Ah, you eventually admit that your SSA's simulated distortion is not as good as PauloPT's. I wonder how it will sound using the PauloPT's component value
Wonder also how Salas can do it fast 
Its only a theoretical fix in Paulo's sim file when he wondered how he can drop apparent THD. The real amp will be another story as Nico also really said in my perception. This is a thing that needs we put the gen the scope the fft and the ears in use. Don't get excited by spice. As why I find the fixes fast in spice, no wonder, I had been studying the simple LAT SSA topology a lot in the recent past to make it thermally stable.
As why I find the fixes fast in spice, no wonder, I had been studying the simple LAT SSA topology a lot in the recent past to make it thermally stable.
Ah, you eventually admit that your SSA's simulated distortion is not as good as PauloPT's. I wonder how it will sound using the PauloPT's component value
I din't know that I was I being interrogated and admitted to a crime so foul?
We are used to such things in Africa. You catch a small Gecko and beat him until he confesses that he is a crocodile and then make him attack foreign visitors.
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I don't know anything about amp design. But I have seen people showing very good FFT charts, as if good FFT chart has very positive correlation with amp quality.
I guess the main thing that will lower or negate the correlation between the two is the precision of the model. But once a model is found satisfactory or shows very positive correlation with measurement and listening in one amp, the model I think should be considered precise for other uses.
I just couldn't understand why the FFT chart of the standard LATSSA was not smooth enough. May be there is a certain level of smoothness where simulated circuit deserves prototyping?
PaulPT & Jay,
How low must a simulated THD value be to be acceptable. The LATSSA which I offered a PCB layout for had a simulated second harmonic almost 100 dB down from the fundamental, or 0.001% and almost monotonic in character at about 45 watt average into an 8 ohm load.
I do not use a Free SPICE program with Free Models. It is one of the original simulators and to my knowledge one of the best available, it is paid for and models are updated regularly.
I have designed amps with simulated results of 0.00006% THD but does it come within four orders of magnitude in practice, I don't believe this for a moment. Even to measure THD at below 0.01% is quite some feat.
In a simulator you optimise component values for models that are all exactly matched perfectly. PCB tracks are zero length and there is no stray capacitance or inductance anywhere.
Components have no leads, or tolerance so what could you expect from a simulator - when you have the time run a simulator with all possible variations of component tolerances and models and create models for real world capacitors, resistors, pcb solder joints and tracks, then your results may become slightly more realistic.
Simulators are a toys and keeps one occupied for months when new to the concept - like a game and you get hooked. In an actual development environment a simulator is a quick tool to evaluate and test a concept - that is all.
Problem is on this forum many believe their amplifier factual specifications are those predicted by the simulator, which I might add, is far from the truth.
If you followed the thread from the outset, you may have noticed that Andrej, was not relying on simulators at all when he set out designing this amp, it was only used to test his concept by confirming or rejecting a suspicion. Andrej tested in reality as he went along, which is what R&D is all about.
Some DIY members may have built hundreds of amps in simulators, speculated over the jargon, that does not mean much in real life.
How low must a simulated THD value be to be acceptable. The LATSSA which I offered a PCB layout for had a simulated second harmonic almost 100 dB down from the fundamental, or 0.001% and almost monotonic in character at about 45 watt average into an 8 ohm load.
I do not use a Free SPICE program with Free Models. It is one of the original simulators and to my knowledge one of the best available, it is paid for and models are updated regularly.
I have designed amps with simulated results of 0.00006% THD but does it come within four orders of magnitude in practice, I don't believe this for a moment. Even to measure THD at below 0.01% is quite some feat.
In a simulator you optimise component values for models that are all exactly matched perfectly. PCB tracks are zero length and there is no stray capacitance or inductance anywhere.
Components have no leads, or tolerance so what could you expect from a simulator - when you have the time run a simulator with all possible variations of component tolerances and models and create models for real world capacitors, resistors, pcb solder joints and tracks, then your results may become slightly more realistic.
Simulators are a toys and keeps one occupied for months when new to the concept - like a game and you get hooked. In an actual development environment a simulator is a quick tool to evaluate and test a concept - that is all.
Problem is on this forum many believe their amplifier factual specifications are those predicted by the simulator, which I might add, is far from the truth.
If you followed the thread from the outset, you may have noticed that Andrej, was not relying on simulators at all when he set out designing this amp, it was only used to test his concept by confirming or rejecting a suspicion. Andrej tested in reality as he went along, which is what R&D is all about.
Some DIY members may have built hundreds of amps in simulators, speculated over the jargon, that does not mean much in real life.
My buddy Hugh R. Dean developed some of the best sounding amps attracting disciples for his AKSA brand the world over.
He used his ears and and some outdated test equipment and never used a simulator until two years ago.
I believe, we are all losing the plot and are guided blindly by simulated results - there is absolutely no correlation between simulation and what it sounds like.
I believe simulators are killing excellent sounding audio.
He used his ears and and some outdated test equipment and never used a simulator until two years ago.
I believe, we are all losing the plot and are guided blindly by simulated results - there is absolutely no correlation between simulation and what it sounds like.
I believe simulators are killing excellent sounding audio.
there is nothing wrong with simulation...
parts that are being simulated they perform 100% as you have said they have no leads and tolerances.problem relies in reality because theres some factor to be considered which affect the the performance of the circuits.
the goal is to match the actual product from the simulation.
you cant convince me that the actual product outperforms the simulated circuit
regards,
joel
parts that are being simulated they perform 100% as you have said they have no leads and tolerances.problem relies in reality because theres some factor to be considered which affect the the performance of the circuits.
the goal is to match the actual product from the simulation.
you cant convince me that the actual product outperforms the simulated circuit
regards,
joel
It could easily be that the real life circuit performs better in some respects than the simulation because the spice models may not be accurate.
I love playing around with a circuit in spice to "get inside" it and understand it and have learnt a lot from it - but I do not trust the results - for me it just gives indications of what measures have what effects.
I love playing around with a circuit in spice to "get inside" it and understand it and have learnt a lot from it - but I do not trust the results - for me it just gives indications of what measures have what effects.
Logically so. It seems that the more expert the designer, the less should be the relative value of the simulator. The more expert the designer, I believe he can see simulated results in a different way than others. He can see more things from the combination of simulated result, topology, actual sound, etc etc.
Very probable. The simulator seems to be a very effective and efficient tool to arrive (quickly) at a good sounding amp, but not excellent, that is (Not until the level of precision of the simulation is close to perfect).
Is it a waste?
having paid for a software and updated it periodically then could not give us what we desire.simulation shows how far the circuit can go free from sources that can affect the circuit.
in real life even a two identical transistors(same number) could not give same output when applied into a circuit.Now is it possible in simulation?specially if we are going to put it as differential transistor.
are we going back to ice age?
regards,
joel
having paid for a software and updated it periodically then could not give us what we desire.simulation shows how far the circuit can go free from sources that can affect the circuit.
in real life even a two identical transistors(same number) could not give same output when applied into a circuit.Now is it possible in simulation?specially if we are going to put it as differential transistor.
are we going back to ice age?
regards,
joel
Perfect definition.
Like all those computers design assistant tools, it can save time and help to feel, evaluate and tune things. But, after all, it is just some kind of Excel sheet computing fairy tails numbers.
On a side, it will never smell the smoke, on the other it will never produce a single note in your loudspeakers.
OMHO, it is not correlated. The sound of an amp depends both on design and components qualities Both have an influence on performance (and performance change the quality of sound). Design is done before SPICE simulation, some components choices after.JAY said:
Spice only help-you in tuning faster and understand where you'll have to work.
Begins the real work with your soldering iron, your oscilloscope and your ears.
It is exactly like cooking. Spice help to write the recipe. Then you have to find the best products and adapt your cooking's times and temperatures according to them with your smell and your eyes.
To give an other image, SPICE helps to bring on the formula one's circuit the best car you can. Then you have to tune-it, according to the driver's feelings and the circuit itself for best performance, if you want to win the race.
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LC,
I would really like you to discuss with you about my protection circuit. And to see his "failure" detection part in your final circuit.
Because it is beautiful, and had proven his efficiency on the worse conditions and different amps for decades, in the worse difficult situations (Big PA systems).
The idea is simple. Instead of analyzing the output signal, integrating-it to detect DC in output etc.. witch is slow and complicated, i just compare input and output signals.
If any difference (a working amp is supposed to be a strait line with gain) you can detect-it instant.
The theoretical circuit is very simple. First, you adjust output signal to the same level than the input one (inverse of the gain amp). Then, in an OP amp or a comparator, you make the difference (you can give some gain on this differential signal if needed).
With a second op Amp, you rectify the error AC signal.
Then,you just have to chose the threshold witch will fire your protection.
This error signal is very interesting, in real world, to see how bad is an amp with a loudspeaker's charge on transients signals ;-). An interesting tool for design too.
This simple and economical circuit will detect instant (µs) everything that can happens bad in an amp: HF oscillations, (even only on transients), DC, and, of course, short circuit on the output. It can use only a double op amp and few resistances around for 1 channel, or 3 amps for 2 channels.
One schematic to illustrate here:
http://www.esperado.fr/images/stories/protection-totale-definitive-mini.gif
(Do not take care of my relay command and power-on delays parts)
Fell free to use-it as you like, if you like. You best original amp need the best original protection. ;-)
I would really like you to discuss with you about my protection circuit. And to see his "failure" detection part in your final circuit.
Because it is beautiful, and had proven his efficiency on the worse conditions and different amps for decades, in the worse difficult situations (Big PA systems).
The idea is simple. Instead of analyzing the output signal, integrating-it to detect DC in output etc.. witch is slow and complicated, i just compare input and output signals.
If any difference (a working amp is supposed to be a strait line with gain) you can detect-it instant.
The theoretical circuit is very simple. First, you adjust output signal to the same level than the input one (inverse of the gain amp). Then, in an OP amp or a comparator, you make the difference (you can give some gain on this differential signal if needed).
With a second op Amp, you rectify the error AC signal.
Then,you just have to chose the threshold witch will fire your protection.
This error signal is very interesting, in real world, to see how bad is an amp with a loudspeaker's charge on transients signals ;-). An interesting tool for design too.
This simple and economical circuit will detect instant (µs) everything that can happens bad in an amp: HF oscillations, (even only on transients), DC, and, of course, short circuit on the output. It can use only a double op amp and few resistances around for 1 channel, or 3 amps for 2 channels.
One schematic to illustrate here:
http://www.esperado.fr/images/stories/protection-totale-definitive-mini.gif
(Do not take care of my relay command and power-on delays parts)
Fell free to use-it as you like, if you like. You best original amp need the best original protection. ;-)
I was asked the same question for my Crescendo SSA modified version.
Answer is NO, of course.
The only way to answer yes would be to build and test a pee-serial of,- let-says- 100 kits, with the same printed circuit and components.
No way to build an amp by yourself without minimum tools: Good eyes and ears, a multimeter, a generator, an osciloscope and a soldering iron. OMHO.
Multimeters are not expensive, and, with a little experience, you can use the sound card of your PC and free softwares to simulate a BF generator and slow oscilloscope.
Why "little experience" ? If you know how to feel-it, you can even detect HF events, even at 3Mhz, with your ears, listening to music.
Of course, i can't hear the hf, but it brings-me in a strange kind of "stoned" feeling. Not obvious, indeed.
I didn't mean that novice. Someone who has already built other amps but who has not a "real" osciloscope and who has some electronics knowledge but couldn't design it's own amplifier from the scratch.
I'd like to have a taste of the SSA sound but I don't own an osciloscope and I couldn't make the appropriate changes in parts values or circuit to, for example, fix an eventual oscilation problem. If it would oscilate at 3 MHz I wouldn't be able to tell either with my ears or with a sound card.
I'd like to have a taste of the SSA sound but I don't own an osciloscope and I couldn't make the appropriate changes in parts values or circuit to, for example, fix an eventual oscilation problem. If it would oscilate at 3 MHz I wouldn't be able to tell either with my ears or with a sound card.
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You will see the zobel resistor smoke
I built my SSA first time round without any major flaws (in other words basically functional) and this was using proto-board.
My zobel resistor smoked and the first option I had was to fool around with capacitors values across the feedback resistors. once stable then one can start tweaking because if you find a problem you can go one step back and look from a different perspective.
Spice did tell me that there is a possibility of oscillation so I expected that in practice there may be. Problem is that spice uses small signal characteristics and oscillation may appear for many other reasons, such as at high volume, high temperature, imbalance in lumped constants, signal coupling between PCB track, all kinds of junk that one can only really establish under dynamic conditions.
If you have not got any decent test equipment, you may still achieve the subjective "sounds absolutely astonishing" results, but these cannot be objectively verified, while your simulator may predict the best or worst performance is really irrelevant.
What is important is that it sounds good to you because you will be using it. Chances are that only 0.5% of the people on this forum actually like the sound of Lazy Cat's SSA on their particular speakers.
The amp, by itself, doesn't make any sound, nor does the speakers, it's the combination of the two that sounds great or mediocre, regardless of simulator results.
Just on another note, DIY guys I find would be more prone to change their amplification to try and improve their perceived sound than build or buy new speakers, ever thought why.
Could it be that it is easier to tweak the amplifier to match the speakers and if so what is the point of having a great simulation or measurement results if your final objective is that it must sound good to you.
Of course our ego's are stroked as well if someone else agrees with the results but we do get annoyed if others think that our results are not up to their expectation.
The only reason that I praised Lazy Cat's design is that I am certain we perceive sound(music) in a similar way. Heck, we may even look alike, or be attracted by the same type of woman, love the same kind of car, drink similar tasting beverages, wear thick black rimmed glasses.
The SSA amp may sound absolutely horrifying to you PaulPT or others, but the problem is really that you will have to write something nice about SSA simply because some knowing people did and maybe you are seen as a novice because you do not agree or maybe you feel you have to change your perceptions because you may have been wrong all your life.
PaulPT, you built Harrison's SYMEF and you were over the moon - that is absolutely great, stick with it (or any other design that you enjoy) until in time you can establish there is something you are missing then build or buy a design that has been reviewed to contain this missing ingredient you are seeking. You actually have to live with a product for some time to find what you like or dislike about it, while it is new it seems to be impressive and that is not what one looks for.
You do not want to marry a woman immediately that is impressive on the first date - you will marry her if she is consistent and predictably stable in her performance as long as you "live".
Could it be that it is easier to tweak the amplifier to match the speakers and if so what is the point of having a great simulation or measurement results if your final objective is that it must sound good to you.
Of course our ego's are stroked as well if someone else agrees with the results but we do get annoyed if others think that our results are not up to their expectation.
The only reason that I praised Lazy Cat's design is that I am certain we perceive sound(music) in a similar way. Heck, we may even look alike, or be attracted by the same type of woman, love the same kind of car, drink similar tasting beverages, wear thick black rimmed glasses.
The SSA amp may sound absolutely horrifying to you PaulPT or others, but the problem is really that you will have to write something nice about SSA simply because some knowing people did and maybe you are seen as a novice because you do not agree or maybe you feel you have to change your perceptions because you may have been wrong all your life.
PaulPT, you built Harrison's SYMEF and you were over the moon - that is absolutely great, stick with it (or any other design that you enjoy) until in time you can establish there is something you are missing then build or buy a design that has been reviewed to contain this missing ingredient you are seeking. You actually have to live with a product for some time to find what you like or dislike about it, while it is new it seems to be impressive and that is not what one looks for.
You do not want to marry a woman immediately that is impressive on the first date - you will marry her if she is consistent and predictably stable in her performance as long as you "live".
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a question...
I have seen this simple amp. evolved as time pass by.one thing that bothers me is the v12 version.on a supply 0f 50v compared to symef which uses 2pairs and actually works for me.surely I can build 3 amps of symef versus a single channel of this v12 using 50v.Is there something I missed thats needs to be enlightened?
regards,
joel
I have seen this simple amp. evolved as time pass by.one thing that bothers me is the v12 version.on a supply 0f 50v compared to symef which uses 2pairs and actually works for me.surely I can build 3 amps of symef versus a single channel of this v12 using 50v.Is there something I missed thats needs to be enlightened?
regards,
joel
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