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Old 12th January 2009, 12:00 AM   #1
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Default Aikido and 30W Class AB power buffer?

Hi,

we already have Moskido - Aikido driving push-pull class A unity gain power buffer.

Does anyone have schematics for simple 30W Class AB power buffer with minimal parts, which could be driven by aikido preamp?
I know it wont sound as good as Class A, but also it should be cheaper, lighter, smaller and consume less electricity.

Thank you.
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Old 12th January 2009, 03:39 PM   #2
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Hi Kacernator,
I have similar need: a powerful buffer AB class ( but 80-100W) to make biamplification.
Little Class A on the mid-tw and class AB on the woofer.
My idea is modify a F4 with less current bias and more voltage rails.
Probabily THD will goes up but I am not so worried...
Just a crazy idea from a rookie!

Cheers,
Paolo
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Old 12th January 2009, 03:53 PM   #3
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I would like to have something about 30W-50W. Maybe F4, but we also need feedback loop in class AB and zobel filter on the output. I am not skilled enough to design it myself .
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Old 12th January 2009, 03:59 PM   #4
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I also have zero skill
But I am not sure we need feedback . I think THD of 1-2% can be fine,
but sure we need precious opinions from experts here!

Cheers,
Paolo
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Old 12th January 2009, 04:04 PM   #5
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Hi,
I can suggest you two alternatives:

-the Thermaltrak diamond buffer by MTlin12 published here on diyaudio that I use together with my Aikido (Paolo: search also on www.audiofaidate.it where I published a revised schematic for correct bias)

-Steve Dunlap's Krill amp, output stage only (also based on diamond buffer). Steve also sells boards and partial kits....

Ciao

Andrea
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Old 12th January 2009, 04:31 PM   #6
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Thanks Andrea,

Time to look at those interesting circuits........

Just curious, what is wrong with my idea of modify a F4 in AB class?
THD?

Cheers,
Paolo
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Old 12th January 2009, 06:15 PM   #7
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Default Krill schematics

Here is the schematics of the full Krill amp with driver and PSU. Users are reporting that Krill sounds fantastic.

http://www.diyaudio.com/forums/attac...amp=1231731980

But when looking at the transformer, it needs 24V at 4A for one rail. In my DC-coupled moskido I have 25V at 5A.
I thought I could make 50W class AB amp with smaller transformer, if not I am staying with moskido, although class A amp draws more idle current also the power circuit is a lot simplier with moskido.
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Old 18th January 2009, 10:55 AM   #8
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Hi Kacernator,

Seems to me there is not much interest about "our" idea/scheme

I do not understand, tubes for voltage gain and solidstate superbuffer for current gain....what is wrong?

I have looked at Krill and the other scheme....beautiful, but to my inexpert eyes the F4 is more "simple" - easy to understand.....

Cheers,
Paolo
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Old 18th January 2009, 11:12 AM   #9
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But F4 is class A.

I quit idea with class AB, because it is more complex. I like simplicity. If I wanted lower power amplifier, I will do headphone amplifier: aikido preamp and class A SE mosfet buffer (Szekeres).

And lastly I must say I love class A sound .
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Old 18th January 2009, 11:51 AM   #10
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You are right,

but i have asked to Nelson Pass if is it possible run the F4 in AB class and he has kind responded of yes; just lower the bias and rise the voltage rails........
So I think you can have to say 100w in class AB with the first 10-15W
in A class. IMO it is a good compromise, no?

Cheers,
Paolo
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