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Old 6th April 2010, 08:23 PM   #21
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on the other hand my dear Uncle Charly

here is a chalenge to something easy that could unite various opinions and various approach from diferent respected forum members ....

you have perfect designs like the DX that provide quality but no protection and no power

then you have the dhr series with cousins still offer more power still offer quality and no protection

you have dr Boras designs that are very nice designs they offer power they offer quality but no protection and not so many bulited arround here to support many details and as dr Bora stated ..."he doesnt design idiot proof amplifiers "

the next power full design will be may be QUASI's designs overdated but working design lots of power but still no protection ....

then you have rods P68 loads of power protection and class AB+B design which is lower quality

if you look at it from any aspect the only workable design is the GREEK DIRTY HARRY BY FOTIOS but still this is might be the best powerfull amplifier in its class of course but not cost effective

then you have the Andrew T approach which is in a few words : overdesign everything to be on the safe side and built amplifiers only based on soar plots of output transitors very nice i think but still not cost effective ....

so here is the chalenge Uncle Charly proper made amplifier in the class of 250W at 8 ohms / simply made offering quality/stability /with idiot proof protection/and cost effective

cost effective = is as much it can be in class AB since we will never manage to produce anything that is DSP related

finally the Lynx coyld be a good approach but still 150w is too liltle power

you see .... my all very good friends i have no design skills (eventhough for this year i have repaired or updated arround 180 amps in my shop ..... ) i am one of the many that construct your amplifiers ...i have constructed from ROD , from Quasi , from Uncle Charly ,From dr Bora, the lynx and a few others that i dont remember ... so anyway you slice it my opinion counts ha ha ha

thanks every one !!!

Last edited by east electronics; 6th April 2010 at 08:42 PM.
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Old 6th April 2010, 08:54 PM   #22
wahab is offline wahab  Algeria
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Single differential using a current mirror have a huge
advantage in low frequency open loop gain , that will
allow high negative feedback ratios.
Implementing current mirrors in symetrical differentials
is not an easy task since the two Vas are not current limited as
in a simple differential where the Vas current is limited either by
bootstrap resistors or a current source.

This require a better global design, as there will be less
negative feedback to correct for the lacks in the chain
from input to output..

In short, single differential amps with current mirrors
are way more tolerant of design issues that are not
extremely critical , thus their adoption in mass produced
amplifiers, using negative feedback as a global cure..
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Old 6th April 2010, 09:03 PM   #23
Bigun is offline Bigun  Canada
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Perhaps I should not cause your head to grow too large, but you deserve some additional credit not given in this thread.

Not only have you built a lot of amplifiers, but this is a DIY forum and your posts have inspired people to build things. I have to admit that it was one of your threads that pulled me into this forum and eventually into this hobby in the first place. In my opinion, you avoid taking things too seriously (most of the time) and you are one of the few people here who have an ability to 'keep themselves honest' and not get stuck doing the wrong things for too long if they aren't yielding good results. You are not shy to borrow ideas from others and use them to have fun.

I believe that the (commercial) future is going to involve more advanced technologies and ideas, providing lots of opportunities for bright young people like Keantoken and Eva etc. But for DIY pleasures there's much to be said for a nice great sounding amplifier project that can still be constructed using the unaided eye and tested without a NASA laboratory.

p.s. I don't see a strong reason why a symmetrical amplifiers shouldn't sound every bit as good as non-symmetrical (even accounting for harmonics), but then again, I haven't built one yet so I will endeavour to try it, perhaps Class A for simplicity.
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

Last edited by Bigun; 6th April 2010 at 09:05 PM.
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Old 6th April 2010, 09:21 PM   #24
Eva is offline Eva  Spain
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His powerful enthusiasm is the thing I like about Carlos, I'd like to see him improving his design skills because the result could be very good
I use to feel like the small child in The Emperor's New Clothes tale
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Old 6th April 2010, 10:04 PM   #25
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Originally Posted by Bigun View Post

Perhaps I should not cause your head to grow too large, but you deserve some additional credit not given in this thread.

Not only have you built a lot of amplifiers, but this is a DIY forum and your posts have inspired people to build things. I have to admit that it was one of your threads that pulled me into this forum and eventually into this hobby in the first place.
Hello Bigun and Carlos

I agree with you Bigun, for me Carlos was one of the first guy who reply to my first question wen, few years ago, I start in the forum and post my first question, after that first question I've learn a lot by reading and following for months all the Dx thread.

Thank Carlos for the times you give to the forum.


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Old 6th April 2010, 10:14 PM   #26
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I would concur with wahab, I have had both blameless and dual differential complimetary designs, both were good to listen too, but the dual differential just stood the test of time for me anyway. As wahab states it is a little more difficult to get working the way you want it to, but the end results are stunning. I am using dual differencial complimentary topology in all three of my amplifiers driving a three way transmission line and the results are absolutely awesome. Also sold a couple but not from wanting to.
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Old 6th April 2010, 10:22 PM   #27
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Default Nice point of view dear Bigun..also dear Sakis, my friend Gaetan

Also Niko Ras and Wahab...interesting point of view.. i am read them all, with interest.

heheheh...i am producing a speaker protection (copy from Slone) dear Sakis..this one let the speaker safe and do not harm sonics.

I have not people complaining about my amplifiers burning... so, i do not think it is an emergency to include protections on them.

I had several burns, but torture tests..full power, clipping square wave, high frequencies, crazy loads using 2.2uf in paralell...full power tests when others do their tests at 10 watts and using 10 kilohertz in place to use full power and 20 kilohertz...i had that crazy transformer too... a defective unit i have found...waiting in the future other one face the same trouble, then i will learn from him about the stuff.

I thank you, dear friends, by the kind is nice to be a counterweigth to ballance hostilities from time to time i face from the owner of the truth, the ones have all knowledge, all skills and sometimes talk with the noise crowd.

heheh...i tried in the google, to see if possible a good version of my words...resulted this..very poor version:

"....those who sometimes lose their precious and
golden time throwing a few crumbs of knowledge
superior to the rude and ignorant mob."

Thanks lord they exist..without them we would not be able to listen music!

Germans!.... watch this!:

Last edited by destroyer X; 6th April 2010 at 10:25 PM.
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Old 6th April 2010, 10:23 PM   #28
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Old 6th April 2010, 10:47 PM   #29
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Default I understand you need professional amplifiers Sakis, with protections

I can show you how to calculate them, how to design them..if you need, as i think you already know how to do that.

I can do that by email..but i think you do not need my help on that.

Will not include protections in mine ones, as they are not professional, they are for audiophile, good units, some of them simple, to be made at home, diy stuff.

Also, you can include, if you need, protections in VAS and in the output, using V/I limiters in all amplifiers, the calculation is basic, very simple, and the diagram is knows by everywhere..also you can design them to limit the way you want.

I prefer the stone age method.... a lot of power transistors..but this is not good for business,as turns the amplifier more expensive...because of that they use these hell limiters.

The schematic posted in the first or second post, shows the limiter..that's the way they have found to reduce costs, reduce heatsink size, reduce quantity of output transistors and reduce quality is a matter of decision.

To me, in my point of view, the inclusion of limiters is dirty and criminal .. in the vision of other people, having other points of view, it is a perfect technical solution...something unavoidable, extremelly needed... something clean and anjelical.


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Germans!.... watch this!:

Last edited by destroyer X; 6th April 2010 at 10:52 PM.
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Old 6th April 2010, 11:51 PM   #30
a.wayne is offline a.wayne  United States
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Originally Posted by Eva View Post
After 50 years building I'm sure you have very good building abilities (at least for building amplifiers in the way they were 25 years ago, because you seem to completely reject all the progress made in the last 25 years )

Creativity and open scientific mind are different abilities. You can build amplifiers for 50 years without developing them. In fact I think you lack both, and it's probably too late in your life to develop them.

I have not been doing anything for 50 years because I'm way younger. However, after 4 years learning class D by myself now I'm the designer of one of the smallest, lightest, most efficient, most cost effective and most powerful subwoofer plate amplifiers currently in the professional audio market. It's (conservatively) rated 4000W @ 2 ohms with greater than 90% efficiency and only 7lbs weight (including heatsink, faceplate and DSP).

This claim is not as eloquent as yours, it's much harder to reject.

Be creative. Make real achievements.
are you saying the same experience every time for 50 yrs ....

Carlos i concur with Bigun, your technical madness has made me take a look from time to time , i enjoy your Bravado and what you bring to the table, so speak freely, those who know you are mad don't care and the others don't count ...

Confucius say: Amp dat can't drive one ohm, have no life for samba

Last edited by a.wayne; 7th April 2010 at 12:11 AM.
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