OpAmp as Input in Power Amplifier - exploration

[No ideas]

i have an 2x 12v transformer
its not that high power though but for 10w its fine

 

[No ideas]

It ia simple but good

found out that people often add a single diode, a resistor and a capacitor to "half bias" it or for some other reason i dont understand

also every time i made an class B circuit it only worked when the input signal went to the inverting input.

 

[arthur]

This amplifier with high voltage opamp

 

[lineup]

This is a mini amp that puts out around 5 Watt.
Single end Class A and the input is NE5532.
Transformer should be 15VAC.
Heatsink for 26 Watt and the output devices are TIP41.

 

[No ideas]

this weird single diode circuit seems to be really good at its job, the lower C2 and higher C7 the less crossover distortion there is

found out that people often add a single diode, a resistor and a capacitor to "half bias" it or for some other reason i dont understand
View attachment 1376511
also every time i made an class B circuit it only worked when the input signal went to the inverting input.

 

[Kay Pirinha]

The RCA Power Transistor Manual from the early 1970ies also shows some related examples.

Best regards!

 

[No ideas]

This is a mini amp that puts out around 5 Watt.
Single end Class A and the input is NE5532.
Transformer should be 15VAC.
Heatsink for 26 Watt and the output devices are TIP41.

no compensation capacitors and zobel networks, nice

 

[tiefbassuebertr]

under

Thread 'Power Amplifier with Small Signal OP-Amp in the Front-End - Overview wanted'

2016-02-08 8:33 pm

Power Amplifier with Small Signal OP-Amp in the Front-End - Overview and Books wanted

There are a lot of topologies for such amplifiers, but I filed they into two main groups:

1) Signal pad by voltage supply rails of small signal operational amplifier
http://sound.westhost.com/ad_fig16.gif
http://nacl.de/audiomap/sac_50.gif
http://www.diyaudio.com/forums/solid-state/41034-abacus-rieder-60-120-amplifier.html (post #5)
Bild: dacmos300jh8qu4m.jpg - abload.de...

• tiefbassuebertr
• Replies: 28
• Forum: Solid State

there are also various versions of such power amplifiers
this example was very popular:
https://www.analog.com/media/en/tec...tes/58052492001115525484056221917334AN211.pdf

R

Thread 'The Alexander amp - current feedback and opamps'

2007-09-20 7:12 pm

I'm sorry for the esoteric question here, but I asked Analog Devices directly and they have yet to respond. My two questions are about the Alexander Power Amplifier from an Analog Devices Application Note:
AN211
http://www.analog.com/UploadedFiles...211.pdf&fterm=alexander&fterm=alexander&la=en

Just to give a brief heads-up, it is a current feedback-type power amplifier that also...

• rtarbell
• Replies: 20
• Forum: Solid State

and this example from attachment is the best sounded class AB power amp, which I have ever heard (Phase Linear 400B with LF356 as front end).

 

[lineup]

no compensation capacitors and zobel networks, nice

No capacitor seems to be needed.
But we should add a Zobel. This is standard even if it does not show ...

 

[No ideas]

intresting yet again now im intrested if i should build that circuit i posted earlier.

 

[cowanaudio]

 

[lineup]

First I thought it does not work,
but perhaps it does.
There is voltage gain in the output!

 

[No ideas]

also i once run an lm741 on 30V rails and it was perfectly fine

 

[stv]

i once run an lm741 on 30V rails

but only once - then magic smoke?

 

[No ideas]

no smoke no heat it was running for 10 min before i pulled it away from the breadboard

 

[No ideas]

but only once - then magic smoke?

it was perfectly fine afterwards

 

[wg_ski]

That output stage is known problematic, though. There are ways of fixing it, but no one ever does.

 

[cowanaudio]

First I thought it does not work,
but perhaps it does.
There is voltage gain in the output!

You'd want just enough gain so the output can be driven to the rails, not too much. With a modern opamp and better driver and output transistors this circuit could work quite well. A proper bias spreader could be beneficial, too.

 

[stv]

There are ways of fixing it, but no one ever does.

is the elektor variant in post #11 better?

 

[No ideas]

on the topic of the 741 i found this schematic, im geniuenly intrested if some company is willing to sell something like this in an to-220 package as an all in one transistor driver, all you need to do is make an separate output from each emitter