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Old 22nd September 2013, 04:37 PM   #1
maouna is offline maouna  Greece
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Default Retro amplifier 50 watt circuit

hello. i want to build one of those old style amplifiers with a single transistor as input stage . I searched the net and i found this circuit.

I would like to hear your comments and suggestions for similar circuits of the same topology...
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Old 22nd September 2013, 04:57 PM   #2
djoffe is offline djoffe  United States
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pretty standard looking example of that retro kind of thing...
C3 and C1 are kind of small for hifi applications...they'll probably cut out the low end some.
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Old 22nd September 2013, 05:00 PM   #3
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Hmm - industrial power transistors for the output transistors. ELEKTOR?
This design may be intended for lowest cost rather than good sound. There is no guarantee that just incorporating a singleton input stage and bootstrapped capacitor VAS in an amplifier is going to result in good audio.

'Nice idea and might add a lot of 2nd harmonic distortion but that might be all.
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Old 22nd September 2013, 05:11 PM   #4
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PAnos consider your self a higher capacitor in the inpou 1ufd after a quick calculation but also an RF filter combination 2 resistors and one capcitor should also be in order .

Expect plenty of harmonics short of tubish sound with out the tube issues .You know all the secrets on pcb design so go ahead do it and let us know . ....

I presume that since we havent talk much for some time that you have your self a proper set of speakers by now ...

Kind regards
busy busy
Sakis
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Old 22nd September 2013, 05:13 PM   #5
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If you want to build something with low distortion, low noise and acceptable frequency response... don't build that. I had one of those years ago and inspite of my best efforts, i couldn't make it sound even just OK. The problem was instability, if the comp cap was large enough to prevent oscillation, it killed the high frequencies. Tried re-routing the wiring, substituted tighter tolerance components, lowered the supply voltage but never could get anything close to real Hi-Fi sound. So I gave up and got rid of it, it was a total waste of time as far as I'm concerned. On the other hand, if you want to build it to learn something, then learn you will! Just don't expect too much from that design performance-wise.

Mike
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Old 22nd September 2013, 05:59 PM   #6
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If you want to build an old style amplifiers with a single transistor input stage, you should look at this one.

Very simple class B amplifier

It uses MOSFETS in the output stage and uses a split power supply, which means that there is no decoupling capacitor on the output.
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Old 22nd September 2013, 06:14 PM   #7
maouna is offline maouna  Greece
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i found the schematic here and i used it for reference : ELECTRONICA / components | projects | applications

some time ago i tried to make my self familiar with this topology and i built something quite simple with spare parts i had aside and i was impressed by the sound quality despite the poor quality parts used.

Sakis yes there has been a lot of time since we last talked. you have an amp schematic named G amp and a thread for it.have you build your amp and test it? Unfortunately i didnt manage to get a good set of speakers,just the one sony speaker i used to have for testing....
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Old 22nd September 2013, 06:18 PM   #8
maouna is offline maouna  Greece
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Quote:
Originally Posted by ingenieus View Post
If you want to build an old style amplifiers with a single transistor input stage, you should look at this one.

Very simple class B amplifier

It uses MOSFETS in the output stage and uses a split power supply, which means that there is no decoupling capacitor on the output.
thanks for suggestion...i will have a look on this .
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Old 22nd September 2013, 06:43 PM   #9
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Another suggestion Retro Amp 50W Single Supply
Regards
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Old 23rd September 2013, 09:54 AM   #10
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The 2 circuits have nothing to do in terms of sound quality the one with the other .


As about the sound Panos is not quality of sound that got your attention more likely is the content of harmonics and the specific color and sonics produced from these circuits .

Kind regards
Sakis
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