now i got it....about sijosae class ab, what is mean by i have to closely match the transistor?

lol, this is one of the few reasons why i suggest against the Sijosae Class AB most of the time.

For a complementary, symmetrical discrete design, matching of transistors between NPN and PNP is important as to make sure that both symmetrical half of the circuit shares load and operates equally.

In this case, for the Sijosae Class AB, you should match the transistor gain (beta, which is also HFE) between the output transistors. As for the bias diodes (the first two transistors with collector shorted to base, this way the transistors acts as diodes for biasing), you should match their VBE instead. Though the latter matching is not really necessary.

Extra: For this exact circuit, matching of transistors should only be necessary for the power section as it's operating in open loop. Without the addition of an opamp wrapping the loop with global feedback, the balance of the rails can drift quite far away. As for the amp section, you don't really need to match the transistors because the opamp global feedback controls any dc offset of buffer stage close to ground (less than 1mV).

Personally, I would use a TLE2426 instead. The discrete rail splitter is not doing any current sinking other than maintaining the center virtual ground between rails. (the caps are actually at the output of the splitter, which means that the caps are actually doing the current sinking). In this case, the TLE2426 and the Discrete rail splitter ARE doing the same thing, with TLE2426's performance slightly better than the discrete rail splitter.

This post has been edited by LittleGhost: Apr 19 2008, 05:47 PM

so, meaning i dont have to closely math the transistor at the amp section of sijosae class ab? i only have to do so at the power section?

yes.

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Added on April 21, 2008, 1:23 pmNew hybrid amp guys.

http://headwize.com/ubb/showpage.php?fnum=3&tid=7342

Looks pretty cool. More like a beef-ed up Millett Hybrid Max. Comes with feedback, dc servo, and runs off high voltage for the tube section.

This post has been edited by LittleGhost: Apr 21 2008, 01:23 PM

helo, asking.. i'm not the electric guy.. love to learn this..

what is the factor to use only single 9V battery.. if i dun want to use 9Vx2.. mind to tell..coz i edi look through the web, simple cmoy use 9vx2...

can use single battery onli.. have to change anything??

some opamps work at higher voltage, some lower. Depending on the voltage swing headroom, you'll have to adjust the source voltage properly>

is it this the the complete schemetic for lisa iii ? http://www.esnips.com/doc/691b453b-16a8-4a...-IIIv1C-Box-Set

very typical walt jung or voltage diamond buffer amp maybe emphasis in supply

wut u mean by adjust source voltage??

Source voltage = your power source. Be it 9V battery, 18V (9Vx2) batteries or 24V Wallwart.

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Added on April 22, 2008, 3:21 pm

with extra non-switching bias that smoothens the crossover distortion curve.
EDIT: Amb did a simulation on the non-switching bias topology and found that it's not really that good. But it does add a form of colorization that is pleasing to the ears.

This post has been edited by LittleGhost: Apr 22 2008, 03:22 PM

ok..got it thx...

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Added on April 23, 2008, 3:54 pmupdate.. on the way to build the small amp .. but have prob.. have to google how to read resistor first.. haha

This post has been edited by xixo_12: Apr 23 2008, 03:54 PM

can always check the resistance with multimeter...

1% and 5% would be diffrent on how to read it..

anyway..Good luck bro..kena racun eh?? whahhahaha

In electronics, one of the basic fundamentals is to read resistor color codes and component identification. Of course you can use the multimeter to double check the resistance.
No short cuts in electronics learning curve, otherwise anyone is nothing more than a casual enthusiast without actual theoritical knowledge.. You wouldn't visit a quack doctor, would you?

racun tarak.. have sony walkman, n wanna see the differences after installing this.. somemore otw to make the it fit on 9 volt casing first

I wonder if anyone has done some class A amplifier? using quality components like nichicon, in order to make it HIFI. apparently some of the well known amplifier circuittry are available for anyone to try diy like nelson pass. can someone tell me, since i am totally new here.

http://www.diyaudio.com/forums/showthread....&threadid=28336

This post has been edited by ccschua: May 4 2008, 05:52 PM

Most of us here are headphone addicts. So I doubt you'll be able to see any high output speaker amplifiers.

However, most of the popular Nelson Pass amps are easy to build due to it's simplicity and elegance in parts count. I'd really say most people can build it and make it work easily.

Oh, and Nelson Pass' patented topologies on the other hand......is super complex. lol.

On the other hand, anyone here built anything lately? This thread requires more active builders/posters.

thanks sifu for the humble advise. You are correct!
I will start to learn it as a knowledge to myself..
not to poison myself to deep hehehe

I just wonder Nelson Pass patented is it really that outstanding. Can it perform better than the say Marantz PM7001 assuming u use top class components.

Is it true class A give u the best of amplification, cause those expansive amp are based on that. I am talking about the preamp and the monoblock.(sorry this is hifi speaker again not head amp)

This post has been edited by ccschua: May 5 2008, 08:59 PM

sound is nearly always subjective. So I really cant say it'll perform better from an Audiophile's point of view. From an engineer's (wannabe) point of view however, i think it's rather refreshing and interesting. Just to name a few examples, his methods of using dynamic bias, cross coupled feedback, and so on.

Depending on how you define your Class A. Is it single ended common emitter? Or is it a push pull complementary output biased heavily to Class A?

EDIT: Saw this on physorg, looks amazingly cool. http://www.physorg.com/news128786808.html

This post has been edited by LittleGhost: May 5 2008, 09:37 PM

What I heard is that NS is coming out with a headphone amp IC that is based on class A.