mini mosfet audio amp design

[Eeyore]

So are you saying the Gainclone is as good as, or better than,
discretes?

It's better than many discrete designs for sure but not as good as some really
excellent ones.

(Not putting you on the spot. Not at all.

Are these circuits any better, then?

http://www.redcircuits.com/Page2.htm

That's more like it.

http://www.redcircuits.com/Page100.htm

That looks fairly OK too.

Or should I just give up on that site...?

It seems to have redeemed itslf now.

Graham

 

[Don Klipstein]

In <75b2c03c-10c9-4a13-9aeb-92d9453e3a22@c19g2000prf.googlegroups.com>,

Since it's still too early or Fourth of July fireworks shows, can you
(or anyone) recommend a link to a low-parts-count, 20W or so into 8-
ohms audio amplifier? Input will be from a laptop or MP3 player, so
no preamp necessary.

National Semiconductor LM1875, available from Digi-Key.

http://www.national.com/ds/LM/LM1875.pdf

The basic circuit uses 7 capacitors and 5 resistors, and that is
including .1 and 100 uF capacitors from each supply rail to ground, and
resistors to ground from both ends of the input coupling capacitor. No
additional semiconductors are used in the basic circuit.

- Don Klipstein ([email protected])

 

[[email protected]]

In <75b2c03c-10c9-4a13-9aeb-92d9453e3...@c19g2000prf.googlegroups.com>,



National Semiconductor LM1875, available from Digi-Key.

http://www.national.com/ds/LM/LM1875.pdf

The basic circuit uses 7 capacitors and 5 resistors, and that is
including .1 and 100 uF capacitors from each supply rail to ground, and
resistors to ground from both ends of the input coupling capacitor. No
additional semiconductors are used in the basic circuit.

- Don Klipstein ([email protected])

I think the original poster was looking for more of an educational
experience, i.e. discretes.

If I were to roll together a power amp, I'd be inclined to try some of
those Class E chips.

 

[[email protected]]

I think the original poster was looking for more of an educational
experience, i.e. discretes.

If I were to roll together a power amp, I'd be inclined to try some of
those Class E chips.

Yep, I was looking for the discretes, but thanks anyway. Only 5 leads
on the LM1875, eh...

Class E chips? Which ones?

Mouser has several Class D chips, but they all look hard to solder.


MD

 

[Eeyore]

If I were to roll together a power amp, I'd be inclined to try some of
those Class E chips.

Class ** E ** ??? Not D ?

Graham

 

[Eeyore]

National Semiconductor LM1875, available from Digi-Key.

http://www.national.com/ds/LM/LM1875.pdf

The basic circuit uses 7 capacitors and 5 resistors, and that is
including .1 and 100 uF capacitors from each supply rail to ground, and
resistors to ground from both ends of the input coupling capacitor. No
additional semiconductors are used in the basic circuit.

Yes, that's another decent one. National make quite a few good audio power
amp ICs.

Graham

 

[[email protected]]

Class ** E ** ??? Not D ?

Graham

Could well be...
http://en.wikipedia.org/wiki/Electronic_amplifier#Class_E

Michael

 

[TheM]

Class ** E ** ??? Not D ?

Graham

While we're on the subject, anyone had good experience with one of these
D-class ic audio amps? I need something simple that handles up to 16V and provides
about 5W of power, with solid efficiency.


Mark

 

[Martin Griffith]

Class ** E ** ??? Not D ?

Graham

It's the Buxsminter fuller version


martin

 

[Eeyore]

It's the Buxsminter fuller version

LOL !

Is it geodesic ?

Graham

 

[[email protected]]

While we're on the subject, anyone had good experience with one of these
D-class ic audio amps? I need something simple that handles up to 16V and provides
about 5W of power, with solid efficiency.

Mark

Something like this?
http://www.ti.com/lit/gpn/tpa3005d2

6W/ch, 8.5V to 18V power

Michael

 

[TheM]

Something like this?
http://www.ti.com/lit/gpn/tpa3005d2

6W/ch, 8.5V to 18V power

Michael

I wonder what the switching does to the radio (located in the same box)?

May be safer to go the usual analog route.

Mark

 

[[email protected]]

Could well be...http://en.wikipedia.org/wiki/Electronic_amplifier#Class_E

Michael

I meant class D. Brain fart. [Dan Quayle: "To waste a mind is
terrible."]

I see these chips advertised from time to time, but never did a
research project on who has good silicon. Much like switcher design, I
suspect the BS runs deep on such amplifier chips.

 

[[email protected]]

Yes, that's another decent one. National make quite a few good audio power
amp ICs.

Graham

http://www.analog.com/en/prod/0,,765_796_AD1994,00.html
They are claiming 0.005% THD.

 

[[email protected]]

On Mar 24, 2:48 pm, Eeyore <[email protected]>
wrote:

Could well be...http://en.wikipedia.org/wiki/Electronic_amplifier#Class_E

Michael

I meant class D. Brain fart. [Dan Quayle: "To waste a mind is
terrible."]

I see these chips advertised from time to time, but never did a
research project on who has good silicon. Much like switcher design, I
suspect the BS runs deep on such amplifier chips.

I wonder how the Class D chips sound compared to the LM3875...

Ah well, my soldering ability won't yet allow me to play with Class D
chips. (Unless they make DIPs that will fit on a breadboard...?)

Michael

 

[[email protected]]

I wonder what the switching does to the radio (located in the same box)?

May be safer to go the usual analog route.

Mark

You would probably want a design where the clock of the amplifier can
be synced to the radio oscillator.

 

[Eeyore]

http://www.analog.com/en/prod/0,,765_796_AD1994,00.html
They are claiming 0.005% THD.

Interesting. I'd not have though of AD as an audio power amp supplier.

Graham

 

[TheM]

You would probably want a design where the clock of the amplifier can
be synced to the radio oscillator.

I'd be more worried about that RC-generated 250KHz falling into the range of
455KHz/2, close enough. AD1992 is using a quartz, though, and who knows where
its harmonics would end in a double-superhet.

Mark

 

[[email protected]]

+1 For Douglas Self.

If your interested in learning about basic amplifier design I would
recommend his book:

Audio Amplifier Design Handbook

http://www.amazon.com/Audio-Amplifi...bs_sr_1?ie=UTF8&s=books&qid=1206449198&sr=8-1

This book will take you through all the stages of a typical linear
audio amplifier: Differential Input, Voltage Amplifier, Current
Amplifier, Feedback, Power Supply etc..


Another

 

[Spehro Pefhany]

Somebody is going to have to explain page 3 of this data sheet to me.
Please don't tell me it is a misprint, as National has had six years to
correct.

At a supply voltage of 15 volts, the curve shows 10 watts out.

Last I looked no single-supply design can drive to below zero or above
supply rail without the use of some inductive tricks that the test circuit
doesn't show.

It's a dual supply-- that's what the "+/-V" means on the X axis of
00503011.

10W into 8 ohms requires about +/-9V peak.

So, converting a 15 volt peak-to-peak output signal (assuming that the
device can swing to both rails) gives about 5.3 volts RMS.

The data sheet specifies an 8 ohm load, so given that Power = volts^2 / load
yields about 3.5 watts out.

What gives?

Jim

Best regards,
Spehro Pefhany