Hello!
I need some help deciphering a schematic I found online for a JMP 2204. Plan use whatever applicable parts I have from my amp to make a combo. I have a decent electrical background and am starting to branch into sound/electronics.
1) From what I can understand, the blue resistors are variable, called potentiometers (volume, bass, treble, gain, etc.) I believe I got them all listed in this schematic. Am I correct in this understanding?
2) I'm new to speakers, and I thought the representation for them was straight forward, or maybe they aren't listed, but I used a pink circle for where I believe they would go on the schematic. Is this also correct? Or am I missing where they go?
3) At first, I believed the speakers to be what I highlighted as green. But then I believe I figured out that they are the diodes. Is this also correct?
These are my main 3 questions before I start looking more deeply into the diagram and construction. Any help you may provide would be greatly appreciated. I'm not looking for a perfect amp, by any means. Just one I can make myself as a project and save money. I currently only have SS and would like to upgrade on a budget on my free time.
Thank you!
Alex
I need some help deciphering a schematic I found online for a JMP 2204. Plan use whatever applicable parts I have from my amp to make a combo. I have a decent electrical background and am starting to branch into sound/electronics.
1) From what I can understand, the blue resistors are variable, called potentiometers (volume, bass, treble, gain, etc.) I believe I got them all listed in this schematic. Am I correct in this understanding?
2) I'm new to speakers, and I thought the representation for them was straight forward, or maybe they aren't listed, but I used a pink circle for where I believe they would go on the schematic. Is this also correct? Or am I missing where they go?
3) At first, I believed the speakers to be what I highlighted as green. But then I believe I figured out that they are the diodes. Is this also correct?
These are my main 3 questions before I start looking more deeply into the diagram and construction. Any help you may provide would be greatly appreciated. I'm not looking for a perfect amp, by any means. Just one I can make myself as a project and save money. I currently only have SS and would like to upgrade on a budget on my free time.
Thank you!
Alex
1. Blue circled are pots but note that one is for setting the bias voltage.
2. Pink circled are the input jack sockets. This is the diagram for a head not a combo.
3. Green highlighted parts are diodes.
You are taking on a monumental task with
serious implications regarding safety.
You haven't put enough thought into this yet.
Sid.
2. Pink circled are the input jack sockets. This is the diagram for a head not a combo.
3. Green highlighted parts are diodes.
You are taking on a monumental task with
serious implications regarding safety.
You haven't put enough thought into this yet.
Sid.
1 - Pots or trimmers. From the pictures online, this amp has 6 pots, so one of them is a trimmer. I would say the lower 25K one (BIAS / Symmetry adjust ??). Sorry, I don't know enough about valves.
2 - No, these aren't speaker crossover outputs but inputs. Speakers go after multi-tap transformer on the right. Note the 4,8,16 Impedance figures.
3 - Correct.
Be careful, High Voltage kills !!
2 - No, these aren't speaker crossover outputs but inputs. Speakers go after multi-tap transformer on the right. Note the 4,8,16 Impedance figures.
3 - Correct.
Be careful, High Voltage kills !!
Thank you for the helpful info. AMP STUFF seems like it will help with some of my questions.
I do not like getting into things without knowing enough about them. There are definitely things i don't know and things I still NEED To know. That's why I cam here. To seek help on things I don't understand.
Yes, I understand tubes create very high voltage and capacitors stay charged even after shutting down/unplugging. I am not buying, building or wiring at the moment. This is the beginning stages of my research. I plan to look deeply into what I"m doing until I'm sure I can do it well and SAFELY. I appreciate your concern for my well-being.
Thank you!
I do not like getting into things without knowing enough about them. There are definitely things i don't know and things I still NEED To know. That's why I cam here. To seek help on things I don't understand.
Yes, I understand tubes create very high voltage and capacitors stay charged even after shutting down/unplugging. I am not buying, building or wiring at the moment. This is the beginning stages of my research. I plan to look deeply into what I"m doing until I'm sure I can do it well and SAFELY. I appreciate your concern for my well-being.
Thank you!
The parts cost would be substantial for the power transformer, output transformer, chassis, tubes,
electrolytic capacitors, sockets, etc. What parts do you have now? Try looking for a used amp instead,
since the total cost may not be that much different, and it would have resale value as well. If your parts
source is a solid state amp, little or nothing in there will be of use in a tube amp, other than the
chassis and enclosure.
Last edited:
Yeah, The chassis and enclosure was all I was planning to keep. Maybe use the speaker if it ended up being usable for this. This is something I've been thinking about and just started to look into more.
I was trying to understand some of the schematic aspect a bit more before I moved on to any further. Since I clearly had some things I didn't know. But everyone has to start somewhere. This is where I am.
I've considered the used route. I could go out and buy a used tube amp, but then I wouldn't learn as much as I could this way.
As far as what I've got, Nothing. after I understood they layout of the schematic, my plan was to start looking into buying parts. I was aware I'd need resistors, caps, switches/pots/, fuses, a transformer, and a choke (I thought the choke was what looked like a transformer on the far right. That was a question for later, but now i know where the choke is), and tubes. There are more parts that I don't know on here, I'm sure. But I was planning on taking it slower, and only address some questions for now.
Maybe it is just better to get a used amp and leave it. I wasn't going to be wreckles and just start wiring things together. But if the costs are going to be as high as you are suggesting, it may just be better to buy a used amp.
I was trying to understand some of the schematic aspect a bit more before I moved on to any further. Since I clearly had some things I didn't know. But everyone has to start somewhere. This is where I am.
I've considered the used route. I could go out and buy a used tube amp, but then I wouldn't learn as much as I could this way.
As far as what I've got, Nothing. after I understood they layout of the schematic, my plan was to start looking into buying parts. I was aware I'd need resistors, caps, switches/pots/, fuses, a transformer, and a choke (I thought the choke was what looked like a transformer on the far right. That was a question for later, but now i know where the choke is), and tubes. There are more parts that I don't know on here, I'm sure. But I was planning on taking it slower, and only address some questions for now.
Maybe it is just better to get a used amp and leave it. I wasn't going to be wreckles and just start wiring things together. But if the costs are going to be as high as you are suggesting, it may just be better to buy a used amp.