Unfortunately, I don't have any speakers to hook up that match the quality of this amp. I'm definitely in pursuit of a nice set to pair with this amplifier. All the research I did on this unit got me very excited to hear it's potential. Thanks for watching!
@@luke144 Thanks for the recommendation! I've heard of the Klipsch name, but have never heard/seen a pair in person. I'll be adding that to my list of things I search for on marketplace now
Thanks for this video. I've been stumped by this very issue. I've thought of replacing those diodes but they seem to measure ok. Now im just going to do it, its the only remaining parts
Glad I could be of any help- good luck with the repair! The one diode I didn't replace though was the double-diode. I left that one in each channel because I couldn't confirm they were bad, and I had no idea how to replace them. When using the (limited) info in the technical/service manual and searching the web, I couldn't find any straightforward answer for a substitute/replacement.
That crossed my mind when I was installing those input transistors. I did bend the leads so that the cases were as close to one another as possible, but I believe your suggestion would be an improvement. It wouldn't take long to implement either. Next time I'm inside that Twelve, I'll couple those transistors up!
Nice work. The thermal protection on the power transistors looks like it will create a major transient when it trips. Of course this will only happen when the amp is being driven hard causing a significant arc inside of the thermal switch.These types of themal cut-off belong on a coffee maker not in an slave amp. This amp Is a speaker killer to boot. Instead You could use the thermal switches to control some power MOSFETS. This way there will be a clean cut-off with no arcing.
Thank you! Working on and learning about this amp really opened my mind to sonic potential in my hifi setup- but learning about its short-comings with lack of speaker protection also made me paranoid to pair this with speakers I cared about. I'm actually working towards finding a nice set to connect this amp to, in the meantime I've been considering possible solutions for speaker protection. I'm going to look into these thermal switches for power MOSFETS that you mentioned.
I have a citation 12 deluxe.. had it since 1985, great amp. I have the 22 as well. Preamp by the 25, source Marantz CD 80 and a Thorens turntable Never had a problem and only had it serviced once. It sure looks like a point to point wiring job 😊 as long as you just show the bottom side 😂
sounds like a killer setup! The wiring on this thing was simple to navigate signal flow and work on- kind of the best of both worlds too with the large single-side circuit board. I feel like it kind of spoiled me, now two-side pcbs seems too busy and full blown point to point is overwhelming looking.
@@killertimes the only thing I had done was recapping it 5 years ago and change the lightbulb twice. And it has been in use with me since before 1988. One of those pieces you can leave for your offspring without worrying about them with big repair bills. Great gear and a perfect buy if found for sale. I would look for a Deluxe, specially if you place it in view. The wooden casing is wonderfull. The matching pre amp is (almost) impossible to find especially in deluxe version. Great to see inside one again, job well done, thnx for saving it. You have one additional subscriber. 👍
This is very funny amo, citation. II IS A LEGEND TUBE AMP, perhaps best Amp I have then step down tube mk 5, this is major step down from this great series, and really nothing special, made on very early RCA transistors, and schematic of this Amp really taken from RCA catalog application of the the transistors... good power supply, does not sound bad at all, I belive, but when compared with today's China power Amp kits based on Pass, or Krell circuit it come short....
The citation two looks like a BEAST! The citation twelve has become my "gateway" amp. Before this project, I had only ever used integrated setups. Now I'm interested in exploring old and new, and considering seeking out some amp kits as well. The ones you mentioned sound familiar, but I will be doing some research to find out more more.
I think it depends on their role in the circuit, and If they're measuring beyond their rated tolerance. If they're bad, or begining to fail, they may be affecting the quality of the sound, and replacing those may make a difference.
the bias is used to adjust out crossover distortion, and given that you've changed the output transistors and some drive transistors it is reasonable to expect it to be different from the schematic. i'd suggest running a 1khz sine wave thru each channel with a scope and dummy load on the output and adjusting the bias so that it is as low as possible without crossover distortion appearing, this will help the amp run cooler for longer. forgive me if u know all this already
Yea it was! The after-market work done to it gave me a heads up on how fragile the traces are and how easy the solder pads could lift off the board. I really had to bring my A-game with desoldering components.
@@maebeans That makes sense, I had a feeling that the parts replaced could play into having different readouts than what the technical manual called for. I've seen testing like you mentioned done quite a few times over the years on various audio electronics repair channels I enjoy watching. I have a function generator and an oscilloscope, but I don't have an apparatus that I could use as a dummy load. I like that suggestion though, and now will have a good excuse to buy some more parts to build a dummy load for future testing. Thanks!
Referring to the small panels that the rca jacks were mounting to? That makes sense, I didn't think they were FR4, but I couldn't quite put my finger on it
I dont know, bro. Why do you write "slow blo" and not "slow blow"? Sencond, should you not put heat sink over those pair of transistors to thermal couple them??? Not a bad work but kinda half-rushed and not thought through, I never saw anything like that. I mean it had a purpose that those are in a case.
Haha yeah, I've seen it on equipment and packages in the past, maybe even spelled like "slo-blo" too. Heat sink compound is a good idea. Sharing my work despite my limitations really feels worth it when I get constructive feedback like yours that helps me learn and grow. Thanks!
I love your channel! Your my favorite TH-camr ❤️
Thanks, I really appreciate that, I'm working on more to share soon
I have two of them. Fantastic amps that drive my AR1's (original). Very valuable info about these dinosaurs.
Unfortunately, I don't have any speakers to hook up that match the quality of this amp. I'm definitely in pursuit of a nice set to pair with this amplifier. All the research I did on this unit got me very excited to hear it's potential. Thanks for watching!
@@killertimesget some Klipsch Forte IIIs. They're affordable in the sound absolutely incredible. 60 watts will be plenty to drive them.
@@luke144 Thanks for the recommendation! I've heard of the Klipsch name, but have never heard/seen a pair in person. I'll be adding that to my list of things I search for on marketplace now
Thanks for this video. I've been stumped by this very issue. I've thought of replacing those diodes but they seem to measure ok. Now im just going to do it, its the only remaining parts
Glad I could be of any help- good luck with the repair! The one diode I didn't replace though was the double-diode. I left that one in each channel because I couldn't confirm they were bad, and I had no idea how to replace them. When using the (limited) info in the technical/service manual and searching the web, I couldn't find any straightforward answer for a substitute/replacement.
Most paired small transistors are best coupled. A bit of thermal past and heat shrink is how I do it. Increases linearity with input stages.
That crossed my mind when I was installing those input transistors. I did bend the leads so that the cases were as close to one another as possible, but I believe your suggestion would be an improvement. It wouldn't take long to implement either. Next time I'm inside that Twelve, I'll couple those transistors up!
Nice work.
The thermal protection on the power transistors looks like it will create a major transient when it trips. Of course this will only happen when the amp is being driven hard causing a significant arc inside of the thermal switch.These types of themal cut-off belong on a coffee maker not in an slave amp. This amp Is a speaker killer to boot.
Instead You could use the thermal switches to control some power MOSFETS. This way there will be a clean cut-off with no arcing.
Thank you!
Working on and learning about this amp really opened my mind to sonic potential in my hifi setup- but learning about its short-comings with lack of speaker protection also made me paranoid to pair this with speakers I cared about. I'm actually working towards finding a nice set to connect this amp to, in the meantime I've been considering possible solutions for speaker protection. I'm going to look into these thermal switches for power MOSFETS that you mentioned.
I have a citation 12 deluxe.. had it since 1985, great amp. I have the 22 as well. Preamp by the 25, source Marantz CD 80 and a Thorens turntable
Never had a problem and only had it serviced once.
It sure looks like a point to point wiring job 😊 as long as you just show the bottom side 😂
sounds like a killer setup! The wiring on this thing was simple to navigate signal flow and work on- kind of the best of both worlds too with the large single-side circuit board. I feel like it kind of spoiled me, now two-side pcbs seems too busy and full blown point to point is overwhelming looking.
@@killertimes the only thing I had done was recapping it 5 years ago and change the lightbulb twice. And it has been in use with me since before 1988. One of those pieces you can leave for your offspring without worrying about them with big repair bills. Great gear and a perfect buy if found for sale.
I would look for a Deluxe, specially if you place it in view. The wooden casing is wonderfull. The matching pre amp is (almost) impossible to find especially in deluxe version.
Great to see inside one again, job well done, thnx for saving it. You have one additional subscriber. 👍
@@annebokma4637 Agreed!
👍
This is very funny amo, citation. II IS A LEGEND TUBE AMP, perhaps best Amp I have then step down tube mk 5, this is major step down from this great series, and really nothing special, made on very early RCA transistors, and schematic of this Amp really taken from RCA catalog application of the the transistors... good power supply, does not sound bad at all, I belive, but when compared with today's China power Amp kits based on Pass, or Krell circuit it come short....
The citation two looks like a BEAST! The citation twelve has become my "gateway" amp. Before this project, I had only ever used integrated setups. Now I'm interested in exploring old and new, and considering seeking out some amp kits as well. The ones you mentioned sound familiar, but I will be doing some research to find out more more.
Would putting superior caps improve the sound?
Probably not.
I think it depends on their role in the circuit, and If they're measuring beyond their rated tolerance. If they're bad, or begining to fail, they may be affecting the quality of the sound, and replacing those may make a difference.
Replacing bad will improve the sound. Upgrading good ones won't. And to be honest this amp sounds great. Mine is driving Quad ESL 57 at this time 👍
gosh the state of that pcb is dire
the bias is used to adjust out crossover distortion, and given that you've changed the output transistors and some drive transistors it is reasonable to expect it to be different from the schematic.
i'd suggest running a 1khz sine wave thru each channel with a scope and dummy load on the output and adjusting the bias so that it is as low as possible without crossover distortion appearing, this will help the amp run cooler for longer.
forgive me if u know all this already
Yea it was! The after-market work done to it gave me a heads up on how fragile the traces are and how easy the solder pads could lift off the board. I really had to bring my A-game with desoldering components.
@@maebeans That makes sense, I had a feeling that the parts replaced could play into having different readouts than what the technical manual called for.
I've seen testing like you mentioned done quite a few times over the years on various audio electronics repair channels I enjoy watching. I have a function generator and an oscilloscope, but I don't have an apparatus that I could use as a dummy load. I like that suggestion though, and now will have a good excuse to buy some more parts to build a dummy load for future testing. Thanks!
Has anyone used one of those places that can make new circuit boards?
That is Bakelite. :)
Referring to the small panels that the rca jacks were mounting to? That makes sense, I didn't think they were FR4, but I couldn't quite put my finger on it
I dont know, bro. Why do you write "slow blo" and not "slow blow"?
Sencond, should you not put heat sink over those pair of transistors to thermal couple them???
Not a bad work but kinda half-rushed and not thought through, I never saw anything like that. I mean it had a purpose that those are in a case.
Haha yeah, I've seen it on equipment and packages in the past, maybe even spelled like "slo-blo" too.
Heat sink compound is a good idea. Sharing my work despite my limitations really feels worth it when I get constructive feedback like yours that helps me learn and grow. Thanks!
Ewww. He just showed amp guts.