SYMEF amplifier

advert

And its square wave response. However the front end filter cap I have changed to 220p instead of 470p

Hi Andrej,

when the specification differences become negligible, forget it, to make any choices based on subjectivity, these systems sound identical.

There is no way that anyone can say with that the SSA and RAS44 will sound different even if SAA reveals that the 3rd harmonic being dominant or that in RAS44 2nd harmonic is dominant.

Practically neither distortions exists. Both amps have bandwidth extending beyond 1MHz, both amps has slew rates of several 100V/uS, both amps phase deviation is less than 1 degree at 100kHz.

Besides, if you listen at normal volume levels both amps added or subtracted artifacts will be below the noise-floor anyway - what is the point?

When your product reaches a certain level of sophistication going beyond this is pointless, they will perform identically. It is only placebo that could cause a subjective difference to be detected.

Andrej, when you get to the point where the technical performance of your amp exceeds a criteria, then I believe that there is no difference in the sound between these products, whomever designed them.

If a designer chooses to introduce some artifacts by means of feedback, filtering, etc. that he believes improves the sonic characteristic, this is most probably what people hear and either like or dislike about a specific product and it may not be as subjective as we think.

I think that most of us on DIY audio have the objective to produce technically perfect amplifiers, however we still see the subjective nature of the designers come into play when speaking of 2nd and 3rd harmonics being dominant and whether bootstraps or CCS improves the sound, etc.

When you reach a point where artifacts are several orders of magnitude below the detection threshold of the human ear, then I believe that it is placebo unless the designer intentionally modifies the signal to produce such an effect.

So Andrej, your amp is as good as it gets. When we are fooling around with numbers beyond the third or fourth decimal point is probably more egotistic than realistic.

For sale,

Clinical ham amplifiers for sale. Do not operate near class D amplifier equipment:rofl::rofl::rofl:
 
good work

And the harmonic distribution, each harmonics contribution as % and THD as %. Of course these are all simulations. My amps are transparent subjectively speaking. Simulating with your front end configuration did change the harmonic distribution as well as THD marginally in the simulation but the ear would not detect it as it is virtually non existent.

I have listened again and again switching between the two configurations on headphones after I have adjusted each config to output the exact same amplitude. Now I must admit that I am convinced that in my first testing claiming a different sound that it was placebo. I can hear absolutely no difference at all.

I have simulated the input circuit in my L-MOSFET version of Andrej's SSA (with input circuit & without input circuit) as well as listened intensely to any change of character of instruments, voices. etc.

The speakers I use are bookshelf size and incorporates the classic Scanspeak 2010 tweeter and Peerless 6.5 inch Aluminium cone woofer in a 27 litre enclosure and Andrej's SSA has been my choice for my office amp for the past 7 or 8 weeks.

I spend most of my time in my office (around 8 - 10 hours per day) and always have music playing so I am very familiar with this amp/speaker combination and have enjoyed it immensely since I built it.

I am not doing blind test because I have to physically switch the input by inserting the front end circuit or removing it, so time passes between listening and re-listening.

The THD curves are plotted on the same graph and the green markers is used to display the harmonics and THD with Onaudio's circuit in place and the red markers without the additional input conditioning.

Honestly, and as much as I would like to report otherwise, I cannot hear any difference at all.

I have for the past two hours irritated my wife to the extent that if I would go and do the same tests on my main system in my lounge, she would shoot me and I would have to do this when she goes out on her own because I played the same song over and over at pretty loud levels for about an hour listening to different things and making notes what I hear that I thought was different.

I am sorry I cannot be of more help Onaudio, you may get better responses from the other 29999 people who might be testing your idea. The problem is the responses are subjective and not of much use really.

I will be following this thread, but I feel my limited contribution to it is now exhausted.

Hi Nico,

Thumbs up for the level of work and sacrifice you have taken. However
1. You did not actually listen to the SYMEF, what have you overlooked ;) ?
2.The human body compensates for persistent stimulus by numbing the senses
For example were you to set the temperature of the shower, it will be warm and pleasant at first, after a while you will feel that the water is not hot enough and increase the temperature. Were you to eat chocolate, you would be unable to distinguish some tastes for some time :)
3. When you finally have the SYMEF connected to your speakers and you crank up the volume, you will be asked for a dance:rofl:
 
I will build it....

Hi Joel,
I see you sorted out your thermal compensation. I hope you have enjoyed the Slone amp. You can use devices from any respectable manufacturer. Hows the progress?

Thanks.

onaudio Im still in middle east country and im going vacation and will be there on first week of december in philippines.I will build your amp. as soon as i get there.and also I have finished sloan class A pcb and will compare both of them.but right now all I can do is prepare the board.anyway whats best of your amp.is its free and we have your guarantee its working.;)
 
Hi Onaudio,
I do not argue the subjective nature of seeing, hearing, feeling, tasting, smelling.

I merely showed a schematic and simulated performance characteristics of the amp I used to test the input circuit with.

I did not present component values because I do not want anyone to build it, I demonstrated the curves simply to say that it is technically no worse than yours, and there was no intention of ridiculing your design, but if you understood it in that way then I apologize profusely.

What I would like to understand simply is your methodology to categorizing subjective experiences into meaningful data that would create the formula for a universally accepted design. I see it as some like blue and some red, making it purple may not appeal to either. I have tasted salty chocolates made in Holland, I nearly puked when I put it in my mouth - but many Dutch people love it.
 
data analysis

Hi Onaudio,
I do not argue the subjective nature of seeing, hearing, feeling, tasting, smelling.

I merely showed a schematic and simulated performance characteristics of the amp I used to test the input circuit with.

I did not present component values because I do not want anyone to build it, I demonstrated the curves simply to say that it is technically no worse than yours, and there was no intention of ridiculing your design, but if you understood it in that way then I apologize profusely.

What I would like to understand simply is your methodology to categorizing subjective experiences into meaningful data that would create the formula for a universally accepted design. I see it as some like blue and some red, making it purple may not appeal to either. I have tasted salty chocolates made in Holland, I nearly puked when I put it in my mouth - but many Dutch people love it.

Hi Nico,

This is going to be an interesting one. Responses will be dealt with by creating a model that can be used to categorize user experience as either very good, good, acceptable,poor and very poor.

I haven't applied a parser and a lexer to your responses yet but they look promising :).

You have done some beautiful work and am only waiting for you to take the final step :)

many thanks
 
Onaudio,
I have reached my audio "Nirvanna" a few years back and have since not bothered to find something different. Regarding Andrej's (Lazy Cat) Super Simple Amplifier, the design it was so refreshingly different that I and others where compelled to participate from inception its inception. It turned out and remains a very worthwhile and enjoyable exercise.

I will make an attempt at yours after our summer holidays kick off in less than a month. Thank you.
 
Disabled Account
Joined 2006
OnAudio,

I did some quick sims on your schematic and this is what I found. Current in your predriver is only 1 ma, current in driver is 100 ma, very high for class AB. Currents in folded cascode are very low, in order of 600 ua, too low in my book.

Nevertheless the circuit has a very nice harmonic spectrum for those that like Hiraga type spectrums although the circuit isnt the low distortion type. What I do like about it is that it surpresses high order distortions effectively and this is not due to the outputstage. I did some quick mods with the currents and was able to lower distortion, just the connection of the current mirror to the rail as I proposed earlier does.

The amp has virtues in my opinion and could indeed sound good but I think you should prototype it and optimise before trying to get 30 000 members to build it. The folded cascode - vas circuit is quite unique and pretty fast.
 
OnAudio,

I did some quick sims on your schematic and this is what I found. Current in your predriver is only 1 ma, current in driver is 100 ma, very high for class AB. Currents in folded cascode are very low, in order of 600 ua, too low in my book.

Nevertheless the circuit has a very nice harmonic spectrum for those that like Hiraga type spectrums although the circuit isnt the low distortion type. What I do like about it is that it surpresses high order distortions effectively and this is not due to the outputstage. I did some quick mods with the currents and was able to lower distortion, just the connection of the current mirror to the rail as I proposed earlier does.

The amp has virtues in my opinion and could indeed sound good but I think you should prototype it and optimise before trying to get 30 000 members to build it. The folded cascode - vas circuit is quite unique and pretty fast.

Hi Homemodder,

Thank you for carrying out the analysis. By optimizing it means deviating from the original design, which means modifications on the model that was used to conceive the amplifier itself. This is not a bad thing if members can get to construct both the original and the modified version, based on user experience we can generate new information that may prove very interesting :). In summary do your modifications improve speed and distortion ?

kind regards
 
Disabled Account
Joined 2006
Has this amp been built and tested as you present it ??. You dont think 600ua is a bit low, how can one be sure the transistor will even turn on.

Yes to both the questions, increasing currents is tricky, can make THD figures worse.

What is this model exactly supposed to be ? If it is the harmonic spectrum you need not worry, as I changed a couple of currents the amp kept it spectrum quite faithfully which was good to see.
 
strategies

Approach A
1. Construct base model and give feedback on listening experience.
2. If base model unsatisfactory, optimize to own tastes or use other members mods that were successful.Tell us about it.
3. If 1 and 2 fail then report failure and recuperate
4. Move on to next amplifier

Approach B
1. Construct optimized mod and tell us about the listening experience.
2. If optimized mod unsatisfactory, revert to base model and tell us about it.
3. If 1 and 2 fail then report failure and recuperate
4. Move on to next amplifier
 
Has this amp been built and tested as you present it ??. You dont think 600ua is a bit low, how can one be sure the transistor will even turn on.

Yes to both the questions, increasing currents is tricky, can make THD figures worse.

What is this model exactly supposed to be ? If it is the harmonic spectrum you need not worry, as I changed a couple of currents the amp kept it spectrum quite faithfully which was good to see.

Hi homemodder,

What are the characteristics of the devices? The currents can be played around within a certain range. Am grateful for your sense of adventure, why don't you try both and let the ear be the judge. In the end we all learn something and your research will have contributed to the state of the art ;) .

kind regards
 
Hi Onaudio, it almost seems as if you want us to design your amplifier for you. Have you made one yourself and does it live up to your expectation. Think of it, if every one of your 30 000 DIYers build one with ancilliaries such as power supply and each spends $ 500 on it you have created the most expensive R&D facility that the audio fraternity has ever seen and that for free!

Have you got pictures of the one you built and the rest of the set-up you use. Speakers play a significant role in the listening experience and that is one reason I can think of that each person will have a different experience. Besides the power supply is the most important part of any amplifier and you do not even mention its requirement.

I will now relax and look from time to time where this thread goes, I have a feeling it will die a natural death.
 
Hi Onaudio, it almost seems as if you want us to design your amplifier for you. Have you made one yourself and does it live up to your expectation. Think of it, if every one of your 30 000 DIYers build one with ancilliaries such as power supply and each spends $ 500 on it you have created the most expensive R&D facility that the audio fraternity has ever seen and that for free!

Have you got pictures of the one you built and the rest of the set-up you use. Speakers play a significant role in the listening experience and that is one reason I can think of that each person will have a different experience. Besides the power supply is the most important part of any amplifier and you do not even mention its requirement.

I will now relax and look from time to time where this thread goes, I have a feeling it will die a natural death.

Hi Nico,

For that $500 members will have contributed immensely to the state of the art and not only that hopefully they will have a great sounding amplifier that they like. I am waiting for the first person to claim that they are the very first ones to build it and love it, and history will remember them for that ;). About the transformer, here is one I was looking at 750VA Power Transformer .

I gave a wonderful design. To claim that members are designing it for me would be wrong. My design is currently complete any mod is their mod. The body of knowledge generated will be for all.And yes they will also tell us about their speakers and whether they are using crossovers etc.

kind regards