Bora is a nice guy from Serbia - Yugoslávia

Oh!...this way he is still happy with those things.

this is good, despite of enormous know how, did not loose passion for those things.

You know, when things turns obligation, normally our interest reduce.

Working with audio...well....may be a little boering.

Beeing a hobby is very nice...but transistors all day may be terrible.

Thanks Lumanauw

regards,

Carlos
 
!

Studio amplifier.

DRPONJA built this.
 

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Tom2 said:


The earlist reference I have is:

Raimondo Caprio, "Precision Differential Voltage-Current Converter",
Electronics Letters, Vol.9 No.6, 22nd March 1973.

Papers with S. Pookaiyaudom as one of the authors that were published
in the later part of the 70's uses the topology.

I think Brett Wilson referred to the cross topology as the Pookaiyaudom
quad (or something like that) in the early 80's in one of his papers???

Tom

Hi Tom,

Thanks for your info!
Do you have any paper in electronic format like pdf or so in the subject you could e-mail me?

Carlos,

I agree with you, sometimes it's better to not know too much, it's much more fun then! :)

Cheers Michael
 
Ultima Thule said,
Do you have any paper in electronic format like pdf or so in the subject you could e-mail me?

The papers I have are xerox copies from journals I copied back in
1990. I have about five references. The copies are in good shape. The papers are short. If you want I can scan them and e-mail them to you.
I'll have to experiment what format works best ( jpg, pdf or tiff??).

I can give you the references if you have access to a university library also.

Tom
 
Carlos,

thank you for telling us about Bora, I started to wonder where our friend was. Our thoughts is with him!

Tom,

if it's not too much job scanning those pages, please do so, I guess pdf is the favourable choice.
Unfortunately I don't have any close access to university library, but please give the refferences.

Many thanks in advance Tom,

Michael
 
Back again

I just returned from a course I attended for a week, a follow up course on Marketing. I enjoyed it a lot. It's not about electronics, nor about audio, but still I liked it.

Carlos, don't be afraid, I still have an affection for analog electronics. Although I hardly do anything with it professionally, it continues to be a hobby of mine, and I enjoy to find simple ways to realize a certain function.

Anyway, it was never my intention to belittle Bora's Delta amplifier, calling it nothing special. I just meant that the design was straightforward. It looks like a lot of attention to detail went into this amplifier.

Regards,

Steven

BTW Tom, could you send me a copy of your scans too?
 
Studio - About

Hello members of DIY-Audio Forum! I’m from Serbia, like Dr. Bora, Viktor, Boban and others. I wish to say hello and to our neighbors, The Croats, The Bosnians, The Slovenians, The Macedonians and The Montenegrins. Simply, The Yugoslavs.
I was really happy when I read all posts in this thread, especially the Subject: "Bora is a nice guy from Serbia - Yugoslavia".
Bora is really nice guy from Serbia! He gave me some his projects and, I can say, 24 hour building support ;-) I made his project called Studio, but with two modules, so I got then stereo Hi-Fi amplifier. It has 2 x 85 W at 8 ohms, Slew Rate 50 V/us, THD 0.003% in frequency band between 20 Hz and 16 kHz etc. You can see details about this project on, now very famous, Boras WEB presentation: www.bas.abshost.net.
Studio is working excellent! I tested it on my Starlet speakers with Visaton drivers (I made them, too)… and overall impression was - "Lets rock 'n' roll!!!". Later, I tested it with some softer music, like Pink Floyd, Simon & Garfunkel, Muddy Waters, some Dixieland music groups… My impressions where then on higher level… I can not use any English word for this… I hope that my Serbs will understand me ;-)
Back to the "Studio"… I added him device for the remote volume control, and 100% my addin for remote on/off…


All in all, I wish to test Studio on better speakers. I think Studio can snow better sound on better speakers than I own.
I have plans to build Boras Legend with The Tube Limiter and The Lead Pro for my guitar. I think that will be good combination for rockin' and blues/jazzin' ;-)


PS: Excuse me for my bad English, but I'm learning… ;-)


Ponjavić Dušan
 
Yes Steven, a long time reading your posts, there are consistence related all your

texts posted.....always you conduct your opinnions and evaluations in a kind way and beeing always fair.

Also you have the use to talk clear what you feel without the intention to hurt people...i could see that.

I could see that you had not bad intentions related your opinnion...and i could see that people that have too much experience, do not turn excited easily, when observe some sligtly different amplifiers, as already watched thousands.

But it is good to see that you have this love inside your heart, related those things, our circuits, amplifiers and simple ideas too.

I feel good with that, this means that my future will be better than i suppose....i was thinking that we had the chance to loose some interest when advancing in knowledge....you saying the opposite, is very good to listen.

regards,

Carlos
 
Bora is keeping silence related internet communications

This way, i think that his problem related his father health is still beeing hard to him.

All of us, soon or latter, we will have to face those life things...the fact that we can be sick, and that the life is not ethernal for no one of us.

I already lost all my more important parents...father and mother already gone... also Grandmother and Grandfather..... i go missing them hardly, with daily rememberings, but feeling happy, as they had good lives, and that i am lucky, as i never lost any of my sons.

My best wishes for Bora.

regards,

Carlos
 
Bora, keep had up to sky.

I didn't knew for that Boras tragedy. I'm really sorry for that. I can almost feel that pain because I've lost my mother five weeks ago. I'm sad because I can not materialize my feelings, maybe that will bi too much to try.
Bora, life goes on, you must keep walking through it, with had up to sky.
 
It is pretty, and with a Professional look, as they use those cables too.

It is so pretty, that i think you could spend some time more to make it completelly perfect.

The output cables can go together inside gray plastic tube, that will confuse it's color with the bottom panel.

Also the wire you have at your rigth can follow the same idea...inside tube, all them together, and panel cables (the ligth red ones... the pretty ones, can be hidden soldered under the board.

This way...you can choice some ligth color....iluminate corners and put some glass or acrilic top....to watch this pretty machine daily.

It will be something to show!...really!

I save the image, it is pretty to see.

You may think..."what a boering guy!, searching for defects in my construction!".... not exactly this way.... i could not silent about that, because your construction is so near the perfection...so close!...why not to turn it perfect?...my intention is positive.

By the way, Doctor Ponja, world languages are very interesting, and there are names that have strange meanings in other languages.... for example, i have the use to smile when i read your nick name (Ponja, do not know if family name).... this remenber in my language, esponja... sponge may be in english... some material that absorbs watter...alike a plastic foam that absorbs watter...and we use here, to call our friends that drink too much...we call them esponja...because they absorb alcoholl alike some sponge can do....the name sounds good to me...if i laugh someday about that.... i was laughing with you, together you...not laughing of you!...completely different.

regards,

Carlos
 
Bora's Studio Amplifier

Hello to all members. I have completed and tested the Studio Amp by our Dr.Bora

Construction,
Input stage matched by hfe DMM.
Output stage using MJ15003/15004.
DC offset around 5mV.

I listened to all type of music with this amp and all I can say is,
What a marvelous piece of electronics.
This amp is fantastic. Soundstage is wide, bass deep and powerfull and the highs are clear and not sharpe.
BTW, my speakers are JMLab.
The preamp used is also Bora's contribution. A headphone amp, full discrete (which I built earlier). Bora recommended it as preamp as well.

To have a second opinion, I took the stereo set to my friends house to compare with his amp (a commercial unit costing over 1,000.00 USD). But I have big problem now!!
I find difficulty to take it back

My heartfull thanks to Bora for all his assistance during constructing the headphone amp and Studio amp.

Sorry I have to borrow a digital camera for the image.
I will do it later once I have completed the full casing.

Cheers.
 
The Studio amplifier

Hi all

I had a chance to build the Studio amplifier by Dr.Jadovic some
time ago and recently I exchange some e/mails with him who
asked me my impressions about this amplifier.Of course I couldn't more positive about its quality, it is in fact a marvellous amplifier
and I do not understand why people didn't post more opinions
about it. Probably because not too many people built it...or too
busy commenting about other devices.....

Anyway, Dr. Jadovic gives on his schematic several alternatives
about the output transistors including the MJ15003/15004. But
he leaves to the consructor the option to use any of the 5
different BJT outputs that are included in his schematic.

One thing is for sure, the 15003/4 are not a good choice, they
are the 2N3055/2955 in a beefy version but still outdated
transistors that do not render justice to this excellent design.
I used the On semis MJ21193/21194 with great improvement
over the 15003/4 (wich I tried also) but I also tryied the MJ802/
MJ 4502 and these are not bad even though the voltage ratings
are quite low if you want a good margin of safety.

All in all the 2SA1943 and 2SC5200 are the best outputs you
can use on this amplifier...and on all the amplifiers that take
BJT's.