The Class - H Amplifier

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#182
ZGarage said:


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"
Click to expand...


I like my Soundcraftsmen gear better than my old NAD or Adcom gear.
 
#184
Those links are exactly how I have always heard and read class G and H work. Class G is a rail stepper and Class H a tracker. Actually, the H link could also be called G/H hybrid depending on the level of set rail. For a chip amp this might be as high as +/-15V then modulate the rail to track the output above this level. It seems some people switch the two so it is becoming more confused on which is which without showing a picture to clarify the definition being used.

-SL
 
#188
Hi SleeperSupra,
Which Carver amp???
Almost anything sounds better than the 400 series cube (they are great for subwoofers).

M 1.0t's are trying, but better. TFM-25 / 45 are better still. TFM-75's can be a good sounding amp, much better than the ealier models.

Then there is the Lightstar (series 1). It sounded the best of all of them I think.

That's a pretty broad spectrum. I'll take my Marantz 300DC over these (hey! I did make that decision).

-Chris
 
#189
Hi Folks,

Class-H and Class-G both switch the Rails, but Class-H uses PWM with Step square waveform, whereas Class-G uses elevated linear waveform...
Class-H has efficiency around 70% and Class-G has 65%....


Donot Mix Tracking Power supplyRails[Carver, Bash, LabGruppen Class-TD stuff] with Class-H, Class-H isnot a Tracking Supply amplifier....
The Answers and references you got on the famous search engine "Google" led you to wrong conclusions.....

K a n w a r
 
#190
Workhorse said:
Hi Folks,

Class-H and Class-G both switch the Rails, but Class-H uses PWM with Step square waveform, whereas Class-G uses elevated linear waveform...
Class-H has efficiency around 70% and Class-G has 65%....


Donot Mix Tracking Power supplyRails[Carver, Bash, LabGruppen Class-TD stuff] with Class-H, Class-H isnot a Tracking Supply amplifier....
The Answers and references you got on the famous search engine "Google" led you to wrong conclusions.....

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

this is right ?
http://en.wikipedia.org/wiki/Electronic_amplifier

This is a G class amplifier...
Gfig11s.gif


at the collector of AB class the voltage is..
An externally hosted image should be here but it was not working when we last tested it.


but in H-class i have a PWM lifter for class AB transistor.
have I something understood ? :cannotbe:

(I have seen many Mackie schematics and it seems me that they
are in class h)

bye :mafioso: 😀
 
#191
Gold_xyz said:


this is right ?
http://en.wikipedia.org/wiki/Electronic_amplifier

This is a G class amplifier...


at the collector of AB class the voltage is..


but in H-class i have a PWM lifter for class AB transistor.
have I something understood ? :cannotbe:

(I have seen many Mackie schematics and it seems me that they
are in class h)

bye :mafioso: 😀
Click to expand...

This might help...

"These definitions are from Audiolab's glossary

Class H amplifier - Class H operation takes the class G design one step further and actually modulates the higher power supply voltage by the input signal. This allows the power supply to track the audio input and provide just enough voltage for optimum operation of the output devices. The efficiency of class H is comparable to class G designs.

Class G amplifier - Class G operation involves changing the power supply voltage from a lower level to a higher level when larger output swings are required. There have been several ways to do this. The simplest involves a single class AB output stage that is connected to two power supply rails by a diode, or a transistor switch. The design is such that for most musical program material, the output stage is connected to the lower supply voltage, and automatically switches to the higher rails for large signal peaks. Another approach uses two class AB output stages, each connected to a different power supply voltage, with the magnitude of the input signal determining the signal path. Using two power supplies improves efficiency enough to allow significantly more power for a given size and weight. Class G is becoming common for pro audio designs."

from

http://www.diyaudio.com/forums/showthread.php?postid=79739#post79739
 
#192
Gold_xyz said:


this is right ?
http://en.wikipedia.org/wiki/Electronic_amplifier

This is a G class amplifier...
Gfig11s.gif


at the collector of AB class the voltage is..
An externally hosted image should be here but it was not working when we last tested it.


but in H-class i have a PWM lifter for class AB transistor.
have I something understood ? :cannotbe:

(I have seen many Mackie schematics and it seems me that they
are in class h)

bye :mafioso: 😀
Click to expand...

Yes thats the version of Douglas Self's Class-G amp....
Yeah Mackie uses Class-H in their new M-series
The reference on Wikipedia for Class-H was Wrong, but I have edited it and made it correct....check it out



ZGarage said:


This might help...

"These definitions are from Audiolab's glossary

Class H amplifier - Class H operation takes the class G design one step further and actually modulates the higher power supply voltage by the input signal. This allows the power supply to track the audio input and provide just enough voltage for optimum operation of the output devices. The efficiency of class H is comparable to class G designs.

Class G amplifier - Class G operation involves changing the power supply voltage from a lower level to a higher level when larger output swings are required. There have been several ways to do this. The simplest involves a single class AB output stage that is connected to two power supply rails by a diode, or a transistor switch. The design is such that for most musical program material, the output stage is connected to the lower supply voltage, and automatically switches to the higher rails for large signal peaks. Another approach uses two class AB output stages, each connected to a different power supply voltage, with the magnitude of the input signal determining the signal path. Using two power supplies improves efficiency enough to allow significantly more power for a given size and weight. Class G is becoming common for pro audio designs."

from

http://www.diyaudio.com/forums/showthread.php?postid=79739#post79739
Click to expand...

Class-H definition is wrong.....Its not a Tracking supply rail amp at all.....

K a n w a r
 
#195
Hi Chris,

Bipolars consume heavy base currents and there saturation voltage is higher in comparision with Mosfets gate drive and RDS related voltage drop for a given amount of current..
Also they exhibit charge storage time effects which made them to use in High frequency [Treble range] switching troublesome...

Carver's use bipolar for switching and thats why they are prone to Rail Sticking and they incorporate certain HF protection circuitry to avoid the destruction....
Also Mosfets cost much lower and require very simple drive circuitry to switch....

In my design there is no rail sticking upto 30KHZ Sine straight loaded with 2 ohms and also in open circuit type no load conditions.....thats just because of Mosfets...as switches

Also it depends upon the designer how HE/SHE would manages to get the circuit work in a reliable manner.....

regards,
K a n w a r
 
#196
Soundcraftsmen describes their class H amp as a signal-tracking rail switcher...


http://www.hifi-museum.com/images/pa/sc_test1_p3.jpg


Workhorse said:


Yes thats the version of Douglas Self's Class-G amp....
Yeah Mackie uses Class-H in their new M-series
The reference on Wikipedia for Class-H was Wrong, but I have edited it and made it correct....check it out





Class-H definition is wrong.....Its not a Tracking supply rail amp at all.....

K a n w a r
Click to expand...
 
#197
Yes there definitions are very well correct....As all Class-H, Class-G, amps Tracks the output signal and switches the Rails accordingly, whereas Tracking Rails Class-TD amp does Track the output signal and but it doesnot switches the Supply Rails as in Classs-H/G but the Supply Rails actually Track the output signal and there are no Tiers in Class-TD Tracking Rails amp....Lab gruppen amp has its Rails 6 Volts above the output signal voltage...i.e. when no output signal the rails are at +-6 Volts and when output signal is at 100V the supply rails are at 106 V....
 
#198
Hi Kanwar,
Also it depends upon the designer how HE/SHE would manages to get the circuit work in a reliable manner.....
Click to expand...
That's possible. I know Carver uses 50A bipolars in the PM 2.0T switching at 2 KHz with no problems. I can't see why they need to control switching time with the MJ15024 / MJ15025 they normally use for commutating transistors. They are fast enough. I think the time constant for switching rails were chosen for different reasons entirely.

Now, for high speed switching Carver does go to mosfets (down convertors).

-Chris
 
#199
so the fig.3 is when the voltage lifter work in switching mode.
when the voltage overcomes the threshold the lift switch on
+/-Vss supply. I do this mode call H-class.

and in fig.4 is when the voltage lifter work in class C.
when the voltage overcomes the threshold the ago a linear
regulation from Vs up to Vss. I do this mode call G-class.

on many sites it seems to say the contrary one.. :yes:
see also http://www.qscaudio.com/support/library/papers/amptalk.pdf


bye 🙂
 

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#200
Souncraftsmen class H appears to be tracking the signal and the text says it increases the B+ voltage proportionally until it hits the maximum of the second supply...

http://www.hifi-museum.com/images/pa/sc_test1_p5.jpg

Workhorse said:
Yes there definitions are very well correct....As all Class-H, Class-G, amps Tracks the output signal and switches the Rails accordingly, whereas Tracking Rails Class-TD amp does Track the output signal and but it doesnot switches the Supply Rails as in Classs-H/G but the Supply Rails actually Track the output signal and there are no Tiers in Class-TD Tracking Rails amp....Lab gruppen amp has its Rails 6 Volts above the output signal voltage...i.e. when no output signal the rails are at +-6 Volts and when output signal is at 100V the supply rails are at 106 V....
Click to expand...
 
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