Hello everyone,
It was a long awaited thread who was born from the next thread:
http://www.diyaudio.com/forums/soli...-fet-amplifier-diy-described-paul-kemble.html
DW300 project - which I want to develop it with power supply diagram and other electronic circuits considered relevant - derived from an electronic scheme published by user @wahab on thread mentioned above. Initials DW come from Donpetru Wahab
In fact, in my version, I presented IRFP240/9240 transistors and added the protection and soft start. After that I changed some values of electronic components to bring them in the optimum functioning of the amplifier. Finally, I designed a PCB that meet the most stringent design rules.
I hope your's enjoy this project that I'm thinking of turning it into a much more laborious project which include: a power supply, input circuits and/or audio preamplifier (schematic and printed circuit). In this respect I'd really like to read some recommendations or opinions.
If you plan to use lateral MOSFET transistors, such as ALF16N20W / ALF16P20W, it is enough to make the following changes:
- replace with a jumpers these electronic components: D101 and R21;
- remove from the circuit components R22 and R23;
- connected in series with the emitter of the transistor Q13 one adjustable potentiometer: 100 or 250 ohms.
!!!! If you think use lateral MOSFET transistors, such as those exemplified above, then I recommend you do not use the amplifier on less than 3 ohms impedance. Do not forget that.
The project presented is a simple prototype, so, depending on the characteristics of bipolar transistors used might to need small adjustments (for example, changing the value of resistor from the bias circuit). This will set in the stage for achieving practical circuit. We can fix these issues - if applicable, remains to be seen - with continued discussion of this topic.
In the second PDF file listed below have submitted plans for achieving copper top and bottom in D.I.Y. regime of the audio amplifier.
The amplifier can be built and in a single layer, replacing the TOP layer with jumpers. In this case, supply routes sits solder.
I think, if anyone wants, to realize some PCB's after pass the practical test of the prototype.
Gerber files of the project below can make available to any user after a modest donation (minimum 20 USD) to my website. Donation can be made by accessing donation button on my website: www.tehnium-azi.ro
After making a donation, you will receive an e-mail Gerber files.
So, the project I would like to extend it will bring them and other useful circuits.
Dw300 project is an audio amplifier with multiple applications, from wide band audio applications and going to the subwoofer's. If you are thinking of looking for a reliable subwoofer amplifier, it is not bad to realize DW300. So, DW300 is an ideal project for subwoofer and not only that. Audio amplifier can charge 300Wrms into 2 ohms OR 150 ... 170W into 4 ohms with THD less than 0.01% (typic 0.007%).
Finally, I would like to read some opinions, a kind of first review, for this project, which can turn into something quite promising. That depends on your's.
It was a long awaited thread who was born from the next thread:
http://www.diyaudio.com/forums/soli...-fet-amplifier-diy-described-paul-kemble.html
DW300 project - which I want to develop it with power supply diagram and other electronic circuits considered relevant - derived from an electronic scheme published by user @wahab on thread mentioned above. Initials DW come from Donpetru Wahab
In fact, in my version, I presented IRFP240/9240 transistors and added the protection and soft start. After that I changed some values of electronic components to bring them in the optimum functioning of the amplifier. Finally, I designed a PCB that meet the most stringent design rules.
I hope your's enjoy this project that I'm thinking of turning it into a much more laborious project which include: a power supply, input circuits and/or audio preamplifier (schematic and printed circuit). In this respect I'd really like to read some recommendations or opinions.
If you plan to use lateral MOSFET transistors, such as ALF16N20W / ALF16P20W, it is enough to make the following changes:
- replace with a jumpers these electronic components: D101 and R21;
- remove from the circuit components R22 and R23;
- connected in series with the emitter of the transistor Q13 one adjustable potentiometer: 100 or 250 ohms.
!!!! If you think use lateral MOSFET transistors, such as those exemplified above, then I recommend you do not use the amplifier on less than 3 ohms impedance. Do not forget that.
The project presented is a simple prototype, so, depending on the characteristics of bipolar transistors used might to need small adjustments (for example, changing the value of resistor from the bias circuit). This will set in the stage for achieving practical circuit. We can fix these issues - if applicable, remains to be seen - with continued discussion of this topic.
In the second PDF file listed below have submitted plans for achieving copper top and bottom in D.I.Y. regime of the audio amplifier.
The amplifier can be built and in a single layer, replacing the TOP layer with jumpers. In this case, supply routes sits solder.
I think, if anyone wants, to realize some PCB's after pass the practical test of the prototype.
Gerber files of the project below can make available to any user after a modest donation (minimum 20 USD) to my website. Donation can be made by accessing donation button on my website: www.tehnium-azi.ro
After making a donation, you will receive an e-mail Gerber files.
So, the project I would like to extend it will bring them and other useful circuits.
Dw300 project is an audio amplifier with multiple applications, from wide band audio applications and going to the subwoofer's. If you are thinking of looking for a reliable subwoofer amplifier, it is not bad to realize DW300. So, DW300 is an ideal project for subwoofer and not only that. Audio amplifier can charge 300Wrms into 2 ohms OR 150 ... 170W into 4 ohms with THD less than 0.01% (typic 0.007%).
Finally, I would like to read some opinions, a kind of first review, for this project, which can turn into something quite promising. That depends on your's.
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I would not say so, you should look the threads with discution over PCB layout roles.
Hi Donpetru. I have an amp based on the Hitachi application notes. The designers of that amp's PCB at the time said that the layout was absolutely critical, with small changes making big differences (always in a bad way) in performance.
I would certainly say that you may have to try a number of iterations of the layout before you get something that performs acceptably. Of course you may be lucky and get it first go.
Tony.
I would certainly say that you may have to try a number of iterations of the layout before you get something that performs acceptably. Of course you may be lucky and get it first go.
Tony.
@Samuel Jayaraj read this:
LATER EDIT: I addition to the quoted words. Input amplifier needs to reach the power output of the above quotation about 0.55Vrms.
Of course, the amplifier can reach 400W/2Ohmi but with distortions greater than those mentioned (in this case THD is below 0.5%, which is within the standard HiFi).
Thanks Tony for the reply.
LATER EDIT: I addition to the quoted words. Input amplifier needs to reach the power output of the above quotation about 0.55Vrms.
Of course, the amplifier can reach 400W/2Ohmi but with distortions greater than those mentioned (in this case THD is below 0.5%, which is within the standard HiFi).
Thanks Tony for the reply.
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donpetru:
Why you have used a zener diode for input pair CCS?. There are much better options for that.
What can you say about the temperature shift that occurs in the current source of the differential pair?
There are far more elegant solutions instead of using C17, C18, R24 and R25.
What is the specific goal of C6 in the scheme?
Why did you put R11? What can you tell me about the additional thermal noise caused by this resistance in the differential pair and gain raised?. Absorbs only 3 volts. This resistance is not very helpful to the transistor Q5!.
R32, R33, R34, R53, R54 and R55 are too high. Use around 330 to 390 ohms (max) for those mosfets.
Why you have used a zener diode for input pair CCS?. There are much better options for that.
What can you say about the temperature shift that occurs in the current source of the differential pair?
There are far more elegant solutions instead of using C17, C18, R24 and R25.
What is the specific goal of C6 in the scheme?
Why did you put R11? What can you tell me about the additional thermal noise caused by this resistance in the differential pair and gain raised?. Absorbs only 3 volts. This resistance is not very helpful to the transistor Q5!.
R32, R33, R34, R53, R54 and R55 are too high. Use around 330 to 390 ohms (max) for those mosfets.
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You're referring to the diode D1? If so, the diode is to reduce the drain voltage J-FET transistors to run correctly.
This shift is very small and can usually be ignored.
What solution mean?
C6 not has very important role but if you follow perfection is good to be there.
Is a resistor which has advantages and disadvantages. An advantage would be that causes transistor Q5 to dissipate less power and at the same time make of that transistor collector terminal to be less noisy the emergence of external electromagnetic influences.
We tested numerous practical value, but if this amp values we have recommended are best.
I don't think it's time to move this topic as long as you have an open source project. But..., who wants more than one PDF will have to pay.
Everyone wants free electronic assemblies tested without work. Then, I invite you to attach here a project designed professionally with all necessary details that you've spent time and money (time, ie a few months). You post for free?
"designed professionally"
Well, yours doesn't look like it meets that criteria.
If I wouldn't build it for free, I certainly wouldn't pay you for it either.
"You post for free? "
I may see if I can re-do a design that I sold in 1997 that was sold commercially, it's a mixed surface-mount and thru-hole amplifier that would be very difficult for the average home constructor. I have the first all thru-hole iteration and there is room for improvement, so I am going to do a second spin and see how it comes out.
Will I offer the design for free when it's ready?
Probably.
My intent is to make 100 boards and offer them at actual cost as well as just offering the design.
Well, yours doesn't look like it meets that criteria.
If I wouldn't build it for free, I certainly wouldn't pay you for it either.
"You post for free? "
I may see if I can re-do a design that I sold in 1997 that was sold commercially, it's a mixed surface-mount and thru-hole amplifier that would be very difficult for the average home constructor. I have the first all thru-hole iteration and there is room for improvement, so I am going to do a second spin and see how it comes out.
Will I offer the design for free when it's ready?
Probably.
My intent is to make 100 boards and offer them at actual cost as well as just offering the design.
donpetru:
No, I am referring to the diode D2 (3.6 volts). Only diodes whose voltages are close to the 5 Volts (not 3.6 volts) are those which have thermal coefficients negligible. As a suggestion, you can associate two or more of these diodes to compensate their thermal coefficients. Preferably, use voltages around 6 volts or more, better (>> Vbe Q5). This results in a great improvement (although there are better solutions, yet).
I give another suggestion: use regulated and well filtered sources to power the low signal stage, completely separating the high power stage. You should look closely at the value of PSRR at high frequencies.
R11 absorbs only 9 mW!. As I said, this resistance does not help much there. Q5 absorbs around 150 mW (roughly). I suggest removing R11 there, more if you use D2 with voltages as I suggested (6 volts or higher, the better).
What is the specific function of C6? You have not said yet.
No, I am referring to the diode D2 (3.6 volts). Only diodes whose voltages are close to the 5 Volts (not 3.6 volts) are those which have thermal coefficients negligible. As a suggestion, you can associate two or more of these diodes to compensate their thermal coefficients. Preferably, use voltages around 6 volts or more, better (>> Vbe Q5). This results in a great improvement (although there are better solutions, yet).
I give another suggestion: use regulated and well filtered sources to power the low signal stage, completely separating the high power stage. You should look closely at the value of PSRR at high frequencies.
R11 absorbs only 9 mW!. As I said, this resistance does not help much there. Q5 absorbs around 150 mW (roughly). I suggest removing R11 there, more if you use D2 with voltages as I suggested (6 volts or higher, the better).
What is the specific function of C6? You have not said yet.
What is the specific function of C6? You have not said yet.
To reduce total THD but at the expense of stability , hence
the heavy VAS shunt compensation with C12 , as high as 22nF.
Electrical diagram of the PDF posted in the first post of this topic is a starting point in developing a project that is meant to be, like many other projects, a small milestone in the evolution of audio amplifiers.
We have already made some small adjustments. I mean amplifier diagram. The new version I'll have a present, like the first, in a PDF. Please do not ask me when I'll present DW300 revision no. 1. I'll try to be as soon as possible.
* wahab, thanks for the answer on the C6;
**diegomj1973, thanks for the replies;
*** by the way, how do your's think if it would replace the amplifier transistors Q6 and Q7 with some J-FET transistors? I did some tests about it, quite optimistic but ... I have some reservations.
We have already made some small adjustments. I mean amplifier diagram. The new version I'll have a present, like the first, in a PDF. Please do not ask me when I'll present DW300 revision no. 1. I'll try to be as soon as possible.
* wahab, thanks for the answer on the C6;
**diegomj1973, thanks for the replies;
*** by the way, how do your's think if it would replace the amplifier transistors Q6 and Q7 with some J-FET transistors? I did some tests about it, quite optimistic but ... I have some reservations.
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