class A amplifier

[Olivier Scalbert]

John Larkin wrote:

11. To sequester technical knowledge in journals, defended by
deliberately obscure abstracts, readable at great expense, the revenue
therefrom going to the IEEE, whether the paper turned out to be useful
or not.

John

Yes, I agree.

Olivier

 

[Olivier Scalbert]

Eeyore wrote:

What is it you're really trying to do and what's its purpose ? Then I may
be able to actually really help you somewhat.

Graham

As I explain to Michael:

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 (the poor MP3 generation);
- 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);
- ...

Nothing else.

Olivier

 

[Olivier Scalbert]

Eeyore wrote:

Well that's good but dare I say you missed out on the practical lab work ?

Take a look at this will you. He's another good amp designer too.
http://www.dself.dsl.pipex.com/ampins/ampins.htm


I hate to see people waste their time walking down blind alleys.

Graham

My last practical lab was 25 years ago.
It was about amplification !
But at 500Mhz, which is not he same domain.

Olivier

 

[Olivier Scalbert]

Eeyore wrote:

Olivier Scalbert wrote:

mrdarrett@gmail.com wrote:
Come now Graham, he didn't mention he wants to become an EE... why be
so mean?

Olivier, why not try this one?
http://diyaudioprojects.com/Solid/ZCA/ZCA.htm

2SK1058 lateral mosfets can be hard to find however.

Michael
Thanks for the link Michael.
I do not want to become EE !
At least good EEs should respect IEEE Code of Ethics (point 5).
http://www.ieee.org/portal/pages/iportals/aboutus/ethics/code.html

I agree with it totally. To ecourage you to build shitty circuits would be
grossly negligent.

If you want to learn about audio amplifiers, some excellent resources can
be found here ....
http://www.dself.dsl.pipex.com/ampins/ampins.htm

Graham

Thanks for the interesting link.
Olivier

 

[Olivier Scalbert]

Rich Grise wrote:

On Mon, 13 Oct 2008 06:44:49 -0700, olivier.scalbert@algosyn.com wrote:

As the gain of the transistor is to low I finally put a (too?) small
BC546 in front of the 2N3055 (Darlington).
See schema:
http://scalbert.dyndns.org/electronics/amplifier/ampli1.png

As I need a preamp for the volume control, I have add another BC546 to
amplify the input signal.
See schema:
http://scalbert.dyndns.org/electronics/amplifier/preamp1.png

I'd do it different, but basically it's right out of the book. Unless
you have to adjust the bias periodically, I'd pick an operating point
and use a fixed resistor for R3, then put the left side of C2 to the
wiper of the volume control pot (in ampli1).

The preamp is pretty much standard; there's no problem with the
volume control, depending on the signal level you're dealing with.

As I suggested above, move the volume control to the input side of
the power amp, and run the preamp full-bore all the time - just design
the circuit so that you get "line out" (about 1VRMS) for your maximum
expected input.

And as far as C4 & R8 (preamp1), you're already ahead of me on that
one. ;-)

Cheers!
Rich


Ok, I will try.

Thanks,

Olivier

 

[Phil Allison]

"Olivier Scalbert"

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. This then allows
to output voltage to swing *above* and below the DC supply and get voltage
gain to boot.

Some 1960s car radios had single transistor, class A output stages with such
inductors - maybe you cna find a schem using Google.

The inductor will need to have low resistance ( say 1 ohm) and inductane of
30 mH, at least.

The secondary winding of an old tube radio output transformer might be
perfect for experimenting.


..... Phil

 

[Eeyore]

Olivier Scalbert wrote:

Eeyore wrote:

Well that's good but dare I say you missed out on the practical lab work ?

Take a look at this will you. He's another good amp designer too.
http://www.dself.dsl.pipex.com/ampins/ampins.htm

I hate to see people waste their time walking down blind alleys.

My last practical lab was 25 years ago.
It was about amplification !
But at 500Mhz, which is not he same domain.

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

Graham

 

[John Fields]

On Tue, 14 Oct 2008 23:40:02 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Olivier Scalbert wrote:
John Fields wrote:

And as I have no good electronic shop near my home, I generally buy my
components at Farnell.
By looking inside the 2006 edition, I have discovered page 936 the ECA
audio caps from Panasonic.
"High fidelity, low distorsion, High resolution, ...."

That is why I will buy these ones !

---
In this case, then, I'm afraid that Graham is right since the audible
output of your circuit will hardly be improved by the use of "High
fidelity, low distorsion, High resolution, ...." capacitors.

Apology please ?

---
For setting him on the right track rather more politely than you, who
likes to beat up on clueless newbies?

You'll get no apology from me, twat.
---

I could smell it 100 miles off.

---
Yeah, sure, _after_ you were told what the odor was.

And, why are you still using miles when you constantly preach that the
English system is evil?

JF

 

[John Fields]

On Tue, 14 Oct 2008 23:46:50 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> 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.
---

and he's been angry and taking it out on the whole world ever since.

No, I just hate audiophools. They are trying to destroy a once proud and technically
highly competent industry with their claims of 'magic parts' and other pixie dust
garbage.

---
You hate a lot more than just "audiophools", buddy-boy.

Just for openers, take a look at your incessant America-bashing.


JF

 

[Bob Masta]

On Wed, 15 Oct 2008 08:05:38 +0200, Olivier
Scalbert <olivier.scalbert@algosyn.com> wrote:

Eeyore wrote:
What is it you're really trying to do and what's its purpose ? Then I may
be able to actually really help you somewhat.

Graham

As I explain to Michael:

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 (the poor MP3 generation);
- 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);
- ...

Nothing else.

Olivier

You can use your sound card with the Daqarta
Signal Generator. (It's totally free.) You can
use it real-time for testing... no need to burn a
CD. You can have any signal last as long as you
like, with no concern for CD track length. You'll
have a lot more signal options than any benchtop
unit, and much lower distortion than standard
"function generators".

I'll be glad to answer questions via the contact
page on the site. (Or here, if they are
relevant.)

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

[John Fields]

On Wed, 15 Oct 2008 02:10:45 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
John Fields wrote:

Just simple facts John.

Graham

---
You're a goddam liar.

You know very well that this is seb and that instead of just putting the
guy down by puffing yourself up as an "expert" (implying that he's a
virtual nonentity) you should be helping him understand where his
deficiencies lie, like Larkin did.

But no, you always have to try to make yourself feel important by trying
to make it seem like everyone is less important.

JF

I have given him a link to a far far better site.
http://www.dself.dsl.pipex.com/ampins/ampins.htm

---
After the fact.

I was very occupied earlier. You see I came back to the thread though.

---
Just like a bad penny.

JF

 

[John Fields]

On Wed, 15 Oct 2008 02:25:49 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields 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.

---
Really?

He did enough homework to, in the real world, build an amplifier that
works, and all you can do is spew destructive criticism in order, it
seems, to denigrate his achievement.

I was doing better in my teens because I learnt about real practical circuits.

---
There you go again with your: "I'm better than you are." crap.

You just can't stand to give anyone credit for their accomplishments, no
matter how small, can you, you miserly wretch?

JF

 

[Olivier Scalbert]

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.

Graham

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 ...


Olivier

 

[John Fields]

On Wed, 15 Oct 2008 12:30:51 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

Olivier Scalbert wrote:

Eeyore wrote:

Well that's good but dare I say you missed out on the practical lab work ?

Take a look at this will you. He's another good amp designer too.
http://www.dself.dsl.pipex.com/ampins/ampins.htm

I hate to see people waste their time walking down blind alleys.

My last practical lab was 25 years ago.
It was about amplification !
But at 500Mhz, which is not he same domain.

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

---
Instead of trying to make him seem like the heavy for not posting what
is essentially irrelevant, why don't you just apologize for being an
asshole?

JF

 

[Olivier Scalbert]

Bob Masta wrote:

You can use your sound card with the Daqarta
Signal Generator. (It's totally free.) You can
use it real-time for testing... no need to burn a
CD. You can have any signal last as long as you
like, with no concern for CD track length. You'll
have a lot more signal options than any benchtop
unit, and much lower distortion than standard
"function generators".

I'll be glad to answer questions via the contact
page on the site. (Or here, if they are
relevant.)

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

Thanks for the link Bob.
In fact, I am using Linux but under wine (which is a free implementation
of windows on unix) it seems to work perfectly !
Thanks very much,

Olivier

 

[YD]

Late at night, by candle light, Eeyore
<rabbitsfriendsandrelations@hotmail.com> penned this immortal opus:

mrdarrett@gmail.com wrote:

He does know his audio stuff though.

Which is why all my posts in this thread are correct.

Graham

But your attitudes are incorrect. Do you really expect an experimenter
having fun to become a pro designer because you demand it?

- YD.

--
Remove HAT if replying by mail.

 

[YD]

Late at night, by candle light, Olivier Scalbert
<olivier.scalbert@algosyn.com> penned this immortal opus:

John Fields wrote:

---
Since John Jardine suggested that he increase the _capacitance_ of C1 to
1000ľF, I'm sure Olivier took that to mean the capacitor would be higher
quality since it would extend the audio response of the amp down to
about 20Hz.

He's already said he's a newbie and just starting out, so why do you
beating him up instead of showing him the right way to do it?

Because you're a real shit, that's why.
---

I take it you've been 'Audiophooled' by reading magazines written by wholesale
fraudsters. Audiophile was it ?

---
And you were never taken in by wholesale fraudsters, ever, because
you've always been able to see through the smoke screens?
---

Graham (pro-audio designer since 1971)

---
Not something I'd boast about, if I were you...

JF

It is not exactly what I mean.
Of course increasing value of C1 will increase the low frequency response.
Problem, I have not 1000ľF at home, I have used 2 500ľF in parallel ...

Should work fine.

And as I have no good electronic shop near my home, I generally buy my
components at Farnell.
By looking inside the 2006 edition, I have discovered page 936 the ECA
audio caps from Panasonic.
"High fidelity, low distorsion, High resolution, ...."

Utter hog-wash. Any old cap within the ratings is good enough. Your
circuit is nice enough for playing around with but doesn't merit any
gold-plated components.

That is why I will buy these ones !

Waste of money, see above.

- YD.

--
Remove HAT if replying by mail.

 

[YD]

Late at night, by candle light, Eeyore
<rabbitsfriendsandrelations@hotmail.com> penned this immortal opus:

John Fields wrote:

Eeyore wrote:
Olivier Scalbert wrote:
john jardine wrote:
For a starter, increase C1 to 1000uF. 'T'll get the response down to about
20Hz.

Thanks !
Done.
I will try to find high quality capacitors later ...

The 'quality' of capaciors is an entire irrelevance with something so primitive.
In fact it's almost a complete irrelevance completely unless you buy Asian junk.

---
Since John Jardine suggested that he increase the _capacitance_ of C1 to
1000ľF, I'm sure Olivier took that to mean the capacitor would be higher
quality since it would extend the audio response of the amp down to
about 20Hz.

No, I'll bet he's referring I expect to audiophool parts, and you of ALL people
should berate him for that.

OTOH if the guy can't distinguish *capacitance value* from *quality* he shouldn't
even have started.

You see, you don't understand this field. The audiophools promote crap circuits built
with absurdly expensive components because they think the cost of the parts is what
determines the result.

This is the kind of thinking that drives the pro-audio guys mad !

Graham

Since Olivier stated early on that he's a beginner you could have said
the above earlier and far more politely.

- YD.
--
Remove HAT if replying by mail.

 

[YD]

Late at night, by candle light, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> penned this immortal
opus:

On Tue, 14 Oct 2008 17:36:08 +0200, Olivier Scalbert
olivier.scalbert@algosyn.com> wrote:

John Larkin wrote:
Hey, this is usenet. It selectively attracts the willfully ignorant,
the arrogant, and the pain sluts who crave public humiliation.

Why not drive the base of your darlington with an opamp?

John

egos ... !

I still have some LM741 but it is perhaps too short no ? What do you
suggest ?

Olivier

Ideally you'd use a driver stage that is fast, quiet, and swings to
both power rails. 741 does none of the above.

Something like LM7301 might be OK for starters.

John

I like the TL07x series. Cheap, plentiful and quite stable unless you
hang too much capacitance on the output, and there's a simple way out
of that.

- YD.
--
Remove HAT if replying by mail.

 

[YD]

Late at night, by candle light, Olivier Scalbert
<olivier.scalbert@algosyn.com> penned this immortal opus:

Eeyore wrote:
What is it you're really trying to do and what's its purpose ? Then I may
be able to actually really help you somewhat.

Graham

As I explain to Michael:

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 (the poor MP3 generation);
- 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);
- ...

Nothing else.

Olivier

Go to http://www.sillanumsoft.org for the free Visual Analyzer. It
works both as a function generator and an audio analyzer. The scope
might be useful for calibrating the settings.

- YD.

--
Remove HAT if replying by mail.