Help me to improve our prehistoric VBE multiplier biasing system

[destroyer X]

Yes dear John, you've got the point

Thank you very much...fully agreement.

I have already found a circuit to be tested.

Soon i will show you all the circuit..... i gonna test it in advance

to publish it here.

regards,

Carlos

 

[vzaichenko]

Carlos,
I think you are looking for a solution which keeps the transistors always on - not necessarily a sliding bias, but a system that uses a "dual bias" approach. Blomley suggested a circuit many years ago in Wireless World, as it was. He separated the output bias regulator from the driver and used a diode splitter to steer current from the signal to the output/driver stages.

One approach I have tried is what I call a "double bias circuit". This uses a standard bias method (using the "proper" Vbe multiplier as I outlined and others have pointed out are mentioned by D Self) but with THREE circuits. One forms the regular bias stabiliser; the other two work from separate current-driven bias supplies between the rails and centre point. The two bias circuits are joined by diodes (see illustration).
THe idea is that when the signal current reduces the bias is maintained by the auxiliary circuits.
What I found is that the concept works, but the main issue was setting it up. With three bias controls, it is necessary to start the adjustment with the aux bias set to zero and first set the quiescent current with the main adjuster. Then, carefully increasing both aux bias currents until the quiescent current JUST starts to increase, maintaining a balance for zero output (this needed three meters connected up).
I also found that the main problem with crossover distortion is at high frequencies. The stored charge in the ouput transistor bases needs to be removed quickly or this acts as its own sliding bias. FOr this reason, I have had better results reducing the base-to-base resistor in the DRIVERS, using triples to increse the available drive, and then just a standard class AB system works OK.
In this approach, reducing the base-to-base resistors to keep the driver(s) in Class A means that only the output transistors have to work in Class B.

Regards
John

My implementation of exactly this mechanism:
>Non-switching OPS<

It really works as expected.

Carlos, very interesting to see what you will come up with.
Looking forward

 

[raul_77]

Hello Carlos,

In this post appear a eschematic of a NVA amp. Can have any relation with your question?

http://www.diyaudio.com/forums/solid-state/212450-beefing-up-nva-ap10p-amp.html#post3026619

Regards

 

[destroyer X]

Very good, as always clever Russian.

Clear explanation, very helpful...interesting that i cannot remember this circuit in Dr. Self book....well..... i may have not read the chapter i suppose.

Already found something to work on dear Vzaichenko, i have received Pionner non switching amplifier circuit...and i am simulating it and soon i gonna build to listen at it.

Thanks very much....i am glad to see you around...to see your schematic and to feel your strong and clever presence tuning positive energies to the cosmos.

Raul...i feel you good too...thank you very much....muchas gracias.

I will produce video explaining what i am reading about Pioneer NSA (Non Switching Amplifier)...well.....what i understood..... not easy to me.

regards,

Carlos

 

[destroyer X]

These videos are very basic, mainly dedicated to my Brazilian friends

Made in English too in respect to my friends in DIY audio, but i am sure people here does not need this kind of video...it is a matter of gratitude as almost all i have learned was because of this forum....but, as i said...the main target is my own people.

In English and Portuguese....2 introductory chapters and soon i will make a reading about Pioneer paper.

https://www.youtube.com/watch?v=nRL1X1cpw8Q

https://www.youtube.com/watch?v=f4n7iY4lrT8

This is for beginners only... expert, or skilled guys may feel this offensive, too much basic and boring...but it has a target.... it may reach some non skilled beginners.

regards,

Carlos

 

[destroyer X]

Here you have.... two final videos.

Now i gonna build and listen.... if not approved i will try other ideas.

https://www.youtube.com/watch?v=c1nL4_s7j1U

https://www.youtube.com/watch?v=qxON9IZmHHk

If you find something wrong with my understanding, then please let me know to fix the message i am sending
to beginners in order to avoid them to learn nonsense...i am still learning audio electronics despite more than
half century trying to understand by myself... i am sure i have a lot to learn.

regards,

Carlos

 

[franzm]

Would this circuit suffice your requirements?
Here is a simpler version.

 

[destroyer X]

Sorry, final video looks i am drunk....negative!, i do not drink..only Coca Cola

It is because deep tired.

I use to wake up early morning...aprox. 02:00.... departure to work is 05:00

I have made this video latter in the night, around 10:00 PM..... so, 19 hours wake up...brain does not work properly this way...my last two neuroniuns had trouble to think...one was sleeping and other too much lazy.

Drunk?... only once in my life..when i had 17 years old.

I have no addictions....well....maybe one...... woman!

regards,

Carlos

 

[destroyer X]

Oooops....no way!

Too much "simple" to my personnal taste dear Franzm.

In my imagination, someone that makes a design like this or is too much good as a designer or too much bad.

regards,

Carlos

 

[destroyer X]

Well dear friends, my friend and partner Mr. Fábio Zimmer made an analysis that made

much more sense to me.

I was not feeling good...i was trusting in the text written by Japanese, due to the fact they know electronics much more than i know...but things was quite strange to me the way voltage would increase.

Now i am feeling good...Zimmer made a better analysis that is much better to my old brain.

Here you have the video explaining what happened.

https://www.youtube.com/watch?v=4v04CnQd8y4

regards,

Carlos

 

[destroyer X]

Analyses posted was result of reading the Pioneer SA7800 service manual

I was feeling strange in the chapter they said how 2.4 volts increases..i was not happy...now i understand why....was wrong the analyses.

Pioneer SA-7800 Manual - Stereo Integrated Amplifier - HiFi Engine

regards,

Carlos

 

[destroyer X]

Please boys ....listen

Here:

https://www.youtube.com/watch?v=AtpcGQ3nj2w

https://www.youtube.com/watch?v=kFDO2ccjDn4

What do you think?

I feel that this thing can match my ultimate model...despite that bad recording i can feel the quality..it is clear to me alike cristal.....very clear....this is very impressive, reason why i gonna "absorb" this non switching technology and gonna apply into my stuff..this way my own amplifier gonna jump one step up!

regards,

Carlos

 

[destroyer X]

Dx Corporation already have decided

End of 2016 we gonna have the release of the top performer amplifier in Brazil...we may even export using Fedex.

I gonna use top secret ultra Dx VAS circuit and will include this NSA.

Amplifier will be called "One Step Up!"

Because gonna be one step up compared to others.... mine one already has that sound from Pioneer NSA.....imagine when include NSA circuit into it...so...one step up.

We gonna see next exciting chapter end of 2016....gonna be released in Brazil only in July 2016.

Dx Corporation exist only in my imagination...it is my dream company with golden panels and diamond volume knobs including the best from the best..the cream from the cream circuits inside....maybe one day.

Maybe Dx Step up....name may variate a little..but sound will be the best.

Auto shift DC biasing point instead of NSA.....a new name for a new circuit that gonna work almost same way.

regards,

Carlos

 

[destroyer X]

I wish you all a happy new year.

Here you have a teaser video....having fun!

https://www.youtube.com/watch?v=WDZ238d-oAs

regards,

Carlos