The Class - H Amplifier

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#161
Hi Kanwar,
That is very interesting. Your rails are switching instead of linear are they not?

Have a good look at the output waveform as the rail switches. You may see a tiny spike on the output. This, if present, will give a harsh quality to the sound. The M 1.0t had this characteristic, certainly the cube as well (M-400, M-400a, M-400t). But, you can get the concept to work then. This would not be a problem with a sub amplifier.

I'll bet you are gaining a lot of knowledge with this design. Good show!

-Chris
 
#162
anatech said:
Hi Kanwar,
That is very interesting. Your rails are switching instead of linear are they not?

Have a good look at the output waveform as the rail switches. You may see a tiny spike on the output. This, if present, will give a harsh quality to the sound. The M 1.0t had this characteristic, certainly the cube as well (M-400, M-400a, M-400t). But, you can get the concept to work then. This would not be a problem with a sub amplifier.

I'll bet you are gaining a lot of knowledge with this design. Good show!

-Chris
Click to expand...

Hi Anatech,

Yeah, its a PWM square wave type switching waveform, not the linear type...
I have implemented a unique technique"Adaptive Slewrate Switching"[my own invented] which automatically compensates the switching slew according to the program signal..Thus the spikes aren't visible or you can say minimized to a much greater extent than any of the other amplifiers[Crest,QSC,RAM].
My amplifier is fullrange upto Sinewave signal of 30KHZ at full power,no Railsticking at all. No Cross-conduction at all...
All the switching drivers are discrete except 2 opamps acting as comparators.....
You were right now i have been able to possess a chunk of knowledge about the Class-H amplifiers ....through these several time consuming experiments....
The size of heatsink is now reduced to about 1/3 of its same wattage Class-AB as well and further more only 5 pairs of C5200 & A1943 were just required to pump out 1700W into 2 ohms....

K a n w a r
 
#163
Hi Kanwar,
You were right now i have been able to possess a chunk of knowledge about the Class-H amplifiers ....through these several time consuming experiments....
Click to expand...
Education is never cheap. But those who do not educate themseves are surely left behind. You are wise.

I am hoping this works out well for you then. Just be sure to look very carefully for these spikes. Here is wishing them to be inaudible on your design. 😉

Now you can design very powerful amplifiers that are more efficient. They should last longer since the temperatures can be lower. This is very good where you are located (too hot for me!).

-Chris
 
#164
anatech said:
Hi Kanwar,

Education is never cheap. But those who do not educate themseves are surely left behind. You are wise.

I am hoping this works out well for you then. Just be sure to look very carefully for these spikes. Here is wishing them to be inaudible on your design. 😉

Now you can design very powerful amplifiers that are more efficient. They should last longer since the temperatures can be lower. This is very good where you are located (too hot for me!).

-Chris
Click to expand...


Hi Chris,

You are wise too by contributing much of your [Carver] experience in this thread...

The Spikes are not audible in any manner in my design, because music isn't a single sinewave but a spectrum of many! and its distribution in program material always uneven with high energy content in low frequency areas only.....

Thanks for the Wish!
Thanks alot
Thanks again......
its the same old
K a n w a r
 
#165
Hi Kanwar,
These artifacts will present more of a sense, or feeling, of harshness. Listener fatigue if you will. A sine wave is repetitive and stable. This gives you a chance to exercise the commutators and examine each part closely. From zero crossing to commutator switching. The performance with complex waveforms will be improved as well.

If you have ever listened to a Carver M1.0, you will know what I mean. They eventually fixed that aspect of the amplifier's performance and the result was more acceptance of the design.

-Chris
 
#166
anatech said:
Hi Kanwar,
These artifacts will present more of a sense, or feeling, of harshness. Listener fatigue if you will. A sine wave is repetitive and stable. This gives you a chance to exercise the commutators and examine each part closely. From zero crossing to commutator switching. The performance with complex waveforms will be improved as well.

If you have ever listened to a Carver M1.0, you will know what I mean. They eventually fixed that aspect of the amplifier's performance and the result was more acceptance of the design.

-Chris
Click to expand...


Yes I understand your fact, I have heard that type of harshness in many switched rail amplifiers namely Crest pro9200 series and QSC PLX3602, but in my design its not present at all...

I have Tweaked many things such as snubbers values accross commutator diodes[Schottky's in my case, not a regular fast recovery], PCB layout as well, Controlled switching slopes, Temperature compensation, Extent of Biasing of output stage to eradicate switching artefacts during transition, Output inductor Filter optimization, Zobel optimization, Envelope optimization, Driverstage was changed recently to further improve the dv/dt capability during transient current peaks over transition...
All these "TWEAKs" let my design to sound excellent not harsh in Treble and Midrange, only sparkle and open sounding.....

I haven't seen or listened a Carver till now!
 
#170
hienrich said:
hi Kanwar

may you share schemes for reference of


Crest pro9200

thanks,

keep on... Im following your threads theyre worth more than a book

macweb

hienrichb@yahoo.com
Click to expand...

Hi Hienrich,

I think you have the Crest pro9200 schematics which were sent by me to you.....

Yes, I know there is no book on Class-H amps😀 😉

Its my pleasure to contribute something to the forum.........

K a n w a r
 
#171
hi

did you sent it to

hienrichb@yahoo.com

you know last week or 2, somebody might have altered my membership profile, my email add was change with another one's
pm, so Ive got to retype again some of the lines

so becuase I was sending an email message through diyaudio
mail sending, it will also appear that the return pm will be that someone else

:whazzat:

sorry for the enconvinience

macweb
 
#178
Workhorse said:


Hi GreG,

Yes you are right but, Class-H isn't meant for Studio or Hi-END HIFI, but its meant for PA, all these pro-amp guys[except me] use this Class-H to draw more with less wastage.
The complexity is very much high Dual CAPS , 2-4 Bridges , lots of switching asthetics involved....

regards,
K a n w a r
Click to expand...

Hello

What about Soundcraftsman and Paul Rolfes?

http://www.hifi-museum.com/pa/sc_fs.htm

They had patents for class H and the magnetic field power supplys on different amps and sounded good. They were also well built and reliable with high power output.

Soundcraftsmen was responsible for "the development of signal-tracking multiple-rail power supplies, fully electronic automatic resetting crowbar circuitry, Phase-Control-Regulation power supplies, and automatic low-impedance power supply selection which became known as Class H circuitry"
 
#179
djk said:
Hi Jens,

I will use your nomenclature for consistency. The saturated rail switch will be referred to as class H, and the linear follower (modulated rail voltage) as class G.

Prior art on class G (3772606):

http://patimg1.uspto.gov/.piw?Docid...ageNum=&Rtype=&SectionNum=&idkey=637608C562C2

An earlier example for CRT deflection (3622899):

http://patimg2.uspto.gov/.piw?Docid...ageNum=&Rtype=&SectionNum=&idkey=2E6E84FB42ED

Early class H (3319175):

http://patimg2.uspto.gov/.piw?docid...=3319175.WKU.%26OS=PN/3319175%26RS=PN/3319175

'Commutation' was Bob Carver's nomeclature for a rail switching design. I believe he coined this term for the diode on the lower rails, also refered to as an ORing diode (as it allows the output stage to use power from either the lower, or the higher supply, as needed). These diodes switch, or commutate as needed. The fast switching, soft recovery types, or newer high voltage Schottky type are best here.

The theoretical class B efficiency is 78.8%, a three rail design like the M1.0 is 87% (after Pol HSU). When you consider bias in a class AB design, 60% is more in line. Pol HSU found that the rail switcher showed even higher efficiency driving reactive loads vs resistive.

At full power, class G and H are slightly less efficient than class AB. However, the majority of the time we are not at full power.
Worst case for the class AB would be at about 50% voltage out, where the rail switchers are king.

Most Carver are three rail designs, most Crest are two rail designs. AB International has an interesting two-and-a-half rail design. Instead of a third set of transformer windings, associated rectifiers, and filter caps, they use 0V as a rail in class H. No improvement on a resistive load line, but much better into a reactive load line, and a reduction in the Vce required for the outputs.

IMO class G sounds better than class H. One example of this is the QSC MX2000, a 1KW per channel design. The original was class G, the 'A' version class 'H'. The original sounds better, and the used market value is higher for that very reason.

Why do any class H?

Cost, it is much lower for class H.

The later Carver M1.0 is an interesting hybrid, being class G on the lower rail, and class H on the higher rail. Good sonics at a reasonable cost.

The Early Effect doesn't seem to be a real issue.

An early example of the 'Tracking Down Converter' or 'BASH' type (3426290):

http://patimg2.uspto.gov/.piw?docid...=3426290.WKU.%26OS=PN/3426290%26RS=PN/3426290
Click to expand...

I have installed quicktime but i cant open these docs :bawling:

It is possible dowload these as acrobat docs or other format ? :scratch:
 
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