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Old 30th April 2011, 09:55 AM   #1
dadod is offline dadod  Croatia
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Default TMC or TPC my dilemma resolved?

I did make some amplifiers with TMC (Transitory Miller Compensaton) and never have any stability problem or ringing with square wave test. That was in practice.
I know from long discussion on this forum and other one that TPC (Twin Pole Compensation) and TMC are theoretically the same thing. I followed Edmond Stuard argument too.
Now I did some simulation to compare TMC to TPC and here is result.
First TMC as I made this amp and listening to it every day.
Here is a schematic, square wave test, first with no parallel capacitor to 8ohm load, and second one with 1uF parallel to load.
dado
Attached Images
File Type: png DADO-TMC-sch.png (92.3 KB, 510 views)
File Type: png DADO-TMC-squarediagram-8_0C.png (94.2 KB, 492 views)
File Type: png DADO-TMC-squarediagram-8_1uF.png (94.3 KB, 469 views)
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Old 30th April 2011, 10:07 AM   #2
dadod is offline dadod  Croatia
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Default TMC or TPC my dilemma resolved?

I tried to simulate TPC amp with similar distorton and OLG.
You can see that square wave has overshoot and ringing. I could not get ride of it with simple additional compensation, and my decision is that TMC is "better" and simpler in practical use. I was thinking about TPC in a way to decrease EMF influence from a loudspeaker on input stage.
I know that for many people this discussion is closed, But I would like to hear other opinion.
Here are TPC diagrams
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File Type: png DADO-TPC-sch.png (92.2 KB, 466 views)
File Type: png DADO-TPC-squarediagram-8_0C.png (91.2 KB, 453 views)
File Type: png DADO-TPC-squarediagram-8_1uF.png (93.3 KB, 113 views)
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Old 30th April 2011, 11:17 AM   #3
lineup is offline lineup  Sweden
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I dont know how to select values in TMC.
Like to hear more how to design TMC.
ostripper uses and recommends it.
And is TMC possible in a Current Feedback Amplifier.
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Old 30th April 2011, 11:54 AM   #4
dadod is offline dadod  Croatia
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lineup,
You can find a lot of TMC explanation in this forum, search for TMC and Edmond Stuart.
Main principle is that serial connection of TMC capacitors is similar to value of Miller cap.
Using Spice you can experiment and see OLG and phase relation.
I never used CF amp, but I think it is possibe.
dado
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Old 30th April 2011, 12:08 PM   #5
lineup is offline lineup  Sweden
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Thanks, dadod
I do that.
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Old 30th April 2011, 01:25 PM   #6
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My explaination is because TMC sets a local feedback around the output stage, it is better in pole splitting effect. TPC also splits poles, but only by virtue of low impedance driving output stage, but feedback mechanism is more agressive everything else being similar.
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Old 30th April 2011, 05:20 PM   #7
artu is offline artu  Chile
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Quote:
Originally Posted by darkfenriz View Post
My explaination is because TMC sets a local feedback around the output stage, it is better in pole splitting effect. TPC also splits poles, but only by virtue of low impedance driving output stage, but feedback mechanism is more agressive everything else being similar.
Yes, that's it
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Old 30th April 2011, 06:36 PM   #8
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TMC also lowers VAS impedance , making for a lower distortion EF2 OPS regardless of load. I'm pushing my new AX/Nikko right to the rails a I type and WOW! Amp has such a clean "top end" at nuclear volume levels. I must again thank E. stuart for the idea.

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Old 30th April 2011, 06:51 PM   #9
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Quote:
Originally Posted by ostripper View Post
I must again thank E. stuart for the idea.

OS
TMC was patented in the 70ths
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Old 30th April 2011, 08:47 PM   #10
dadod is offline dadod  Croatia
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Quote:
Originally Posted by ostripper View Post
TMC also lowers VAS impedance , making for a lower distortion EF2 OPS regardless of load. I'm pushing my new AX/Nikko right to the rails a I type and WOW! Amp has such a clean "top end" at nuclear volume levels. I must again thank E. stuart for the idea.

OS
OS, you were the one who inspired me to start to experiment and thanks for that.
You are quite sure, it looks for me, that you have found your AMP.
Maybe there is a better and still simple SS amp, don't stop to explore different circuit ideas.
dado
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