I just got this working in simulation:
But i wonder, is this my own design or did i just memorize someone elses schematic ?
Note that i did not look at any schematics while doing this one, i just tried randing things until it worked and similation showed reasonable currents through stuff.
An externally hosted image should be here but it was not working when we last tested it.
But i wonder, is this my own design or did i just memorize someone elses schematic ?
Note that i did not look at any schematics while doing this one, i just tried randing things until it worked and similation showed reasonable currents through stuff.
Try to get equal current in Q8-Q9 pair.
Put AM-meter in their collectors and adjust R13 until balans.
Q11-Q12, BD139, BD140 is a good choice.
They take ~10 mA in this circuit.
And this is probably a good current level to drive those HEXFET.
Overall you have done a good job
May only be some small adjustments needed.
And should not be difficult to build, as it is very straight forward design.
Put AM-meter in their collectors and adjust R13 until balans.
Q11-Q12, BD139, BD140 is a good choice.
They take ~10 mA in this circuit.
And this is probably a good current level to drive those HEXFET.
Overall you have done a good job
May only be some small adjustments needed.
And should not be difficult to build, as it is very straight forward design.
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A good start...some recommendations and experiments...
It's a good start. I'd recommend a few things:
1. current mirror load in the top of the Q8/Q9 diff pair would make automatic good balance and lower distortion.
2. is it oscillating, or is it a picture artifact? I can't quite tell...
3. You're leaving a fair amount of output swing unrealized by running both the drivers and the output devices on the same rails. The MOSFETS Vgs diminishes the available output swing considerably.
4. Emitter resistors in the input stage can sometimes be useful to increasing the linearity of the input stage...this can help lower distortion (you might have to increase the tail current a bit to compensate)
5. C3 can help stability, but usually costs you a little output distortion...still, the balance of that with Cdom (not shown, but typically from collector to base of Q2), gives nice trade off of stability and distortion.
Experiments:
1. Replace R10 by a short...I don't think that much would change...
2. What is your output offset voltage with no signal at the input?
Keep your investigations going...you are on a good track.
It's a good start. I'd recommend a few things:
1. current mirror load in the top of the Q8/Q9 diff pair would make automatic good balance and lower distortion.
2. is it oscillating, or is it a picture artifact? I can't quite tell...
3. You're leaving a fair amount of output swing unrealized by running both the drivers and the output devices on the same rails. The MOSFETS Vgs diminishes the available output swing considerably.
4. Emitter resistors in the input stage can sometimes be useful to increasing the linearity of the input stage...this can help lower distortion (you might have to increase the tail current a bit to compensate)
5. C3 can help stability, but usually costs you a little output distortion...still, the balance of that with Cdom (not shown, but typically from collector to base of Q2), gives nice trade off of stability and distortion.
Experiments:
1. Replace R10 by a short...I don't think that much would change...
2. What is your output offset voltage with no signal at the input?
Keep your investigations going...you are on a good track.
This design have been built and apart from a misplaced resistor on the board, it worked on the first try. Unfortunately the misplaced resistor caused damage to the fets which died half a day later but after replacement to IRF540 and IRF9540 the amp was up and running again.
Heres a few pics:
Heres a few pics:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Looks a sort of like Hafler 220 circuit. Hafler used better outputs (Hitachi's) and mirror LTP inputs. But lots of 2N5401s and 2N5550s my 2cents
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New low power version
After building that twelve mosfet monster i've now started thinking about a low power version to serve strictly as satellite channels.
This is the idea:
The unmarked resistors on the top are 100ohm, the third unmarked one will need to be determined since i originally designed this circuit to include BD130/140 drivers.
R11 will also need to be modified, its 820 ohms in the monster.
After building that twelve mosfet monster i've now started thinking about a low power version to serve strictly as satellite channels.
This is the idea:
An externally hosted image should be here but it was not working when we last tested it.
The unmarked resistors on the top are 100ohm, the third unmarked one will need to be determined since i originally designed this circuit to include BD130/140 drivers.
R11 will also need to be modified, its 820 ohms in the monster.
First channel is playing!!
Heres the first channel of above schematic, playing on the bench:
Heres the first channel of above schematic, playing on the bench:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
R9 is not needed, i just forgot to remove it from the schematic.
And heres the other channel built, tested and working.
Pics:
And heres the other channel built, tested and working.
Pics:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Heres an updated schematic and some more pics:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Would the last amp be a good project for a beginners first solid state amp (so far i've made only chip amps with only positive power supply).
How powerful toroid would i need to power two of those amps? Would a computers soundcard be enough to drive this amp or is a preamp needed?
I would appreciate any info on this or reference to other, more noob-friendly amp projects that would be solid state and 30W+.
Sorry for my bad english.
Mart,
How powerful toroid would i need to power two of those amps? Would a computers soundcard be enough to drive this amp or is a preamp needed?
I would appreciate any info on this or reference to other, more noob-friendly amp projects that would be solid state and 30W+.
Sorry for my bad english.
Mart,
Forgot to mention, that the amp would be used to run two shelf-speakers: Visaton W130S 5" midbass+FRS8 3.3" fullrange, cutting freq. is at 1000hz. At the moment im running a chip amp, built with a TDA1554 chip @ 2x"22W", so the next amp would have to be better than that chip, otherwise it would be worth the trouble.
Mart,
Mart,
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I'm using a 2x26VAC 300VA toroid for mine, turns out to about 2x35VDC after the rectifier.
Im not so sure about this beeing suitable as a first time project, there are simpler circuits out there.
This design can be driven from a soundcard output no prollem, i have a 100ohm alps volume pot in between.
If you do decide to build this, make a proper board since mine is just a prototype, i'm going to design a proper board for this amp.
However i can say this: DO NOT BUILD THE 12 MOSFET MODEL!!!! It's not done yet!
Im not so sure about this beeing suitable as a first time project, there are simpler circuits out there.
This design can be driven from a soundcard output no prollem, i have a 100ohm alps volume pot in between.
If you do decide to build this, make a proper board since mine is just a prototype, i'm going to design a proper board for this amp.
However i can say this: DO NOT BUILD THE 12 MOSFET MODEL!!!! It's not done yet!
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