Class 'D' audio amplifiers

[audioguru]

Sir..You have helped me in Stereo FM Receiver Project with TEA5711...Thank you for your kind help !!!
have you made any ClassD amp???
I am planning to make a ClassD Amp for Subwoofer.
Would like to suggest any good schematic with pcb ready , upto 500Watts?

I have never made a class-D amp.
Also I never made an amp with more power than 100W.

 

[audioguru]

On his website Rod Elliot has many amplifiers and audio acessories. But for a class-D amplifier he recommends a module made by ColdAmp.
The module provides 240W into 8 ohms or 400W into 4 ohms. Two modules can be bridged for 800W (or less if the supply voltage is less) into 8 ohms.
**broken link removed** shows a basic amplifier with links to the datasheet and applications note for the amplifier module.

**broken link removed** shows a complete sub-woofer amplifier with crossover.

 

[pravpa]

On his website Rod Elliot has many amplifiers and audio acessories. But for a class-D amplifier he recommends a module made by ColdAmp.
The module provides 240W into 8 ohms or 400W into 4 ohms. Two modules can be bridged for 800W (or less if the supply voltage is less) into 8 ohms.
**broken link removed** shows a basic amplifier with links to the datasheet and applications note for the amplifier module.

**broken link removed** shows a complete sub-woofer amplifier with crossover.

AG..Thanks for your Great Help...!!!
Links you have provided..it's like a encyclopedia !!!

 

[ronsimpson]

Something to read

 

[tvtech]

Hi Guys

A local company here has just released a series of high- powered Amps. Class D and powered by SMPS.

Light and wonderful and all.

I don't have faith in the SMPS part.

I can see failures of note. Besides trying to quell noise injecting itself back into the Amp...I loathe SMPS.

Unpredictable, canno't take a sustained 20 second Voltage overload from the Grid....because the Main Smoothing cap will burst.

And then the circuitry it powers will be compromised. Because the whole thing is unstable. If it even works anymore.....

But and I mean BUT: There are companies like Delta Electronics who employ Engineers who design SMPS thoroughly. Sealed enclosure.....dissipating around 90W continiously.....for almost Six years now. Like my Lappie. Many times I have wondered when all other stuff fails around me with surges etc, this Lappie PSU has never failed

I take my hat off to Delta Electronics Engineers. Proper SMPS design is a dark art.

Not like the TV SMPS I have to fix daily here.

Regards,
tvtech

 

[Nigel Goodwin]

Not like the TV SMPS I have to fix daily here.

Perhaps you should move to a country with a decent mains infrastructure?

 

[tvtech]

Perhaps you should move to a country with a decent mains infrastructure?

LOL

I really don't enjoy SMPS.

Relatively easy to fix though. Because all the Chinese ones here use Exactly the same parts and all blow up the same way....boring

I kid you not...around (from what I have seen)....maybe 30 different "brands". Always the same insides as in PSU (they vary track layouts here and there)...to try and look original. All the same PSU spares though. Good old 2SC3807 is what they ALL use in conjunction with the Chopper Transistor.

Loptx......another problem though. I swear there are like a Gazillion Loptx manufacturers in China....all BSC...and some numbers etc.

None are the same unless the they match EXACTLY with original faulty one. It is almost like China has a passion for winding things....differently....how crazy is that ?

PSU.....easy. LOPTX.....difficult.

Anyway, out of here.

Regards,
tvtech

 

[Mr RB]

Appliances are designed to fail, particularly the SMPS section. You see this all the time in TVs and Videos where there is plenty of free PCB space to put the electros in a cool place, but they deliberately put small electros right next to the heatsink. The engineers know that 30-40% of the units will fail in just over 12 months (just outside warranty) which greatly increases sales for the whole industry.

I used to constantly redesign SMPS supplies in repair by using longer legs on some caps, laying them down etc to get the cap body away from heatsinks, and increasing the time before failure to a few years instaed of one year.

 

[tvtech]

Appliances are designed to fail, particularly the SMPS section. You see this all the time in TVs and Videos where there is plenty of free PCB space to put the electros in a cool place, but they deliberately put small electros right next to the heatsink. The engineers know that 30-40% of the units will fail in just over 12 months (just outside warranty) which greatly increases sales for the whole industry.

I used to constantly redesign SMPS supplies in repair by using longer legs on some caps, laying them down etc to get the cap body away from heatsinks, and increasing the time before failure to a few years instaed of one year.

Hi Roman

You are correct. Electrolytic caps close to heatsinks is a problem still. However, things have got worse since you fixed your last CRT....

Some Genius in .....let us say....China developed a TV SMPS. The sets are all identical PSU wise. Just "upgraded" from anything from a 37cm to handle a 84cm the same. Bigger heatsinks for bigger sets.

Pile of poo. All the same and all blow up the same way.

No Electro's on the Primary Side to wear out...gradually......these PSU's just freak out when your Mains has a little issue.

Roman do you remember some SMPS designs that used a 47uf and a 22uf on the Primary side? Believe it or not....some of those old sets are floating around here.

And the tubes don't look like new.....but I am often amazed that they have lasted that long. And the PSU too.

Change the 47uf and 22uf in the Primary.....and it can look OK.....for a Twenty year old set. Of course, your Line Transistor will be shot too. Change it.

I am rambling on. You don't have them here.

Hell, there was a reliable TV psu of note.

Regards,
tvtech

 

[Mr RB]

Yeah I don't pull apart as many appliances these days as 10 years back, but still enough that I've seen flatscreen sets with modular type PSUs and modular backlight inverters etc.

Same basic problem, they are designed to fail! The engineers that design the PSUs know their stuff and likely have charts of how many fail per X months of use.

And you can still re-engineer PSUs the same way we always did; better spec semis, better spec and sized and positioned caps, improved cooling and airflow and even bolting extra heatsink metal on the sinks. That's the kind of thing I do on my own personal equipment, and they never fail more than ONCE, then they get taught a lesson.

 

[Nigel Goodwin]

Yeah I don't pull apart as many appliances these days as 10 years back, but still enough that I've seen flatscreen sets with modular type PSUs and modular backlight inverters etc.

Same basic problem, they are designed to fail! The engineers that design the PSUs know their stuff and likely have charts of how many fail per X months of use.

Cheap crap sets fit cheap crap electrolytic's - you don't get failures in the better makes where they fit better quality ones.

 

[Sangoma]

Cheap crap sets fit cheap crap electrolytic's - you don't get failures in the better makes where they fit better quality ones.

Yes, the Samsung story is a prime example, daft prices to repair, but a few pounds worth of capacitors and half an hours work and all works again.

They even denied the problem (after it was obvious it was widespread), but some people were lucky and had the sets repaired by them.

 

[Mr RB]

Cheap crap sets fit cheap crap electrolytic's - you don't get failures in the better makes where they fit better quality ones.

Point taken! Some manufacturers design in a longer life and a better quality appliance.

Of course in repair you tend to see more of the brands that were designed to fail quickly.