anyone have the pa 600 amp pcb layout? im trying to build it and ill be needing the layout....thanks
hacknet said:
I think you got it a bit backwards here. 120 VAC rails would give something like 1700 W into 8 Ohms and 3400 W into 4 Ohms. You're sure you're not thinking about 70 VDC rails with something like a 2*50 VAC transformer?
Read up a bit on the workings of an amplifier and it's power supply? You know your 3 A continuous would give you 70 W right?
Speaking of Dr. Leach
and the Low TIM amp projects, here's a link to his site at Georgia Tech -- with a wealth of links to other sites:
http://users.ece.gatech.edu/~mleach/
and the Low TIM amp projects, here's a link to his site at Georgia Tech -- with a wealth of links to other sites:
http://users.ece.gatech.edu/~mleach/
I strongly recommend not to build that circuit. I've had to repair some PA amplifiers using that topology and it proved to have some seious flaws
Supply rejection is very very poor, supply ripple appears freely at the output with only 20-30dB or less attenuation due to the way the output of the op-amp is coupled to the Vas
Supply rejection is specially poor when there are two or more channels sharing the same PSU and supply rails fluctuate in almost a chaotic way. The op-amp may correct for fluctuations happening in a single rail at a time but it has nothing to do against simultaneous differential fluctuations in both rails
The biasing of the Vas is also unpredictable since it suffers very strong fluctuations during real operation. It may travel freely between class B and 50mA when there are two or more channels sharing the same PSU
More recent versions of that circuit use cascodes at the output of the op-amp and solve all those problems. I tried adding 2N5401/2N5551 cascodes to one of the old PA amps I repaired and found supply ripple to be no longer appreciable on the oscilloscope [maybe 30-40dB improvement]. Bias fluctuations on the Vas also stopped, but the circuit was frequency compensated to allow for too little phase margin and the small phase-lag introduced by those cascodes was enough to cause oscillation at high output levels and to destroy a couple of output devices while testing. After that I reverted to the original circuit since the amplifier itself was not worth the time required to play with frequency-compensation and test it until decent stability margin is achieved
Supply rejection is very very poor, supply ripple appears freely at the output with only 20-30dB or less attenuation due to the way the output of the op-amp is coupled to the Vas
Supply rejection is specially poor when there are two or more channels sharing the same PSU and supply rails fluctuate in almost a chaotic way. The op-amp may correct for fluctuations happening in a single rail at a time but it has nothing to do against simultaneous differential fluctuations in both rails
The biasing of the Vas is also unpredictable since it suffers very strong fluctuations during real operation. It may travel freely between class B and 50mA when there are two or more channels sharing the same PSU
More recent versions of that circuit use cascodes at the output of the op-amp and solve all those problems. I tried adding 2N5401/2N5551 cascodes to one of the old PA amps I repaired and found supply ripple to be no longer appreciable on the oscilloscope [maybe 30-40dB improvement]. Bias fluctuations on the Vas also stopped, but the circuit was frequency compensated to allow for too little phase margin and the small phase-lag introduced by those cascodes was enough to cause oscillation at high output levels and to destroy a couple of output devices while testing. After that I reverted to the original circuit since the amplifier itself was not worth the time required to play with frequency-compensation and test it until decent stability margin is achieved
That PA600 schematic is a good alternative as long as the output of the op-amp is cascoded
The amplfiier I mentioned previously was from 1990 I think and it used LM318 as input op-amp, MJE340 and MJE350 as Vas and predrivers [triple darlington output as opposed to double on that PA600 schematic], a pair MJ15022/MJ15023 as drivers and three more pairs as outputs with +-70V rails
MJE1502x are slow [2 to 4Mhz FT] devices and using them both as drivers and outputs causes two poles to appear at too low a frequency in the open loop frequency response. This seriously hurts phase margin and stability of the circuit. I considered replacing the drivers by MJE15031/MJE15032 but it would require heat-sink machining and I had already wasted too much time with that amplifier
I think that the same amplifier built with modern 30-50Mhz FT MJE1503x drivers and >20Mhz FT Toshiba or Sanken outputs would show plenty of phase margin, and 2N5401/2N5551 cascodes from the output of the op-amp to the base of the Vas would ensure decent PSRR
For smaller powers the Leach amp is an excelent alternative and with some modifications supply rails may be increased from +-56V to +-90V, but component count and complexity is markedly higher due to the discrete input stage
The amplfiier I mentioned previously was from 1990 I think and it used LM318 as input op-amp, MJE340 and MJE350 as Vas and predrivers [triple darlington output as opposed to double on that PA600 schematic], a pair MJ15022/MJ15023 as drivers and three more pairs as outputs with +-70V rails
MJE1502x are slow [2 to 4Mhz FT] devices and using them both as drivers and outputs causes two poles to appear at too low a frequency in the open loop frequency response. This seriously hurts phase margin and stability of the circuit. I considered replacing the drivers by MJE15031/MJE15032 but it would require heat-sink machining and I had already wasted too much time with that amplifier
I think that the same amplifier built with modern 30-50Mhz FT MJE1503x drivers and >20Mhz FT Toshiba or Sanken outputs would show plenty of phase margin, and 2N5401/2N5551 cascodes from the output of the op-amp to the base of the Vas would ensure decent PSRR
For smaller powers the Leach amp is an excelent alternative and with some modifications supply rails may be increased from +-56V to +-90V, but component count and complexity is markedly higher due to the discrete input stage
and for example HI FI amps like yamaha and that stuff, what kind of IC use?
is possible to made an powerfull HIFI amp like brand yamaha, pionner,.... ?
is that possible?
sorry for my question, but i want to build an nice amp, not an crap one 😀
i have an yamaha RX-v595 and i want something better 😀
is possible to made an powerfull HIFI amp like brand yamaha, pionner,.... ?
is that possible?
sorry for my question, but i want to build an nice amp, not an crap one 😀
i have an yamaha RX-v595 and i want something better 😀
Eva, thanks for your comments.
I'm well aware of these problems, however at least for me they proved to be "academic".
The amp was intended as a high power, easy-to-build and easy-to-understand project for PA use... I've built and used several of these for years, and while the sound is not "high end", it proved to be an economic and reliable design. Cerntainly learned something from fiddling around with this circuit.
I'm currently using a CFB circuit similar to Elektor's Titan / Gigant which in turn is strikingly similar to the big Accuphase amps. It is way more stable, sounds way better, but is also much more complex and definitely not a project for the beginner or unexperienced.
Anybody feels like adding the cascode stage and re-doing the frequency compensation? Switching to newer output devices would be fine as long as they are not too costly. Kind of defeats the purpose of this very simple circuit...
I'm well aware of these problems, however at least for me they proved to be "academic".
The amp was intended as a high power, easy-to-build and easy-to-understand project for PA use... I've built and used several of these for years, and while the sound is not "high end", it proved to be an economic and reliable design. Cerntainly learned something from fiddling around with this circuit.
I'm currently using a CFB circuit similar to Elektor's Titan / Gigant which in turn is strikingly similar to the big Accuphase amps. It is way more stable, sounds way better, but is also much more complex and definitely not a project for the beginner or unexperienced.
Anybody feels like adding the cascode stage and re-doing the frequency compensation? Switching to newer output devices would be fine as long as they are not too costly. Kind of defeats the purpose of this very simple circuit...
Pa300
OliverD
Since you seem to be very knowledgeable on this amplifier and I'm trying
to build one (one channel only), it seems pertinent that I ask you a
couple of questions, if you don't mind:
- What kind of thermister does it it use in the protection circuit?
KTY81-122, can it be replaced by another PTC with 1K ohm
This is a Philips type very difficult to get in the States.
- Do you think is a bad practice to replace the polyesterene caps, 33
and 47 as in the scematic, by regular ceramic caps? I don't seem to
be able to find that type of caps in these values...
There are a multitude of questions I have before I finish the board
but I don't want to impose on you. Suffice to say that I'm having a
terrible time to make heads and tails of the terrible resolution of
the pictures on the layout of the board, I had to make it by hand
figuring out what goes where, almost a mission impossible. But it's
done, almost finished, and I only need to know as of right now
those answers to my two questions.
By the way would you have a decent picture of the layout you
could publish on this thread just to check my board, please?
I'd appreciate your output.
OliverD
Since you seem to be very knowledgeable on this amplifier and I'm trying
to build one (one channel only), it seems pertinent that I ask you a
couple of questions, if you don't mind:
- What kind of thermister does it it use in the protection circuit?
KTY81-122, can it be replaced by another PTC with 1K ohm
This is a Philips type very difficult to get in the States.
- Do you think is a bad practice to replace the polyesterene caps, 33
and 47 as in the scematic, by regular ceramic caps? I don't seem to
be able to find that type of caps in these values...
There are a multitude of questions I have before I finish the board
but I don't want to impose on you. Suffice to say that I'm having a
terrible time to make heads and tails of the terrible resolution of
the pictures on the layout of the board, I had to make it by hand
figuring out what goes where, almost a mission impossible. But it's
done, almost finished, and I only need to know as of right now
those answers to my two questions.
By the way would you have a decent picture of the layout you
could publish on this thread just to check my board, please?
I'd appreciate your output.
PA300
Oliver D
Do not bother about the layout of the board, a good friend of mine
answered my prayers and sent me the layout, very clear and discernable...Thanks anyway.
On the other hand I would appreciate if you could tell about the
other two questions I asked.
Thanks
Oliver D
Do not bother about the layout of the board, a good friend of mine
answered my prayers and sent me the layout, very clear and discernable...Thanks anyway.
On the other hand I would appreciate if you could tell about the
other two questions I asked.
Thanks
No answers to your questions at the moment but I have the article somewhere if you wanna have it (pdf).
PA300
I have two questions for you guys:
Is that possible to replace the polysterene caps 33 and 47 pf in design
by regular ceramic ones without any degradation on the quality of the sound?
How about the PTC KTY81-122 in the protection circuit, is there any
replacement for this Philips device?
I'd appreciate any output...
I have two questions for you guys:
Is that possible to replace the polysterene caps 33 and 47 pf in design
by regular ceramic ones without any degradation on the quality of the sound?
How about the PTC KTY81-122 in the protection circuit, is there any
replacement for this Philips device?
I'd appreciate any output...
why having problems? any way on PCB
😀 😀
hi,
the amp is close to Jan Duponts, Lynx and the other one on
Delta Audio, which provides lay outs and specs.
So for those who need to understand this amp very well
I think Jan is very willing to help you guys.
try Audio Circuits Denmark or Delta Audio.
regards,
hienrich😀 😀
http://www.audio-circuit.dk/
😀 😀
hi,
the amp is close to Jan Duponts, Lynx and the other one on
Delta Audio, which provides lay outs and specs.
So for those who need to understand this amp very well
I think Jan is very willing to help you guys.
try Audio Circuits Denmark or Delta Audio.
regards,
hienrich😀 😀
http://www.audio-circuit.dk/
John Mateus, so, you really decided to melt your Brazilian Speakers.
Those speaker you have Mat... are export models, we cannot find them here, as they were made for North American Market, Bravox factory in my country is concentrated in Automobile Market, as they used to sale to all factories we have, and thousand cars are produced each day and exported to all world...each one of them with a 4 Bravox Triaxial included...waterproof speakers, yes, they can work inside your swiming pool.... already tested 5 years under the sea to see oxide protection....passed in the that test.
So, you have a precious woffers in your home, and now working very hard to construct a "melting machine".... do not forget to put some fuses in the output Mat...please!
The amplifier you are working is really pretty, and your work is very nice, not only the board but also the chassis mechanics you do, but people had not the chance to see the pretty works you have been doing..i am lucky...i could see them.
E não é que ficaste apaixonado por esta maquina mesmo?, seu Portuga danado!.....and you turn yourself in love with that amplifiers, and i cannot wait to see it ready and pumping the New Jersey's fresh air.
The board design you made, the perfect art work, can be a good contribution to forum guys, as it is pretty and well done.... and also they do not know exactly the amplifier you are talking about...well, i could not see the schematic around.
Apareça no Skype para que conversemos até dar câimbras na lingua e dôres nas mandibulas, de tanto balançar os queixos....Appear in the Skype communications to talk with me man... i have a lot to say....we can talk alike parrots for all morning man!
Óh raios!...... regards,
Carlos
Those speaker you have Mat... are export models, we cannot find them here, as they were made for North American Market, Bravox factory in my country is concentrated in Automobile Market, as they used to sale to all factories we have, and thousand cars are produced each day and exported to all world...each one of them with a 4 Bravox Triaxial included...waterproof speakers, yes, they can work inside your swiming pool.... already tested 5 years under the sea to see oxide protection....passed in the that test.
So, you have a precious woffers in your home, and now working very hard to construct a "melting machine".... do not forget to put some fuses in the output Mat...please!
The amplifier you are working is really pretty, and your work is very nice, not only the board but also the chassis mechanics you do, but people had not the chance to see the pretty works you have been doing..i am lucky...i could see them.
E não é que ficaste apaixonado por esta maquina mesmo?, seu Portuga danado!.....and you turn yourself in love with that amplifiers, and i cannot wait to see it ready and pumping the New Jersey's fresh air.
The board design you made, the perfect art work, can be a good contribution to forum guys, as it is pretty and well done.... and also they do not know exactly the amplifier you are talking about...well, i could not see the schematic around.
Apareça no Skype para que conversemos até dar câimbras na lingua e dôres nas mandibulas, de tanto balançar os queixos....Appear in the Skype communications to talk with me man... i have a lot to say....we can talk alike parrots for all morning man!
Óh raios!...... regards,
Carlos
pa-600 pcb
I don’t know much about this amplifier, and this is the only first time I’ve seen the schematic posted by OliverD in zip. I’am beginning to have interest in the circuit as I’m looking for real power. Halojoy said it is well documented ,however, no PCB detail has been presented and hobby is not enjoyable by only reading the quotes in forum without actually doing the unit.
After reading the forum I have decided to make myself the layout of pcb in one week time that I could also share to my co-countryman C3PO. I do not want to make it in a hurry but for those who want to use my idea, please do so and let me here your words if it’s a real killer as they mentioned.
Please check everything in layout for it is not the actual and or original component sizes, orientation, heat sink limitation or there may be errors against schematic. There are no considerations made as is only an idea based on lynx mentioned by Hienrich.
Layout is done by excel. Sorry, I don’t know any drawing software. I hope the moderator can convert this to .gif and please teach me how to.
I don’t know much about this amplifier, and this is the only first time I’ve seen the schematic posted by OliverD in zip. I’am beginning to have interest in the circuit as I’m looking for real power. Halojoy said it is well documented ,however, no PCB detail has been presented and hobby is not enjoyable by only reading the quotes in forum without actually doing the unit.
After reading the forum I have decided to make myself the layout of pcb in one week time that I could also share to my co-countryman C3PO. I do not want to make it in a hurry but for those who want to use my idea, please do so and let me here your words if it’s a real killer as they mentioned.
Please check everything in layout for it is not the actual and or original component sizes, orientation, heat sink limitation or there may be errors against schematic. There are no considerations made as is only an idea based on lynx mentioned by Hienrich.
Layout is done by excel. Sorry, I don’t know any drawing software. I hope the moderator can convert this to .gif and please teach me how to.
pa-600 pcb
moderator dear,
I can't send my pcb layout. It was drawn in excel. pls give me an instruction to convert in GIF
moderator dear,
I can't send my pcb layout. It was drawn in excel. pls give me an instruction to convert in GIF