let's tweak this amp!!!!!

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#21
MikeB said:
To be absolutely honest, i personally do not like this amp/design (too many flaws, problems to be expected), i guess you are better served if you go after one of quasi's amps. These are well regarded high power amps and "finished" designs and you will get support...

sorry,
Mike
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I agree, but then, he did ask for tweaks 🙂
 
#27
Yes...if he decided to do this one...let`s help him the way we have done

Because if we go really to suggest him a better amplifier...hehe...at least 5 different ideas will appear.

You know those things...each one has their own preferences.

Fratello fa molto benne...piace questo.... avanti.

He is doing what he wants...he like this one...let him go ahead with our attention an support.

Also, there are many sophisticated designs that will make you give a shot over the boards when comparing with this one.

Last year i knew a guy that developed his own amplifier...and he could win one 1000 dollares Yamaha Receiver...so.... let him develop this old schematic, to conclude things too.

Things are subjective, as you know, as distortion in highs sometimes are considered Effect...beeing defect!....and there are people that say that this means high frequency quality.

Some other amplifiers that have mufled trebles, are considered by many as warm and delicated sound...and some guys prefered those ones.

This one, using as bass...will produce a nice extended bass range... with those thunder sound that continues alike damping... some guys love this Petrol Barrel sound...that fake and loooooonnnng booommmm...well..... despite recognize this is not high fidelity...i love those fake bass.

Well...High Fidelity is alive music, to stand over a higher stand above the Orchestra...or be married 30 years without jump over the fence...hehe.

regards,

Carlos
 
#28
ilimzn said:
C4. DON'T use a 4V rating, a 63 or 100V 1000uF cap is not that big any more, and since the audio signal current goes through it, you really want a good performance.as long as you remember that if the output stage ever blows, you MUST replace this cap. This is often missed when repairs are made!
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This thread isn't so bad even if the Elektor 100 watter is.
Ilimzn's words should be part of the repair 10 commandments, let's highlight them.
 
#29
MikeB said:
Hi ilimzn, maybe i am not paranoid enough... 😉 I never blew non fake output devices... yet... But i also do not operate at +/- 60v.

Mike
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Neither did I, but I did come across a number of 'second source' replacements that were not really that. In general, the Vce and Ic max parameters are the same, but it's a different device. Just recently I had a 'direct replacement' that had a Vce of 120V instead of 150, and Ft of 10MHz instead of 30 - according to the manufacturers datasheet! I've also had a number of BDV64/65C that had abysmal SOA performance. They were all 'genuine replacements' until you manage to get an actual datasheet with the relevant graphs (usually they just print the numbers, no graphs) and then you see it's not the same device at all.
BDX66/67 have been obsolete dince the late 80s - and semelab, although using the exact same processes, is very expensive. The other replacement is a virtual 'no-name'. Given this situation, it is easyer to find a current replacement from a reputable manufacturer.
 
#31
I think that paralleling output transistors there is need of a forced current sharing, how i can do this? simply doubling emitter resistors(one per transistor) or leaving that resistor and adding 0,1ohm 5w collector resistors?
i attached the 2 configurations...
then A or B (or others)
 

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