To all (sorry for such a long post from a newbie!),
Great Forum - I have been lurking, unregistered, for quite some time. Great stuff!
I am new to the world of solid state power amps, but have fiddled with tubes for quite some time now. I am a mobile DJ, always in search of better sound, more power, and ... did I say more power?
I stumbled upon an ebay deal, a couple of minutes to go, $20 USD, and $20 shipping. Owner said one side worked, the other did not. I won the bid, the unit was shipped, and I, of course, opened it up!
This monstrocity is called a "Proximity Dual Channel DC Amplifier, Model 500", produced by Kairon Limited, Montreal, Quebec. Google searches produce nothing, so I decide to spelunk what this thing is actually made of.
At first glance, this looks like two mono amps in one box - the only thing common between them is the ground and mains. There are two sets of everything else. Here is a list of the components that I could identify - I will only describe one set - the other appears to be an exact duplicate:
- Transformer: Lazare Model LH3737 Primary 115V, Secondary 105CTV, 500 A.
- Bridge rectifier: J775-4-7826
- Capacitors: 10,000 MFD, 75V (there are two of these bridged)
The amplifier circuits are similar to the ones described on the forums and boards I have been reading. Attached to the heat sinks (two aluminum finned, black anodized, sinks, facing each other) I see 4 diodes?, two labeled FT317/848, two labeled FT417/914. I see 8 round transistors?, two are Motorola 2N6809/7839, the other 6 are Motorola MJ15024/8226.
Oh, yeah, there is a fan in the chassis as well.
I have not plugged this in yet, nor do i plan to until i do some testing of the circuits/leads/etc.
What do I have here? Is this thing worth fixing / messing with? Will I kill myself in the process?
The overall condition of the amplifier circuits does not look very good. It appears that there was moisture in the case, and some of the pads look like they are separating from the circuit boards.
BTW, The transistors and diodes "plug" into the circuit boards through the heat sink- they are not soldered directly to the board.
What I would like to end up with is essentially two STEREO amps in one box (or two boxes). I would like to convert each side to stereo and allow them to be bridged. that way I can drive a stereo pair of speakers from one side of the amp, and a subwoofer from the other side, or 4 speakers from both sides of this amp.
Any and all comments, insights and amplifier suggestions are greatly appreciated.
Thanks,
Keith Kibler
Coatesville, PA
Great Forum - I have been lurking, unregistered, for quite some time. Great stuff!
I am new to the world of solid state power amps, but have fiddled with tubes for quite some time now. I am a mobile DJ, always in search of better sound, more power, and ... did I say more power?
I stumbled upon an ebay deal, a couple of minutes to go, $20 USD, and $20 shipping. Owner said one side worked, the other did not. I won the bid, the unit was shipped, and I, of course, opened it up!
This monstrocity is called a "Proximity Dual Channel DC Amplifier, Model 500", produced by Kairon Limited, Montreal, Quebec. Google searches produce nothing, so I decide to spelunk what this thing is actually made of.
At first glance, this looks like two mono amps in one box - the only thing common between them is the ground and mains. There are two sets of everything else. Here is a list of the components that I could identify - I will only describe one set - the other appears to be an exact duplicate:
- Transformer: Lazare Model LH3737 Primary 115V, Secondary 105CTV, 500 A.
- Bridge rectifier: J775-4-7826
- Capacitors: 10,000 MFD, 75V (there are two of these bridged)
The amplifier circuits are similar to the ones described on the forums and boards I have been reading. Attached to the heat sinks (two aluminum finned, black anodized, sinks, facing each other) I see 4 diodes?, two labeled FT317/848, two labeled FT417/914. I see 8 round transistors?, two are Motorola 2N6809/7839, the other 6 are Motorola MJ15024/8226.
Oh, yeah, there is a fan in the chassis as well.
I have not plugged this in yet, nor do i plan to until i do some testing of the circuits/leads/etc.
What do I have here? Is this thing worth fixing / messing with? Will I kill myself in the process?
The overall condition of the amplifier circuits does not look very good. It appears that there was moisture in the case, and some of the pads look like they are separating from the circuit boards.
BTW, The transistors and diodes "plug" into the circuit boards through the heat sink- they are not soldered directly to the board.
What I would like to end up with is essentially two STEREO amps in one box (or two boxes). I would like to convert each side to stereo and allow them to be bridged. that way I can drive a stereo pair of speakers from one side of the amp, and a subwoofer from the other side, or 4 speakers from both sides of this amp.
Any and all comments, insights and amplifier suggestions are greatly appreciated.
Thanks,
Keith Kibler
Coatesville, PA
Hi Keith,
Seems like you got yourselves a real monster!
The power transformers, 105V CT would give just below +/- 70V DC, confirmed by the 75V cap rating. Assuming about 60 to 65V peak output voltage, that translates into some 250W per channel. It really depends on the state if it is worthwhile to fix it.
As a minimum, you should get yourself a multimeter to be able to check supply voltages, output offset, that kind of thing. And safety goggles 😉 . A picture posted might be helpful as well.
Jan Didden
Seems like you got yourselves a real monster!
The power transformers, 105V CT would give just below +/- 70V DC, confirmed by the 75V cap rating. Assuming about 60 to 65V peak output voltage, that translates into some 250W per channel. It really depends on the state if it is worthwhile to fix it.
As a minimum, you should get yourself a multimeter to be able to check supply voltages, output offset, that kind of thing. And safety goggles 😉 . A picture posted might be helpful as well.
Jan Didden
Hi djkib,
I have unwillingly repaired these before. They are a fire hazard. They are poorly designed and every single one I've seen go down has taken out the speakers. Usually in flames. It is not uncommon to see fire extinguisher powder inside these amps. Guess why ....
What you really have is a case, heatsinks, fan and transformer. Worth the money you spent. Rebuild it as something else - with more heatsinking for the power the transformer will supply. I was given one after the third blow up (first time I saw it). The guy had about five of them ... boom boom boom boom boom. I used the case for a power supply.
-Chris
I have unwillingly repaired these before. They are a fire hazard. They are poorly designed and every single one I've seen go down has taken out the speakers. Usually in flames. It is not uncommon to see fire extinguisher powder inside these amps. Guess why ....
What you really have is a case, heatsinks, fan and transformer. Worth the money you spent. Rebuild it as something else - with more heatsinking for the power the transformer will supply. I was given one after the third blow up (first time I saw it). The guy had about five of them ... boom boom boom boom boom. I used the case for a power supply.
-Chris
Use the whole darn thing as a power supply. Take out the amp sections and bring the power supplies out to the speaker terminals. Oh, you may need to add more if it's only got one set of speaker terminals.
Then build a suitable amp in a separate enclosure, or two monoblocks. You'll be limited to Class AB stuff, maybe the high power amp on the ESP site.
Then build a suitable amp in a separate enclosure, or two monoblocks. You'll be limited to Class AB stuff, maybe the high power amp on the ESP site.
Hi paulb,
There is enough room inside to build a decent stereo amplifier. The manufacturer chose not to. I don't like the idea of that much raw power on the speaker terminals. Too dangerous.
Really, this thing was a box of air with a big transformer, caps and a couple heatsinks on standoffs. One on top of the other with a fan at the end, on the case I think. The first one I saw gave me the creeps.
-Chris
There is enough room inside to build a decent stereo amplifier. The manufacturer chose not to. I don't like the idea of that much raw power on the speaker terminals. Too dangerous.
Really, this thing was a box of air with a big transformer, caps and a couple heatsinks on standoffs. One on top of the other with a fan at the end, on the case I think. The first one I saw gave me the creeps.
-Chris
To all,
Thanks for the great ideas...
After more investigation, I do plan on replacing all the amplifier sections.
Now, what amps should I build? I was looking at the Leach designed amps, but I don't know how to go about modifying the amp to handle the power from the transformer.
Any and all suggestions are welcome to this newbie!
Thanks,
Keith
Thanks for the great ideas...
After more investigation, I do plan on replacing all the amplifier sections.
Now, what amps should I build? I was looking at the Leach designed amps, but I don't know how to go about modifying the amp to handle the power from the transformer.
Any and all suggestions are welcome to this newbie!
Thanks,
Keith
Hi djkib,
Think of some power amps you really like and figure out what general circuits they use. Then find a kit or schematic / project that is close to what you know you like and build it. We all have varying opinions, but the amp will be in your house. Just build one that is safe and doesn't go unstable.
Take your time with this and don't rush in.
-Chris
Think of some power amps you really like and figure out what general circuits they use. Then find a kit or schematic / project that is close to what you know you like and build it. We all have varying opinions, but the amp will be in your house. Just build one that is safe and doesn't go unstable.
Take your time with this and don't rush in.
-Chris
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