Bora is a nice guy from Serbia - Yugoslávia

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fotios

fotios

Member
Joined 2007
fotios said:


Dr. Jagodic, as Sakis Petropoulos says there is no problem with YOURS original design if the supply does not exceeds +/- 45Vdc. But Sakis wish to use it in P.A. applications thus the supply must exceed +/- 65Vdc to take an output of 200Wrms. And the problem is there, because the instability caused. YOURS original design with so high supply presents a d.c. offset of -200mV and during operation the swing of output goes more negative. Also the Mosfets are very sensitive in accidental pluggins or unplaggins in the amplifier's input. I don't have experiene with mosfets and quasi complementary outputs, but mr. Nelson Pass suggested to remove the diode so the output goes more positive. Also, according to your suggestion i removed the source resistors in their correct place (as mr. Pass said to me, these resistors are indispensable for the proper sharing of current). To resolve the dc offset i proposed the VR1 between the emitters of difference amplifier transistors. Also mr. Pass propossed the 2 zeners in this place shown in draw exactly to protect the gates from unwanted spikes. And for a more symmetrical output swing, according to an app. note of RCA i added a driver 2N5551 in the upper pair of mosfets. But i am not in possesion to confirm that this circuit works. Can you please throw a glance in the modified circuit quoted bellow to make your comments or your suggestions before its posting in the thread "Mosfet protection diodes"?
Kind Regards
Fotios Anagnostou

An externally hosted image should be here but it was not working when we last tested it.
Click to expand...

I apologize for the spelling mistakes. Where you read OUR please place YOURS to not misunderstood. I am not colaborate with mr. Sakis Petropoulos. I am not interested about Mosfets. Particularly i hate Mosfets. I hate my country and his inhabitants and i only love the ancient Hellas and my ancient ancestors. I am occupied only with BJTs and i am lone investigator. I have gived my credentials through MY project "Dirty Harry". Carlos knows better. Ask him. Please don't attack to me. The only that i make is to help someone. There is not any company. I have not any proffit from yours project. Mr. Sakis make the 30 amplifiers not me. And you Carlos?
Kind Regards
FOTIOS ANAGNOSTOU THE ONLY AND ONE
 
east electronics

east electronics

Member
Joined 2006
eastelectronics.gr
this is not easy

many times i tryied to ask for help about my problem without hurting anyone .....

it seems that how many times i apologize to dr Bora it doesnt work ...i apologize for something i said while furious with my project ....

if dr Bora or any body else doesnt accept an apologie then there is not much i can do ....

my intention about the use of the amplifiers considering how many i am gona make and what exactly was my original specs abou the amp exist in the original mail and answer i got from dr Bora and i have absolutely no problem to publish that to make shure what went wrong in the first place .....

in my world dr bora....good technicians will always focus on solving technic problems and simply forget all tha bla bla bla about who said what and how wrong or right this might was ......

about a zilion times i thanked you in public about the things you did ...so from my point of view all is ok

you dont wana bother any more with this problem ????? Very good dr Bora so do us a favour and let all these wonderfull people who are willing to see legends to opetrate stable and powerfull in rails above 60volts .......

finaly lets not forget that in my last e mail i asked you to take a last look at it so we can solve this together and nobody else bothers with it .....still got no answer so here i am asking for protection methods and look what hapens


fair well dr bora best regards sakis
 
I

Iyremenko

Disabled Account
Joined 2007
This design has some serious drawbacks, likewise abrupt changes in bias current when there is a variation in Rail voltage, which is causing the unstability, neither the differential current is constant nor the Vas current is constant because there are no CCS or some form of current stabilization.It is simply a adaptation of quasicomplementary BJT amplifier in which the NPN BJTs are just replaced by N-channel Mosfets, nothing else. No VAS emitter degeneration is seen and also the CFP formed by lower Mosfet+BJT combination is very much prone to oscillation. Low efficiency is another "key" feature of this design.A silly design in nature.
 
east electronics

east electronics

Member
Joined 2006
eastelectronics.gr
thank you sir

for your very kind words

this amplifier is working like hell considering the specs and the original requirements ... versus simplicity and cost

also it very easilly outperfoms other amps much more complicated and with all these modern techniques

another thing i said to Andrew t is that ...

on the road you will find both rolls royce and hundai .... if this amplifier is huyndai to you i am absolutely fine with that .....

no mater what i thank you for your opinion and the things you say

thank you sir
 
B

boraomega

R.I.P.
Joined 2005
bas.elitesecurity.org/
fotios said:


I apologize for the spelling mistakes. Where you read OUR please place YOURS to not misunderstood. I am not colaborate with mr. Sakis Petropoulos. I am not interested about Mosfets. Particularly i hate Mosfets. I hate my country and his inhabitants and i only love the ancient Hellas and my ancient ancestors. I am occupied only with BJTs and i am lone investigator. I have gived my credentials through MY project "Dirty Harry". Carlos knows better. Ask him. Please don't attack to me. The only that i make is to help someone. There is not any company. I have not any proffit from yours project. Mr. Sakis make the 30 amplifiers not me. And you Carlos?
Kind Regards
FOTIOS ANAGNOSTOU THE ONLY AND ONE
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Fotios, none of those things are addressed to you. Your only “sin” (if there is one?) is maybe your naïve approach and good heart that inspired you to attempt to help in a situation of which you haven’t been informed sincerely about all fact and intentions. Enjoy your life my friend and be a bit more cautious next time. My extremely high opinion about Greek people (that I cherished through most of my life in my heart… and I know why!!!) won’t be changed! As a great man CARLOS would say: “Don’t wary… be happy!”

FINAL!!! This is all I have to say regarding entire story about my LEGEND amp and Mr. Sakis. I won’t respond in any way in a future as far as this issue is concerned PERIOD!
 
B

boraomega

R.I.P.
Joined 2005
bas.elitesecurity.org/
Just for relaxing... a good joke for all good friends:

Man is sitting in his ”Maybach” Mercedes awaiting for a green on a traffic light when suddenly another guy with Fiat Seicento smashed into his car in full speed. Still I shock, Maybach driver looked at big display on cockpit where small info window just popped up saying:
“New hardware found!”
“Do you want to install it?”
:smash:
 
B

boraomega

R.I.P.
Joined 2005
bas.elitesecurity.org/
Well “alex mm”, I am glad for you and your progress in audio area. My “OMNI-protector” is one good, reliable and very flexible solution addressing several important issues at the same time and universally applicable to almost all modern solid state amps (of course -with appropriate minor changes in values here and there). I can frequently read treads about DC protection solutions, speaker ON delay etc. etc. and I am quite often tempted to jump into discussion and suggest my OMNI as a solution, but then, it’s not in my nature to neither explicitly suggest anything to anyone nor to push my solutions under their noses!
 
V

viktor1986

Member
Joined 2005
!

here is my OMNI
 

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G

gaborbela

Member
Joined 2005
HI
Finally I have all the information about the Studio amp so now I can each the PC board and start collecting all the parts .
I would like to know if I use 36-0-36V DC to power up the amp do I have to replace some parts (resistors) .
I know I will get out less power but I have these transformer so I would like to us it .
Please let me know , any comment welcome .

Regards
 
B

boraomega

R.I.P.
Joined 2005
bas.elitesecurity.org/
Well "gaborbela", I haven't tried it with that supply voltage, but it is very unlikely anything significant "on ears" will happen apart from lower output power. For putting it back to full characteristics it posses with nominal supply, it will be necessary to recalculate some values, but I have to tell you that at the moment I am really not in a position to spend time to do that for you... sometimes later - of course, but not now! That shouldn't stop you from making this amp, because it will probably perform good enough that you won't be able to notice any significant difference "on ears"!
You can always contact me directly on my E-mail available on my WEB site!
 
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