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Old 14th November 2011, 05:10 PM   #91
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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.
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Old 15th November 2011, 11:51 AM   #92
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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.
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Old 15th November 2011, 03:45 PM   #93
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Quote:
Originally Posted by homemodder View Post
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 ?

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Old 15th November 2011, 04:21 PM   #94
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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.
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Old 15th November 2011, 04:21 PM   #95
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Default 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
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Old 15th November 2011, 04:34 PM   #96
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Quote:
Originally Posted by homemodder View Post
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
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Old 15th November 2011, 05:06 PM   #97
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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.
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Old 15th November 2011, 05:31 PM   #98
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Quote:
Originally Posted by Nico Ras View Post
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.

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Old 15th November 2011, 05:53 PM   #99
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Quote:
Originally Posted by Nico Ras View Post
I will now relax and look from time to time where this thread goes, I have a feeling it will die a natural death.
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Old 15th November 2011, 05:58 PM   #100
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OnAudio, pictures are what will exhonerate now!
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