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Old 1st October 2012, 12:38 PM   #3261
shaan is offline shaan  India
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Quote:
Originally Posted by Nico Ras View Post
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.
Been going through the early posts and this caught my eyes. I now understand why my simulator says the opposite of what the SSA presents at its output. Feels like a kind of freedom from an old false belief.

Well, I still use Simetrix to simulate the turn-on thump protector which uses an IRF540, a 1000uF cap and a couple of resistors; and the real world time delay is very close to 1 second, almost same what the sim says.
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Old 1st October 2012, 12:42 PM   #3262
shaan is offline shaan  India
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Quote:
Originally Posted by AKSA View Post
Jay,

The AKSA is not particularly transparent. Subjectively it may seem so, but there is considerable second harmonic.

Cheers,

Hugh
Jay says,

Quote:
Originally Posted by Jay View Post
Yes, I have been expecting this comment, as I was not so sure what "transparent" should mean to everyone

The sweet tubey sound is the second harmonic right? What I mean with transparent is the perception as if the singer is there (along with the emotion that always draw my attention to the music). No bipolar amp that I have heard can beat my tube amp (in the past) in term of this. But my AKSA clone strangely can beat my class-A amp in this aspect, that's why I keep it, even tho bipolar sound is not my cup of tea...
Would you still say that you don't like second harmonic, eh Jay?

edit- No offence. :P
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Old 1st October 2012, 12:55 PM   #3263
Jay is offline Jay  Indonesia
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Originally Posted by shaan View Post
So you are discrediting the BIGBT for the matching issue, I see it now.
I like to build better circuits. The best if possible. It's just my way to predict the "future". I don't want to buy 200 transistors, just to find out that my prediction match reality.

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Originally Posted by shaan View Post
IMO, one should not dismiss something as bad if they can't afford it.
That's not my way. I listen first and try to find the red line from every experience, so my search can be closer and closer.

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Originally Posted by shaan View Post
As a matter of fact, I can't afford the BIGBT with my current income, and in future maybe I will. And when I try the BIGBT and fail to like its sound only then will I be acceptable to make comments on it, provided I do it the way it should be done, i.e. matching the BJTs. Looking at this config through the glasses of my previous familiarity with any particular config will be plain prejudice from my part. No offense.

No offense. You have good ears. Just lack of experience (With bad ears, experience usually does not help much). Why not build the BIGBT amps by yourself, then make comment. Who knows you will have the same opinion as mine.

SSA BIGBT HP is very good, because it is designed by good designer. Type of output stage doesn't matter much imo. Which one will you choose: favorite output stage that does not work, or mediocre output stage that works very well.

I never said that SSA BIGBT HP is not good. It is very very good. At least it is the best that I have simulated. I'm just looking for amp projects. And no amp should stop my search for the best one


Quote:
Originally Posted by shaan View Post
There is some special attributes about DOZ when played in low volume, that you can't achieve with a symmetrical amp, like SSA. And this, in no way is a discredit to SSA,
Your mind is occupied with crediting or discrediting. That is the truth about DOZ/JLH and SSA. T/SSA is very scalable into high power with lowish THD (THD is not increasing exponentially with power and frequency), an important feature of the topology.

Quote:
Originally Posted by shaan View Post
because SSA can make the sound ALIVE and the feeling of being in a LARGE auditorium starts brewing inside your head, something DOZ just can't do
Homemodder have already told you the effect of loudspeaker. I prefer mediocre amp with excellent speaker than excellent amp but mediocre speaker. The effect of loudspeaker is so so dominant to the sound, compared to the effect of amplifiers. Go build/design speakers. But they are far more costly than building amps.

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Originally Posted by shaan View Post
I see, CFP. Now it's clear as daylight... As you know I am using LATFETs at output, without zobels. Obviously our two configs are parsecs away from each other, so I won't dare to compare it to your's.
You forget that I have built many amps. I have hundreds of power transistors, more than a hundred amplifiers. I build amps for fun. Otherwise, what should I do with my parts?
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Old 1st October 2012, 01:18 PM   #3264
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by shaan View Post
Jay says,

Yes, I have been expecting this comment, as I was not so sure what "transparent" should mean to everyone. The sweet tubey sound is the second harmonic right? What I mean with transparent is the perception as if the singer is there (along with the emotion that always draw my attention to the music). No bipolar amp that I have heard can beat my tube amp (in the past) in term of this. But my AKSA clone strangely can beat my class-A amp in this aspect, that's why I keep it, even tho bipolar sound is not my cup of tea...

Would you still say that you don't like second harmonic, eh Jay?

edit- No offence. :P
Hehehe. No, I don't like distortions, whatever the order. But I like listening to music as if the singer and the instruments are there. Should an amp have a second order distortion for this? No.

I want ALL distortions down, but I believe on the monotonic spectrum. It means second order cannot be as high as fifth order. I want minimum total distortion, as long as the higher order are lower than the lower order.

BTW, I like to find and collect the best amp for each topology. And I'm still curious about the Lin topology (I want to know what is the most expensive amp utilizing this topology). Do you have suggestion on which amp to replace my AKSA clone?
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Old 1st October 2012, 01:23 PM   #3265
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<No dissonance/fatigue>
Dear Jay, dissonance does not equal fatigue. Sharp dissonant intervals and chords play a prominent role in many traditional musical cultures. But I will agree that IMD could cause listening fatigue.

In my very humble opinion you cannot hear an amplifier, you can hear a speaker. The amount of harmonic or non-harmonic artifacts that an amplifier introduced into a listening chain is really negligible although we all would like to claim hearing vast differences between amplifiers.

Listening to LC's (early) SSA is enjoyable, relaxing and just plain nice. Whether odd or even order harmonics or how exactly they are distributed were responsible is really not the point.

Lazy Cat got the recipe right and it complimented the rest of my listening chain that is why I think this amp is a worthy and remain an integral part of music enjoyment.
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Last edited by Nico Ras; 1st October 2012 at 01:27 PM.
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Old 1st October 2012, 01:39 PM   #3266
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Quote:
Originally Posted by Jay View Post
Type of output stage doesn't matter much imo.
+1

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Originally Posted by Jay View Post
At least it is the best that I have simulated.
I would never rely on SIM to evaluate an amp. Only real measurements and listenings.
Sim is just a tool to save time when you are about to calculate values, evaluate and compare different solutions in a schematic you are trying to define, OMHO.
Quote:
Originally Posted by Jay View Post
I prefer mediocre amp with excellent speaker than excellent amp but mediocre speaker.
An excellent amp with a mediocre speaker can provide-you a very natural reproduction, limited in bandwidth, tone balance, and/or level. But a bad amp with an excellent speaker can be terrific: You can hear all the distortions right in your face.
Each bad amp driving my speakers (JBL driver +spherical wooden horn) can turn them in an horrible thing, and change its tonal balance in a drastic way. It is like a microscope where you look in a surface you supposed clean :-)
The thing i do not understand is why we can afford with pleasure such high distortions from any speakers, and so few from amps.
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Last edited by Esperado; 1st October 2012 at 01:56 PM.
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Old 1st October 2012, 02:02 PM   #3267
shaan is offline shaan  India
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Quote:
Originally Posted by Jay View Post
I like to build better circuits. The best if possible. It's just my way to predict the "future". I don't want to buy 200 transistors, just to find out that my prediction match reality.
Fine. All's well.

Quote:
That's not my way. I listen first and try to find the red line from every experience, so my search can be closer and closer.
So you listened the BIGBT built in LC's way and then simulated it to find it to be very good. Fine, all's well again.

Quote:
No offense. You have good ears. Just lack of experience (With bad ears, experience usually does not help much). Why not build the BIGBT amps by yourself, then make comment. Who knows you will have the same opinion as mine.
I never said that I won't build it or my future opinion won't match yours.

Quote:
SSA BIGBT HP is very good, because it is designed by good designer. Type of output stage doesn't matter much imo. Which one will you choose: favorite output stage that does not work, or mediocre output stage that works very well.
Lateral output, as it offers least headache in biasing and stability, and gives good sound, it works very well and its my favorite. BIGBT isn't my favorite, as I yet haven't tried it. It might be, might not be. I will tell you in future.

Quote:
I never said that SSA BIGBT HP is not good. It is very very good. At least it is the best that I have simulated. I'm just looking for amp projects. And no amp should stop my search for the best one
I'm confused, BIGBT is good because it simulated well? And bad because it demands buying 200 trannies? Where is the working prototype which had strong character, and was that good and why. Thanks.

Quote:
Your mind is occupied with crediting or discrediting. That is the truth about DOZ/JLH and SSA.
What do you mean? What truth? Please enlighten me.

Quote:
T/SSA is very scalable into high power with lowish THD (THD is not increasing exponentially with power and frequency), an important feature of the topology.
What are you suggesting by the above? That it simulates with pretty decent graphs?

Quote:
Homemodder have already told you the effect of loudspeaker. I prefer mediocre amp with excellent speaker than excellent amp but mediocre speaker. The effect of loudspeaker is so so dominant to the sound, compared to the effect of amplifiers. Go build/design speakers. But they are far more costly than building amps.
What does that has to do with BIGBT being worst because of 200 trannies?

Quote:
You forget that I have built many amps. I have hundreds of power transistors, more than a hundred amplifiers. I build amps for fun. Otherwise, what should I do with my parts?
I have 50s of transistors and 50s of amps. So I guess I'm only halfway there to throwing away my scope and rely on simulator.

I'm confused as this argument doesn't seem to go anywhere. I've made my points clearly in earlier posts and don't think they need an explanation. At least I didn't declare anything to be good or bad with any reference to the simulator.

I'll stop here for my own safety.
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Old 1st October 2012, 02:16 PM   #3268
shaan is offline shaan  India
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Quote:
Originally Posted by Esperado View Post
An excellent amp with a mediocre speaker can provide-you a very natural reproduction, limited in bandwidth, tone balance, and/or level. But a bad amp with an excellent speaker can be terrific: You can hear all the distortions right in your face.
Ah, thanks for posting this Christophe. It makes sense. Honestly I got confused by the claim that says otherwise. I test all my amps into the same fullrange speaker, which is a bargain between good and bad, so that the test ground for all the amps is the same, i.e. average speakers.

Not to say that I don't dream of having feastrexes though.
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Old 1st October 2012, 03:28 PM   #3269
Jay is offline Jay  Indonesia
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Originally Posted by shaan View Post
Lateral output, as it offers least headache in biasing and stability, and gives good sound, it works very well and its my favorite. BIGBT isn't my favorite, as I yet haven't tried it. It might be, might not be. I will tell you in future.
Yes, latfet is my favorite too. It has weaknesses, but it seems that the SSA is the best place for it.

But I still cannot decide soundwise: a latfet or a highly biased hexfet.

Quote:
Originally Posted by shaan View Post
I'm confused, BIGBT is good because it simulated well? And bad because it demands buying 200 trannies? Where is the working prototype which had strong character, and was that good and why. Thanks.
The issue is with the way each person differently appreciate the sound. I just want that sound that keeps me listening. It is not an easy thing to understand.

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Originally Posted by shaan View Post
What do you mean? What truth? Please enlighten me.
About what you said (DOZ vs SSA), it is true.

Quote:
Originally Posted by shaan View Post
What are you suggesting by the above? That it simulates with pretty decent graphs?
Quote:
Originally Posted by shaan View Post
I have 50s of transistors and 50s of amps. So I guess I'm only halfway there to throwing away my scope and rely on simulator.
Now your mind is occupied by the idea that (free) simulators "do not work"

I'm lucky because I found simulation has good correlation with reality. Of course good engineering judgement (comes from experience) is required.

It doesn't matter if a simulated 0.0013% is actualy 0.1% or 0.7%. What matters is relative comparisons. There are ways/tricks how to setup simulators such that the result can be usefully interpreted. Consistency is the key. I simulated my commercial amps, and compare with similar topology, soundwise and by simulation. That's why I dare to say that simulation is "consistent" with reality (i.e. after the correlation has been verified).
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Old 1st October 2012, 03:55 PM   #3270
Jay is offline Jay  Indonesia
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Originally Posted by Nico Ras View Post
Listening to LC's (early) SSA is enjoyable, relaxing and just plain nice. Whether odd or even order harmonics or how exactly they are distributed were responsible is really not the point.
SSA harmonics distribution imo is consistently good, so not an issue. I think latfet really find his home in the SSA. It's deficiency (i.e. dull sounding) is cured and what is left is the famous latfet sound.
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