Harman Kardon Citation 19 Recap
- Thread starter AmCan
- Start date
I did own a couple 19's. 
AmCan
Active Member
Yes I have some thoughts. I have done the Driver Boards already but I have been hesitant to post pictures them because I have learned some things since and I am going to make a major change. Plus I forgot to take a picture before I put them back in place. Basically C1 & C6 are the 2 most important caps on the whole board. C1 is the input cap and C6 is the negative feedback cap. I would use either the Mundorf E-Caps http://www.partsconnexion.com/capacitor_ele_mundorf_bipol.html or the Jensens axials [100uf 150V & 470uf 150V]. http://www.partsconnexion.com/capacitor_ele_jensen_axial.html Either one will take some skill to mount either in an axial direction, or in a stand mount direction. I can post some pictures of a stand mount of an axial cap if you have never done it.
There are 2 more alternatives. 1. An easier approach and a good one would be to simply get some Nichicon Muze radials. They are more powerful then the Elnas in my experience. Then bypass them with a .01 REL RTE http://www.partsconnexion.com/capacitor_film_reliablecap.html, which are about $6 ea. Even if you use the Jensens or the Mundorf I would bypass them with this cap and also use the RTE to replace the .01 ceramics on the board. The RTE rated "better than the SoniCap Platinum (which costs four times as much) with its smoothness and lack of glare." In the Great Capacitor Shoot-Out http://www.laventure.net/tourist/caps.htm . I have used the RTE's in my phono stage and I love them. I also used them to replace the ceramics on the 19.
Word of advice for those who are wondering like I was - Do not increase the capacitance for C1, or C6 because they determine the amplified frequency range and it is already full bandwidth. This is where I made a slight misjudgement in increasing C1 to 220uf, which is o.k. - it was just overkill. Increasing the bandwidth too much can cause oscillations that could harm the amplifier. A typical value for an input cap is 4.7uf to 10uf. HK used a 100uf! However, the amp was designed to be full bandwidth and can handle this value. Just don't go any higher here or anywhere for that matter other than the main capacitor bank. I was told the main capacitor back could handle 22K but I couldn't find a 22K that would fit. You will notice the Driver Assay board has a .1uf and its role is as a zobel capacitor, which is only there to counteract speaker inductance and stabilize the amp against stray frequencies that may cause catastrophic oscillations. It doesn't contribute to sound and although I upgraded mine it is not necessary.
[Note: I would like to thank everyone over at DIYAudio who helped me out tremendously to understand the circuit diagram.]
I originally used a Jensen 220uf for the input cap and bypassed it with a Vitamin Q because I was looking for a vintage tone sound - which I really like the vitamin Qs. I used a Nichicon for the 470uf and bypassed it with a Vishay 1837. After having done that I learned about the the role of C1 & C6 in how they determine bandwidth and now see it is more important than I originally anticipated. Also, in the interim I ended up upgrading the power supply of my HK 17 Preamp to all Blackgates http://www.audiokarma.org/forums/showthread.php?t=395148&page=5 and they are as good as a film cap IMHO! Therefore I am now hunting down Blackgates for C1 & C6. If you can afford them there is nothing better that I would recommend. I am not even going to bypass them because I read that it can ruin their sound.
I will post some pics tonight of my first attempt at the driver boards. Also C16 is tricky too to upgrade and I can talk more about that later.
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AmCan
Active Member
Blackgates have finally arrived!
My Blackgates for the driver board finally came in
and hopeful I can get to putting them in soon but the I have several projects on the go right now and some of them relate to the real world. These are for C1 & C6 but I also got several more for the Citation 17 Preamp and I also have a HK730 that I use to use before I bought my Citation gear. I wish I could have hoarded more but I am also upgrading some vintage Braun L-910s http://www.audiokarma.org/forums/showthread.php?t=428692 and my play cash only goes so far. I think I paid close to $100 just for these 4 caps but the 470uf were double the 100ufs ($60 & $30). I also want to replace the analog input jacks because they are loose. I had been trying to make my Audioquest interconnects but the left cable kept cutting out. I thought I was soldering it wrong or something. I did the terminals 3x & then realized its the wiring on the 19's input jacks that are loose.
My Blackgates for the driver board finally came in
and hopeful I can get to putting them in soon but the I have several projects on the go right now and some of them relate to the real world. These are for C1 & C6 but I also got several more for the Citation 17 Preamp and I also have a HK730 that I use to use before I bought my Citation gear. I wish I could have hoarded more but I am also upgrading some vintage Braun L-910s http://www.audiokarma.org/forums/showthread.php?t=428692 and my play cash only goes so far. I think I paid close to $100 just for these 4 caps but the 470uf were double the 100ufs ($60 & $30). I also want to replace the analog input jacks because they are loose. I had been trying to make my Audioquest interconnects but the left cable kept cutting out. I thought I was soldering it wrong or something. I did the terminals 3x & then realized its the wiring on the 19's input jacks that are loose.Attachments
AmCan
Active Member
Driver Board 1st Attempt Pictures
Last night I pulled out the Driver Boards again to put in my Blackgates. As promised though, here is my 1st attempt at replacing the caps, which worked out excellent, however, I wanted to upgrade C & C6 to Blackgates. I original used a Jensen bipolar audiophile grade cap, which isn't cheap either, and bypassed it with a vintage Sprague Vitamin Q tone cap. This is the same tone cap used in guitar tone pots. I love listening to that vintage Gibson & Strat sound so I thought i would give it a try. It certainly didn't sound like a Marshall Amplifier but I suspect that most of the tone comes from the preamp & I will be curious to hear the effects of not putting this back in. If I lose my treble sparkle i will most likely try to move this to my preamp, which already has several vintage PIO on the output Board.
**Warning**
One thing to note is that if you replace the C16 Mylar you have to use the long leads like this to get it out of your way or you will not be able to screw back in the board if you block the screw beneath its position. I used a nice vintage Sprague Difilm here, again for the vintage tone sound. This is a bypass cap for the bias pot. The main reason for this cap is to make the high frequency characteristics of the amp more similar between the push and pull sides. So the value used here will determine the high frequency bypass. I used a 1.5uf, where it calls for a 1uf only because I wanted to use the vintage Sprague difilm. My understanding is that this bypass will effect gain. However, the value decreases further out towards the end of the leads and measured closer to 1.35uf. Try to use matched pairs and perhaps something like an MCap or Clarity Cap, which are on the smaller side. Up to this point I have not measured the bias current because I could not get to where it needs to be measured but I bought some extra long alligator clips w/ leads for my DMM and plan to do it this time around. In using the amplifier it would barely get warm at times so I don't suspect that thee is a problem with the bias settings.
Last night I pulled out the Driver Boards again to put in my Blackgates. As promised though, here is my 1st attempt at replacing the caps, which worked out excellent, however, I wanted to upgrade C & C6 to Blackgates. I original used a Jensen bipolar audiophile grade cap, which isn't cheap either, and bypassed it with a vintage Sprague Vitamin Q tone cap. This is the same tone cap used in guitar tone pots. I love listening to that vintage Gibson & Strat sound so I thought i would give it a try. It certainly didn't sound like a Marshall Amplifier but I suspect that most of the tone comes from the preamp & I will be curious to hear the effects of not putting this back in. If I lose my treble sparkle i will most likely try to move this to my preamp, which already has several vintage PIO on the output Board.
**Warning**
One thing to note is that if you replace the C16 Mylar you have to use the long leads like this to get it out of your way or you will not be able to screw back in the board if you block the screw beneath its position. I used a nice vintage Sprague Difilm here, again for the vintage tone sound. This is a bypass cap for the bias pot. The main reason for this cap is to make the high frequency characteristics of the amp more similar between the push and pull sides. So the value used here will determine the high frequency bypass. I used a 1.5uf, where it calls for a 1uf only because I wanted to use the vintage Sprague difilm. My understanding is that this bypass will effect gain. However, the value decreases further out towards the end of the leads and measured closer to 1.35uf. Try to use matched pairs and perhaps something like an MCap or Clarity Cap, which are on the smaller side. Up to this point I have not measured the bias current because I could not get to where it needs to be measured but I bought some extra long alligator clips w/ leads for my DMM and plan to do it this time around. In using the amplifier it would barely get warm at times so I don't suspect that thee is a problem with the bias settings.
Attachments
AmCan
Active Member
Analog Jacks
I know I probably shouldn't make 2 significant changes at once but these analog terminals are too loose to be safe. The left channel can cut in and out if the analog cables are moved so it is time to upgrade these.
I know I probably shouldn't make 2 significant changes at once but these analog terminals are too loose to be safe. The left channel can cut in and out if the analog cables are moved so it is time to upgrade these.
Attachments
AmCan
Active Member
AmCan
Active Member
If its good enough for Audioquest it is good enough for me. :yes:
It was just funny as I was sitting there stripping the thermostat wire I had to take a picture. I am using a small piece of Audioquest left over from my speaker cables for the signal path from the analog jacks to the Driver Board but I am using the thermostat wire to connect to the stereo/mono switch & to ground. I bought the thermostat wire for a speaker project; I am rewiring the capacitor network and it is ridiculous to think, when you look at them both, the difference in price. SUPPOSEDLY the AUDIO GRADE wire won't corrode as fast. I guess I will find out and report back on it as soon as either corrodes.
AmCan
Active Member
I figured an orientation shot is needed here as it is easiest to work on this beast turned up on its end.
and now right side up view
The key to soldering 3 wires to a 10gauge piece of Romex is my wife's 100W soldering iron she uses for stained glass work. Its so hot it takes but a few seconds for the solder to flow, rather than holding my 45W soldering iron on the connection for 2 minutes and it still doesn't flow.
I still need to solder these signal wires back to the terminal boards but I can no longer use the blue connector terminal so i am looking for an inventive way to make a custom attachment. I have something in mind but I will get to it tonight, plus I am finally ready to measure the bias current, which finally makes sense to me. I find if I stare at something long enough it all starts to make sense to me. I must say I am ready for a kit and would love to make a tube DAC next. Does anyone know a good tube DAC kit? I would like to match the dual mono design.
and now right side up view
The key to soldering 3 wires to a 10gauge piece of Romex is my wife's 100W soldering iron she uses for stained glass work. Its so hot it takes but a few seconds for the solder to flow, rather than holding my 45W soldering iron on the connection for 2 minutes and it still doesn't flow.
I still need to solder these signal wires back to the terminal boards but I can no longer use the blue connector terminal so i am looking for an inventive way to make a custom attachment. I have something in mind but I will get to it tonight, plus I am finally ready to measure the bias current, which finally makes sense to me. I find if I stare at something long enough it all starts to make sense to me. I must say I am ready for a kit and would love to make a tube DAC next. Does anyone know a good tube DAC kit? I would like to match the dual mono design.
Attachments
AmCan
Active Member
UGH!:sigh: I am waiting for some copper crimpers to come from Parts Connection to couple the wires back to the Driver Boards otherwise I may just end up soldering them back to the terminal posts. I tried to using something else but the connection was too loose. Hopefully tomorrow. Its killin me to not have had music all weekend - at least descent music.
But, hey, thanks for the compliment, i appreciate it.
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AmCan
Active Member
Nice looking work. :yes: Do you really want to leave the bridge switch?
Steve
Good point. I could leave the switch there to fill the space but take it out of the chain. What do I do exactly? The black wires are going to the left channel Driver Board, and there is one blue wire from the left channel jack going to ground. They aren't even involved with the switch at all. The right channel driver board has 3 wires that connect to it coming off the switch and only one wire connecting the jack to the switch. So my guess is that i need one wire going straight to ground from the jack and the other 2 going back to the Driver Board? Most likely the upper white and red wire. Is that correct?
Westy56
A symphony of paradox
AmCan
Active Member
I am sure its an easy problem for a pro. I am mostly good at replacing apples for apples but when I try to mod something then I get into trouble. If the switch was noisy I would be concerned. I probably should have at least upgraded the switch when I did the jacks. So far I have made that misstep with the Bridge Rectifier, the output transistor resistors, and this switch. There are a lot of steel connecting wires tied in with the output transistors that I would like to replace with copper as well. Its interesting to see some of these things knowing that these were hand assembled back in 1978. I will get to those when I replace the .5ohm 10W resistors. I was thinking about what I should tackle after this anyway. Either the Bridge Rectifiers, or I go back to the resistors. Can you imagine changing all the wires back in there? :bash: Any thoughts on what I should tackle next?
Attachments
Westy56
A symphony of paradox
Blue Shadow
Waiting for Vintage Gear from this century
Maybe a bit of forced air cooling. The 19 seems to run fairly warm.