i would like to receive comments about the layout of the amplifier.
anything that might prevent future problems.
i have added two electrolytic capacitors in both rails that are not in the original design because I have seen it here and the worst that could happen is not use them.
anything that might prevent future problems.
i have added two electrolytic capacitors in both rails that are not in the original design because I have seen it here and the worst that could happen is not use them.
Attachments
here is the image
hxxp://farm4.static.flickr.com/3080/2864619412_8c76bb8564_b_d.jpg
change hxxp for http in the url
hxxp://farm4.static.flickr.com/3080/2864619412_8c76bb8564_b_d.jpg
change hxxp for http in the url
Hi
Just a few points.... I would at least fill the empty space with copper. I would also take the negative feedback from a point in the center of where the two output resistors connect, that being node labeled "OUT", where the Zobel now resides. Having the DC blocking cap grounded to the same trace as the decoupling cap might create issues as well.(Buzzzzzzz) It needs it's own ground trace, a clean ground trace, without the current pulses from the decoupling cap corrupting it, such as the signal GND. Does Q9 need to be mounted to sense the temperature of the drivers, Q's 5 & 6? (reffering to the scematic here ) Typically with a feedback pair OS the drivers have to be thermally compensated, but maybe not here....I haven't built this one.
Anyway, good luck🙂
Just a few points.... I would at least fill the empty space with copper. I would also take the negative feedback from a point in the center of where the two output resistors connect, that being node labeled "OUT", where the Zobel now resides. Having the DC blocking cap grounded to the same trace as the decoupling cap might create issues as well.(Buzzzzzzz) It needs it's own ground trace, a clean ground trace, without the current pulses from the decoupling cap corrupting it, such as the signal GND. Does Q9 need to be mounted to sense the temperature of the drivers, Q's 5 & 6? (reffering to the scematic here ) Typically with a feedback pair OS the drivers have to be thermally compensated, but maybe not here....I haven't built this one.
Anyway, good luck🙂
I think the decoupling caps are too far apart.
Moving the power rails and power ground to the middle of the PCB and having the decoupling adjacent to each other fed from very short tracks should perform better.
Q9 MUST monitor the temperature of Q5 AND Q6.
Three transistors inline and facing the same direction allows a flat strip of aluminium/copper to thermally couple these together and perform as a small heatsink if you decide to increase the driver bias current. 220r limit total driver bias dissipation to just 190mW for the pair.
Moving the power rails and power ground to the middle of the PCB and having the decoupling adjacent to each other fed from very short tracks should perform better.
Q9 MUST monitor the temperature of Q5 AND Q6.
Three transistors inline and facing the same direction allows a flat strip of aluminium/copper to thermally couple these together and perform as a small heatsink if you decide to increase the driver bias current. 220r limit total driver bias dissipation to just 190mW for the pair.
In general, yes, but Rod's PCB layout does not have any provision for this, and he's said that all those hundreds of his builder-customers have never reported a problem. I suspect it's partly the stability and simplicity of the circuit, partly the (relatively) low power dissipation.AndrewT said:
When I designed a PCB for this amp, I tried putting in thermal coupling between Vbias and driver transistors, but the Vbias Rod uses is a TO92 type thing which does not even fit into any heatsink, so I just put them physically close to each other and left them at that.
To92 can be clamped or glued to any sink. Alternatively drill a tight fitting hole and insert into the thermal paste filled recess.
But the author of this amplifier did not put the Q9 TO-92 transistor on the heatsink. instead its on the PCB.
tcpip said:
then extend the To92 with three flexible wires/cords back to the PCB pad locations.metal said:
I have had a board of my own design where the VBE transistor isnt near either driver, and it actually works quite well, while being thermally stable. I guess it is because the circuit is so simple.
The biggest problem I had was oscillation with the power devices, but fitting the larger decoupling capacitors on the board, as IntArt has done, solved the problem. I've suggested this a few times on Rod's own message board and it has indeed helped a few others - maybe this is where IntArt got the idea from 🙂
The biggest problem I had was oscillation with the power devices, but fitting the larger decoupling capacitors on the board, as IntArt has done, solved the problem. I've suggested this a few times on Rod's own message board and it has indeed helped a few others - maybe this is where IntArt got the idea from 🙂
Hi
I suspect it is the relative low power of the TO-220 devices resulting in little temperature change. If you replaced them with smaller TO-92 parts, I bet you may have issues with bias compensation. But hey, if it works, why modify it?
Take a lighter and heat the transistors while measuring the output's current and see if it changes.🙂
I love the 3A, built one when I was young.. actually the same
circuit (to-3 3055/2955) was published by pop. electronics
in the 80's.
It worked flawlessly as I built it on those little radio shack
breadboards. I put mine on a VERY large heatsink and
didn't mount the Vbe thermally but it survived for years.
Being young and dumb I didn't even bother to wire the zobel
network (whats a zobel) to it and it still worked.😀
Great amp to start with, probably
the one I would have my
kids build as a intro to DIY, virtually foolproof .
P.S. - In a hot environment, small heatsink, or subwoofer
application I would thermally mount Q9 to the main HS.
Also, sink them drivers if you are going to use >35V rails.
circuit (to-3 3055/2955) was published by pop. electronics
in the 80's.
It worked flawlessly as I built it on those little radio shack
breadboards. I put mine on a VERY large heatsink and
didn't mount the Vbe thermally but it survived for years.
Being young and dumb I didn't even bother to wire the zobel
network (whats a zobel) to it and it still worked.😀
Great amp to start with, probably
the one I would have my
kids build as a intro to DIY, virtually foolproof .
P.S. - In a hot environment, small heatsink, or subwoofer
application I would thermally mount Q9 to the main HS.
Also, sink them drivers if you are going to use >35V rails.
As the PA3 amp's OP stage has CFP topology, you'll need to mount the Vbe multiplier's transistor (Q9) on one of the driver's heatsink instead of on the main heatsink.
A SCHEMATIC FROM A WEB PAGE
is not enough to start constructing one amplifier
requires a lot of expirience and a lot of knowldge since construction of various circuits might include "tricks" inside .....
in the particular case even a quick look at esp pages will provide more than enough information for many many amps ....
every now and then we should drop a thank you to rod for all he did to diy community .....
thank you very much rod ......
is not enough to start constructing one amplifier
requires a lot of expirience and a lot of knowldge since construction of various circuits might include "tricks" inside .....
in the particular case even a quick look at esp pages will provide more than enough information for many many amps ....
every now and then we should drop a thank you to rod for all he did to diy community .....
thank you very much rod ......
another thing
i consider my shelf among the ones that love the P3 amp cosidered the simplicity its made is one of the best i heard in all my life ....
i discovered this amp some 2years ago constructed so far more than 10 versions of it ( all of the the same but very litle changes and layouts )
a lay out that had ltp transistors in a position that can be glued together ( eventhough matched ) made also some diference ....
i can carry on with all my small mods here and there but i think there is no point in it since i just gave you one example of what i ment above
i consider my shelf among the ones that love the P3 amp cosidered the simplicity its made is one of the best i heard in all my life ....
i discovered this amp some 2years ago constructed so far more than 10 versions of it ( all of the the same but very litle changes and layouts )
a lay out that had ltp transistors in a position that can be glued together ( eventhough matched ) made also some diference ....
i can carry on with all my small mods here and there but i think there is no point in it since i just gave you one example of what i ment above
true uncle charly
but this board may be perfect ( since provided by rod tested by rod and so on ) .....
may be perfect but doesnt have the "looks " i like my boards symmetric ..... square ....all in same line and so on .....
the funny thing is that may be this boards play better than mine ..... but still it doesnt look good to me ....
for p101 for example that rod says that lay out is very critical i buy directly from rod just to be on the safe side .....
for P3 i like to play my shelf ...here is another board that was never tested ....some time in the future may be
but this board may be perfect ( since provided by rod tested by rod and so on ) .....
may be perfect but doesnt have the "looks " i like my boards symmetric ..... square ....all in same line and so on .....
the funny thing is that may be this boards play better than mine ..... but still it doesnt look good to me ....
for p101 for example that rod says that lay out is very critical i buy directly from rod just to be on the safe side .....
for P3 i like to play my shelf ...here is another board that was never tested ....some time in the future may be
Attachments
yeah Sakis, symmetrical, like a butterfly..
(above board has all OP,drivers, and Vbe on main HS, VAS
separate)
Quasi has boards, Elliot has boards, nah ..Do It Yourself.
Then you can make it to fit YOUR application - EXACTLY.
All is well for these guys to make board available for DIY'ers,
but that is no fun ,stuff a board with parts ..it works ,whoopee.
It's better to take the schematic ,modify it, lay it out.
If I can't have my "style" in my amp, I don't want it. I'll go
buy a Sony.
An externally hosted image should be here but it was not working when we last tested it.
(above board has all OP,drivers, and Vbe on main HS, VAS
separate)
Quasi has boards, Elliot has boards, nah ..Do It Yourself.
Then you can make it to fit YOUR application - EXACTLY.
All is well for these guys to make board available for DIY'ers,
but that is no fun ,stuff a board with parts ..it works ,whoopee.
It's better to take the schematic ,modify it, lay it out.
If I can't have my "style" in my amp, I don't want it. I'll go
buy a Sony.
Rodd Elliot produce those board for living
I think he use pay his home bills because of his production of boards and amplifiers.... say... the money that enters because boards sold cooperates, helps, for his living, help him to give a confortable life to his sons and family.
As soon as we provide boards to our communitty, we will not be contributing with him.... hundreds will copy layout, will produce, and of course will not buy boards from him.
For sure we do not need to buy his boards... we can do them by ourselves...this is the "spirit" here... but we can be cooperative not showing board plans here.... well.... this is a matter of personal decision, it is up to you, your conscience, your decision... your education, your own class, elegance, character quality.
Rodd Elliot is a cooperative person in many ways, his pages goes teaching thousand folks about electronics, for free and gladly.... seems to me we can be good to him too, avoiding to publish things that may reduce his sells..... well.... this is the way i think....but i know each person has their own judgement and decisions about that... i have to respect your personal decision folks, despite i do not feel good watching that.
This does not break forum rules.... so.... be happy with your conscience folks.
No!... i do not appreciate Rodd very much...one of my first problems into this forum was because of him (2004)...because of his board....someone have asked and with innocence i have made a board and published.. someone have complained protecting Rodd.... i felt this fair and removed the board i have published.... it is not a matter to love or not to love Rodd Elliot, it is a matter of respect other guys job and the ways they use to earn money for living.
I remember he said something alike:
- "I use to sell those boards, layout published does not helps me, does not contributes with me, what DIY audio forum does is not my responsability... if this happens in my forum will be immediatelly removed"
Despite he was rigth.... i felt very bad....because made with innocence...i did not knew he use to sell his boards for living.... was not a good moment inside my heart.
Non complete images are better than perfect boards designs... as this finishes with the chances Rodd has to sell his boards.
"Esto no es malo o criminal ... es simplemente molesto ... indelicada una actitud que va en contra de las necesidades de un buen hombre .... hacer el diseño de circuitos no es ningún problema ... publicalos es que puede ser perjudicial"
regards,
Carlos
I think he use pay his home bills because of his production of boards and amplifiers.... say... the money that enters because boards sold cooperates, helps, for his living, help him to give a confortable life to his sons and family.
As soon as we provide boards to our communitty, we will not be contributing with him.... hundreds will copy layout, will produce, and of course will not buy boards from him.
For sure we do not need to buy his boards... we can do them by ourselves...this is the "spirit" here... but we can be cooperative not showing board plans here.... well.... this is a matter of personal decision, it is up to you, your conscience, your decision... your education, your own class, elegance, character quality.
Rodd Elliot is a cooperative person in many ways, his pages goes teaching thousand folks about electronics, for free and gladly.... seems to me we can be good to him too, avoiding to publish things that may reduce his sells..... well.... this is the way i think....but i know each person has their own judgement and decisions about that... i have to respect your personal decision folks, despite i do not feel good watching that.
This does not break forum rules.... so.... be happy with your conscience folks.
No!... i do not appreciate Rodd very much...one of my first problems into this forum was because of him (2004)...because of his board....someone have asked and with innocence i have made a board and published.. someone have complained protecting Rodd.... i felt this fair and removed the board i have published.... it is not a matter to love or not to love Rodd Elliot, it is a matter of respect other guys job and the ways they use to earn money for living.
I remember he said something alike:
- "I use to sell those boards, layout published does not helps me, does not contributes with me, what DIY audio forum does is not my responsability... if this happens in my forum will be immediatelly removed"
Despite he was rigth.... i felt very bad....because made with innocence...i did not knew he use to sell his boards for living.... was not a good moment inside my heart.
Non complete images are better than perfect boards designs... as this finishes with the chances Rodd has to sell his boards.
"Esto no es malo o criminal ... es simplemente molesto ... indelicada una actitud que va en contra de las necesidades de un buen hombre .... hacer el diseño de circuitos no es ningún problema ... publicalos es que puede ser perjudicial"
regards,
Carlos
