class A amplifier

On Oct 16, 8:42 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Wed, 15 Oct 2008 10:07:47 -0700 (PDT), mrdarr...@gmail.com wrote:
On Oct 14, 12:27 pm, Olivier Scalbert <olivier.scalb...@algosyn.com
wrote:
mrdarr...@gmail.com wrote:
Say... what *is* your ultimate objective, by the way? If you want a
good (reasonably efficient, relatively cheap, good sound quality,
medium power) solution quickly, you may be happy with the LM3886.
http://www.national.com/mpf/LM/LM3886.html

Best wishes,

Michael

Thanks for the link to the LM3886.

What is my ultimate objective ?
Mmmm, ... difficult question !
;-)

For now, it is having fun.
And for me (and for now) having fun is:
- to be able to build something real that I can touch and listen (I am
building software all day long);
- to experiment with my children;
- to learn something;
- to mix theory and practice;
- to exchange ideas with people;
- listening music on something I have build and designed;
- writing some code to generate different audio waveforms at different
frequencies. I will put them on cd for testing (I have a scope but no
function generator);
- to sniff solder smoke;
- to burn my fingers with hot components (practice the Joule effect);
- ...

I am not interested in buying a new amplifier (I have already a Cyrus)
Or perhaps a Nad C325BEE ...

Olivier

These look interesting too.
http://sound.westhost.com/project12a.htm
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm

The H. C. Lin amplifier from 1956 started the whole Class AB (B?)
thing, eh?

Michael

Good grief, people keep building minor variations on the same circuit
for, what, 45 years now?

John

More like 52 going on 53, looks like...

Oh well, it's either that or Class A...

Any progress on reducing the distortion in high-power Class D amps
yet?

Michael

 

On Oct 16, 9:14 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Thu, 16 Oct 2008 09:00:43 -0700 (PDT), mrdarr...@gmail.com wrote:
On Oct 16, 8:42 am, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Wed, 15 Oct 2008 10:07:47 -0700 (PDT), mrdarr...@gmail.com wrote:
On Oct 14, 12:27 pm, Olivier Scalbert <olivier.scalb...@algosyn.com
wrote:
mrdarr...@gmail.com wrote:
Say... what *is* your ultimate objective, by the way? If you want a
good (reasonably efficient, relatively cheap, good sound quality,
medium power) solution quickly, you may be happy with the LM3886.
http://www.national.com/mpf/LM/LM3886.html

Best wishes,

Michael

Thanks for the link to the LM3886.

What is my ultimate objective ?
Mmmm, ... difficult question !
;-)

For now, it is having fun.
And for me (and for now) having fun is:
- to be able to build something real that I can touch and listen (I am
building software all day long);
- to experiment with my children;
- to learn something;
- to mix theory and practice;
- to exchange ideas with people;
- listening music on something I have build and designed;
- writing some code to generate different audio waveforms at different
frequencies. I will put them on cd for testing (I have a scope but no
function generator);
- to sniff solder smoke;
- to burn my fingers with hot components (practice the Joule effect);
- ...

I am not interested in buying a new amplifier (I have already a Cyrus)
Or perhaps a Nad C325BEE ...

Olivier

These look interesting too.
http://sound.westhost.com/project12a.htm
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm

The H. C. Lin amplifier from 1956 started the whole Class AB (B?)
thing, eh?

Michael

Good grief, people keep building minor variations on the same circuit
for, what, 45 years now?

John

More like 52 going on 53, looks like...

Oh well, it's either that or Class A...

Or, Heaven forbid, a few new ideas?

John

Class D? Class G?

Michael

 

[Eeyore]

Olivier Scalbert wrote:

Eeyore wrote:

I understand now. Now if you'd mentioned a bit of this in the OP, we might have
got off to a better start.

In my first post I have said that I have not done analog electronics
since a long time ...
which is true !

;-)
Anyway, no problem, we can continue ...

Oh, I doubt John Fields will allow that. He's a sad old git who will just shout me
down now. Shame since I could have taught you the whole gamut of output stage
operational ranges.

Graham

 

[John Fields]

On Thu, 16 Oct 2008 19:52:16 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

Olivier Scalbert wrote:

Eeyore wrote:

I understand now. Now if you'd mentioned a bit of this in the OP, we might have
got off to a better start.

In my first post I have said that I have not done analog electronics
since a long time ...
which is true !

;-)
Anyway, no problem, we can continue ...

Oh, I doubt John Fields will allow that. He's a sad old git who will just shout me
down now. Shame since I could have taught you the whole gamut of output stage
operational ranges.

Awww...

And now you won't because I made you cry, poor baby, and it's my fault
that you won't help Olivier?

Grow up.

JF

 

[Olivier Scalbert]

john jardine wrote:

A beautiful description. It's what drives me as well. If something is not
enjoyable, then through choice it should not be pursued.
I sometimes get the feeling that many professionals (of all callings!) are
born with their boots on, (a local expression) hence never need to pass
through a learning phase .


John,

When I will complete my amplifier (in few years !), I will do some
plasma speakers !
http://www.youtube.com/watch?v=2Lr8tVC-Qx0

;-)

Olivier

 

[Phil Allison]

"John Larkin"

"Phil Allison"


Agree, but I have no negative supply yet. I have to found or buy or
build
one.


** Consider changing you circuit to include an inductor in place of the
load
resistor - best if you put one in the collector circuit.

Schematic?


** See schem near bottom of page - left click on it to get readable size.

http://www.siliconchip.com.au/cms/A_30859/article.html

This shows a mid 1960s, AWA ( Australian made) all transistor, 12v car
radio.

The 2N301 output transistor ( operating in class A) has an inductor in the
collector circuit, with the speaker wired across it.

Such output stages delivered about 4 watts and had a nice "tone" .



Oh, that changes things. Oliver proposed an emitter follower, and the
issue I brought up was the limited negative swing associated with the
passive pulldown. This circuit moves the load into the collector, with
no feedback, which increases swing but kills low-end response and
makes Zout very high.

** There is no lack of low end response - you arrogant ass.

NFB can easily be added, if wanted.

And needs a big inductor.

** The component is about match box size.

I told the OP where to get one for nothing.

Some big old AM transmitter plate modulators used this inductor-load
config, since it let the RF stage B+ swing from almost ground to twice
the supply voltage. Inefficient as hell, of course, as class A is.

** Approaches 50% efficiency at full output.

I sort of like the emitter follower with an active current sink.

** Yawnnnnnnn.

Vastly inferior power and efficiency.



....... Phil

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
Olivier Scalbert wrote:
Eeyore wrote:

I understand now. Now if you'd mentioned a bit of this in the OP, we might have
got off to a better start.

In my first post I have said that I have not done analog electronics
since a long time ...
which is true !

;-)
Anyway, no problem, we can continue ...

Oh, I doubt John Fields will allow that. He's a sad old git who will just shout me
down now. Shame since I could have taught you the whole gamut of output stage
operational ranges.

Awww...

And now you won't because I made you cry, poor baby, and it's my fault
that you won't help Olivier?

Indeed, because anything I say now, you will simply shoot down in flames.

Graham

 

[Eeyore]

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
Rich Grise wrote:
Eeyore wrote:
"olivier.scalbert@algosyn.com" wrote:

I want to do a small class-A music amplifier + preamp. I want to find
the best trade-off between simplicity and sound quality.

Stop mucking about with stuff you don't understand and simply buy a modern
hi-fi amp.

Graham, don't be a dork. The guy wants to _BUILD_ stuff! He needs to be
encouraged - the "let's build it and see how it works" mentality is all
too rare these days.

I agree with the principle but it seems he hasn't done his homework first. His
present course of action is more likely to involve learning how to let the magic
smoke out. So I have directed him here ....
http://www.dself.dsl.pipex.com/ampins/ampins.htm

Where he will find a wealth of first class info.

The class A emitter follower is not a bad initial learning experiment,
and has some interesting variants. What's the point of just copying
old circuits? That's not design.

A Class A emitter follower ISN'T an old circuit ?

The point is that it's HIS circuit. And it has some potentially
interesting variations. IF you allow yourself to think.

It's a lousy circuit and I won't waste any time trying to dress up its well-known
shortcomings. If he wants a good class A output stage he needs to go back to the drawing
board.

Graham

 

On Oct 16, 2:06 pm, Olivier Scalbert <olivier.scalb...@algosyn.com>
wrote:

john jardine wrote:
A beautiful description. It's what drives me as well. If something is not
enjoyable, then through choice it should not be pursued.
I sometimes get the feeling that many professionals (of all callings!) are
born with their boots on, (a local expression) hence never need to pass
through a learning phase .

John,

When I will complete my amplifier (in few years !), I will do some
plasma speakers !http://www.youtube.com/watch?v=2Lr8tVC-Qx0

;-)

Olivier

Nice! I wonder if it has good low-frequency response?

Could have trouble getting UL certified...

M

 

[John Larkin]

On Fri, 17 Oct 2008 08:43:54 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

"John Larkin"
"Phil Allison"


Agree, but I have no negative supply yet. I have to found or buy or
build
one.


** Consider changing you circuit to include an inductor in place of the
load
resistor - best if you put one in the collector circuit.

Schematic?


** See schem near bottom of page - left click on it to get readable size.

http://www.siliconchip.com.au/cms/A_30859/article.html

This shows a mid 1960s, AWA ( Australian made) all transistor, 12v car
radio.

The 2N301 output transistor ( operating in class A) has an inductor in the
collector circuit, with the speaker wired across it.

Such output stages delivered about 4 watts and had a nice "tone" .



Oh, that changes things. Oliver proposed an emitter follower, and the
issue I brought up was the limited negative swing associated with the
passive pulldown. This circuit moves the load into the collector, with
no feedback, which increases swing but kills low-end response and
makes Zout very high.


** There is no lack of low end response - you arrogant ass.

I hate to shock you, but inductors trend towards short circuits at low
frequencies. Sorry.

And what's the damping factor here?

NFB can easily be added, if wanted.

But it doesn't have any. Loop dynamics would be interesting.

And needs a big inductor.

** The component is about match box size.

I told the OP where to get one for nothing.


Some big old AM transmitter plate modulators used this inductor-load
config, since it let the RF stage B+ swing from almost ground to twice
the supply voltage. Inefficient as hell, of course, as class A is.

** Approaches 50% efficiency at full output.


I sort of like the emitter follower with an active current sink.


** Yawnnnnnnn.

Having trouble staying awake again, I see. Do you guys get decent
coffee down there?

John

 

[Phil Allison]

"John Larkin Cunthead "

** Consider changing you circuit to include an inductor in place of
the
load resistor - best if you put one in the collector circuit.

Schematic?


** See schem near bottom of page - left click on it to get readable
size.

http://www.siliconchip.com.au/cms/A_30859/article.html

This shows a mid 1960s, AWA ( Australian made) all transistor, 12v car
radio.

The 2N301 output transistor ( operating in class A) has an inductor in
the
collector circuit, with the speaker wired across it.

Such output stages delivered about 4 watts and had a nice "tone" .



Oh, that changes things. Oliver proposed an emitter follower, and the
issue I brought up was the limited negative swing associated with the
passive pulldown. This circuit moves the load into the collector, with
no feedback, which increases swing but kills low-end response and
makes Zout very high.


** There is no lack of low end response - you arrogant ass.

I hate to shock you, but inductors trend towards short circuits at low
frequencies. Sorry.

** How idiotic.

NFB can easily be added, if wanted.


But it doesn't have any.

** See above - you asinine fuckwit.

And needs a big inductor.

** The component is about match box size.

I told the OP where to get one for nothing.

** Lack of reply noted.

Larkin = just another loathsome, ASD fucked, septic ASS !!!





...... Phil

 

[John Larkin]

On Fri, 17 Oct 2008 14:11:49 +1100, "Phil Allison"
<philallison@tpg.com.au> wrote:

"John Larkin Cunthead "



** Consider changing you circuit to include an inductor in place of
the
load resistor - best if you put one in the collector circuit.

Schematic?


** See schem near bottom of page - left click on it to get readable
size.

http://www.siliconchip.com.au/cms/A_30859/article.html

This shows a mid 1960s, AWA ( Australian made) all transistor, 12v car
radio.

The 2N301 output transistor ( operating in class A) has an inductor in
the
collector circuit, with the speaker wired across it.

Such output stages delivered about 4 watts and had a nice "tone" .



Oh, that changes things. Oliver proposed an emitter follower, and the
issue I brought up was the limited negative swing associated with the
passive pulldown. This circuit moves the load into the collector, with
no feedback, which increases swing but kills low-end response and
makes Zout very high.


** There is no lack of low end response - you arrogant ass.

I hate to shock you, but inductors trend towards short circuits at low
frequencies. Sorry.


** How idiotic.


NFB can easily be added, if wanted.


But it doesn't have any.


** See above - you asinine fuckwit.



And needs a big inductor.

** The component is about match box size.

I told the OP where to get one for nothing.


** Lack of reply noted.

Larkin = just another loathsome, ASD fucked, septic ASS !!!

Speaking of damping factor, you're getting a little boomy yourself
lately.

John

 

[Olivier Scalbert]

mrdarrett@gmail.com wrote:

Nice! I wonder if it has good low-frequency response?

Could have trouble getting UL certified...

M
Back to the 80s, I have listened a plasma tweeter from the Magnat

company. It was amazing. No mechanical moving part, no directivity.
The sound is everywhere in the room.
One asks them if they have something for medium and bass.
(Marketing ?) answer is "no" due to patents owned by the army ...

I think that the major problem is the production of ozone, which was not
good for health. Perhaps that also interests army !

Olivier

 

[John Fields]

On Fri, 17 Oct 2008 02:38:08 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
Olivier Scalbert wrote:
Eeyore wrote:

I understand now. Now if you'd mentioned a bit of this in the OP, we might have
got off to a better start.

In my first post I have said that I have not done analog electronics
since a long time ...
which is true !

;-)
Anyway, no problem, we can continue ...

Oh, I doubt John Fields will allow that. He's a sad old git who will just shout me
down now. Shame since I could have taught you the whole gamut of output stage
operational ranges.

Awww...

And now you won't because I made you cry, poor baby, and it's my fault
that you won't help Olivier?

Indeed, because anything I say now, you will simply shoot down in flames.

---
If you have a defensible position, how could I?

I think this whole "gamut of output stage" thing is made up, but prove
me wrong; let's see what you've got...

JF

 

[John Fields]

On Fri, 17 Oct 2008 02:40:29 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
Rich Grise wrote:
Eeyore wrote:
"olivier.scalbert@algosyn.com" wrote:

I want to do a small class-A music amplifier + preamp. I want to find
the best trade-off between simplicity and sound quality.

Stop mucking about with stuff you don't understand and simply buy a modern
hi-fi amp.

Graham, don't be a dork. The guy wants to _BUILD_ stuff! He needs to be
encouraged - the "let's build it and see how it works" mentality is all
too rare these days.

I agree with the principle but it seems he hasn't done his homework first. His
present course of action is more likely to involve learning how to let the magic
smoke out. So I have directed him here ....
http://www.dself.dsl.pipex.com/ampins/ampins.htm

Where he will find a wealth of first class info.

The class A emitter follower is not a bad initial learning experiment,
and has some interesting variants. What's the point of just copying
old circuits? That's not design.

A Class A emitter follower ISN'T an old circuit ?

The point is that it's HIS circuit. And it has some potentially
interesting variations. IF you allow yourself to think.

It's a lousy circuit and I won't waste any time trying to dress up its well-known
shortcomings. If he wants a good class A output stage he needs to go back to the drawing
board.

---
What he needs is a little guidance and since you profess to be able to
run through the gamut of output stages, why not offer a little help
instead of the little game you're playing?

JF

 

[Eeyore]

John Larkin wrote:

"Phil Allison" wrote:
"John Larkin"

I sort of like the emitter follower with an active current sink.

** Yawnnnnnnn.

Having trouble staying awake again, I see. Do you guys get decent
coffee down there?

Better by far than the active current sink is the active DRIVEN transistor !

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
John Fields wrote:

Graham, why are you so aggressive with me ?
What is your problem ?

---
I believe both of his parents died when he was very young

Fairly young and was that simply a guess ?
---
No, you mentioned it in one of your earlier posts,
---

But it never made me aggressive.

---
Hogwash.

You may pretend to passivity, but whenever you get a chance you jump on
someone's case and try to shout them down relentlessly.

I can't abide fools. I've seen so many (including the ones the neglect first class advice
and go on to trash entire companies) to have time for them any more. Life isn't long
enough for that.

Graham

 

On Oct 16, 11:15 pm, Olivier Scalbert <olivier.scalb...@algosyn.com>
wrote:

mrdarr...@gmail.com wrote:
Nice! I wonder if it has good low-frequency response?

Could have trouble getting UL certified...

M

Back to the 80s, I have listened a plasma tweeter from the Magnat
company. It was amazing. No mechanical moving part, no directivity.
The sound is everywhere in the room.
One asks them if they have something for medium and bass.
(Marketing ?) answer is "no" due to patents owned by the army ...

I think that the major problem is the production of ozone, which was not
good for health. Perhaps that also interests army !

Olivier

In the 80s, most things were Made in the USA or Made in Japan.
Nowadays I'm sure the Chinese would be more than happy to infringe any
patents you are able to provide.

Plus the patents have probably expired by now...

Michael

 

[Sandbox Moderator]

On Fri, 17 Oct 2008 08:19:10 -0500, John Fields wrote:

On Fri, 17 Oct 2008 02:40:29 +0100, Eeyore
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
Rich Grise wrote:
....
Graham, don't be a dork. The guy wants to _BUILD_ stuff! He
needs to be encouraged - the "let's build it and see how it
works" mentality is all too rare these days.

What's the point of
just copying old circuits? That's not design.

This isn't the design group. The point of copying old circuits is making
actual components perform as expected by actually putting them together
and seeing what actually happens.

A Class A emitter follower ISN'T an old circuit ?

The point is that it's HIS circuit. And it has some potentially
interesting variations. IF you allow yourself to think.

It's a lousy circuit and I won't waste any time trying to dress up its
well-known shortcomings. If he wants a good class A output stage he
needs to go back to the drawing board.

What he needs is a little guidance and since you profess to be able to
run through the gamut of output stages, why not offer a little help
instead of the little game you're playing?

I think Eeyore needs a Pamprin.

Cheers!
Rich

 

[John Larkin]

On Fri, 17 Oct 2008 16:19:36 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

"Phil Allison" wrote:
"John Larkin"

I sort of like the emitter follower with an active current sink.

** Yawnnnnnnn.

Having trouble staying awake again, I see. Do you guys get decent
coffee down there?

Better by far than the active current sink is the active DRIVEN transistor !

Graham

The logical conclusion is to stop playing with class A circuits and go
to Best Buy and get a Panasonic receiver.

John