a few things to think about:
1) the last two pairs of transistors aren't working. you may need to rewire them;
2) you may want to think about how to add some feedback to the circuitry: the 741 is working in open loop, like a comparator.
3) cross-over distortion, anyone?
4) you are blowing the 741. It cannot take +/- 50v supply rails.
5) find something a little bit better to use than the 741?
............
It needs a lot of work before it can sound good.
1) the last two pairs of transistors aren't working. you may need to rewire them;
2) you may want to think about how to add some feedback to the circuitry: the 741 is working in open loop, like a comparator.
3) cross-over distortion, anyone?
4) you are blowing the 741. It cannot take +/- 50v supply rails.
5) find something a little bit better to use than the 741?
............
It needs a lot of work before it can sound good.
This design will not work. Too many mistakes. Please learn more. First, the 741 is 35 years old, and not good for audio. Second, it can ONLY take +/- 22V at best, not +/- 50V. Third, there is no bias resistor on the input. Four, the output cap is unnecessary. Five, there is no feedback loop, so the amp will latch to one power supply. Six, it 'might' put out 250 W max.
Don't be discouraged, but try more to understand the circuit.
Don't be discouraged, but try more to understand the circuit.
I think the others have already pointed out all the serious
errors at least. Well, I think you need to bias also the first
transistor pair since you AC couple from the op amp.
There is no shortcut around learning the basic theory of
transistors and amplifiers I am afraid. Getting a good textbook
on electronics is indispensible, but depending on your background
knowledge may still be difficult to understand. There are also
many good introductory texts on the internet if you search
around.
In addition to this,
try to study a few schematics of working amps and ask yourself
why they look so different from yours. I am sure a lot of people
will be helpful trying to answer your question about these
schematics and how they work.
Just don't try to build your design, at least no without wearing
protective glasses and having a fire extinguisher handy.
errors at least. Well, I think you need to bias also the first
transistor pair since you AC couple from the op amp.
There is no shortcut around learning the basic theory of
transistors and amplifiers I am afraid. Getting a good textbook
on electronics is indispensible, but depending on your background
knowledge may still be difficult to understand. There are also
many good introductory texts on the internet if you search
around.
In addition to this,
try to study a few schematics of working amps and ask yourself
why they look so different from yours. I am sure a lot of people
will be helpful trying to answer your question about these
schematics and how they work.
Just don't try to build your design, at least no without wearing
protective glasses and having a fire extinguisher handy.
Duo said:Well, this circuit is functional, just not as an amplifier.
We could say in the design specifications that it is a high speed, high current, single use latch. It will always remember its first state, and to reset the state, you simply replace the 741 opamp.
Sorry...
Not even that, I am afraid, since it is AC coupled. I may be wrong
though. I am a bit too tired to think clearly right now. It will
produce a pulse, though, depending on the polarity the initial
polarity of the input signal, ie. if the 741 will survive long enough
to do even that.
I am not using 741, it´s a simple scheme. I am using the LM386 with 100 of gain.
When i put the speaker on the output of LM386, the sounds is very good. The problem is the output stage.
My question is about the output stage.
The Crossover distorcion is low.
Can one help me one the OutPut stage ????
When i put the speaker on the output of LM386, the sounds is very good. The problem is the output stage.
My question is about the output stage.
The Crossover distorcion is low.
Can one help me one the OutPut stage ????
Sorry, Mr Brasil, you have much to learn but you can take shortcut by looking at this amp:
http://www.audio-circuit.dk/LYNX_main.html
http://www.audio-circuit.dk/LYNX_main.html
peranders said:
If he just want's to get something running maybe. If he also
wants to learn how amplifiers work then it is not a good one
to start with in my opinion. Already the way the op amp is
used is likely to confuse him for ages considering what his
present knowledge of electronics seems to be.
I think he said he actually didn't use a 741 but some op amp
that could take the higher voltage (if I understood him right).
Then maybe he just needs to buffer it for current capability.
PicancoNet said:
it is hard to fix. the lm386 is a power amp ic for single rail applications. so you may have to a lot of tweaking to get it to work in a dual rail applications.
One concept to consider is here:
http://www.diyaudio.com/forums/showthread.php?postid=182929#post182929
and it should work with your lm386, but you need to do so in a single rail fashion, with DC blocking on the output and no external gain setting resistors (probably not so great performance).
At least it won't blow up much.
The output and driver stages have base emitter shorts. After the 741 evaporates not much else can happen.
I really, really suggest you just copy someone elses amplifier as it is obvious you know very little about amplifier design. It is not as easy as it looks but you need education on transistor biasing, feedback networks and device selection. At least study other designs and determine why each part is there. Designers do not put in parts for no reason. Every part serves a purpose and if the designer did not feel it was justified, it would not be there.
The way I learned amplifier design was by first building copies of other people's amplifiers. It took me perhaps 10 years of this before I could design a reliable, good sounding amplifier.
Good Luck.
The output and driver stages have base emitter shorts. After the 741 evaporates not much else can happen.
I really, really suggest you just copy someone elses amplifier as it is obvious you know very little about amplifier design. It is not as easy as it looks but you need education on transistor biasing, feedback networks and device selection. At least study other designs and determine why each part is there. Designers do not put in parts for no reason. Every part serves a purpose and if the designer did not feel it was justified, it would not be there.
The way I learned amplifier design was by first building copies of other people's amplifiers. It took me perhaps 10 years of this before I could design a reliable, good sounding amplifier.
Good Luck.
I started out trying to build amps based on opamps driving current gain stages becuase they were easy and they work when done right.
There's nothing more satisfying though, IMO, then designing and building your own discrete amplifier.
All you need is the will and the time and it'll all fall together.
There's nothing more satisfying though, IMO, then designing and building your own discrete amplifier.
All you need is the will and the time and it'll all fall together.
I would have to say the same thing.
A bunch of my early posts here at diyaudio demonstrate when I was trying to get into amplifiers but didn't know enough theory.
After working a great deal with other's designs and reverse engineering, I have become able to design my own amplifiers.
It's a very tricky thing to accomplish, but once you do, it becomes second nature after some good hard practice.
Just recently I designed and built a four channel 450W/ch amplifier similar to some designs I have seen. It uses CFP output, balanced input with mirrors, CCS, VAS with CCS, Vbe multiplier bias, etc. Basically a mix of the blameless amplifier by D. Self and some of Rod Elliot's designs on his site. With my own selection of parts and values and configuration. I designed it out of known theory in my head, put it on paper, checked it out, and then built it.
I am very pleased with the design, it sounds very good and it's really stable. The trick of it all is that I spent 6 years studying theories and only within the past year have I been able to successfully design something this nice.
It definitely takes a lot of work, as any engineer or hobby DIY'er will tell you.
A bunch of my early posts here at diyaudio demonstrate when I was trying to get into amplifiers but didn't know enough theory.
After working a great deal with other's designs and reverse engineering, I have become able to design my own amplifiers.
It's a very tricky thing to accomplish, but once you do, it becomes second nature after some good hard practice.
Just recently I designed and built a four channel 450W/ch amplifier similar to some designs I have seen. It uses CFP output, balanced input with mirrors, CCS, VAS with CCS, Vbe multiplier bias, etc. Basically a mix of the blameless amplifier by D. Self and some of Rod Elliot's designs on his site. With my own selection of parts and values and configuration. I designed it out of known theory in my head, put it on paper, checked it out, and then built it.
I am very pleased with the design, it sounds very good and it's really stable. The trick of it all is that I spent 6 years studying theories and only within the past year have I been able to successfully design something this nice.
It definitely takes a lot of work, as any engineer or hobby DIY'er will tell you.
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