Class A “class D killer” amplifier with THD less than -120dB

[fpitas]

How many amps does that actually translate into a "problem" with? I guess a 5W room heater would be okay, tho

Class AB often has residual crossover distortion, seen at higher frequencies and very low power outputs. There's a good reason Benchmark installed a feed-forward auxiliary amp stage.

 

[Chrispy]

Class AB often has residual crossover distortion, seen at higher frequencies and very low power outputs.

Audible, tho?

 

[fpitas]

Audible, tho?

With a horn? Yes. You're certainly using a normal amp in a way the manufacturer never intended.

 

[Chrispy]

With a horn? Yes. You're certainly using a normal amp in a way the manufacturer never intended.

Just how sensitive are those horns? So what did you use that was audible and what do you use now?

 

[fpitas]

Just how sensitive are those horns? So what did you use that was audible and what do you use now?

The TAD driver is 111dB/W:

TAD TD-2002

This 1" Throat driver is also based upon the very successful Model TD-2001, which has been the mainstay in the professional sound industry for this size driver. Among the significant improvements designed by the TAD Engineers is the redesigned Aluminum 3 slit phasing plug. As with the TD-4003

www.proaudiodesign.com

Or about 20 - 25dB more sensitive than your normal cone driver. I tried a few other amps 11 years ago when I started playing, but the "right" way, pretty much standard for recording studio design, was to use class A. These days I could use the Benchmark AB, or class D.

 

[LKA]

I would like to present my "Class-D killers" here. They have low power consumption and low distortion, hence the naming.

 

[LKA]

H-ENG (Homeless Engineer)
100W/4R, Class B, single supply, CFA retro amp

 

[LKA]

LeXaN
170W/4R, Class B, current driven, CFA amp

 

[LKA]

LeXaN Buffer
170W/4R, Class B+G, current driven, power buffer

 

[Blumlein 88]

What is with wanting to kill class D amps?

Class D amps are powerful, efficient, inexpensive and provide excellent performance making them THE VALUE proposition among amplifiers. Yet everyone wants an alternative. Makes no sense.

 

[voodooless]

Makes no sense.

I for one welcome our new Class-B overlords

It's always fun to see what performance you can get out of electronics, no matter what class of amplifier it is. And these look quite impressive.

 

[LKA]

I hate them I am ancient
IMHO, Class B+G is better than Class-D in terms of efficiency, distortion, etc

 

[voodooless]

I hate them
IMHO, Class B+G is better than Class-D in terms of efficiency, distortion, etc

Can you back that up? Distortion-wise, we can already see what's going on. Efficiency-wise though would be nice to have a comparison.

 

[DSJR]

Just do what you do, make 'em reliable and abuse-tough (as my fifty year old US made prosumer power amps are and still with half-decent performance today, albeit with deliberate limitimg into 4 ohms and below) and dress 'em nice, hopefully at not too silly a price and I'm sure you'll have a market for them.

 

[restorer-john]

Efficiency-wise though would be nice to have a comparison.

Class D love quoting efficiency numbers at full power. Who cares about efficiency at full power?

Seriously, if you are cranking it near full power, nobody gives a chit about being green and saving the planet, do they? They are partying hard.

I'm more interested in efficiency at low powers. The levels most people listen to music, most of the time. And a class AB amp hardly pulls much at all in that situation. I have small-medium power integrated amplifiers running barely over 10W idling along. Some might pull 20W.

Class D SMPS supplies pull more than that on their own. Class D 'efficiency' is a mirage.

 

[Matias]

Class D love quoting efficiency numbers at full power. Who cares about efficiency at full power?

Seriously, if you are cranking it near full power, nobody gives a chit about being green and saving the planet, do they? They are partying hard.

I'm more interested in efficiency at low powers. The levels most people listen to music, most of the time. And a class AB amp hardly pulls much at all in that situation. I have small-medium power integrated amplifiers running barely over 10W idling along. Some might pull 20W.

Class D SMPS supplies pull more than that on their own. Class D 'efficiency' is a mirage.

While that is true for class AB and I agree, class A amps are another matter.

 

[digitalfrost]

Class D love quoting efficiency numbers at full power. Who cares about efficiency at full power?

Seriously, if you are cranking it near full power, nobody gives a chit about being green and saving the planet, do they? They are partying hard.

I'm more interested in efficiency at low powers. The levels most people listen to music, most of the time. And a class AB amp hardly pulls much at all in that situation. I have small-medium power integrated amplifiers running barely over 10W idling along. Some might pull 20W.

Class D SMPS supplies pull more than that on their own. Class D 'efficiency' is a mirage.

I measured only two integrated amps but they pulled 50W idle each. Also I think usage patterns may have changed. My amps run all day long. I don't turn on the amp in the evening and listen for 2-3hrs. I have them hooked up to the PC and I need audio to just work. Two amps because of Sat/Sub. So with the AB amps before, I wasted 100W most hours of the day just for the opportunity to have sound.

My class D amp is specced at 7W idle power consumption, but it also has auto/on off. For the sats I use AHB2 which only consumes 12W idle. Whish that one had auto-on as well...

 

[restorer-john]

While that is true for class AB and I agree, class A amps are another matter.

Yes, totally. Scary low efficiency. Even that big Marantz I pictured above is the equivalent of a couple of outdoor medium floodlights in Class A. Or an entire house of LED lights...

 

[computer-audiophile]

H-ENG (Homeless Engineer)
100W/4R, Class B, single supply, CFA retro amp

A job well done! I like it!

BTW: Do you use 'sPlan' as a CAD program for the schematic drawing? (I used to use it a lot and still have it somewhere on my hard drive).

 

[Sokel]

Class D love quoting efficiency numbers at full power. Who cares about efficiency at full power?

Seriously, if you are cranking it near full power, nobody gives a chit about being green and saving the planet, do they? They are partying hard.

I'm more interested in efficiency at low powers. The levels most people listen to music, most of the time. And a class AB amp hardly pulls much at all in that situation. I have small-medium power integrated amplifiers running barely over 10W idling along. Some might pull 20W.

Class D SMPS supplies pull more than that on their own. Class D 'efficiency' is a mirage.

That's true,I had a look at my big one and the graph is not so encouraging.
About 40-50(?)% at low levels,even less at really low: