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Old 30th December 2011, 07:34 AM   #81
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Quote:
Originally Posted by dadod View Post
...Yes I would like to use it with tupbe pre and no global feedback, ...Damir
I was interested this because of the same reason
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Old 30th December 2011, 08:45 AM   #82
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Edmond Stuart View Post
Hi Damir,

But what happens in case of square waves or a sine of say 250kHz? An ideal OPS should show the same (low) cross-conduction, though that's not always possible.

Cheers,
E.
Hi Edmond,
Here is square waves test at 5k, 100k, end 200kHz.
It is still with my input stage, GNF, and input filter. What do you say about it?
Damir
Attached Images
File Type: jpg DADO-EDMOND-AB2-PP-square5k.jpg (225.8 KB, 196 views)
File Type: jpg DADO-EDMOND-AB2-PP-square100k.jpg (224.9 KB, 185 views)
File Type: jpg DADO-EDMOND-AB2-PP-square200k.jpg (209.7 KB, 181 views)
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Old 30th December 2011, 11:34 AM   #83
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Hi Damir,

It doesn't look good.

edit: In the meantime I tried to make the high impedance low offset version working,
but I'm still experiencing troubles: above 100kHz, let alone square waves, it goes berserk.
So I give up and try to improve the original version of AB2.
Regarding to offset, you might use a DC servo to zero both voltage and current offset.
What about that?

Cheers,
E.
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Last edited by Edmond Stuart; 30th December 2011 at 11:42 AM.
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Old 30th December 2011, 11:47 AM   #84
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Originally Posted by ontoaba View Post
............
BTW: not good to call another is idiot just because feel genius, because it is bad for people relation.
Not my words. Instead, I was talking about 'Einsteins' and 'smarty pants'.

Cheers,
E.
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Old 30th December 2011, 12:09 PM   #85
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Edmond Stuart View Post
Hi Damir,

Regarding to offset, you might use a DC servo to zero both voltage and current offset.
What about that?

Cheers,
E.
Hi Edmond,
Do you mean to use a DC servo for AB2 as OPS for tube preamp, or AB2 used in all bipolar amp with GNF? I am interested in both, thermal and bias stability is annoying with standard bias spreader even if TT transistors are used.
Damir
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Old 30th December 2011, 12:20 PM   #86
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Default mods

Looking at some modifications of my circuit, I got the impression that not everybody fully understand every detail of the AB2 circuit. Of course, those mods do work (more or less), but as they deviate too much from Class-I and AB2, I think it's more appropriate to post those circuits on a more general thread about sliding bias circuits. For example this one: Variable operating biass output ?

In order to ease the distinction between circuit which belongs to Class-I (and look-alikes) and those which do not, what about an (short) explanation of the basic principles of Class-I and AB2?
Any interest?

Cheers,
E.
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Old 30th December 2011, 12:26 PM   #87
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Default servo

Quote:
Originally Posted by dadod View Post
Hi Edmond,
Do you mean to use a DC servo for AB2 as OPS for tube preamp, or AB2 used in all bipolar amp with GNF? I am interested in both, thermal and bias stability is annoying with standard bias spreader even if TT transistors are used.
Damir
Hi Damir,

I mean a servo for the preamp version. Integrated with an all bipolar amp is another story. It depends on the input stage whether you need a servo or not.

Cheers,
E.
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goed verliezen dan dooft het licht…(H.M. van Randwijk)
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Old 30th December 2011, 12:45 PM   #88
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Edmond Stuart View Post
Looking at some modifications of my circuit, I got the impression that not everybody fully understand every detail of the AB2 circuit. Of course, those mods do work (more or less), but as they deviate too much from Class-I and AB2, I think it's more appropriate to post those circuits on a more general thread about sliding bias circuits. For example this one: Variable operating biass output ?

In order to ease the distinction between circuit which belongs to Class-I (and look-alikes) and those which do not, what about an (short) explanation of the basic principles of Class-I and AB2?
Any interest?

Cheers,
E.
This a great to explain all what is in those circuits, I am very interested.
Damir
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Old 30th December 2011, 01:08 PM   #89
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Edmond

Nice results, could you direct me to Ken Peters paper, I must have missed it.
Who patented TMC ??? Something tells me it was probably had from this forum.

Seasons greetings to you and family and prosperous new year.
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Old 30th December 2011, 02:02 PM   #90
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Quote:
Originally Posted by homemodder View Post
Edmond

Nice results, could you direct me to Ken Peters paper, I must have missed it.
Hi Homemodder,

Probably you mean Kendall Castor-Perry.
Anyhow, his paper has been published in Jan's Linear Audio Vol. 2.
Perhaps Jan is willing to scan 24 pages and send them to you
A patent of the same circuit can be found here: New Linear Audio publication!

Quote:
Who patented TMC ??? Something tells me it was probably had from this forum.
Please, look here: Bob Cordell Interview: Negative Feedback

Quote:
Seasons greetings to you and family and prosperous new year.
Thanks, the same to you.

Cheers,
E.
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