Hi Guys,
attached is a schematic with 3 similar output stages, the only difference is the resistor arrangement around the output driver stages.
I would like to know whats your opinion about these 3 different arrangements, pros and cons.
Especially myself wondering why type C is so selldom seen in amplifier designs, at least typical symmetrical designs use to have type A or B as an output driver stage.
Cheers Michael
attached is a schematic with 3 similar output stages, the only difference is the resistor arrangement around the output driver stages.
I would like to know whats your opinion about these 3 different arrangements, pros and cons.
Especially myself wondering why type C is so selldom seen in amplifier designs, at least typical symmetrical designs use to have type A or B as an output driver stage.
Cheers Michael
Attachments
Type B is recomended by Dougself over type A. He said type B has a better transistor-turnoff properties, due to crossing resistor.
I don't know if I'm wrong, but type A seems to sound better for me in low biased classAB (cold amp).
Type C commonly found in Elektor's power amp design, usually from Mr. T. Giesberts.
I don't know if I'm wrong, but type A seems to sound better for me in low biased classAB (cold amp).
Type C commonly found in Elektor's power amp design, usually from Mr. T. Giesberts.
Type B is the "Triple Darlington" stage used in the Leach Amp. Both the predriver and driver transistors run in Class A (IE they never turn off thus reducing crossover distortion). This is the output stage I use the most.
Type A is really just a predriven Emitter Follower stage, and the predrivers/drivers run in class AB.
Pass on type C but I have seen it used on the Cyrus One.
Type A is really just a predriven Emitter Follower stage, and the predrivers/drivers run in class AB.
Pass on type C but I have seen it used on the Cyrus One.
Crown Audio uses type C,
they say its Class AB+B.
the Lynx Amp uses type A.
Leach uses Type B.
and some Rotel amps uses Type B,
I did some listening tests to both B and C on my cloned and modified
RB1090 rotel amp.
Type C delivers tighter bass and smoother highs.
Type B produces a bit grainy bass but highs same as Type C.
But the final soundstage still depends on the builder.
more power,
hienrich
they say its Class AB+B.
the Lynx Amp uses type A.
Leach uses Type B.
and some Rotel amps uses Type B,
I did some listening tests to both B and C on my cloned and modified
RB1090 rotel amp.
Type C delivers tighter bass and smoother highs.
Type B produces a bit grainy bass but highs same as Type C.
But the final soundstage still depends on the builder.
more power,
hienrich
I see most power amplifiers having larger supply rails utilizes
deep darlington connection such as these connections.
For in theory, output devices suffer from large beta droop
specially when operated near their SOA limits.
so connections such as these yields beta equal or greater
than a million depending on each driver , predriver , output,
BJT's beta (hfe).
I hope am not wrong, just an idea from some sources
more power,
hienrich
deep darlington connection such as these connections.
For in theory, output devices suffer from large beta droop
specially when operated near their SOA limits.
so connections such as these yields beta equal or greater
than a million depending on each driver , predriver , output,
BJT's beta (hfe).
I hope am not wrong, just an idea from some sources
more power,
hienrich
Ultima Thule said:
Nice discussion, any reason you didn't consider predriver emitter resistors to the opposite rail? I first saw this in Otala's design IIRC. I've not tried it recently, did on the bench many years ago with a low power experimental design. They took down the Otala schematics on the web, found it in the Google cache but I don't get the images, anyone have them?:
http://64.233.161.104/search?q=cach...otala+amplifier+later+schematic&hl=en&start=2
tmblack said:
As I wrote, I use version B, so I can tell my experiences for this solution:
I think that resistors depended by the transistors. For driver, I use MJE1503x type. My experience, that this transistors like high bias, so I run them with 50-100mA, which means 12-24ohms for the drivers. I allways bypass this resistor with 0.1-1uF.
But for lower power application I use BD139/140 as driver, and for this pair 10mA bias is enough, which means 100-120ohms.
The predriver type means allways more problems for me. High power application MJE340/350 can be good, but they are bit slow (10MHz) compared to the drivers (MJE1503x 30MHz). So I had amplifier with MJE1503x predrivers. For the predriver 5-10mA enough in higher power. This results 240-470phms. The capacitor is possible, but not so important.
Predrivers for low power amp can be any low power transistor, say 2N5401/5551, MPSA42/92, BC639/640. The bias is about 2-5mA, with 470ohm - 1kohm emitter resistors
sajti
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