.net/articles/ots7.html
I modded my Citation II with a hybrid of some of Kevin's mods and Jim McShane's power supply upgrades and think it's one of the best amps I've ever heard.
---Gary
Funny, I sold one for around $200 around 23 years ago, then immediately regretted that I had not tried to sell for $1000 first, despite issues--weird noises--I was very honest and outspoken about. It sold quickly the morning it was listed, and I got a dozen more calls. I later saw them listed at prices up to $4000. Even CII transformers were listed for more than what I got. I had loved the sound of the amp when it wasn't acting up.
On the weird noises part, the circuit screams high gain with pentodes everywhere, so I'd be concerned about stability.
On the weird noises part, the circuit screams high gain with pentodes everywhere, so I'd be concerned about stability.
wow, i'm happy!
Well, the amp needs 7 tubes, but will probably get all 10 (what would i do with 3 6550's?), but am really excited about my purchase! Honestly i had 3 minutes to research qnd decide to buy it - there as guy next in line willing to pay more. I knew nothing about it before, but the pictures looked like a good find, so i bought it. That's my story...
Just cracked the case with a tech tonight - 2 burned resistors and the original caps look good, but they're gonna go too. And the fuse was blown, so need to proceed cautiously.
Of course i will post progress here.
Well, the amp needs 7 tubes, but will probably get all 10 (what would i do with 3 6550's?), but am really excited about my purchase! Honestly i had 3 minutes to research qnd decide to buy it - there as guy next in line willing to pay more. I knew nothing about it before, but the pictures looked like a good find, so i bought it. That's my story...
Just cracked the case with a tech tonight - 2 burned resistors and the original caps look good, but they're gonna go too. And the fuse was blown, so need to proceed cautiously.
Of course i will post progress here.
The power transformer is pretty robust so it is likely that one of the rectifiers or a filter cap has failed. The voltage doubler caps lead a tough life. The inrush currents are pretty fierce and mine used to blow the fuse after a certain number of power cycles - I eventually found appropriately rated fuses that did not undergo fatigue failure due to inrush..
Gee, I'm working on another one right now. It's a nice enough amplifier.
The best advice I have seen "out there" on the net is to redo the supply grounding on the capacitor sub-panel. Replacing the rectifiers is one of those things you have to do on every single amplifier if the old selenium units were used. I like to replace any old replacement silicon rectifiers I run into as well. The new parts are better. Hexfreds? Why? Personally, I do not think they buy you anything at all. Snubbers will also lower any high frequency garbage on the AC line. Use new filter capacitors as well.
One critical mistake I see made are coupling capacitors that are too large physically. That is just dumb. You should keep coupling capacitors close to the same value that the originals are. When replacing resistors, and most will be out of tolerance by now, make sure you check the voltage rating on the new ones! Also, metal film resistors are not appropriate unless you do use the ones meant for high power and high voltage. Almost anything is going to be far better than the original carbon composition types. Metal Oxide resistors are a good choice, and they perform very well. Wire-wound resistors in the power supply should be replaced with the same type and value.
If you are doing the work yourself, consider taking a ton of photos before you begin and as you work. These will be your memory. Then, I'd recommend that you strip the sub-assemblies from the main chassis. Work on each sub-assembly on your bench where you can really get int there easily. Strip the components (desolder) and clean up the connection points/terminals. At this point, you may want to remove the older tube sockets and chassis mounted parts as well. This allows you to clean the chassis thoroughly. You could touch up the areas with paint that need it. Certainly give the chassis a clean and polish. Most painted surfaces will come up nicely when you buff them. A wire wheel will look after surface corrosion under the chassis.
Any connector changes you want to make should be done now. Enlarging holes will be easy . Then you are in a position to replace old sockets if you wish - but build them up with new components before mounting them! It makes the job much easier and neater doing it that way. Then you have relatively few connections to make with things mounted in the chassis. Rebuilding the two PCBs is a natural outside the amp too.
Rebuilding a tube based product isn't that bad a job. It is time consuming, and a fair amount of work. But, it's not that hard to do as long as you don't try to rush things. Keep "improvements" to a minimum until you have it working again. Try to keep in mind that the people who designed this amplifier originally really did know what they were doing. We just have some better parts today.
This is a good amplifier. I like the higher output power, but I think the Eico HF-87 sounds a lot better. To each his own, and there are many amps that sound a lot worse than this one too. Now, as for it needing work - yeah. Every old amp needs a rebuild. Unless a transformer is damaged, your rebuild costs will not change whether or not there is some burned components. It all needs rebuilding.
Now, from the sounds of things, you do need to find a good, clean audio tech to do the work for you. Going to Jim would be a good idea. Anyone who does clean work close to you should fit the bill. Just stay clear of those people who need to modify everything. You also do not need the audiophool approved parts either, just use the good standard industrial parts. My own advice would be to avoid paying too much for tubes. Currently manufactured tubes are every bit as good as the "NOS" ones. I have had very good results with Electroharmonix tubes. After that is done, you should be able to enjoy your amp for many years.
-Chris
The best advice I have seen "out there" on the net is to redo the supply grounding on the capacitor sub-panel. Replacing the rectifiers is one of those things you have to do on every single amplifier if the old selenium units were used. I like to replace any old replacement silicon rectifiers I run into as well. The new parts are better. Hexfreds? Why? Personally, I do not think they buy you anything at all. Snubbers will also lower any high frequency garbage on the AC line. Use new filter capacitors as well.
One critical mistake I see made are coupling capacitors that are too large physically. That is just dumb. You should keep coupling capacitors close to the same value that the originals are. When replacing resistors, and most will be out of tolerance by now, make sure you check the voltage rating on the new ones! Also, metal film resistors are not appropriate unless you do use the ones meant for high power and high voltage. Almost anything is going to be far better than the original carbon composition types. Metal Oxide resistors are a good choice, and they perform very well. Wire-wound resistors in the power supply should be replaced with the same type and value.
If you are doing the work yourself, consider taking a ton of photos before you begin and as you work. These will be your memory. Then, I'd recommend that you strip the sub-assemblies from the main chassis. Work on each sub-assembly on your bench where you can really get int there easily. Strip the components (desolder) and clean up the connection points/terminals. At this point, you may want to remove the older tube sockets and chassis mounted parts as well. This allows you to clean the chassis thoroughly. You could touch up the areas with paint that need it. Certainly give the chassis a clean and polish. Most painted surfaces will come up nicely when you buff them. A wire wheel will look after surface corrosion under the chassis.
Any connector changes you want to make should be done now. Enlarging holes will be easy . Then you are in a position to replace old sockets if you wish - but build them up with new components before mounting them! It makes the job much easier and neater doing it that way. Then you have relatively few connections to make with things mounted in the chassis. Rebuilding the two PCBs is a natural outside the amp too.
Rebuilding a tube based product isn't that bad a job. It is time consuming, and a fair amount of work. But, it's not that hard to do as long as you don't try to rush things. Keep "improvements" to a minimum until you have it working again. Try to keep in mind that the people who designed this amplifier originally really did know what they were doing. We just have some better parts today.
This is a good amplifier. I like the higher output power, but I think the Eico HF-87 sounds a lot better. To each his own, and there are many amps that sound a lot worse than this one too. Now, as for it needing work - yeah. Every old amp needs a rebuild. Unless a transformer is damaged, your rebuild costs will not change whether or not there is some burned components. It all needs rebuilding.
Now, from the sounds of things, you do need to find a good, clean audio tech to do the work for you. Going to Jim would be a good idea. Anyone who does clean work close to you should fit the bill. Just stay clear of those people who need to modify everything. You also do not need the audiophool approved parts either, just use the good standard industrial parts. My own advice would be to avoid paying too much for tubes. Currently manufactured tubes are every bit as good as the "NOS" ones. I have had very good results with Electroharmonix tubes. After that is done, you should be able to enjoy your amp for many years.
-Chris
Hi Kevin,
I read your page and only have one concern.
I have a strong aversion to using much larger values of capacitance. This can create other problems.
-Chris
I read your page and only have one concern.
Really? Photoflash capacitors wouldn't be my choice at all. They were not manufactured with that service in mind. If you want to improve the bias section, retain the original capacitor values and make a simple electronic filter instead. You will still get the variable (with line voltage) aspect, but will have much lower noise.
I have a strong aversion to using much larger values of capacitance. This can create other problems.
-Chris
Part of the McShane treatment includes a significant increase in the value of the doubler stack capacitors. To tame the potentially increased turn on surge, negative temperature coefficient (NTC) inrush current limiting thermistors are added. The amp will occasionally clang at turn on in its stock configuration. It never clangs, even with increased doubler stack capacitance, after the NTC parts are installed.
The best small signal complement is RCA 12BY7As in the voltage amp positions and GE JAN 12BY7As in the phase splitter posititons. However, all GE JAN is far from bad.
For O/P tubes, ElectroHarmonix (EH) KT88s are the "budget" choice and "reissue" GEC KT88s the "top shelf" pick. If only EI KT90 type IIs or early type IIIs were available. They aint!
The best small signal complement is RCA 12BY7As in the voltage amp positions and GE JAN 12BY7As in the phase splitter posititons. However, all GE JAN is far from bad.
For O/P tubes, ElectroHarmonix (EH) KT88s are the "budget" choice and "reissue" GEC KT88s the "top shelf" pick. If only EI KT90 type IIs or early type IIIs were available. They aint!
Cripes,
, look at when that was written, (~15yrs ago, and it dates much further back to an early issue of the original paper edition of Positive Feedback) thanks for pointing it out to me. It should be removed, but I have little enough time as it is, rewriting stuff from decades ago is not high on my list of priorities, (not that I even remember writing that) and I agree that photoflash aren't suitable, but enjoyed a brief spurt of popularity back in the 1980s due to their extremely low ESR and before people figured out that they caught on fire. The load current in the bias supply is pretty low and I never had any problems with those caps, but I don't recommend this approach any longer. (And haven't since early in the Clinton era.)This amplifier uses a doubler and because the plate current is 400mA (stock with decent tubes) the supplies in this case really do benefit from additional capacitance. IIRC the high voltage secondary is rated at well over 1A (1.7A?) - the key is managing inrush.. (I don't like NTC, they wear out somewhat spectacularly..)
Hi Eli,
Increasing capacitance seems to be a popular change. I still don't agree with the practice. Especially since there are other ways to reap the benefit that does not include large increases. Note that the original tolerances where extremely loose, so increasing a capacitor by 20% is not an issue. It's those huge increases I think are in error.
Turn on surges can be tamed with NTC parts. However, using a relay to short out the resistance element is a better way to deal with the issue. If I want to include anti-surge measures, that's the route I take. I mean, you're making a change. Why not take a little extra time and do it properly? Mind you, with much larger capacitors installed, a higher primary resistance is a good thing.
If I happen to have RCA, GE or Westinghouse tubes on hand, I'll happily use them. If I don't, there is no way I'm going to pay the extra $$ for the NOS parts. Besides, Electroharmonix tubes are extremely consistent, and very, very quiet tubes. Their outputs are not a "budget" choice at all. I've used them for a long while now, and they are actually every bit as good as - say an RCA stockpile. Understand that I have been dealing with tubes professionally since the 70's. The Electroharmonix tubes are actually a pretty darn safe bet. The Sovtek tubes are also extremely good. But. They are Russian tubes marked with the closest North American designation. The Electroharmonix tubes are different in that they are as marked. I have a set of 6550EH tubes sitting here for a future project. I view these as top quality parts, not as something that is expendable for testing. BTW, those re-issue brands from New Sensor are equivalent in quality. The difference is supposed to be that the characteristics are reverse engineered from that brands products. Keep in mind too, tubes were a commodity item that were shipped back and forth between manufacturers.
To each his own. But we should keep facts straight and honest. There is nothing wrong with the Electroharmonix, just as there isn't with any of the brands that New Sensor markets. The one thing these new tubes have over the NOS ones is consistency from tube to tube. That also means consistency from one half section to the other! We live in times much easier than the days when NOS and National were the only options. Having to plug in an ECG tube was especially distasteful, but those days are over.
-Chris
Increasing capacitance seems to be a popular change. I still don't agree with the practice. Especially since there are other ways to reap the benefit that does not include large increases. Note that the original tolerances where extremely loose, so increasing a capacitor by 20% is not an issue. It's those huge increases I think are in error.
Turn on surges can be tamed with NTC parts. However, using a relay to short out the resistance element is a better way to deal with the issue. If I want to include anti-surge measures, that's the route I take. I mean, you're making a change. Why not take a little extra time and do it properly? Mind you, with much larger capacitors installed, a higher primary resistance is a good thing.
If I happen to have RCA, GE or Westinghouse tubes on hand, I'll happily use them. If I don't, there is no way I'm going to pay the extra $$ for the NOS parts. Besides, Electroharmonix tubes are extremely consistent, and very, very quiet tubes. Their outputs are not a "budget" choice at all. I've used them for a long while now, and they are actually every bit as good as - say an RCA stockpile. Understand that I have been dealing with tubes professionally since the 70's. The Electroharmonix tubes are actually a pretty darn safe bet. The Sovtek tubes are also extremely good. But. They are Russian tubes marked with the closest North American designation. The Electroharmonix tubes are different in that they are as marked. I have a set of 6550EH tubes sitting here for a future project. I view these as top quality parts, not as something that is expendable for testing. BTW, those re-issue brands from New Sensor are equivalent in quality. The difference is supposed to be that the characteristics are reverse engineered from that brands products. Keep in mind too, tubes were a commodity item that were shipped back and forth between manufacturers.
To each his own. But we should keep facts straight and honest. There is nothing wrong with the Electroharmonix, just as there isn't with any of the brands that New Sensor markets. The one thing these new tubes have over the NOS ones is consistency from tube to tube. That also means consistency from one half section to the other! We live in times much easier than the days when NOS and National were the only options. Having to plug in an ECG tube was especially distasteful, but those days are over.
-Chris
Hi Kevin,
Yeah, I thought that article was odd. I was not comfortable pointing it out given your normal take on service. I wonder what else is floating out there on the web?
Most home tube amplifiers used voltage doublers back then. I don't like them very much either. Still, they were sized properly for the load. Remember that most cap input tube supplies that used a 5U4 only hung 50 uF (maximum) on for a first filter. The push-pull action cancelled out the common hum components in the output transformer. Supply ripple is not an issue as long as the level is within reason. In earlier products, seeing a 20 uF, or even 8 uF was not uncommon. Early silicon rectifiers still were not able to deal with the high peak currents that we normally see these days (peak to average comparison, not the absolute levels). The selenium assemblies were even less able to take abuse. From long experience and my own tube amps, I do not see a case for increasing filter capacitance over what the original values were. If a tube amp needs a new power transformer, it presents a great opportunity to go to a full wave type transformer. Bridge rectifiers work well too, and you end up with ripple at 120 Hz, much easier to filter.
-Chris
Yeah, I thought that article was odd. I was not comfortable pointing it out given your normal take on service. I wonder what else is floating out there on the web?
I began seeing destruction almost immediately in my shop back then. It seemed that the people recommending these at the time were simply looking for low cost parts. Don't forget that there was also a glut of these caps on the market around the same time. I think it was due to the guys who specialized in "mods" and home brew techs who saw this as a way to increase profits. They really did make a mess when they failed.
Most home tube amplifiers used voltage doublers back then. I don't like them very much either. Still, they were sized properly for the load. Remember that most cap input tube supplies that used a 5U4 only hung 50 uF (maximum) on for a first filter. The push-pull action cancelled out the common hum components in the output transformer. Supply ripple is not an issue as long as the level is within reason. In earlier products, seeing a 20 uF, or even 8 uF was not uncommon. Early silicon rectifiers still were not able to deal with the high peak currents that we normally see these days (peak to average comparison, not the absolute levels). The selenium assemblies were even less able to take abuse. From long experience and my own tube amps, I do not see a case for increasing filter capacitance over what the original values were. If a tube amp needs a new power transformer, it presents a great opportunity to go to a full wave type transformer. Bridge rectifiers work well too, and you end up with ripple at 120 Hz, much easier to filter.
-Chris
I fixed the article.. It has been a couple of years since I last ftp'd into the site and the linux tools I use aren't very user friendly - still it was pretty trivial to fix once I remembered how use my FTP tool..
**As always any advice on the web should be taken with a grain of salt - even trusted sources can't always be trusted. I imagine there is a lot of advice out there that seemed reasonable at the time that has since been disproven.**
A full wave doubler is used in the Citation II, my problem with doublers is that the ripple current through those caps is obscene if the load current is significant, even off the cuff I suspect ripple currents of over an amp. The Citation II was designed at time when silicon rectifiers were replacing tube rectifiers in higher current applications, and the original capacitors were quite large for the day and would have IMHO been larger still had the technology existed at a reasonable price point. The argument at the time besides simplifying the power transformer was that this also resulted in lower supply impedances and better regulation than had been the case with tube based supplies, and I imagine this was true with fresh capacitors - a few years down the road this probably was no longer true.
**As always any advice on the web should be taken with a grain of salt - even trusted sources can't always be trusted. I imagine there is a lot of advice out there that seemed reasonable at the time that has since been disproven.**
A full wave doubler is used in the Citation II, my problem with doublers is that the ripple current through those caps is obscene if the load current is significant, even off the cuff I suspect ripple currents of over an amp. The Citation II was designed at time when silicon rectifiers were replacing tube rectifiers in higher current applications, and the original capacitors were quite large for the day and would have IMHO been larger still had the technology existed at a reasonable price point. The argument at the time besides simplifying the power transformer was that this also resulted in lower supply impedances and better regulation than had been the case with tube based supplies, and I imagine this was true with fresh capacitors - a few years down the road this probably was no longer true.
Just FYI, a HEALTHY Cit II is one of the most stable amps you can find. It was designed to be unconditionally stable into any load. Once that amp is redone stability will not be an issue.
The amp screams high OPEN LOOP gain, but the beauty of those wideband pentodes is the amp has enough gain to use multiple nested feedback loops and a very moderate amount of global NFB. Closed loop gain is typical of the time - 1.5 volts in gives 60 watts out.
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